Can we correct climate models to better predict record weather?

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Flooding in Bad Neuenahr-Ahrweiler, Germany on July 15

FERDINAND MERZBACH / NEWS5 / AFP via Getty Images

Record-breaking climate events, such as Canada’s highest temperature on record, surpassed by nearly 5 ° C last month, will be increasingly likely over the next few decades, new research suggests. It comes as the ability of climate models to predict such extremes has been called into question following a series of intense weather events around the world.

Erich Fischer of ETH Zurich, Switzerland, and his colleagues ran computer models to simulate the average maximum temperature of the hottest week of the year in parts of North America and Europe to to see if they could produce temperatures that broke wide margins records. They might – in some emissions scenarios, records have been broken by more than one degree by 2030, not the 0.1 ° C or 0.2 ° C usually predicted.

The researchers conclude that the likelihood of such record-breaking events is largely due to the rate at which the Earth is warming, and not just how much it has warmed, which is 1.1 ° C up to present and continues to increase. “It’s really the rate of change,” says Fischer.

Geert Jan van Oldenborgh of the Royal Netherlands Meteorological Institute, who has linked the recent heat wave in North America to climate change, says it is worrying that some statistical models have indicated that the region’s records were impossible. Such models have a theoretical distribution of extreme values, which gives an upper limit for the temperatures in an area. This limit generally increases smoothly with climate change.

“Then this heat wave came and it was way above the upper limit [for the region]. It is rather surprising and unsettling that our theoretical picture of heat wave behavior has been shattered so brutally, ”says van Oldenborgh.

The heat wave is not the only event that has rocked climatologists in recent times. Germany has been hit by deadly floods while China’s Henan experienced its heaviest rainfall in a millennium, killing people in flooded subways. “It shocked me,” says Tim Palmer of the University of Oxford.

So what about future events? On a general level, climate models have done a good job of predicting large-scale changes due to climate change, says Peter Stott of the UK Met Office. “Not just the increase in global average temperature, but the increase in temperature extremes and precipitation. It has been made very clear, and it is indeed happening.

However, older models did not capture the intensity of some regional extremes like those seen in Canada, says Stott. The good news, he says, is that some new climate models have a higher level of spatial detail, closer to weather models, down to a grid of squares 2 kilometers in diameter, which will better predict extremes. local. Modelers also have a better understanding of the processes that cause short but intense precipitation, such as that seen in Germany and China.

However, the higher resolution required for some models usually requires more computing power – and resolution isn’t the only issue for projecting extremes: Another big issue is timescales. Much of climate modeling works on centuries-old timescales, but some scientists have now turned to decadal forecasts, which could be roughly described as weather forecasts designed to predict the next few years. These have already been shown to predict Atlantic hurricanes.

“There is definitely a movement towards these ten-year predictions. They are not meant to predict what climate change will do, but what climate change is doing now, ”says Ted Shepherd of the University of Reading, UK.

While many modelers say that more computing power alone isn’t a silver bullet for projecting extremes, it should help. One example is the computation required to produce numbers from the complex calculations of the Navier-Stokes equations, which can be used to model motion in the atmosphere.

More processing power would give more accurate numbers, Palmer says. “It basically comes down to IT.” He called for a ‘CERN for climate change’, a supercomputing project that he said could be executed for around 200 million euros per year. This has yet to happen, but initiatives are underway that could help climate models, such as an EU-backed project to build a ‘digital twin’ of Earth.

And it’s worth remembering that climate models are constantly improving, says Tim Osborn of the University of East Anglia, UK. He says models may not be able to simulate records like the heat in North America because they fail to capture a complex combination of processes, such as an interaction between a clear sky, a faint sky. soil moisture and wind direction, but the truth is we just don’t know yet.

Better climate models will be essential to adapt to climate change and inform early warning systems to prevent deaths. But it’s not like we need them to take action to mitigate the cause of climate change: humanity’s greenhouse gas emissions. “I don’t think it’s the models,” Shepherd said. “I think people don’t just take action on climate change for other reasons. They put their heads in the sand. It’s hard to imagine things that didn’t happen.

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ANOTHER OPINION: Heat burns dome across climate models | Opinion

The insanely high temperatures of the past week in the northwestern United States and Canada were – and are – very frightening. The heat and the fires it caused killed hundreds of people and are believed to have killed a billion sea creatures. Daily temperature records have been broken by more than 5C (9F) in some places. In Lytton, BC, the heat reached 49.6C (121F). The forest fires that consumed the city produced their own thunderstorms, as well as thousands of lightning strikes.

An early study shows that human activity has made this thermal dome – in which a high-pressure ridge acts as a cover preventing hot air from escaping – – at least 150 times more likely. The World Weather Attribution Group of scientists, which uses computer climate models to assess global heating trends and extreme weather conditions, warned that last week had passed even their worst-case scenarios. While it has long been recognized that the climate system has thresholds or tipping points beyond which humans risk losing control of what happens, scientists have not hidden their concern that ‘a generally cold part of the Pacific Northwest had been turned into a furnace. A climatologist said that the prospect opened by the thermal dome “takes my breath away.”

SIGNS OF TROUBLE of climate change are not limited to North America. Pakistan and Siberia have also seen record temperatures in recent weeks, as have Moscow, Helsinki and Estonia. In Madagascar, the worst drought in 40 years has left one million people facing food shortages. Climate author David Wallace-Wells suggested that current conditions should be seen as harbingers of a “permanent emergency.” As policymakers struggle to absorb the very serious implications for human societies of current models, it is frankly difficult to accept the suggestion that these models may underestimate the threat. The prospect of the jet stream blocking and weather systems such as tropical storms stop moving in the way we’re used to, carries nightmarish possibilities. Warmer weather is on its way to California, with most of the wildfire season ahead.

IF THERE IS ANYTHING positive to learn from this new information and reports of the suffering and destruction caused by the heat, it may intensify the pressure on policymakers to act. The Switzerland-based Financial Stability Board issued a warning on Wednesday ahead of the G20 meeting in Venice this weekend. He urged finance ministers and central banks to take more account of “far-reaching” climate impacts. The magnitude of these impacts will depend on decisions taken by governments over the coming months and years. So far, the binding commitments to reduce carbon emissions needed to avoid temperature rises above 2 ° C stand out in their absence. With each worrying news about the climate, the stakes ahead of the November Cop26 conference keep growing.

Environmentalists used to shake their heads when very unusual weather conditions were reported in terms that ignored the contribution of climate change. Now, thanks to the science of attribution, the connection is firmly established. To avoid future thermal domes, countries like the United States and Canada must stop pumping so much energy into the climate system.

The Guardian, Manchester, England, July 8


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Heat dome burning through climate models | Other voices

The insanely high temperatures of the past week in the northwestern United States and Canada were – and are – very frightening. The heat and the fires it caused killed hundreds of people and are believed to have killed a billion sea creatures. Daily temperature records have been broken by more than 5C (9F) in some places. In Lytton, BC, the heat reached 49.6C (121F). The forest fires that consumed the city produced their own thunderstorms, as well as thousands of lightning strikes.

An early study shows that human activity has made this thermal dome – in which a high pressure ridge acts as a cover preventing hot air from escaping – at least 150 times more likely. The World Weather Attribution Group of scientists, which uses computer climate models to assess global heating trends and extreme weather conditions, warned that last week had passed even their worst-case scenarios. While it has long been recognized that the climate system has thresholds or tipping points beyond which humans risk losing control of what happens, scientists have not hidden their concern that ‘a generally cold part of the Pacific Northwest had been turned into a furnace. A climatologist said that the prospect opened by the thermal dome “takes my breath away.”

The worrying signs of climate change are not limited to North America. Pakistan and Siberia have also seen record temperatures in recent weeks, as have Moscow, Helsinki and Estonia. In Madagascar, the worst drought in 40 years has left one million people facing food shortages. Climate author David Wallace-Wells suggested that current conditions should be seen as harbingers of a “permanent emergency.” As policymakers struggle to absorb the very serious implications for human societies of current models, it is frankly difficult to accept the suggestion that these models may underestimate the threat. The prospect of the jet stream jamming and weather systems such as tropical storms stop moving in the way we’re used to, carries nightmarish possibilities. Warmer weather is on its way to California, with most of the wildfire season ahead.

If there is anything positive to be learned from this new information and reports of the suffering and destruction caused by the heat, perhaps it is that it intensifies the pressure on policy makers to take action. . The Switzerland-based Financial Stability Board issued a warning on Wednesday ahead of the G20 meeting in Venice this weekend. He urged finance ministers and central banks to take more account of “far-reaching” climate impacts. The magnitude of these impacts will depend on decisions taken by governments over the coming months and years. So far, the binding commitments to reduce carbon emissions needed to avoid temperature rises above 2 ° C stand out in their absence. With every worrying news about the climate, the stakes ahead of the November Cop26 conference keep growing.

Environmentalists used to shake their heads when very unusual weather conditions were reported in terms that ignored the contribution of climate change. Now, thanks to the science of attribution, the connection is firmly established. To avoid future thermal domes, countries like the United States and Canada must stop pumping so much energy into the climate system.


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Climate models have predicted extreme weather fluctuations. Can the damage be reversed?

William Brangham:

Scientists have linked extreme weather fluctuations, from heat waves to torrential rains, to climate change, and these extremes are not limited to Europe.

Last month, ground temperatures in the Arctic Circle reached over 100 degrees Fahrenheit. Much of the western United States is suffering from severe drought, which has provided tinder ready for the wildfires that erupted particularly early this year.

And for the first time in recorded history, deforestation and fires in the Amazon, coupled with warmer temperatures, are causing parts of the rainforest to spit out more carbon dioxide than it absorbs. Scientists fear this reversal may be a tipping point, where one of the best ways to store massive amounts of Earth’s carbon is now becoming a carbon emitter.

And now Gavin Schmidt is joining me. He is a climatologist and senior climate advisor to NASA.

Gavin Schmidt, nice to see you again on “NewsHour”.

We see this devastation and flooding in Europe and also here in the United States. The West is cooking with this drought and forest fires. These are the things that climate models have always predicted would happen, right, more and more of these extreme fluctuations.

Director Gavin Schmidt, NASA Goddard Institute for Space Studies: So climate models predicted that the globe as a whole would get warmer and at the same time we would see more heat waves and we would see more intense precipitation and exacerbation of signals of drought, especially in places like the southwest or the Mediterranean region, where you see a lot more demand for evaporation pulling water out of the soil, making droughts caused by a lack of rainfall more severe for the people on the ground.


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The Guardian: Thermal dome burns through climate models | Opinion

The recent incredibly high temperatures in the northwestern United States and Canada were – and are – very frightening. The heat and the fires it caused killed hundreds of people and are believed to have killed a billion sea creatures.

Daily temperature records have been broken by more than 9 degrees Fahrenheit in some places. In Lytton, British Columbia, the heat reached 121 degrees. The forest fires that consumed the city produced their own thunderstorms, as well as thousands of lightning strikes.

An early study shows that human activity has made this thermal dome – in which a high pressure ridge acts as a cover preventing hot air from escaping – at least 150 times more likely. The World Weather Attribution Group of scientists, which uses computer climate models to assess global heating trends and extreme weather conditions, has warned that the heat of two weeks ago exceeded even their worst-case scenarios.

While it has long been recognized that the climate system has thresholds or tipping points beyond which humans risk losing control of what happens, scientists have not hidden their concern that ‘a generally cold part of the Pacific Northwest had been turned into a furnace. A climatologist said that the prospect opened by the thermal dome “takes my breath away.”

The worrying signs of climate change are not limited to North America. Pakistan and Siberia have also seen record temperatures in recent weeks, as have Moscow, Helsinki and Estonia. In Madagascar, the worst drought in 40 years has left one million people facing food shortages. Climate author David Wallace-Wells suggested that current conditions should be seen as harbingers of a “permanent emergency.”

As policymakers struggle to absorb the very serious implications for human societies of current models, it is frankly difficult to accept the suggestion that these models may underestimate the threat. The prospect of the jet stream blocking and weather systems such as tropical storms stop moving in the way we’re used to, carries nightmarish possibilities. And California still has most of its wildfire season ahead.

If there is anything positive to be learned from this new information and reports on the suffering and destruction caused by the heat, perhaps it is that it intensifies the pressure on policymakers to act. On July 7, the Swiss-based Financial Stability Board issued a warning ahead of the G20 meeting in Venice this weekend. He urged finance ministers and central banks to take greater account of far-reaching climate impacts.

The magnitude of these impacts will depend on decisions taken by governments over the coming months and years. So far, the binding commitments to cut carbon emissions needed to avoid temperature rises above 2 degrees Celsius are notable for their absence. With each worrying news about the climate, the stakes ahead of the November Cop26 conference keep growing.

Environmentalists used to shake their heads when very unusual weather conditions were reported in terms that ignored the contribution of climate change. Now, thanks to the science of attribution, the connection is firmly established. To avoid future thermal domes, countries like the United States and Canada must stop pumping so much energy into the climate system.

The Guardian newspaper, London

The Guardian newspaper, London


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North American heatwave broke records

Climatologists have been shocked by recent deadly heat waves in western Canada and the northwestern United States, which have exceeded all global heating forecasts

Climate scientists have warned that the world is already experiencing episodes of extreme heat that are only expected to occur on a much hotter planet.

The extraordinary heat that engulfed northwestern Canada and the United States last week broke temperature records by several degrees, with temperatures exceeding 40 ° C for days and reaching 49.6 ° C in the village of Lytton, Canada.

Soon after, Lytton was destroyed in forest fires. In Western Canada, nearly 500 people are estimated to have died and experts expect the death toll to rise.

Without the influence of man-made climate change, the heat wave would have been “virtually impossible,” according to a rapid attribution analysis by an international team of 27 leading climatologists who have worked tirelessly to publish the study.

Climate change, they found, has made the heat wave at least 150 times more likely to occur – such extreme heat not occurring according to current statistical analyzes.

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The results have prompted scientists to question their understanding of the impact of climate change on heat waves, which could lead to the revision of some climate models.

Friederike Otto, from the Environmental Change Institute at the University of Oxford, one of the study’s authors, said climate science has been “a little complacent” about how it understands sea waves. heat.

The intensity of heat waves is increasing in orders of magnitude not seen for other extreme events, she said. “Heat waves are how climate change is killing us. This is how climate change manifests itself more strongly.

Using computer observations and stimulation, the scientists compared the past climate in the region covering Portland, Seattle and Vancouver with current trends after global warming of around 1.2 ° C since the end of the 19th century.e century.

They found that the temperatures during last week’s event were so extreme that it was difficult to estimate with certainty how rare the event was, but suggested that it amounted to a single event in a thousand. years in the current climate.

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Geert Jan van Oldenborgh of the Royal Netherlands Meteorological, another of the authors, told reporters that the heat wave had shattered previous temperature records of up to 5 ° C – “an extraordinary event”.

“For comparison, here in the Netherlands we were really shocked when the previous record was broken by 1.8 ° C and it’s more than double. “

The heat wave, said Van Oldenborgh, is “both a major disaster and weather event, but also a major scientific challenge to understand what happened.”

He said the state of climate science in 2020 would have shown that the heat wave was “fundamentally impossible” and that more research was needed to understand how it happened and whether such an event could occur in other parts of the world.

“It’s rather shaking that our theoretical picture of heat wave behavior has been shattered so brutally,” he said. “We are much less certain of how the climate [change] affects heat waves than we were two weeks ago.

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The authors of the article identified two possible explanations for the extreme jump in maximum temperatures observed in North America.

The first is ‘really bad luck’ and that, although exaggerated by climate change, it remains a very low probability event. However, in a future world characterized by global warming of 2 ° C, such an extreme heat wave could occur once every 5 to 10 years, according to the study.

Another explanation is that the climate system in this region has crossed a threshold that has increased the likelihood of such extreme heat well beyond the gradual rise in temperature peaks that have been observed so far.

In this scenario, record-breaking heat waves like last week’s event are already more likely to occur than climate models predict – which the team of scientists says needs further investigation.

“This is such an exceptional event that we cannot rule out the possibility that we are facing extreme heat today that we only expected to reach higher levels of global warming,” said Otto.

If this second scenario turns out to be correct, it could lead to the revision of climate models.

If an essential climate process is missing from current climate models, these will “definitely need to be improved,” Van Oldenborgh said.


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Canadian hell: northern heat surpasses worst climate models | Climate crisis

If you had made a list of possible locations for Hell on Earth before this week, the tiny mountain village of Lytton in Canada probably wouldn’t have occurred to you.

Few people outside of British Columbia had heard of this community of 250 people. Those who had it were more likely to view it as bucolic. Nestled at the confluence of rivers in the forested foothills of the Lillooet and Botania mountain ranges, the municipal website boasts: “Lytton is the perfect place for nature lovers to connect with incredible natural beauty and the freedom of the countryside. ‘fresh air.”

Over the past seven days, however, the village has been making headlines around the world for an incredibly prolonged and intense temperature spike that has turned the romance into hell.

US President Joe Biden and Canadian Prime Minister Justin Trudeau have warned worried populations to prepare for more. Shocked climatologists wonder how even the worst-case scenarios failed to predict such furnace conditions so far north.

Johan Rockström, director of the Potsdam Institute for Climate Impact Research, said recent extreme weather anomalies were not represented in global computer models used to project how the world might change with more emissions . The fear is that weather systems will be blocked more frequently due to human emissions. “This is a risk – of a severe regional climate impact triggered by global warming – that we have underestimated so far,” he said.

In Lytton, it was as if time itself had stagnated. Trapped in a vast dome of heat that enveloped western Canada and the northwestern United States, temperatures had no choice but to rise.

In Lytton, the Canadian national heat record was broken Monday, shattered Tuesday, then erased Wednesday when the local monitoring station recorded 49.6 ° C (121 ° F).

After the unbearable heat came the suffocating fire. First the forest burned down, then parts of the city. On Wednesday evening, Mayor Jan Polderman issued the evacuation order. ” It’s horrible. The whole town is on fire, “he said on television.” It took about 15 minutes from the first sign of smoke and, suddenly, fire everywhere. “On Thursday, satellite images showed a fires erupt around the village and a cloud of smoke widening in the area.

Heatwave in Canada: Resident films escape wildfire as flames engulf Lytton village - video
Heatwave in Canada: Resident films escape wildfire as flames engulf Lytton village – video

Police stations and hospitals have reported an increase in the number of heat-related deaths – 486 in British Columbia and dozens more south of the border. The roads twisted as the asphalt spread. At least one city has suffered power cuts.

The psychological, political and economic impacts are harder to quantify, but for many the horror has been accompanied by a sense of astonishment that these northern territories are hotter than the Middle East. David Phillips, the Canadian government’s senior climatologist, summed it up in an interview with CTV. “I mean, it’s just not something that looks Canadian.”

A woman and her cat rest inside a tent at the Oregon Convention Center cooling station in Portland, United States. Photograph: Kathryn Elsesser / AFP / Getty Images

More and more people in more countries feel that their climate belongs to another part of the world. Across the border in Washington state, the maximum heat measured at Olympia and Quillayute was 6 ° C above the previous all-time record, according to the Weather Prediction Center. In Oregon, the city of Salem hit 47C, shattering the previous record of 9C. Several parts of California and Idaho also recorded new highs.

The week before, Northern Europe and Russia also suffocated in an unprecedented heat bubble. June records were broken in Moscow (34.8C), Helsinki (31.7C), Belarus (35.7C) and Estonia (34.6C).

Further east, Siberia experienced an early heat wave that helped reduce the amount of sea ice in the Laptev Sea to an all-time high for the time of year. The city of Oymyakon, Russia, widely considered the coldest inhabited place on earth, was warmer (31.6 ° C) than it ever was in June. This follows an incredibly prolonged heat wave in Siberia last year that lasted for several months.

Carlo Buontempo, director of the Copernicus Climate Change Service, said there was a clear human imprint on this “very abnormal” event. Without emissions from cars, farms and industry, he said, record temperatures in western North America would only be expected once every tens of thousands of years, but the probability increases with the levels of greenhouse gases. “In today’s climate, having an extremely hot June is common and likely to happen twice in three decades. However, an analysis of numerous computer models suggests that by the end of the century, these extreme temperatures are more likely than not. It is estimated that human influence increased the likelihood of a new record several thousand times. “

Dome

The rise in temperatures is visible all over the world. Even in the Middle East, temperatures over 50 ° C were once outliers, but parts of Pakistan, India, Australia, the United States and Canada are now regularly approaching or exceeding this mark. .

But the intensity of the heat in the northwestern Americas this year and in Siberia last year took many scientists by surprise and suggested that additional factors could be involved in the northern latitudes.

One theory is that the recent spike in temperature may have been caused not only by global warming, but by the slowing of weather systems that remain stuck in one place for an extended period of time, giving them time to escalate and recede. cause more damage. This was a major factor in the devastation in Texas caused by Hurricane Harvey in 2018, which remained over Houston for several days rather than blowing inland and weakening. The stranded high pressure fronts were also blamed for the scorching heat wave in Europe in 2019.

Experts at the Potsdam Institute and elsewhere believe that the rapid warming of the Arctic and the decline of sea ice are causing the jet stream to move in large meanders, called Rossby resonance waves, trapping weather systems at high and low pressure in one place. for longer.

This theory remains disputed, but Michael Mann, director of the Earth System Science Center at Pennsylvania State University, said this week’s surprisingly fierce heat in Lytton and elsewhere should prompt climatologists to consider additional impacts of the weather. ‘human activity.

“We should take this event very seriously,” he wrote in an email. “You’re warming the planet, you’re going to see an increase in the incidence of extreme heat. Climate models capture this effect very well and predict large increases in heat extremes. But something else is happening with this heat wave, and indeed, with many of the very persistent extreme weather conditions we’ve seen in recent years in the United States, Europe, Asia and elsewhere, where models don’t capture not quite the impact of climate change. “

Whatever interactions to blame, scientists agree that the easiest way to reduce the risk of further temperature shocks is to cut fossil fuel emissions and stop deforestation.

“It seems that this heat wave is still a rare phenomenon in the current climate, but that it remains dependent on our decisions,” he added. Friederike Ottosaid the associate director of the Environmental Change Institute at the University of Oxford. “If the world does not quickly eliminate the use of fossil fuels and other sources of greenhouse gas emissions like deforestation, global temperatures will continue to rise and such deadly heat waves will become even more severe. current. “



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