New Research Finds Climate Models Usually Do It Right

New climate research, conducted primarily in San Diego, reveals that a study of Earth’s temperatures during the last ice age confirms some widely held ideas about climate change.

Lead author Alan Seltzer, a paleoclimatologist at the Wood’s Hole Institute of Oceanography, studied ancient water as a way to better understand never-before-recorded planetary temperatures.

New Research Finds Climate Models Usually Do It Right

Hear this story from Erik Anderson.

New Research Finds Climate Models Usually Do It Right

Working in the oceanography laboratory of the Scripps Institution of Oceanography at Jeffery Severinghaus in La Jolla, Seltzer analyzed the composition of ancient groundwater in San Diego and other places around the world.

“A huge amount of our planet’s land surface, like about a third of our planet’s land surface, contains ancient water that has fallen as rain or entered the subsoil as runoff from the earth. rivers during the last ice age, ”said Seltzer.

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After chemically dating the water using radiocarbon techniques, the researchers measured the amount of rare gases dissolved in the water. They compiled data on all continents except Antarctica.

“Paleo noble gas temperature records are so powerful because they are based on a physical principle and are not influenced much by life – which always complicates everything – or by extreme short-term events,” said co-author Martin Stute, researcher in the Department of Environmental Sciences at Barnard College and Associate Principal Investigator at the Lamont-Doherty Earth Observatory.

This technique allowed researchers to extrapolate the temperature of the planet during the last ice age.

He also confirmed the results that determine ocean temperatures during this period, giving scientists more confidence in models that predict climate change.

“This gives the models a little more confidence in a longer term climate perspective well beyond human observation,” said Seltzer.

Researchers can tell with more confidence what the temperature of the earth will be based on the amount of carbon in the air.

“The most important thing he tells us is that the models are actually on the right track and we can believe the models more than before so that we can believe them,” Severinghaus said.

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Previous work seriously underestimated the climate’s sensitivity to greenhouse gases, according to Severinghaus. Climate change could be more destabilizing than current forecasts predict, he said.

“The rather high climate sensitivity that our results suggest is not good news regarding future global warming, which could be stronger than expected using previous best estimates,” said co-author Werner Aeschbach, researcher at the Institute of Environmental Physics, University of Heidelberg, Heidelberg, Germany.

“In particular, our overall review strengthens the conclusion from several single rare gas case studies that the tropics were significantly colder during the last ice maximum than today. The unpleasant implication for the future is that the warmer regions of the world are not immune from further warming, ”he said.

The results are published in the current edition of the journal Nature.


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Scientists explain why climate models cannot r

image: Warming rate during the rapid warming period (1975 / 01-1997 / 12) (a) and warming gap period (1998 / 01-2013 / 12) (b) and the change in warming rate during the period of hiatus from the period of rapid warming (c). All warming rates are derived from 28 simulated global temperature time series (bars) and six observed (vertical lines).
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Credit: © Science China Press

A new study led by Dr Wei and Dr Qiao of the First Institute of Oceanography at the Department of Natural Resources provides an assessment of the performance of recently published CMIP6 models to simulate the slowdown in global warming observed in the early 2000s. This study reveals that the key to simulating and predicting short-term temperate change is to separate and properly simulate the two distinct signals i.e. the human-induced long-term warming trend and natural variabilities, in particular those at interannual, interdecadal and multidecadal scales. . This work was published online in SCIENCE CHINA Earth Sciences on April 15, 2021.

After the unprecedented warming during the last quarter of the 20th century, the growth of global surface temperature unexpectedly slowed between 1998 and 2013 despite the sharp increase in greenhouse gas emissions; this phenomenon is called hiatus or slowing down of global warming to be more precise. Slowing global warming challenges existing scientific understanding of the mechanisms of global temperature change, so has been one of the most worrying issues in recent climate research and even the public.

However, the sophisticated and advanced climate models of CMIP5 could not simulate this slowdown in warming. Over the period 1998-2013, the models mainly show a rapid warming surge that deviates considerably from the observed flat temperature time series. The models considerably overestimate the rate of warming observed over the recent period. IPCC AR5 said: “Almost all historical CMIP5 simulations do not reproduce the recent observed warming gap.” As a result, the ability to simulate and predict sophisticated climate models has been called into question.

Now, CMIP6 model data is gradually released since 2020. Newly developed models include a better understanding of the mechanisms of global temperature change, in particular more reasonable physical processes of natural variability. Successful simulations of the global warming slowdown are expected in next-generation models. As data from 28 new models becomes available, there is a need to timely review the ability of CMIP6 models to exhibit the recent slowing of warming.

Against six widely used global surface temperature datasets, the research team at the First Institute of Oceanography at the Department of Natural Resources are evaluating the performance of the 28 newly released CMIP6 models to simulate the recent slowdown in warming and find that the Most CMIP6 models still fail to reproduce. slowing warming, although they show encouraging improvements over the CMIP5 models (Figure 1).

In addition, they explored possible reasons for the difficulty of CMIP6 models in simulating the recent slowdown in warming. They reveal that it is associated with model shortcomings in simulating temperature change signals distinct from the long-term human-induced warming trend and / or the three crucial natural variabilities at interannual, interdecadal and multidecadal scales ( Figure 2).

This study reveals that the key to simulating and predicting short-term temperate change is to separate and properly simulate the two distinct signals, i.e. the human-induced long-term warming trend and variability. natural, in particular those at interannual, interdecadal and multidecadal scales. . This suggests that key-scale variabilities require more attention in models, given their vital roles in modulating the change in the rate of warming at decadal to multi-decadal scales. This result can provide important information for simulating and predicting short-term climate change.

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This research was funded by the National Natural Science Foundation of China (No. 41806043 and 41821004).

See the article: Wei M, Shu Q, Song Z, Song Y, Yang X, Guo Y, Li X, Qiao F. 2021. Could CMIP6 climate models reproduce the slowdown in global warming of the early 2000s? Science China Earth Sciences, 64, https://doi.org/10.1007/s11430-020-9740-3


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New information on acid formation may help refine atmospheric and climate models

Atmospheric acidity is increasingly established by organic acids, such as formic acid and carbon dioxide. The former contributes to the development of aerosol particles as a precursor to raindrops and thus affects the pH of rainwater and cloud growth..

Diagram of the main emission sectors and primary emissions, meteorological and chemical processes, impacts on air quality and climate, and measurement and analysis tools used to analyze the effects of changes in emissions . Image credit: B. Franco et al, Ubiquitous atmospheric production of organic acids mediated by cloud droplets, Nature, May 2021.

In previous models of the atmospheric chemistry of acid formation, formic acid had played an insignificant role. The chemical processes involved in its formation were not fully understood.

Under the aegis of the Forschungszentrum Jülich, an international research team has now succeeded in filling this gap and decoding the dominant mechanism of the development of formic acid. This further improves atmospheric and climatic models. The results of the study were recently published in the peer-reviewed journal Nature.

The Germans are familiar with acid rain, especially from their experience in the 1980s. The reason for acid rain was that the sulfur oxides and nitrogen oxides released into the air by humans form acid. nitric and sulfuric acid by reacting with water droplets in clouds. The pH of acid rain is around 4.2 to 4.8, which is lower than that of pure rainwater which has a pH of 5.5 to 5.7. Normal acidity is due to the natural carbon dioxide content of the air.

But the chemical process that takes place in most of the formic acid found in the air was not known until now. Dr Bruno Franco and Dr Domenico Taraborrelli from the Jülich Energy and Climate Research Institute – Troposphere have now successfully decoded it: formaldehyde is naturally formed by the photo-oxidation of volatile organic compounds.

Methanediol is formed when formaldehyde reacts in cloud droplets with water molecules. Most of this methanediol is released and then reacts with OH radicals, sometimes called “atmospheric detergents”, to form formic acid by a photochemical process. A smaller part also forms formic acid by reacting with the liquid phase of the water droplets and this acid is dispersed by rain.

According to our calculations, the oxidation of methanediol in the gas phase produces up to four times more formic acid than what is produced in other known chemical processes in the atmosphere..

Domenico Taraborrelli, Energy and Climate Research Institute, Forschungszentrum Jülich

This amount lowers the pH of rainwater and clouds to 0.3, which underlines the contribution of organic carbon to the natural acidity present in the air.

Initially, the two researchers tested their concept using MESSy, a global model of atmospheric chemistry, and compared the results with remote sensing data. To perform the modeling, the team used the Jülich JURECA supercomputer. The results were confirmed by subsequent experiments carried out in the SAPHIR atmosphere simulation chamber at Jülich.

We assume that the demonstrated mechanism is also active in aqueous aerosols and applies to other organic acids such as oxalic acid, which are not sufficiently taken into account in atmospheric chemistry models to date..

Domenico Taraborrelli, Energy and Climate Research Institute, Forschungszentrum Jülich

One of the impacts of this could be a better understanding of aerosol particle growth and cloud formation.

Journal reference:

Franco, B., et al. (2021) Pervasive atmospheric production of organic acids mediated by cloud droplets. Nature. doi.org/10.1038/s41586-021-03462-x.

Source: https://Www.Fz-Juelich.De/


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ECB climate models are built on obsolete scenarios

The author is professor of environmental studies at the University of Colorado

The late Kenneth Arrow, who won the Nobel Prize in Economics in 1972, previously worked as a long-term weather forecaster in the US military. When he realized that this weather forecast was no more accurate than random guesses, Arrow passed the message on to his superiors. “The commanding general is well aware that the forecast is not good,” Arrow was told. “However, he needs it for planning purposes.”

Much like the commanding general of Arrow, the European Central Bank is currently conducting an economy-wide climate stress test. This makes sense because climate change is real and serious. The ECB test, which aims to assess “the exposure of euro zone banks to future climate risks. . . under different climate scenarios ”, is also ambitious and far-reaching. As ECB Vice President Luis de Guindos wrote in March, it looks 30 years away and covers around 4 million companies worldwide and 2,000 banks – “almost all monetary financial institutions in the area euro ”.

Unfortunately, the scenarios on which the ECB relies are obsolete, calling into question the entire exercise. Although somewhat technical, come into the rabbit hole with me on this one as things get interesting quickly.

The ECB and more than 60 other central banks belong to the Network for Greening the Financial System. This volunteer group covers most of the global economy and advocates for climate stress tests to assess financial resilience “to what-if, extreme, but plausible scenarios.” However, these scenarios are accompanied by a health warning, namely: the most commonly used “were designed about 10 years ago and do not correspond well to recent trends in emissions”.

In fact, as my colleagues and I have documented, these scenarios have dramatically overstated carbon dioxide emissions since 2005. Moreover, even the most recent NGFS scenarios are out of step with real world data. This could lead to bad decisions and possibly even higher systemic risks.

The NGFS uses three main scenarios to guide climate assessments. “Orderly” assumes that policy change begins now, leading to net zero emissions by 2070, with emissions reaching 2100 and severe environmental consequences.

The NGFS is clear that compromises are needed to reduce emissions. A carbon tax could accelerate the transition to net zero and promote carbon capture technologies. At the same time, however, it would increase the costs of some raw materials and force companies to review their operations. This could lead to lower short-term growth but much higher long-term growth – the opposite of the greenhouse scenario.

Unfortunately, some of the other assumptions underlying the three NGFS scenarios are implausible.

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For example, they assume global emissions of carbon dioxide from fossil fuels in 2020 of about 36 gigatonnes. Yet in 2020, these emissions were closer to 33 Gt, a gap that is only partly due to the dire economic consequences of the pandemic. By 2040, this little mistake becomes very important. The “greenhouse” scenario predicted around 45 Gt of fossil fuel emissions. Yet even before the commitments made at last month’s climate summit, the International Energy Agency is projecting around 35 Gt of emissions in 2040. The gap widens as you move forward. future. According to a recent analysis in Nature, fossil fuel emissions would be around 25 Gt by 2100, under assumed 2019 policies and technologies. Yet the greenhouse scenario projects 81 Gt, or more than three times that.

Stress tests use “what-if, extreme” scenarios and, as the NGFS clearly shows, these must be “plausible”. Yet it is simply not convincing that the world collectively decides to convert much of its energy supply to coal, which would be necessary for fossil fuel emissions to exceed 80 Gt by 2100.

The ECB uses its climate scenarios in the same way that Arrow General used his ‘bad’ weather forecast – because there is no alternative for planning purposes. Nevertheless, it is urgent to take stock. Because these climate scenarios are usually out of sight and technical, those who rely on them may not know how much they have diverged from the real world. Because they are institutionalized, changing these stress tests will also be difficult.

Nonetheless, if financial institutions are to perform meaningful climate stress tests, it is imperative that they be based on the latest scientific data and not on improbable scenarios.


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Climate models predict sea level soar if Paris targets are exceeded

May 5 (UPI) – If world leaders and policymakers fail to find a way to cut emissions and limit warming to 2 degrees Celsius, the target set by the Paris Agreement, new models suggest that ice losses in Antarctica will cause a dramatic rise in sea level.

According to a study published Wednesday in the journal Nature, current trends in global warming have caused planet Earth to exceed the goals of the Paris Agreement by 2060.

If that happens, the researchers and their models predict that the destabilization of Antarctic ice sheets will ensure an unstoppable sea-level rise of between 17 and 21 centimeters by the end of the century.

To limit the damage caused by climate change, whether it be prolonged droughts or rising waters, scientists generally agree that world leaders should strive to limit warming to 1.5 degrees Celsius above pre-industrial levels – the most ambitious goal set by the Paris Agreement.

However, climatologists believe that policymakers can also ensure a habitable planet by achieving a slightly less aggressive goal and limiting warming to 2 degrees.

But if world leaders can’t find a way to achieve one of the two goals of the Paris Agreement, the scientists said, all bets are off.

For the new study, a team led by researchers at the University of Massachusetts Amhurst examined the likely behavior of Antarctic ice under different warming scenarios.

According to the analysis, if global warming is limited to between 1.5 and 2 degrees, the most recent models of ice loss in Antarctica predict that the southern continent’s ice sheet would contribute between 6 and 11 centimeters to the rise in level. from the sea by 2100.

If global warming approaches 3 degrees above pre-industrial temperatures, models predict that loss of Antarctic ice will contribute 17 to 21 centimeters to sea level rise by the end of the century.

If current warming trends continue, Earth and the Antarctic ice sheet will reach the tipping point of an uncontrolled rise in sea level by 2060.

As significant amounts of ice cap destabilization accumulate as the climate warms, even moderate warming will ensure that Antarctica will continue to experience significant ice loss over the next several centuries.

The latest models suggest that further warming beyond the Paris Agreement targets will ensure seas rise more than 10 meters by 2300.

Conversely, models show that if policymakers can meet the goals of the Paris Agreement, long-term sea level rise can be limited to 1 meter.

Some studies have shown that the Antarctic ice sheet will continue to melt for the next 300 years, even if warming has slowed considerably. But if the warming continues, the melting and rising sea levels will accelerate more dramatically and faster, the researchers say.

Researchers suggest that the source of Antarctica’s vulnerabilities lies along the coast.

As the continent’s coastal glaciers shrink, they become increasingly vulnerable to warm water currents and less able to slow the descent of inland ice.

This pattern of accelerating ice loss has become particularly apparent in Greenland, where warming trends have been more pronounced.

“If the world continues to heat up, the enormous glaciers of Antarctica could start to behave like their smaller counterparts in Greenland, which would be disastrous in terms of sea level rise,” the first author studied. Rob DeConto, Co-Principal of the Amhurst Land School. and sustainability, said in a press release.

Recent studies have shown that melt rates in much of Greenland have accelerated dramatically over the past decades.

One study even showed that Greenland is now losing four times more ice each year than it was almost two decades ago.


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