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Luis Miguel Goitizolo

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6/11/2018 10:28:33 AM
Cloud Lightning

Unusual outburst of red sprites during storm over Europe, and cosmic ray mapping expands

Red Sprites
© Martin Popek
Red Sprites June 8, 2018 @ Nýdek, Czech republic

Sprite lightning
storm over Europe

This weekend, a powerful mesoscale convective system (MSC) of thunderstorms over central Europe produced a furious outburst of sprites. "It was unreal," says Martin Popek of Nýdek, Czechia, a veteran photographer of the upward directed bolts. "I recorded more than 250 sprites in only 4.5 hours of observation! That's nearly as many as I typically see in the entire summer thunderstorm season."

This is a jellyfish sprite--so called because it resembles the eponymous sea creature. Jellyfish sprites are typically very large, stretching as much as 50 km between the tops of their heads to the tips of their tentacles below. "Regular jellyfish sprites are associated with very strong positive cloud-to-ground lightning strokes in the underlying convective storms," notes lightning scientist Oscar van der Velde of the Technical University of Catalonia, Spain.

However, not all of the jellyfish were regular. Some were "decapitated"--without heads. "I recorded about 20 sets of tentacles only," says Popek.

Here is one example of many:

red sprite decapitated
© Martin Popek
red sprites europe
© Martin Popek
Red Sprites June 8, 2018 @ Nýdek, Czech republic
"In my experience, this is quite rare," he adds.

"It is rare," agrees van der Velde. "We don't know why they sometimes look like this." He speculates that atmospheric waves called "gravity waves" sometimes interfere with the normal formation of jellyfish, leaving them headless. "Mesospheric gravity waves likely help focus the electric field to trigger downward streamers," he says. "But note that sprite morphology is not fully understood--not even for regular jellyfish. We have a lot to learn."

Comment: Red sprites were only officially recognised in 1989.

Another observer in the Czech Republic, Daniel Ščerba-Elza, also photographed the display. "It was extremely active," says Ščerba-Elza. "I recorded about 69 sprites, much more than usual. The storms were about 250 - 300 km away in Austria and Hungary. This is a good distance because it allows you to see over the tops of the thunderheads." He made a summary video of the outburst.

Such an outburst before summer even begins may be a good omen for sprite photographers as thunderstorm season gains steam. Stay tuned for more sightings.

Global cosmic radiation measurements

For the past two years, and the students of Earth to Sky Calculus have been traveling around the world, launching cosmic ray balloons to map our planet's radiation environment. Our sensors travel from ground level to the stratosphere and bring their data back to Earth by parachute. Here is a plot showing radiation vs. altitude in Norway, Chile, Mexico, and selected locations in the USA:

cosmic radiation world
Note: Data from Sweden and several other US states are omitted for the clarity of the plot.

We're about to add a new country to the list: New Zealand. On June 18th, a team of students from Earth to Sky is traveling to New Zealand's north island to launch 3 cosmic ray balloons in only 10 days. Soon, we will know more about cosmic rays above Earth's 8th continent.

Cosmic rays are, essentially, the subatomic debris of dying stars, accelerated to nearly light speed by supernova explosions. They travel across space and approach Earth from all directions, peppering our planet 24/7. When cosmic rays crash into Earth's atmosphere, they produce a spray of secondary particles and photons that is most intense at the entrance to the stratosphere. This secondary spray is what we measure.
cosmic radiation visualization
The purpose of our mapping project is to study how well Earth's atmosphere and magnetic field protects us from cosmic rays. As the plot shows, the shielding is uneven. More radiation gets through to the poles (e.g., Norway) and less radiation penetrates near the equator (e.g., Mexico).

But there's more to the story. Our launch sites in Chile and California are equidistant from the equator, yet their radiation profiles are sharply different. Chile is on the verge of the South Atlantic Anomaly, which almost surely distorts the radiation field there. Our flights over New Zealand may shed some light on this, because our launch sites in New Zealand will be the same distance from the equator as the sites in Chile. Stay tuned!

Technical note: The radiation sensors onboard our helium balloons detect X-rays and gamma-rays in the energy range 10 keV to 20 MeV. These energies span the range of medical X-ray machines and airport security scanners.

Cosmic rays in the atmosphere

Readers, thank you for your patience while we continue to develop this new section of We've been working to streamline our data reduction, allowing us to post results from balloon flights much more rapidly, and we have developed a new data product, shown here:
cosmic radiation plot
This plot displays radiation measurements not only in the stratosphere, but also at aviation altitudes. Dose rates are expessed as multiples of sea level. For instance, we see that boarding a plane that flies at 25,000 feet exposes passengers to dose rates ~10x higher than sea level. At 40,000 feet, the multiplier is closer to 50x. These measurements are made by our usual cosmic ray payload as it passes through aviation altitudes en route to the stratosphere over California.

What is this all about?

Approximately once a week, and the students of Earth to Sky Calculus fly space weather balloons to the stratosphere over California. These balloons are equipped with radiation sensors that detect cosmic rays, a surprisingly "down to Earth" form of space weather. Cosmic rays can seed clouds, trigger lightning, and penetrate commercial airplanes. Furthermore, there are studies ( #1, #2, #3, #4) linking cosmic rays with cardiac arrhythmias and sudden cardiac death in the general population.Our latest measurements show that cosmic rays are intensifying, with an increase of more than 13% since 2015:
cosmic radiation increase
Why are cosmic rays intensifying? The main reason is the sun. Solar storm clouds such as coronal mass ejections (CMEs) sweep aside cosmic rays when they pass by Earth. During Solar Maximum, CMEs are abundant and cosmic rays are held at bay. Now, however, the solar cycle is swinging toward Solar Minimum, allowing cosmic rays to return. Another reason could be the weakening of Earth's magnetic field, which helps protect us from deep-space radiation.

The radiation sensors onboard our helium balloons detect X-rays and gamma-rays in the energy range 10 keV to 20 MeV. These energies span the range of medical X-ray machines and airport security scanners.

The data points in the graph above correspond to the peak of the Reneger-Pfotzer maximum, which lies about 67,000 feet above central California. When cosmic rays crash into Earth's atmosphere, they produce a spray of secondary particles that is most intense at the entrance to the stratosphere. Physicists Eric Reneger and Georg Pfotzer discovered the maximum using balloons in the 1930s and it is what we are measuring today.

"Choose a job you love and you will not have to work a day in your life" (Confucius)

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Luis Miguel Goitizolo

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6/11/2018 4:44:16 PM

Katherine Frey / The Washington Post via Getty Images

A 1,000-year flood in Maryland shows the big problem with so much asphalt

The rain started to fall in Ellicott City, Maryland on the afternoon of May 27. Nearby tributaries of the Patapsco River were already dangerously swollen from last month’s steady precipitation. The storm intensified, and floodwaters soon tore through Ellicott City’s main street, submerging the first floors of buildings, sweeping away cars, and killing at least one person.

The storm was a so-called “1,000 year flood,” meaning it had a 0.1 percent chance of occurring this year. But this “exceptionally rare” event is deja vu for residents — they’re still picking up the pieces from a similar flood that destroyed the area back in July 2016.

After that big flood, Robin Holliday spent months rebuilding her business, HorseSpirit Arts Gallery. She didn’t expect a flood like that to happen again, but she also didn’t think the proposed watershed management plan was strong enough. Discouraged, she started to think about leaving. The recent flood solidified her decision.

So what’s behind the propensity for floods in Ellicott City? Part of the problem is its vulnerable location: the town lies at the foot of a hill where river branches meet the Patapsco River. And, of course, climate change makes storms wetter and increases the frequency of severe, record-breaking weather. But there’s another thing people are pointing out: concrete.

When hard, impermeable concrete replaces absorbent green spaces, it’s much easier for floodwaters to overwhelm stormwater drainage. “That’s what happened in Ellicott City,” says Marccus Hendricks, an assistant professor at the University of Maryland School of Architecture, Planning, and Preservation.

Ricky Carioti / The Washington Post via Getty Images

In Ellicott City, development has flourished.

“Nearly one-third of the Tiber-Hudson sub-watershed that feeds into historic Ellicott City is now covered by roads, rooftops, sidewalks and other hard surfaces that don’t absorb water,” the Baltimore Sun wrote in 2016.

In a press release, the Sierra Club’s Maryland Chapter called for a stop to development in the Tiber-Hudson watershed: “We may not have control over severe weather events (except by fighting climate change), [but] we can take ownership over the role that development played in this disaster.”

At a recent press conference, a local county official said that Howard County, home to Ellicott City, has been taking steps to prepare for more floods.

“We’re focusing on making sure that what has been approved is being done by the code and by law, making sure that stormwater regulations are being abided by,” said Allan Kittleman, the Howard County executive. Since the flood in 2016, he said the county has designed and engineered more stormwater retention facilities, but larger projects will take time.

This is far from the first time that development and asphalt have had a violent run-in with climate change. Last summer, Hurricane Harvey drenched sprawling Houston with trillions of gallons of water and caused $125 billion in damage. The area saw a 25 percent increase in paved surfaces between 1996 and 2011, according to Texas A&M professor Samuel Brody. Brody found that every square meter of Houston’s pavement cost about $4,000 more in flood damage.

And, rapidly developing or not, our cities are full of these paved surfaces. In the majority of the country, surfaces like pavement or brick make up just 1 percent of the land. Yet in cities, hardscapes account for upwards of 40 percent of land area.

Environmental change coupled with development will likely make this issue one of major national importance, Brody tells Grist.

“Every week, there’s some urbanized area that floods. We look up and say, ‘Oh that’s never happened before and it’s never going to happen again.’ But if you look at the big picture, it’s happening all the time with increasing severity.”


"Choose a job you love and you will not have to work a day in your life" (Confucius)

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Luis Miguel Goitizolo

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6/12/2018 10:50:25 AM

A Yellow Alert Has Just Been Issued For 2 Major Volcanoes In North America

Massive eruptions of Hawaii’s Kilauea volcano and Guatemala’s Fuego volcano have captivated the entire world in recent days, and now it looks like even more volcanoes are starting to wake up. In fact, yellow alerts were just issued for Mexico’s Mt. Popocatepetl and Alaska’s Great Sitkin volcano. Mt. Popocatepetl and Great Sitkin both sit along the “Ring of Fire” that roughly encircles the perimeter of the Pacific Ocean, and many are becoming concerned that we may be witnessing some sort of “chain reaction” as volcanoes all over the globe begin to exhibit signs of increased activity. This even includes some unusual happenings at Yellowstone, and we will cover that near the end of this article. But to start with, let’s take a look at the yellow alert that was just issued for Mt. Popocatepetl. The following comes from a government website in Mexico

In the last 24 hours, through the monitoring systems at Popocatépetl volcano, were registered 30 exhalations with emissions of steam and gas (image 1). At night was possible to observed incandescence that increase with some exhalations(image 2).

At the time of this report the emission are dispersed to the south-southwest direction (image 3).

CENAPRED emphasizes that people SHOULD NOT go near the volcano, especially near the crater, due to the hazard caused by ballistic fragments (image 4) and in case of heavy rains leave the bottoms of ravines by the danger of landslides and debris flows.

The Volcanic Traffic Light Yellow Phase 2.

The scenarios foreseen for this phase are:

1. Explosive activity of low to intermediate level.

2. Ash fall in nearby towns.

3. Possibility of short range pyroclastic flows and mudflows.

Any signs of activity at Mt. Popocatepetl should always be taken very, very seriously.

It is known as the most dangerous volcano in North America for a reason. Experts tell us that centuries ago this volcano actually “covered entire Aztec cities” with super-heated mud…

Historians tell us that Popocatepetl had a dramatic impact on the ancient Aztecs. Giant mud flows produced by massive eruptions covered entire Aztec cities. In fact, some of these mud flows were so large that they buried entire pyramids in super-heated mud.

But we haven’t witnessed anything like that in any of our lifetimes, so it is hard to even imagine devastation of that magnitude.

In addition to Mexico City’s mammoth population, there are millions of others that live in the surrounding region. Overall, there are about 25 million people that live in the immediate vicinity of Popocatepetl. Thankfully, we haven’t seen a major eruption of the volcano in modern times, but at some point that will change.

In a worst case scenario, Mt. Popocatepetl could absolutely devastate Mexico City, kill countless numbers of people and collapse the Mexican economy overnight.

So let us pray that we don’t see a major eruption there any time soon.

Meanwhile, a yellow alert has also been issued for Alaska’s Great Sitkin volcano. The following comes from the Alaska Volcano Observatory

AVO/USGS Volcanic Activity Notice

Volcano: Great Sitkin (VNUM #311120)

Current Volcano Alert Level: ADVISORY
Previous Volcano Alert Level: NORMAL

Current Aviation Color Code: YELLOW
Previous Aviation Color Code: GREEN

Issued: Sunday, June 10, 2018, 1:26 PM AKDT
Source: Alaska Volcano Observatory
Notice Number:
Location: N 52 deg 4 min W 176 deg 6 min
Elevation: 5709 ft (1740 m)
Area: Aleutians

Volcanic Activity Summary: Earthquake activity at Great Sitkin Volcano has been elevated over the past five days, and earlier today at 11:39 AKDT (19:39 UTC), a signal that may represent a short-lived steam explosion was detected by seismic data. AVO is thus raising the Aviation Color Code and Alert Level to YELLOW/ADVISORY.

Great Sitkin Volcano is monitored by a five-station seismic network on Great Sitkin Island and with additional seismic stations on the nearby islands of Igitkin, Adak, Kagalaska, and Kanaga. A six-element infrasound array to detect explosions (atmospheric pressure waves) was installed on Adak Island in June, 2017, although it is currently (June 2018) only partly operational. AVO also uses satellite imagery to monitor Great Sitkin Volcano.

Recent Observations:
[Volcanic cloud height] not applicable
[Other volcanic cloud information] Unknown

Remarks: Great Sitkin Volcano is a basaltic andesite volcano that occupies most of the northern half of Great Sitkin Island, a member of the Andreanof Islands group in the central Aleutian Islands. It is located 43 km (26 miles) east of the community of Adak. Great Sitkin erupted at least three times in the 20th century, most recently in 1974. That eruption produced at least one ash cloud that likely exceeded an altitude of 25,000 ft above sea level. A poorly documented eruption occurred in 1945, also producing a lava dome that was partially destroyed in the 1974 eruption. A seismic swarm occurred from July 2016 through the end of 2017.

Unlike Mt. Popocatepetl, Great Sitkin is located very far away from any large population centers, and so even a full-blown eruption of that volcano would not be that catastrophic.

Of course the same cannot be said about Yellowstone. As I have written aboutmany times, a full-blown eruption at Yellowstone could potentially change all of our lives in a single moment. That is why the unusual activity that is happening there right now is such a concern

Yellowstone’s Steamboat Geyser, the largest in the world, has now erupted eight times in less than three months, in a geological puzzle that has fascinated scientists working at the site.

The most recent Steamboat eruption occurred Monday just after 9 a.m. “It was unbelievable,” Jamie Farrell, a geologist at the University of Utah who happened to be at the geyser during the eruption, told Newsweek. He’s seen plenty of other geysers go off—but not Steamboat, which is capable of the largest eruptions of all currently active geysers.

Eruptions of Steamboat do not happen that often. As Mac Slavo has noted, the last one was in September 2014…

Until this recent series of eruptions, the last time Steamboat blew was in September 2014. Steamboat’s latest eruption was Monday morning when the geyser shot boiling hot water hundreds of feet into the air. Steam billowed from the geyser for hours longer. Steamboat is located in the Norris Geyser Basin, known to have the hottest and most changeable thermal area in nearly 3,500-square-mile wilderness park that sits on a volcanic hot spot called a caldera. That accounts for the geyser’s towering columns of steam (it’s very, very hot underground) but leaves a major fear-provoking question unanswered: Why now, and is it a sign the giant volcano is waking up?

We better hope that Yellowstone is not awakening. In a previous article, I described what a full-blown eruption of Yellowstone might look like…

Hundreds of cubic miles of ash, rock and lava would be blasted into the atmosphere, and this would likely plunge much of the northern hemisphere into several days of complete darkness. Virtually everything within 100 miles of Yellowstone would be immediately killed, but a much more cruel fate would befall those that live in major cities outside of the immediate blast zone such as Salt Lake City and Denver.

Hot volcanic ash, rock and dust would rain down on those cities literally for weeks. In the end, it would be extremely difficult for anyone living in those communities to survive. In fact, it has been estimated that 90 percent of all people living within 600 miles of Yellowstone would be killed.

Experts project that such an eruption would dump a layer of volcanic ash that is at least 10 feet deep up to 1,000 miles away, and approximately two-thirds of the United States would suddenly become uninhabitable. The volcanic ash would severely contaminate most of our water supplies, and growing food in the middle of the country would become next to impossible.

In other words, it would be the end of our country as we know it today.

Throughout human history, great societies have been taken down by natural disasters, and despite all of our advanced technology we are extremely vulnerable as well.

So the fact that our planet is becoming increasingly unstable is a major concern, and I believe that this is going to have major implications for our future.

Michael Snyder is a nationally syndicated writer, media personality and political activist. He is the author of four books including The Beginning Of The End andLiving A Life That Really Matters.


"Choose a job you love and you will not have to work a day in your life" (Confucius)

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Luis Miguel Goitizolo

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6/12/2018 5:26:46 PM

Here’s what war with North Korea would look like

A full-blown war with North Korea wouldn’t be as bad as you think. It would be much, much worse.

Late last September, I moderated a discussion about North Korea with retired Navy Adm. James Stavridis, whose 37-year military career included a stint running NATO, and Michèle Flournoy, the No. 3 official at the Pentagon during the Obama administration, who has helped shape US policy toward North Korea since 1993.

It was a chilling conversation. Stavridis said there was at least a 10 percent chance of a nuclear war between the US and North Korea, and a 20 to 30 percent chance of a conventional conflict that could kill a million people or more. Flournoy said President Trump’s tough talk about North Korea — which has included deriding Kim Jong Un as “Little Rocket Man” and threatening to rain “fire and fury” down on his country — made it “much more likely now that one side or the other will misread what was intended as a show of commitment or a show of force.”

The Trump administration, for its part, seems more confident in its ability to manage North Korea with precision. National Security Adviser H.R. McMaster is pushing something known inside the White House as a “bloody nose” strategy of responding to a North Korean provocation with a set of limited US military strikes. McMaster seems to believe that Kim would passively absorb the attack without hitting back and risking all-out war.

I covered the Iraq War from Baghdad. I saw the aftermath of a conflict built atop sunny scenarios and rosy thinking. I’ve seen the cost of wars that the American people were not prepared for and did not fully understand. The rhetoric around North Korea is raising those same alarm bells for me. For all the talk of nuclear exchanges and giant buttons, there has been little realistic discussion of what a war on the Korean Peninsula might mean, how it could escalate, what commitments would be required, and what sacrifices would be demanded.

So I’ve spent the past month posing those questions to more than a dozen former Pentagon officials, CIA analysts, US military officers, and think tank experts, as well as to a retired South Korean general who spent his entire professional life preparing to fight the North. They’ve all said variants of the same thing: There is a genuine risk of a war on the Korean Peninsula that would involve the use of chemical, biological, and nuclear weapons. Several estimated that millions — plural — would die.

Even more frightening, most of the people I spoke to said they believed Kim would use nuclear weapons against South Korea in the initial stages of the fighting — not just as a desperate last resort.

Danush Parvaneh/Vox; AP Images

“This would be nothing like Iraq,” Flournoy told me. “It’s not that the North Korean military is so good. It’s that North Korea has nuclear weapons and other weapons of mass destruction — and is now in a situation where they might have real incentives to use them.”

The experts I spoke to all stressed that Kim could devastate Seoul without even needing to use his weapons of mass destruction. The North Korean military has an enormous number of rocket launchers and artillery pieces within range of Seoul. The nonpartisan Congressional Research Service estimates that Kim could hammer the South Korean capital with an astonishing 10,000 rockets per minute — and that such a barrage could kill more than 300,000 South Koreans in the opening days of the conflict. That’s all without using a single nuclear, chemical, or biological weapon.

And retired South Korean Gen. In-Bum Chun, who spent 40 years in uniform thinking about a confrontation with North Korea, underscored that Kim also has a different kind of weapon: 25 million people — including 1.2 million active-duty troops and several million reservists — who have been “indoctrinated since childhood with the belief that Kim and his family are literal gods whose government must be protected at all costs.”

“You’re talking about people who have basically been brainwashed their entire lives,” Chun said. “It would be like what you saw on Okinawa during World War II, where Japanese civilians and soldiers were all willing to fight to the death. This would be a hard and bloody war.”

What follows is a guide to what a conflict with North Korea might look like. War is inherently unpredictable: It’s possible Kim would use every type of weapon of mass destruction he possesses, and it’s possible he wouldn’t use any of them.

But many leading experts fear the worst. And if all of this sounds frightening, it should. A new war on the Korean Peninsula wouldn’t be as bad as you think. It would be much, much worse.

Destroying Kim’s nuclear arsenal would require a ground invasion and facing Kim’s chemical and biological weapons

The official position of the Trump administration, like that of its predecessors, is that North Korea’s nuclear program is unacceptable and that Pyongyang has to give up all its nuclear weapons. If the US and South Korea went to war with the North, their key strategic goal would be to capture or destroy all of Pyongyang’s nuclear sites, as well as the bases that house its long-range missiles.

In a startlingly blunt letter to Rep. Ted Lieu (D-CA) last October, Rear Adm. Michael Dumont, speaking on behalf of the Joint Chiefs of Staff, said the “only way to ‘locate and destroy — with complete certainty — all components of North Korea’s nuclear weapons programs’ is through a ground invasion.”

Danush Parvaneh/Vox; AP Images

Estimates of the exact numbers of US troops that would take part in a push north vary widely, but current and former military planners uniformly believe it would require vastly more forces than took part in the invasions of Iraq or Afghanistan.

A South Korean military white paper from 2016, for instance, said the US would need to deploy 690,000 ground troops to South Korea if war broke out. Bruce Bennett, a senior researcher at the RAND Corporation who has spent decades studying North Korea generally and the Kim family specifically, believes those numbers are on the high side, but he thinks the US would need to send at least 200,000 troops into North Korea. By way of comparison, that would be significantly more troops than the US had in either Iraq or Afghanistan at the peaks of those two long wars.

The 2016 assessment says the Pentagon would also need to send 2,000 warplanes and other aircraft to South Korea. The US hasn’t had that much airpower deployed to a single conflict since Vietnam.

The experts I spoke to believe Kim and his generals know that US ground forces are better trained and equipped than North Korean troops, and that North Korea’s aging fleet of 1,300 Soviet-era warplanes is no match for Washington’s state-of-the-art stealth fighters and other jets. So what would happen if US and South Korean troops started pouring into North Korea while American planes launched wave after wave of airstrikes?

The consensus view is that Kim would try to level the playing field by using his vast arsenal of chemical weapons, which is believed to be the biggest and most technologically advanced in the world. (Kim is estimated to have between 2,500 and 5,000 metric tons of deadly nerve agents like sarin, which can cause paralysis and, ultimately, death.)

With so many artillery pieces and rocket launchers trained on Seoul, Kim has the ability to quickly blanket the densely packed city with huge amounts of nerve agents. The human toll would be staggeringly high: The military historian Reid Kirby estimated last June that a sustained sarin attack could kill up to 2.5 million people in Seoul alone, while injuring nearly 7 million more. Men, women, and children would very literally choke to death in the streets of one of the world’s wealthiest and most vibrant cities. It would be mass murder on a scale rarely seen in human history.

Kim also has large quantities of VX, an even deadlier chemical weapon, and has already shown a willingness, and ability, to use it against civilian targets abroad. Last February, two women trained by North Korean intelligence agents walked up to Kim’s estranged half-brother Kim Jong Nam, while the 45-year-old walked through an airport in Malaysia, and smeared his face with VX. Authorities there said he suffered a “very painful” death from his exposure to the nerve agent.

Retired Lt. Gen. Chip Gregson, the Pentagon’s top Asia official from 2009 to 2011, says the attack was a vivid illustration of the North Korean chemical weapons program’s technological sophistication — and of what may face US and South Korean troops if war were to break out.

“VX is the worst of the worst,” Gregson told me. “It’s a crowd killer. It’s odorless, colorless, and doesn’t dissipate quickly. The fact that they were able to use it so precisely — to kill only one person and not even injure the two handlers — indicates a high degree of technical skill and a clear willingness to use a weapon of mass destruction against civilian targets. That needs to be factored into the equation when we think about what Kim would do to preempt an attack or retaliate for one.”

The Pentagon already assumes that its airbases in and around South Korea would be among the first places Kim tried to hit with chemical weapons like sarin. US military officials don’t think North Korea would necessarily succeed in killing many of the pilots and other troops stationed there, all of whom are equipped with gas masks and other protective gear. But they worry an attack could nevertheless make it significantly harder for the US to launch air raids against the North by causing panic and chaos on the bases that house the American warplanes, bombers, and troops.

Retired Air Force Lt. Gen. Jan-Marc Jouas, the former deputy commander of US forces in South Korea, said the initial phases of any offensive against North Korea depend on American and South Korean planes being able to hit Kim’s nuclear facilities, military bases, chemical and biological weapons caches, radar systems, and missile defense arrays.

The air campaign — which would dwarf the “shock and awe” of the Iraq War in size and scope — would be designed to decimate North Korea’s ground forces and destroy the thousands of artillery pieces trained on the South Korean capital before they could be used to level Seoul.

Danush Parvaneh/Vox; AP Images

Washington would also try to kill senior North Korean military commanders and government officials, including Kim. (So-called “decapitation” strikes are part of the current US and South Korean war plan for a conflict with North Korea, OPLAN 5015, which explicitly talks about targeting the country’s top leadership.)

“Air power is dependent on the number of sorties that can be flown,” Jouas told me, using the military’s term for an individual air combat mission. “And it’s a lot harder to generate sorties if your airfield is under attack.”

Jouas said Air Force personnel conduct chemical weapons drills where they practice doing their jobs in gas masks and other equipment they’d wear if the bases were under actual attack. They try to game out all the various ways North Korea could hit the facilities, and to prepare accordingly. It isn’t easy.

“We anticipate conventional attacks, we anticipate chemical attacks, we anticipate cyberattacks, and we anticipate North Korean special operations forces being inserted into the bases,” he told me. “We’d still be able to fly — and to ultimately defeat North Korea — but there would be an unquestionable impact on our operations.”

Gregson thinks Kim wouldn’t only use his chemical weapons against military targets in South Korea. The Pentagon has a sizable military presence in neighboring Japan, and the island of Guam is a US territory that is home to more than 163,000 American citizens. Both are well within range of Kim’s missiles and rockets — and Gregson expects both would be hit.

Andrew Weber, formerly the assistant secretary of defense for nuclear, chemical, and biological defense programs, told me that the US and South Korea would also need to be prepared for Kim to use biological weapons against both military and civilian targets.

North Korea’s arsenal is thought to include smallpox, yellow fever, anthrax, hemorrhagic fever, and even plague. They are some of the most frightening substances on earth, and Weber expects some of them to be used against South Korean ports, airfields, and cities as a way of killing large numbers of civilians and troops while causing terror on a nationwide scale.

“We would expect to see cocktails of fast-acting biological agents designed to stop troops in their tracks and regular infectious agents that would take more time to kill people,” he told me. “There would be a significant military impact, and a significant psychological one. It’s hard to overstate just how frightening these types of weapons are.”

In an October 2017 report, researchers from Harvard’s Belfer Center noted that minute quantities of anthrax “equivalent to a few bottles of wine” could kill up to half the population of a densely populated city like Seoul. North Korea could theoretically fire missiles with payloads of anthrax or other biological weapons into South Korea, or use drones to disperse the lethal substances from the air.

The researchers wrote that Kim could also have some of his citizens secretly bring the weapons into the South:

North Korea has 200,000 special forces; even a handful of those special forces armed with BW would be enough to devastate South Korea. What is alarming about human vectors is that they do not need sophisticated training or technology to spread BW amongst the targets, and they are difficult to detect in advance of an attack. It is theoretically possible that North Korean sleeper agents disguised as cleaning and disinfection personnel could disperse BW agents with backpack sprayers. Another possibility is that North Korean agents will introduce BW into water supplies for major metropolitan areas.

In 2011, Weber helped design a war game centered on a simulated North Korean biological weapons attack on the South. The exercise, Able Response, brought together hundreds of military and civilian officials from the US and South Korea. The goals were to figure out the best ways to detect an attack, identify what substance had been used, limit the spread of the virus, and then rush vaccines and other medical care to the infected to save as many lives as possible.

The exercises led to concrete policy changes, including closer coordination between the South Korean military and the country’s public health system. US bases in South Korea received new environmental surveillance systems designed to quickly detect the presence of a biological agent. All US troops in South Korea are vaccinated against anthrax and smallpox (South Korean troops aren’t, to the consternation of Weber and other US officials).

Still, Weber said his main takeaway was the near impossibility of preventing biological weapons from killing an astonishing number of people. The death toll in each year’s exercise was often close to a million. In some cases, it was significantly higher because the infection spread to Japan or other nearby countries.

“It only takes one or two people to deliver bioweapons, and tiny quantities of a bacteria or virus can cause a massive number of casualties,” he told me. “You wouldn’t need a missile. You’d need a backpack.”

Joe Wilson for Vox

The scary logic behind a North Korean nuclear attack

There’s a giant question that looms over any discussion of North Korea’s growing arsenal of nuclear weapons: Would Kim actually be willing to use one?

North Korea is thought to have about 50 nukes. The US, by contrast, has an astonishing 6,800 nuclear weapons (surpassed only by Russia, which has an estimated 7,000 weapons). Trump — or one of his successors — could respond to a North Korean nuclear strike by destroying every major North Korean city in a matter of hours.

Experts inside and outside the US government who study North Korea say that Kim is a rational leader with a singular focus on maintaining control of his country. They don’t think he’s stupid, or suicidal. And for a long time, they believed that Kim would only use his nuclear weapons if he were facing military defeat and the imminent collapse of his government. It would be the last gasp of a dying regime, one determined to kill as many of its enemies as possible before the end came.

Those assessments have now changed. Most of the experts I spoke to believe North Korea would use nuclear weapons at the beginning of a war — not at the end. And most of them believe Kim would be making a rational decision, not a crazy or suicidal one, if he gave the launch order.

One of the best explanations for why came from Bennett, the RAND researcher. He’s mademore than 100 trips to the Korean Peninsula and interviewed an array of North Korean defectors. He also jokes that he’s “kinda, sorta” made it into North Korea itself, including once walking through a newly discovered tunnel that North Korean troops had dug beneath the Demilitarized Zone that separates North and South Korea. He remembers that the walls were covered with graffiti praising Kim.

Bennett began his career at RAND during the height of the Cold War and believes it’s impossible to understand why Kim would go nuclear without also understanding why Soviet leaders were prepared to do so.

“In the Cold War, we specifically talked about a logic called ‘use them or lose them,’ which referred to the fact that the Soviet Union understood that the first goal of an American preemptive attack would be to knock out their nuclear weapons before they could be fired at the US,” Bennett told me. “Now think about how Kim is looking at the world. He knows that any US and South Korean strike would be designed to destroy or capture his nuclear weapons. That means he’d need to either use them early or risk losing them altogether.”

There’s another big-picture reason Kim might decide to go nuclear: a Cold War-era concept known as “decoupling.”

In the 1950s, the Soviet Union was much stronger militarily than Germany, France, or the other countries of Western Europe. The US had formally committed to protecting those nations from a Soviet invasion, and Bennett told me that American military planners were prepared to use small-scale tactical nuclear weapons against the advancing Russian troops to stop the assault.

That entire calculus began to change once the Soviet Union developed long-range nuclear missiles capable of reaching the continental US. European leaders openly wondered how far Washington would be willing to go to protect their countries from the Soviet Union given the new risks to the American homeland.

“By the time you get to the late ’50s, the French in particular are saying, ‘Wait a minute, if the US uses nuclear weapons against Soviet ground forces in Europe, the Soviets are going to fire nuclear weapons at the US. Is the US prepared to trade New York City for Paris?’” Bennett told me.

That’s why North Korea’s new generation of long-range missiles capable of hitting the mainland US is such a game changer.

The North Korean constitution says the country’s ultimate aim is the reunification of the entire Korean Peninsula under the Kim family’s control, which would be impossible to pull off with US troops already deployed to South Korea and Washington formally committed to going to war on the South’s behalf.

So if Kim actually wants to try to reunify the two Koreas, he needs to somehow break up the US-South Korea alliance. If the US were no longer willing to defend Seoul, then South Korea — which has no nuclear weapons of its own — would be a lot easier to invade and defeat. But how do you break up that alliance? How do you convince the US not to come to South Korea’s defense in case of war?

Being able to credibly threaten to destroy New York or Washington definitely helps. Kim can now force American leaders to stop and think whether it’s really worth risking a possible nuclear attack on the US mainland just to defend South Korea from a North Korean attack. North Korea has missiles capable of reaching the West Coast and is thought to have nuclear warheads that would fit on top of them. They could destroy a major nuclear city. To modify a phrase from the Cold War, would Trump be prepared to trade San Francisco for Seoul?

If Kim decides the answer is no, using a nuclear weapon against South Korea no longer seems crazy or suicidal. It starts to seem rational. And one particular South Korean city starts to seem like the likeliest target.

In July 2016, Kim test-fired three missiles as part of what a North Korean state-run news agency described as mock “pre-emptive strikes at ports and airfields in the operational theater in South Korea, where the U.S. imperialists nuclear war hardware is to be hurled” in case of a future conflict between the two sides.

That was widely seen as an implicit threat to use nuclear weapons against the South Korean port city of Busan, which would play a vital role in any Pentagon effort to build a force big enough to defend the South or to lead a preemptive strike on the North.

The US currently has around 28,500 troops stationed in South Korea and would need to deploy hundreds of thousands more if war broke out with the North. The US would also have to send in thousands of additional tanks, armored personnel carriers, bombers, fighter jets, helicopters, and artillery pieces.

The problem is that the Pentagon’s cargo planes can only ferry in a few hundred troops or a couple of tanks at a time. That means the vast bulk of the US troops and equipment would need to come by boat, a laborious process that could take six weeks or longer to complete. The American ships would unload at Busan, and the best way for Kim to destroy those ports — and significantly slow US efforts to send in enough troops to make a difference in the fight — would be to nuke the city.

Jouas, the retired Air Force general, told me that North Korea’s thinking about whether to use a nuclear weapon early in a conflict has likely changed as the country has built more of the weapons and developed missiles and rockets capable of hitting more distant targets.

“In the past, when North Korea had a limited number of nuclear weapons, the assessment was that they’d marshal them to use only as a last resort,” he told me. “Now that their inventory has grown, it’s easier to imagine them using some of the weapons at the onset of hostilities to try to shape the way the rest of the war would unfold.”

Bruce Klingner, a 20-year veteran of the CIA who spent years studying North Korea, told me that Iraqi leader Saddam Hussein had stood by in 2002 as the US methodically built up the forces it used to invade the country — and oust Hussein — the following year. He said there was little chance that Kim would follow in Hussein’s footsteps and patiently allow the Pentagon to deploy the troops and equipment it would need for a full-on war with North Korea.

“The conventional wisdom used to be that North Korea would use only nuclear weapons as part of a last gasp, twilight of the gods, pull the temple down upon themselves kind of move,” said Klingner, who now works for the conservative Heritage Foundation. “But we have to prepare for the real possibility that Kim would use nuclear weapons in the early stages of a conflict, not the latter ones.”

We also have to prepare for the fact that if the US and North Korea do actually come to blows, China will get involved — and not in the ways that either Washington or Pyongyang might expect.

The China problem

In a recent essay in Foreign Affairs, Oriana Skylar Mastro, a North Korea expert at Georgetown University, argues persuasively that the US fundamentally misunderstands China’s relationship with the Kim government. US officials have long believed that Beijing is committed to North Korea’s survival and might take steps to ensure that Kim’s regime doesn’t collapse and send millions of starving refugees flowing into China. That line of thinking, she writes, is “dangerously out of date.”

Mastro continues:

Today, China is no longer wedded to North Korea’s survival. In the event of a conflict or the regime’s collapse, Chinese forces would intervene to a degree not previously expected — not to protect Beijing’s supposed ally but to secure its own interests.

More specifically, she and several of the other experts I spoke to believe that China would quickly send hundreds of thousands of troops into North Korea to seize control of the country’s nuclear sites and prevent Kim from using the weapons. Chinese and North Korean troops wouldn’t be working together against a common enemy; they’d be trying to kill each other.

“China would have to fight its way into North Korea,” Mastro told me in an interview. “For the North Koreans, enemy No. 1 is obviously the United States, but enemy No. 2 is China. They understand they’d have to potentially fight both countries.”

Things would get really complicated, and really dangerous, once Chinese troops made their way to the nuclear facilities. The Pentagon has spent years practicing how to send US special operations forces into North Korea to seize Pyongyang’s nuclear weapons if there were signs that Kim’s government was collapsing. The problem is that Chinese troops would almost certainly be sent into North Korea at the same time, and with the same goal, as the US forces.

Mastro notes that Chinese troops would only need to advance 60 miles into North Korea to take control of all of the country’s highest-priority nuclear sites and two-thirds of its highest-priority missile sites. Given that enormous geographic advantage, Beijing’s troops would almost certainly arrive before the US ones do.

“When our special forces run into the Chinese special forces, what do we do? Are we going to shoot at each other or shake hands?” Bennett told me. “That’s an incredibly risky decision to make on the fly.”

There’s no reason to think the countries would necessarily come to blows. The US could live with the North Korean nuclear weapons ending up in China’s hands, since Beijing already has a sizable nuclear arsenal and relatively stable relationships with both Washington and many of its neighbors in the region.

But Beijing would be intervening to protect its own interests, not those of the US. A war between North and South Korea would almost certainly end with the creation of a reunified country led by the pro-US government in Seoul; China would want to make sure it wasn’t left out in the cold.

In this, and this alone, a war with North Korea would bear some similarities to the war in Iraq. When the Bush administration ousted the Saddam Hussein regime in 2003, it wasn’t prepared for what became a concerted and years-long Iranian push to ensure that Iraq’s political system was dominated by Shia political parties with close ties to Tehran. Iran has largely gotten its way: Several of Iraq’s postwar leaders have allowed Iranian militias to operate within the country, and Baghdad has noticeably chilly relationships with Saudi Arabia and Iran’s other regional rivals.

All of which is to say that China, like Iran, would be trying to stabilize postwar Korea on its own terms, not those of the US. And it would be doing so against a Trump administration that is notably hostile and fearful of China’s rising global influence.

Joe Wilson for Vox

Trump and Kim have the ability to start a nuclear war. Will they walk back from the brink?

So how scared should we be?

That, more than anything else, is the question that’s been on my mind for the weeks I’ve spent reporting this story. The good news is that the experts I spoke to don’t think war is inevitable, or even probable. Most, like Jung Pak, a former North Korea analyst for the CIA, believe that Kim is a rational leader who has been careful during his years in power to walk right up to the edge without going over it.

“People say he’s young and untested, but he’s not that young anymore and he’s not that untested anymore,” she said, noting that Kim has led his country since 2011 and has managed to massively expand his nuclear arsenal without triggering a war with the US or South Korea. “He’s a brutal dictator that is aggressive and vindictive and prone to violence, but he’s a rational leader making fundamentally rational choices. He knows how to dial things up, but he also knows how to recalibrate and dial them back down.”

Danush Parvaneh/Vox; AP Images

Pak and others note there have been some recent, fragile signs of diplomatic progress. North and South Korea just announced plans for their athletes to train together in advance of the Winter Olympics and enter the opening ceremonies as one team, under the flag of a reunified Korea. The North and South Korean governments are holding ongoing talks, and South Korea and the US agreed to postpone new military exercises until after the Olympics, a move widely seen as a goodwill gesture to North Korea. Trump is for the moment saying he’scommitted to diplomacy and believes he would “probably have a very good relationship with Kim Jong Un.”

But here’s the bad news, and the reason hours of conversations with some of the people who know North Korea best have left me feeling profoundly unsettled: It’s easy to imagine a misunderstanding or accidental run-in between the two skittish countries leading to a full-blown war.

“I have queasy feeling that we’re in 1914 stumbling towards Sarajevo,” Sen. Angus King (I-ME)said during a Senate Armed Services Committee hearing last September, a reference to the assassination of an Austrian archduke that triggered the devastation of World War I. “And what worries me is not an instantaneous nuclear confrontation, but an accidental escalation based upon the rhetoric that’s going back and forth.”

King continued:

That’s what worries me, is a misinterpretation, a misunderstanding, an event: a shooting down of a bomber, a strike on a ship that leads to a countermeasure, that leads to a countermeasure, and the end result is that if Kim Jong Un feels his regime is under attack, then the unthinkable happens.

He then asked Joint Chiefs of Staff Chairman Gen. Joseph Dunford, who was testifying at the session, if the US and North Korea had any direct lines of communication that could be used to defuse a tense situation before it spirals out of control.

“We do not,” Dunford replied.

And that’s the most dangerous aspect of the current standoff, and the issue that could most easily lead to a conflict whose potential human costs are so high — millions dead, millions more wounded, major cities lying in ruins — as to be almost unimaginable.

The US is led by a hotheaded president who lacks military experience, is prone to unpredictable flashes of rage and fury, talks openly of destroying another sovereign country, and has alarmed advisers with his ignorance about America’s massive number of nuclear weapons and seemingly blasé attitude toward their use. (Secretary of State Rex Tillerson’s comment that Trump was a “****ing moron” came after the president told his top advisers that he wanted a tenfold increase in the size of the US nuclear arsenal.)

North Korea is led by Kim, a man who rarely leaves his own country, has executed scores of relatives and high-ranking officials, literally starves his own people to free up money for his country’s nuclear program, and regularly uses apocalyptic language to describe what he sees as a coming war with the US and South Korea.

Maybe next week Kim will test-fire a missile that flies too close to Guam or Hawaii and Trump will decide enough is enough. Or maybe a US ship will accidentally drift into North Korean waters and Kim’s navy will open fire. With no lines of communication, a simple mistake could set off a cascading series of responses that ultimately lead to all-out war. In a situation this combustible, there are an enormous number of moves — some intentional, some accidental — that could light the match.

Danush Parvaneh/Vox; AP Images

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Solar cycle 24 minimum will continue a 'long decline' in solar activity

solar cycle activity length graph

Solar cycle activity versus cycle length. The activity is the sum of the monthly sunspots for the entire cycle. SC24 (in red) is still provisional, and the dashed arrow indicates a possible path it might follow until the solar minimum takes place. The Dalton Minimum (purple), Gleissberg Minimum (blue), and Modern Maximum (orange) cycles are indicated. The Modern Maximum is a period of seven consecutive high activity solar cycles in a period that coincides with high anthropogenic CO2 emissions and global warming (1935-2005). The longest such stretch of high solar activity known.
Solar cycle 24 is ending and we are approaching a time of minimal solar activity between solar cycles 24 and 25, known as a solar minimum. Despite claims that we understand how the Sun works, our solar predictive skills are still wanting, and the Sun continues to be full of surprises.

The surprising 2008 solar minimum

Solar scientists did not pay much attention to the early warning signs that the Sun was behaving differently during solar cycle 23 (SC23), and to most the surprise came when the expected solar minimum failed to show up in 2006. The SC23-24 minimum took place two years later (Dec 2008, according to SIDC), and despite showing only a tiny difference in total solar irradiation compared to previous minima of the space age, it displayed significantly reduced solar wind speed and density, extreme-UV flux was 10% reduced, the polar fields were 50% smaller, and the interplanetary magnetic field strength was 30% below past minima. In response to the changes in the Sun, the density of the Earth thermosphere dropped 20% lower than in previous minima. In 2007 Svalgaard & Cliverproposed a floor to the interplanetary magnetic field at 1 AU in the ecliptic plane of 4.6 nT based upon 130 years of data. This floor has implications for the solar wind during grand minima. After the solar minimum, in 2011, Cliver & Lingwere forced to revise down the floor to 2.8 nT, a 40 percent reduction! The SC23-24 minimum was truly shocking to solar scientists, showing them how little they knew of what happens to the Sun when it becomes very inactive. And it was just a centennial-type solar minimum, not a grand-type solar minimum.

We are now approaching the SC24-25 solar minimum, and again the Sun's behavior surprises us. Or doesn't it? On April 26, NOAA informed us that "current solar cycle 24 is declining more quickly than forecast."

The rapid decline in solar activity plus the appearance of the first SC25 spots suggest that SC24 could be both a low-activity and short solar cycle. This would not be unusual since cycle length and cycle activity do not correlate significantly (figure 1).

solar cycle activity length graph

Solar cycle activity versus cycle length. The activity is the sum of the monthly sunspots for the entire cycle. SC24 (in red) is still provisional, and the dashed arrow indicates a possible path it might follow until the solar minimum takes place. The Dalton Minimum (purple), Gleissberg Minimum (blue), and Modern Maximum (orange) cycles are indicated. The Modern Maximum is a period of seven consecutive high activity solar cycles in a period that coincides with high anthropogenic CO2 emissions and global warming (1935-2005). The longest such stretch of high solar activity known.
We have read at WUWT both that the solar minimum may have already happened, or that it might take place in 2026. None of these opinions appear to be based on much fact, so we should examine the question in more detail.

Defining a solar minimum

While intuitively we all understand that a solar minimum is the period of time that shows the least amount of solar activity between two cycles, how the solar minimum is defined can make a difference of months in the date of the minimum. Harvey & Whitereviewed in 1999 the different methods used to define a solar minimum:
"In addition to the time of a minimum in the smoothed sunspot number, historically the basis for the determination of the time of cycle minimum since 1889 includes the time of the minimum or minima in the monthly averaged sunspot number, the number of spotless days, the start and end times of the minimum phase, the number of regions belonging to the outgoing (old) and incoming (new) cycles, and the use of different smoothing windows."
Some of them are shown in table 1 from Harvey & White 1999.
sunspot solar cycle
© Source: Harvey & White 1999
Table 1. Illustration of the problems of defining the solar minimum. Column 2 shows the date given by prominent researchers. Columns 3-7 give the date of the minimum activity as calculated by different methods.
According to Harvey & White 1999, the SC22-23 minimum should be placed, based on an average of five parameters, on Sep. 1996. The Solar Influences Data Center (SIDC), responsible for the World Data Center for Sunspot Index and Long-term Solar Observations (WDC-SILSO) at the Royal Observatory of Belgium (Brussels), uses the following 13-month smoothing formula:

Rs= (0.5 Rm±6 + Rm±5 + Rm±4 + Rm±3 + Rm±2 + Rm±1 + Rm) / 12 .......[1]

Where Rs is the smoothed sunspot number and Rm the monthly sunspot number for the central month. The end months in the average are given half weight.

This formula produces Aug. 1996 for the SC22-23 minimum so, despite being very simple, the result is generally quite close to more complex calculations.

This formula requires that at least 7 months have passed since the minimum and produces a 6-month delay in the calculation of monthly solar activity. For this article, I wanted to reduce this delay without compromising accuracy too much, so I have used the following 9-month smoothing formula with a more skewed weighting:

Rs= (Rm±4 + 3 Rm±3 + 5 Rm±2 + 7 Rm±1 + 10 Rm) / 42 .......[2]

Figure 2 shows the result of smoothing [2] compared to SIDC smoothing [1].
SIDC smoothing solar cycle

Figure 2. Sunspot smoothing used in this article [2] (grey line) compared to the SIDC smoothing [1] (black line).
Have we reached already the SC24-25 minimum?

The answer is almost certainly not. We can base this answer on two kinds of data. The first is the number of spotless days. Astronomers have been counting the number of spotless days since 1818, and this number in the current minimum, as of first of June is 198 (Figure 3). As the solar minimum usually takes place after at least half of the spotless days in a minimum have taken place (the rising phase of the cycle is usually faster than the declining phase), that would imply that this minimum should have less than 400 spotless days if it ended now. Such a low number has only taken place in minima between very active solar cycles during the Modern Maximum in solar activity (1935-2005). Given that SC24 has been a low-activity cycle we should expect 200-300 spotless days more before the minimum is reached, and that is about a year of very low solar activity.

number of days per solar minimum
Figure 3. Number of spotless days per cycle minimum transition (red) and the yearly international sunspot number (Sn, inverted, green) since 1818. Note that, in general, a low amplitude cycle is preceded by a solar cycle transition with a high number of spotless days, and vice versa. The blue dot to the lower right represents the number of spotless days (198) for the current cycle transition.
The second kind of data are the number of SC25 sunspot groups. SC25 sunspots have been appearing since December 2016, but the solar minimum is usually located at the time when the numbers of SC24 and SC25 sunspot groups are even, or slightly later. As it can be seen in figure 4, we aren't there yet.
solar cycle minimum
© Solar-Terrestrial Centre of Excellence.
Figure 4. Monthly number of sunspot groups (having received a NOAA number) from SC24 (black) and from SC25 (white) since 2016. The red curve represents the smoothed monthly international sunspot number.
When is it most likely that the SC24-25 minimum will occur?

Most of the analyses I have seen have one problem. They only look at a subset of solar cycles, and the space-age records are biased by the high activity of the Modern Maximum. I have been inspired particularly by Belgian astronomer Jan Janssens'SC24 tracking webpage. Using the smoothing filter [2], and following Janssens, I have defined the starting point of the analysis of each minimum as the last month that showed ≥ 30 monthly smoothed sunspots before the minimum. In figure 5 I have represented the number of months it took for each transition from that starting point to reach its solar minimum (lowest smoothed monthly sunspot number or central month when several consecutive zero values).

solar cycle minimum

Distribution of solar cycles by the time it takes them to go from ≥ 30 monthly smoothed sunspots to their solar minimum. The distribution shows a clear difference between cycles with less than 14 months and cycles with more than 19 months.
The distribution is clearly bimodal. 13 transitions took between 8 and 14 months to reach the solar minimum from ≥ 30 smoothed sunspots (short or fast solar minima), while 11 transitions took between 19 and 44 months (long solar minima). For the SC24-25 transition the value of 30 smoothed monthly sunspots was reached in October 2016, 20 months ago as of this writing. For graphical convenience I have divided the long solar minima in two groups. The medium solar minima (19-32 months), and the slow solar minima (38-44 months).

solar cycle minimum

Comparison of the present solar minimum (in red) to the group with fast (short) solar minima.
The present solar minimum does not belong to the group characterized by short solar minima. The sunspot number is falling too abruptly, and the solar minimum should have been hit by December 2017 to belong to the group. As of June (corresponding to January 2018 smoothed data) the smoothed sunspot number is still decreasing and given the evolution it will decrease again next month.

solar cycle minimum

Comparison of the present solar minimum (in red) to the group with medium speed solar minima.
The present solar minimum could belong to the medium group. This group includes solar cycle minima from the Dalton and Gleissberg extended minima, but also the unusual 1986 SC21-22 minimum. If SC24-25 belongs to this group the minimum should take place between May 2018 and September 2019. For that to happen the decrease in sunspots should slow down soon, since the chance that its smoothed value hits zero or near-zero is quite low, as only one of the seven (SC6-7) in this group did so.

solar cycle minimum

Figure 8. Comparison of the present solar minimum (in red) to the group with slow solar minima.
The present solar minimum could also belong to the slow group. As we can see fast declines in sunspots are common in the early phase of this group, but they are usually followed by a recovery of activity that can last up to a year before the decline resumes. The last SC23-24 minimum belonged to this group and they usually reach very low values or even zero as in the case of the extreme 1810 SC5-6 Dalton solar minimum. If SC24-25 belongs to this group, the minimum should take place between late 2019 and mid-2020. For that to happen the decrease in sunspots should actually revert soon and increase for several months before declining again.

Considering all solar minima since 1750, we can say that it is most likely that the SC24-25 minimum will take place between the summer of 2018 and the summer of 2020.

Reasons why it is likely that SC24-25 turns out to be a long solar minimum

The reason why a slower decay of sunspots had been predicted for SC24 is that the rising and decaying phases of past solar cycles were generally slower for low-activity cycles than for high-activity cycles, so the minima of low-activity cycles tend to last longer than average. We can see this in figure 9.

solar cycle minimum

Figure 9. Solar minima since 1750 and the sunspot record. Solar minima are represented as black boxes with their length corresponding to their time below 30 sunspots (grey horizontal line), and classified as fast, medium, or slow according to their time to the minimum as in figure 5. Arrows mark the positions of the cyclical lows of the centennial and bicentennial solar cycles.
More than half of the minima between a high-activity and a low-activity cycle are long, and every minimum between two low-activity cycles is long. Since SC24 is a low-activity cycle, and SC25 is expected to be also a low-activity cycle, the SC24-25 minimum is expected to be a long one.

Additionally, we observe that most of the long minima, and particularly the longest ones, take place at the lows of the centennial and de Vries (210-yr) cycles of solar activity (arrows in figure 9). As we are currently at a centennial low in solar activity it is more likely than not that the SC24-25 minimum is a long one. Thus, SC24 should not be a particularly short cycle.

We can also get an idea of when the SC24-25 minimum might take place by looking at the speed that some solar features are "migrating" towards the equator. Sunspots are not useful for this, but looking at regions of local maxima in the spectral corona at the Fe XIV 530.3 nm line we can still see them appearing closer to the equator (figure 10; Aliev et al., 2017).

solar cycle minimum

Figure 10. Latitudinal-temporal diagram of the position of local corona maxima at the solar spectral corona in the green Fe XIV 530.3 nm line. Source: Aliev et al., 2017. Arrows mark the position of solar maxima, and vertical black lines of solar minima. Red lines indicate the axis of the displacement over time towards the equator of the position of corona maxima. Blue lines indicate the same for the displacement towards the poles. Lines added by me.
Analysis of the rate of displacement (figure 10, red lines) of active coronal regions, as observed at the green 530.3 nm coronal line, suggests that the SC24-25 minimum could be reached by February 2019. For more on the green spectral line in the solar corona see here.

A similar analysis has been done more in depth by Petrovay et al., 2018 using another feature of the green coronal line, the rush-to-the-poles (RTTP) coronal polar regions. These are active coronal regions that appear at ~ 55-60° at the time of the solar minimum but move progressively closer to the poles, reaching them near the time of the solar maximum (blue lines in figure 10). This "migration" is postulated to be a manifestation of the buildup of the poloidal field.

Petrovay et al., 2018 find a correlation between the rise rate of the RTTP and the time delay from the ending of the RTTP to the maximum of the following cycle. A rapid rise of the RTTP rate indicates the maximum of the next cycle will take place earlier. From that correlation they expect the maximum of SC25 to occur at October 2024.

From that prediction they use two other known correlations, the Waldmeier effect, or anti-correlation between time from cycle minimum to maximum and cycle amplitude (figure 11A), and the correlation found between the amplitude 2.5 years before the minimum and the amplitude at maximum (figure 11B). Using these two correlations Petrovay et al., 2018 deduce that SC24-25 minimum will take place at April 2019 and SC25 will have an amplitude of 130 smoothed sunspots, same as SC16 and slightly above SC24 (116 sunspots). The date they give is in general agreement with the rest of the information presented here.

solar cycle minimum
© Petrovay et al., 2018.
Figure 11. Solar cycle correlations. A) Correlation between cycle rise time from minimum to maximum (trise, in years) vs maximum cycle amplitude (Rmax, in smoothed sunspots), known as the Waldmeier effect. B) Correlation between maximum cycle amplitude Rmax and sunspot number value 2.5 years before the previous minimum R(tmin − 2.5). Red dashed: fit to all data points; blue solid: cycle 19 treated as outlier.
Other official predictions for the coming solar minimum

The Australian Bureau of Meteorology Space Weather Services runs a solar activity pageon monthly sunspot numbers and 10.7 cm solar radio flux. They predict a solar minimum slightly lower than the SC23-24 minimum for July 2019. No information is provided about the model they use.

SILSO also runs several prediction methods. The Standard Curves method (SC, based on Waldmeier) and the Combined Method (CM, based on Denkmayr & Cugnon) are part of the 13-year sunspot number and forecast graph displayed at SILSO home page(figure 12A). Over the past year the CM method performed quite badly, predicting more than double the activity that has been observed (figure 12A, black curves), while the SC method has performed better. For the next year the SC method predicts a fall to zero sunspots average for at least 11 months starting this month (figure 12B). I consider that prediction to be very unlikely. The CM method predicts a solar minimum for February 2019 (figure 12C), which is in general agreement to the evidence presented. A third method not shown, the McNish & Lincoln method, is also available at the forecasts page of SILSO, and predicts the solar minimum for December 2018.

Solar cycle minimum
Figure 12. WDC-SILSO sunspot record and forecasts. A) 13-year record of daily (yellow), monthly (blue), and monthly smoothed (red) sunspots. Dotted line shows the 12-month sunspot prediction by the Standard Curves Method, and Dashed line by the Combined Method. In red the current prediction, and in black the prediction from May 2017. B) 12-month sunspot prediction by the Standard Curves Method. C) 12-month sunspot prediction by the Combined Method.
solar cycle minimum

Table 2. Predicted dates for the coming solar minimum presented in the article. The predictions are centered on March 2019.

At this time everything appears to indicate that the SC24-25 minimum should take place by late 2018 to mid-2019. If this is the case SC24 will be ~ 10-10.5 years long, not unusual for a solar cycle. The time from ≥ 30 sunspots to the minimum should be above 24 months, but probably below the 38 months of the SC23-24 minimum. Since the length of the low activity period is usually related to its depth, it is likely that the SC24-25 minimum should not be as deep as the SC23-24 minimum. This is in contrast with the recent prediction by James Marusek at WUWT that "this upcoming period of minimal sunspots shall be longer and deeper than the last one."

As usual, extreme opinions that this could be a monster minimum (David Archibald, 2017), or that it will take place so soon (or already) that will make SC24 one of the shortest cycles, are unlikely to be correct.

If the minimum takes place indeed by early 2019, we can expect the next minimum by 2029-30, indicating that the current period of below average solar activity should extend until ~ 2032. Afterwards I expect that solar activity should return to levels typical of the 20th century Modern Maximum.


Aliev, A. K., Guseva, S. A., & Tlatov, A. G. (2017). Results of Spectral Corona Observations in Solar Activity Cycles 17-24. Geomagnetism and Aeronomy, 57(7), 798-802.

Cliver, E. W., & Ling, A. G. (2011). The floor in the solar wind magnetic field revisited. Solar Physics, 274(1-2), 285-301.

Harvey, K. L., & White, O. R. (1999). What is solar cycle minimum?. Journal of Geophysical Research: Space Physics, 104(A9), 19759-19764.

Petrovay, K., Nagy, M., Gerják, T., & Juhász, L. (2018). Precursors of an upcoming solar cycle at high latitudes from coronal green line data. Journal of Atmospheric and Solar-Terrestrial Physics.

Svalgaard, L., & Cliver, E. W. (2007). A floor in the solar wind magnetic field. The Astrophysical Journal Letters, 661(2), L203.

Comment: Further reading: Study predicts next phase of solar cycle will bring on 'Mini Ice Age' as early as 2020


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