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Explaining climate change science & rebutting global warming misinformation

Scientific skepticism is healthy. Scientists should always challenge themselves to improve their understanding. Yet this isn't what happens with climate change denial. Skeptics vigorously criticise any evidence that supports man-made global warming and yet embrace any argument, op-ed, blog or study that purports to refute global warming. This website gets skeptical about global warming skepticism. Do their arguments have any scientific basis? What does the peer reviewed scientific literature say?


Why children must emit eight times less CO2 than their grandparents

Posted on 14 August 2020 by Zeke Hausfather

This is a re-post from Carbon Brief

Global emissions of CO2 need to decline precipitously over the next few decades, if the world is to meet the Paris Agreement goals of limiting global warming to “well below 2C” and, ideally, below 1.5C.

If these goals are to be met, young people would have to live the greater part of their lives without contributing significantly to global emissions. Essentially, they would have fewer “allowable” CO2 emissions during their lifetime, compared with older generations.

To determine just how much smaller their personal CO2 limits would be, Carbon Brief has combined historical data on emissions and population with projections for the future. In a world where warming is limited to 1.5C, the average person born today can emit only an eighth of the lifetime emissions of someone born in 1950.

The interactive tool, below, shows the size of each person’s “carbon budget” during their  lifetime – based on when and where they were born.

It looks at two different scenarios: one where the world limits warming to well below 2C above pre-industrial levels by 2100; and one were warming is limited to 1.5C.

It also considers two different ways of sharing future allowable emissions: one where each country tracks “optimal” pathways taken from models; and another, focused on equality, where each person can use the same portion of future emissions, no matter where they live.

In all cases, younger generations will have to make do with substantially smaller lifetime carbon budgets than older generations, if the Paris limits are to be respected. This is because most of the allowable emissions have already been used up, meaning young people will not have the luxury of unmitigated emissions enjoyed by older generations.

The idea for this analysis was first proposed to Carbon Brief by Dr Ben Caldecott at the University of Oxford. The methodology used – and its limitations – are explained in detail at the end of this article. Carbon Brief is now working to further develop the analysis with Dr Caldecott and his colleagues.



Skeptical Science New Research for Week #32, 2020

Posted on 12 August 2020 by doug_bostrom

Respecting the journal editorial process

Each week we scan between 450 and 650 articles for relevance to Skeptical Science's remit: communication of the science of climate change itself the many affected branches of scientific inquiry by climate change. 

The 100+ journals we cover encompass a galaxy of expertise we cannot hope to replicate, let alone exceed. Our appropriate role is to assess the raw filtrates from our feeds purely for what they may add to public understanding of our central topic. "Does this article connect to climate change?" That's the sole question we ask of each item appearing on the screen.

We also don't bring "an agenda" to this process. The single qualitative metric we employ is "did a team of journal editors and reviewers deem this work worth publishing?" Our raw feed filters are fed directly from journal publishing systems, so the answer to that question is always "yes." 

For these reasons readers from time to time (and all too rarely) will spot articles identifying potential benefits of global warming. Some articles come from academic branches we didn't even know exist, and that have the whiff of scary unfamiliarity. Commonly we see articles identifying and trying to correct insufficient understanding of some particular aspect of global warming or its upshots. These latter are not warts or defects. Iterative progress and refinement is of course the norm in scientific research.

Skeptical Science was founded to combat denial of climate science and New Research is part of that effort. Exposing the torrent of scientific publication around climate science is helpful to grasping climate change as an unavoidable challenge. In doing this work we've learned that the final two stops on the railroad of climate science denial are "The System Isn't Fair" followed shortly down the track by the slightly less populated "They're All Lying In Concert." These destinations are actually figments of denier imagination. Even Brigadoon is more plausible.

In reality we see a process that is not error-free but sometimes does contort itself to be inclusive of outré thinking. A fine example of that is how the Taylor and Francis journal Temperature has squeezed in a paper by Valentina Zharkova claiming (yet again) upcoming global cooling, as an "editorial." Zharkova's work is a redo of a previous publication that was retracted due to a basic misunderstanding on the behavior of the barycenter of the solar system. In an abundance of generosity, here's a second attempt gifted to Zharkova by the only means possible. Unfair? Hardly. 

We publish journal editorials in New Research from time to time, in the section "Informed opinion and nudges." Often these are synthesis of many results suggesting possible or obvious topics for concentrated scrutiny. Zharkova's "editorial" doesn't really fit that standard model. Normally we'd expect such a work to appear as a regular peer-reviewed research result. But we'd rather err on the side of fairness; the last thing we want is to appear to be suppressing research that doesn't "go with the flow." The editors of Temperature chose to publish Zharkova's latest work and we'll take that as enough, perhaps bending over a bit backward to be consistent with our general principles of operation. And after all, links to articles here are reports, not endorsements. 

Look for "Editorial" in the "Other" section if you're interested in Zharkova's take on future climate. Open access and free to read. 

87 Articles

Physical science of global warming & effects

Implications of different aerosol species to direct radiative forcing and atmospheric heating rate



Scientists discover new ‘human fingerprint’ on global drought patterns

Posted on 11 August 2020 by Guest Author

This is a re-post from Carbon Brief by Daisy Dunne

Human-caused climate change has “intensified” patterns of extreme rainfall and drought across the globe, a new study finds.

There is a detectable “human fingerprint” on decreasing rainfall over the US, central Asia and southern Africa, according to the results. It is also detectable on increasing rainfall in the Sahel region of Africa, India and the Caribbean.

In addition to increasing greenhouse gas emissions, aerosols released by human pollution and large volcanic eruptions have also been “major contributing agents” to global drought patterns through the industrial era, the research says.

The findings “tackle the problem of identifying the human influence of drought patterns across the world”, a climate scientist tells Carbon Brief.


Droughts are among the most expensive weather-related disasters in the world (pdf), affecting ecosystemsagriculture and human society.

But understanding how climate change is affecting drought risk at a global scale can be fraught, explains Dr Andrew King, a climate extremes research fellow at the University of Melbourne. King, who was not involved in the new paper, tells Carbon Brief:

“It is difficult in many regions of the world due to the short observational record coupled with the prolonged nature of droughts. Unfortunately, this yields relatively few events to analyse.”

For the new study, published in Nature Climate Change, scientists made use of an emerging technique in climate science known as “human fingerprinting”. Lead author Dr Céline Bonfils, a physicist at the Lawrence Livermore National Laboratory, explains to Carbon Brief:



Cranky Uncle cartoons available as PPT slides

Posted on 10 August 2020 by John Cook

Since finishing the Cranky Uncle vs. Climate Change book, I’ve frequently dipped into that 176-page clip-art library, reshaping the cartoons to fit the 1920 x 1080 pixel format for Powerpoint presentations. I’ve also adapted many of the cartoons for the Cranky Uncle video series.

Over the last few weeks, a few people have asked if they could use some of my Cranky Uncle cartoons in their climate talks. In response, I’ve now collected a bunch of 1920 x 1080 Cranky Uncle cartoons and uploaded them all in a freely available Powerpoint presentation. Any educators, scientists, activists, or climate communicators giving a talk about climate change are welcome to use any of the cartoons in your talks. They are free to use (but letting us know the context of how you used them in the comment thread below would be much appreciated).


Almost all the cartoons come from the Cranky Uncle book with a few exceptions. One is a cartoon I drew of Scott Pruitt. This was actually in the first draft of the book, which I wrote back when Pruitt was head of the EPA. Pruitt actually featured quite a lot in that first draft – which I think was a way for me to cope with the frustration of the endless series of scandals following him. My editor wisely advised me to trim Pruitt from the book, suggesting it would date very quickly. Sure enough, Pruitt was fired before I even finished the first draft!

Another cartoon I drew after the book was finished was a cartoon I drew for a Guardian article by Dana Nuccitelli. As is usual for Dana, his article was excellent and went viral so that the article got featured on the Guardian homepage – which meant my cartoon appeared on the Guardian homepage for a short while. That was fun!



2020 SkS Weekly Climate Change & Global Warming Digest #32

Posted on 9 August 2020 by John Hartz

Story of the Week... Toon of the Week... Coming Soon on SkS... Poster of the Week... SkS Week in Review...

Story of the Week...

Drawdown Review 2020: How To Address Global Warming In A Responsible Manner

Project Drawdown

Source: Project Drawdown

Project Drawdown is a non-profit organization that relies on the collaborative efforts of many scientists, economists, and technology specialists from around the world to craft intelligent ways of meeting the challenge of a warming planet. Three years ago, the group published its first book, entitled Drawdown, which presented 100 strategies for meeting the goals agreed to by the vast majority of the world’s nations in Paris in 2015.

Three years later, it has updated that original with a new report entitled Drawdown Review, which dares to suggest humanity can manage the climate crisis effectively using only the tools available today. Of course, that assumes we have the will to address the problem as responsible adults.

Drawdown Review is too complex and detailed to compress it into a short article. It is packed with graphs, charts, and footnotes, and we urge you to read it for yourself. Its ten most salient findings are reproduced below, prefaced by these words from the foreword:

“At present, global efforts come nowhere near the scale, speed, or scope required [to address the most recent IPCC report]. Yet many of the means to achieve the necessary transformation already exist. Almost daily, there is promising evolution and acceleration of climate solutions, alongside growing efforts to sunset fossil fuel infrastructure and prevent expansion of these antiquated and dangerous energy sources.”

Click here to access the entire article originally posted on the Clean Technica website.

Drawdown Review 2020: How To Address Global Warming In A Responsible Manner by Steve Hanley, Clean Technica, Aug 8, 2020



2020 SkS Weekly Climate Change & Global Warming News Roundup #32

Posted on 8 August 2020 by John Hartz

A chronological listing of news articles linked to on the Skeptical Science Facebook Page during the past week: Sun, Aug 2, 2020 through Sat, Aug 8, 2020

Editor's Choice

Five Years After Speaking Out on Climate Change, Pope Francis Sounds an Urgent Alarm

The encyclical ‘Laudato Si’ motivated many people to take action on global warming, but governments, the pope said, have lagged far behind.

Pope Francis

Pope Francis delivers his blessing from the window overlooking St. Peter's Square at the Vatican during the Sunday Angelus prayer earlier this month. Credit: Filippo Monteforte/AFP/Getty 

When Pope Francis issued his landmark teaching document on climate change in 2015, his words went straight to the heart of Susan Varlamoff.

Varlamoff, 70, a biologist, read Rachel Carson's Silent Spring in the 1960s and speaks proudly of a Catholic faith that embraces science and calls on church members to take care of the earth. Her sister, she said, died from cancer as a child, and she wondered whether her father's liberal use of pesticides in their suburban yard might have been the cause.

She asked Archbishop Wilton Gregory, who was then the leader of 1.2 million Catholics in Atlanta and across much of Georgia, whether she could write a review for the archdiocese of the Pope's "Laudato Si': On Care for our Common Home," the first encyclical to be dedicated to the environment.

Instead, he asked for an action plan.

Click here to access the entire article as posted on the InsideClimate News website. 

Five Years After Speaking Out on Climate Change, Pope Francis Sounds an Urgent Alarm by James Bruggers, InsideClimate News, Aug 7, 2020



Why we don't act: Climate Change Psychology

Posted on 7 August 2020 by Guest Author

Little kids are bad at delayed gratification. But unfortunately so are adults. I take a look at why weighing future benefits against present costs makes climate change such a challenging conundrum.

Support ClimateAdam on patreon:



Skeptical Science New Research for Week #31, 2020

Posted on 5 August 2020 by doug_bostrom

100 Articles

Physical science of global warming & effects

Analyzing the Arctic Feedback Mechanism between Sea Ice and Low-Level Clouds Using 34 Years of Satellite Observations

Observations of global warming & effects

Sea‐Level Rise Driving Increasingly Predictable Coastal Inundation in Sydney, Australia (open access)

The recent state and variability of the carbonate system of the Canadian Arctic Archipelago and adjacent basins in the context of ocean acidification (open access)

Remote Tropical Western Indian Ocean Forcing on Changes in June Precipitation in South China and the Indochina Peninsula (open access)

Instrumentation and observational methods of climate & global warming

The tipping points and early-warning indicators for Pine Island Glacier, West Antarctica (open access)

Validation of reanalysis Southern Ocean atmosphere trends using sea ice data (open access)

Differences in tropical high clouds among reanalyses: origins and radiative impacts (open access)

Evaluation of a New Carbon Dioxide System for Autonomous Surface Vehicles (open access)

CLASSnmat: A global night marine air temperature data set, 1880–2019 (open access)



Announcing a new partnership between SkS and

Posted on 4 August 2020 by BaerbelW

As many good things come in threes (as the saying goes), we are happy to announce a third partnership between Skeptical Science and other websites. in Brazil is joining in Germany and Nauka o Klimacie in Poland to leverage translated rebuttal material and to make the information readily available in other languages than English and with a focus on a specific region.


Here is Fakebook.Eco's English press release announcing our new partnership:

The world’s prime Web resource against climate denial and Brazil’s first on-line platform to fight environmental disinformation have joined forces. Skeptical Science is the new content partner of, having agreed to make its Portuguese content available on the Brazilian website.

Skeptical Science was created by Australian cognitive scientist John Cook, a research assistant professor at George Mason University, as an effort to improve the communication of climate science to the public and fight climate denial. It displays a vast set of rebuttals to the most common fallacies, misunderstandings and myths about climate change, in three levels of depth – from basic to advanced. It is run by a global network of volunteers and volunteer translators and has content available in 23 languages – including Portuguese. is a collaboration among climate activists, journalists and scientists led by Brazilian climate advocacy network Observatório do Clima, with the support of five science and environment news portals and blogs. It offers rebuttals of frequent fallacies about several environmental issues and also near-real-time fact-checks of environmental information in the public discourse.

“I’m thrilled to have Skeptical Science as a partner. From the inception, it has been a big inspiration to, and adapting their content will take us to another level”, says Claudio Angelo, founder and senior collaborator of

While incorporating Portuguese rebuttal versions from SkS on their website the team will apply tweaks as needed to the rebuttal content in order to make them more applicable to their Brazilian readership or to include newer research findings. In the latter case we'll get the information about updates applied and can in turn use them to also update the original rebuttal versions (and their translations!) - a real win-win situation!



We've been having the wrong debate about nuclear energy

Posted on 3 August 2020 by Guest Author

This is a re-post from Yale Climate Connections by Karin Kirk

Many Americans these days seem unable to avoid controversy on practically any topic, so why not embrace the discord and wade into the especially volatile arena of nuclear energy? Advocates claim it’s the only way to meet global climate goals, while opponents dig in their heels over safety, national security, and radioactive waste concerns.

And then there’s money, and lots of it, involved: a frequent common thread even – or perhaps especially – on the issues most splitting opinions on all-things-nuclear.

But the debate on both sides often misses key points. A central tenet of much of the pro-nuclear rhetoric is a misleadingly gloomy portrayal of renewable energy options. Meanwhile, absolutist arguments against nuclear energy too often apply primarily to older plants no longer being built. And at times both sides tend to hang their hats on optimistic advances in technologies that may or may not become commercially available in time to make needed progress toward decarbonization.

Given a pressing need to re-think the world’s energy systems, it’s worthwhile talking about nuclear energy. But first, spurious and inflammatory claims have to be cast aside in favor of a fair appraisal of the best and quickest ways to move beyond fossil fuels.

Root of the problem: Need for non-intermittent energy

Progress in greening the U.S. electricity grid is well underway. Coal is declining while renewables grow. But that formula goes only so far. Energy analysts point out that to decarbonize fully, a low- or no-carbon energy source is needed to fill in the gaps around the edges of intermittent generation.

Consider the case of California, a leading state in the deployment of renewables. Although solar energy handles most of the demand during the daylight hours, it cannot keep pace with evening energy use. Presently, natural gas “peaker” plants are used to complement solar and wind, continuing the state’s reliance on fossil fuels.

Electricity gap graphic

In order to phase out emissions from natural gas, either carbon capture needs to be added to gas power plants, or a low-carbon option can be used, such as improved renewables storage or nuclear power.

It’s important to note that not all eggs need to go into one basket. The nation’s present energy infrastructure relies on a combination of technologies, and a diverse approach seems likely to continue.



2020 SkS Weekly Climate Change & Global Warming Digest #31

Posted on 2 August 2020 by John Hartz

Story of the Week... Opinion of the Week... Toon of the Week... Coming Soon on SkS... Poster of the Week... SkS Week in Review... 

Story of the Week...

Rising Seas Could Menace Millions Beyond Shorelines, Study Finds

As climate change raises sea levels, storm surges and high tides will push farther inland, a team of researchers says.

Flooding in Bangladesh

Bangladesh, above, is particularly at risk, along with Virginia and North Carolina in the United States, and parts of France, Germany, India and China. Credit: Munir Uz Zaman/Agence France-Presse — Getty Images

As global warming pushes up ocean levels around the world, scientists have long warned that many low-lying coastal areas will become permanently submerged.

But a new study published Thursday finds that much of the economic harm from sea-level rise this century is likely to come from an additional threat that will arrive even faster: As oceans rise, powerful coastal storms, crashing waves and extreme high tides will be able to reach farther inland, putting tens of millions more people and trillions of dollars in assets worldwide at risk of periodic flooding.

The study, published in the journal Scientific Reports, calculated that up to 171 million people living today face at least some risk of coastal flooding from extreme high tides or storm surges, created when strong winds from hurricanes or other storms pile up ocean water and push it onshore. While many people are currently protected by sea walls or other defenses, such as those in the Netherlands, not everyone is.

If the world’s nations keep emitting greenhouse gases, and sea levels rise just 1 to 2 more feet, the amount of coastal land at risk of flooding would increase by roughly one-third, the research said. In 2050, up to 204 million people currently living along the coasts would face flooding risks. By 2100, that rises to as many as 253 million people under a moderate emissions scenario known as RCP4.5. (The actual number of people at risk may vary, since the researchers did not try to predict future coastal population changes.)

Click here to access the entire article as originally posted on The New York Times website.

Rising Seas Could Menace Millions Beyond Shorelines, Study Finds by Brad Plumer, Climate, New York Times, June 30, 2020



2020 SkS Weekly Climate Change & Global Warming News Roundup #31

Posted on 1 August 2020 by John Hartz

A chronological listing of news articles linked to on the Skeptical Science Facebook Page during the past week: Sun, July 26 through Sat, Aug 1, 2020

Editor's Choice

The four types of climate denier, and why you should ignore them all

The shill, the grifter, the egomaniac and the ideological fool: each distorts the urgent global debate in their own way

Mer de Glace glacier in the French Alps

‘Serious debates about what to do about the climate crisis are turning into action. The deniers have nothing to contribute to this.’ Signs of global warming on the Mer de Glace glacier in the French Alps. Photograph: Konrad K/SIPA/REX/Shutterstock

Anew book, described as “deeply and fatally flawed” by an expert reviewer, recently reached the top of Amazon’s bestseller list for environmental science and made it into a weekly top 10 list for all nonfiction titles.

How did this happen? Because, as Brendan Behan put it, “there’s no such thing as bad publicity”. In an article promoting his book, Michael Shellenberger – with jaw-dropping hubris – apologises on behalf of all environmentalists for the “climate scare we created over the last 30 years”.

Shellenberger was named a hero of the environment by Time magazine in 2008 and is a loud advocate of nuclear power, but the article was described by six leading scientists as “cherry-picking”, “misleading” and containing “outright falsehoods”.

The article was widely republished, even after being removed from its first home, Forbes, for violating the title’s editorial guidelines on self-promotion, adding further heat to the storm. And this is why all those who deny the reality or danger of the climate emergency should be ignored. Obviously, I have broken my own rule here, but only to make this vital point once and for all.

The science is clear, the severity understood at the highest levels everywhere, and serious debates about what to do are turning into action. The deniers have nothing to contribute to this.

Click here to access the entire opinion piece as originally posted on The Guardian website.

The four types of climate denier, and why you should ignore them all, Opinion by Damian Carrington, Comment is Free, Guardian, July 31, 2020



The Trump EPA is vastly underestimating the cost of carbon dioxide pollution to society, new research finds

Posted on 30 July 2020 by dana1981

This is a re-post from Yale Climate Connections

Government rulemakers looking to decide how much money to spend to avoid adding more greenhouse gases to the atmosphere need a good estimate of what a warming climate will cost in social damages, for example through more extreme weather events.

That point makes the “social cost of carbon” one of the most critically important metrics underlying regulation of climate pollutants. An estimate of the dollar costs of each ton of carbon pollution caused by climate change, the social cost of carbon guides federal agencies that are required to consider the costs and benefits of proposed regulations. Federal agencies so far have used the social cost of carbon while writing regulations with more than $1 trillion in economic benefits.

In 2010, a governmental interagency working group in the Obama administration established the first federal social cost of carbon estimate of $45 per ton of carbon dioxide pollution. In 2017, newly inaugurated President Donald Trump quickly disbanded the interagency group by executive order, and within months his EPA slashed the metric to between $1 and $6. The latest research by an independent team of scientists concludes that the social cost of carbon should actually start at about $100 to $200 per ton of carbon dioxide pollution in 2020, increasing to nearly $600 by 2100.

Should presumptive Democratic nominee Joe Biden win the presidency in the November election, his federal agency appointees will undoubtedly set about revising the social cost of carbon to reflect the up-to-date climate science and economics research. The revised social cost of carbon will in turn justify more stringent federal climate regulations. A Donald Trump second term would instead result in another four years of underestimated climate impact costs and continued delays in efforts to curb carbon pollution.

A history of attacks

Since its inception, the social cost of carbon has been a target of those opposing climate regulations, including many Republican office holders in Washington, D.C. The neutered social cost of carbon estimate has now been used to justify weakening three major climate regulations: undoing the Clean Power Plan, freezing vehicle fuel efficiency standards, and, in July 2020, setting airplane greenhouse gas standards to levels matching those the industry already has already met.

In December 2017, congressional Democrats asked the Government Accountability Office to examine the Trump EPA’s new method for calculating the social cost of carbon. The GAO published its report in June 2020.



Skeptical Science New Research for Week #30, 2020

Posted on 29 July 2020 by doug_bostrom

86 Articles

Observations & observational methods of global warming & effects

Forced Changes in the Arctic Freshwater Budget Emerge in the Early 21st Century

Ocean Acidification from Below in the Tropical Pacific

Snow cover duration trends observed at sites and predicted by multiple models

New insights into the world's longest series of monthly snowfall (Parma, Northern Italy, 1777‐2018)

Late 1990s’ cool season climate shift in eastern North America

Ice loss in High Mountain Asia and the Gulf of Alaska observed by CryoSat-2 swath altimetry between 2010 and 2019 (open access)

Trends in winter light environment over the Arctic Ocean: a perspective from two decades of ocean‐colour data

Greening hiatus in Eurasian boreal forests since 1997 caused by a wetting and cooling summer climate

Impacts of Oceanic and Atmospheric Heat Transports on Sea Ice Extent (open access)

Change in the heatwave statistical characteristics over China during the climate warming slowdown

Instrumentation of global warming

Statistical predictability of the Arctic sea ice volume anomaly: identifying predictors and optimal sampling locations (open access)

Multidecadal trend analysis of in situ aerosol radiative properties around the world (open access)

Modeling & simulation of global warming & global warming effects

Time of Emergence & Large Ensemble Intercomparison For Ocean Biogeochemical trends

Comparison of equilibrium climate sensitivity estimates from slab ocean, 150‐year, and longer simulations

Greater Future U.K. Winter Precipitation Increase in New Convection-Permitting Scenarios

Projected Changes in South Asian Monsoon Low Pressure Systems (open access)

Future changes in precipitation-caused landslide frequency in British Columbia

Dynamical and hydrological changes in climate simulations of the last millennium (open access)

Trends and spatial shifts in lightning fires and smoke concentrations in response to 21st century climate over the national forests and parks of the western United States (open access)

Cloudy-sky contributions to the direct aerosol effect (open access)

An Internal Atmospheric Process Determining Summertime Arctic Sea Ice Melting in the Next Three Decades: Lessons Learned from Five Large Ensembles and Multiple CMIP5 Climate Simulations

Projected changes in extreme precipitation indices from CORDEX simulations over Ethiopia, East Africa

Projections of tropical cyclone rainfall over land with an Eulerian approach: case study of three islands in the West Indies

Evaluation and ensemble projection of extreme high and low temperature events in China from four dynamical downscaling simulations



Why low-end ‘climate sensitivity’ can now be ruled out

Posted on 28 July 2020 by Guest Author, Zeke Hausfather

This is a re-post from Carbon Brief by Piers Forster, Zeke Hausfather, Gabi Hegerl, Steven Sherwood, and Kyle Armour

After four years of labour and detailed discussions by an international team of scientists, we are able to quantify better than ever before how the world’s surface temperature responds to increasing CO2 levels. 

Our findings, published in Reviews of Geophysics, narrow the likely range in “equilibrium climate sensitivity” (ECS) – a measure of how much the world can be expected to warm for a doubling of CO2 above pre-industrial levels.

Constraining ECS has remained a holy grail in climate science ever since US meteorologist Jules Charney suggested a possible range of 1.5C to 4.5C in his 1979 report. His estimate was largely based on the world’s first two global climate models, which gave different estimates of 2C and 4C when they performed a simple experiment where atmospheric CO2 levels were doubled.

Since then, despite more than 40 years of research, much improved understanding of atmospheric processes, as well as many more detailed observations, this range has stubbornly persisted. 

Now, bringing together evidence from observed warming, Earth’s distant past and climate models, as well as advances in our scientific understanding of the climate, our findings suggest that the range of ECS is likely to be between 2.6C and 4.1C. 

This narrowed range indicates that human society will not be able to rely on a low sensitivity to give us more time to tackle climate change. But the silver lining to this cloud is that our findings also suggest that very high ECS estimates are unlikely. 



Wildfires off to slow start in much of the West, but trouble expected starting in mid-July

Posted on 27 July 2020 by Guest Author

This is a re-post from Yale Climate Connections by Jeff Masters

Wildfires burned much less acreage in the U.S. than average during the first half of the year, but with hot and dry conditions expected over much of the nation in the coming months, fire activity is likely to ramp up.

The National Interagency Fire Center, or NIFC, reports that approximately 1.5 million acres burned in the U.S. from January through June. This is 60% of the 2010-2019 average of 2.4 million acres and puts 2020 in a virtual tie for the fourth-lowest acreage burned by this point in the year. NIFC records extend back to 2000.

Trouble is still expected as the peak season for wildfire danger arrives in July. As summarized at Carbon Brief and Climate Signals, recent decades have brought a significant increasing trend in the number of large fires and the total area burned per year in the U.S. In the West, human-caused climate change has been directly linked to drier conditions and increases in forest fire activity. At the same time that climate change is amplifying fire risk, the number of people living in known fire-prone areas (the wildland-urban interface) has sharply increased, compounding the threat to people and property.

Year-to-date firesFigure 1. Total U.S. acreage burned in wildfires during the January-June period, for the years 2000-2020. (Image credit: NOAA)



2020 SkS Weekly Climate Change & Global Warming Digest #30

Posted on 26 July 2020 by John Hartz

Story of the Week... Toon of the Week... John Cook in the News... Coming Soon on SkS... Climate Feedback Claim Review... SkS Week in Review... Poster of the Week...

Story of the Week...

Major new climate study rules out less severe global warming scenarios

An analysis finds the most likely range of warming from doubling carbon dioxide to be between 4.1 to 8.1 degrees Fahrenheit

Hog Fire near Susanville, CA

Flames ripped through trees as the Hog Fire jumped Highway 36 about five miles from Susanville, Calif., on Monday. (Josh Edelson/AFP/Getty Images).

The current pace of human-caused carbon emissions is increasingly likely to trigger irreversible damage to the planet, according to a comprehensive international study released Wednesday. Researchers studying one of the most important and vexing topics in climate science — how sensitive the Earth’s climate is to a doubling of the amount of carbon dioxide in the atmosphere — found that warming is extremely unlikely to be on the low end of estimates.

These scientists now say it is likely that if human activities — such as burning oil, gas and coal along with deforestation — push carbon dioxide to such levels, the Earth’s global average temperature will most likely increase between 4.1 and 8.1 degrees Fahrenheit (2.3 and 4.5 degrees Celsius). The previous and long-standing estimated range of climate sensitivity, as first laid out in a 1979 report, was 2.7 to 8.1 degrees Fahrenheit (1.5 to 4.5 Celsius).

If the warming reaches the midpoint of this new range, it would be extremely damaging, said Kate Marvel, a physicist at NASA’s Goddard Institute of Space Studies and Columbia University, who called it the equivalent of a “five-alarm fire” for the planet. 

Click here to access the entire article originally posted on The Washington Post website. 

Major new climate study rules out less severe global warming scenarios by Andrew Freedman & Chris Mooney, Capital Weather Gang, Washington Post, July 22, 2020



2020 SkS Weekly Climate Change & Global Warming News Roundup #30

Posted on 25 July 2020 by John Hartz

A chronological listing of news articles linked to on the Skeptical Science Facebook Page during the past week: Sun, July 19 through Sat, July 25, 2020

Editor's Choice

The Climate Expert Who Delivered News No One Wanted to Hear

From 2009: How a scientist known as the “father of global warming” watched his dire predictions for the planet come true.

James Hansen: Illustration by John Cuneo  

James Hansen on curbing coal emissions: “The science is clear. This is our one chance.” Illustration by John Cuneo

A few months ago, James Hansen, the director of nasa’s Goddard Institute for Space Studies, in Manhattan, took a day off from work to join a protest in Washington, D.C. The immediate target of the protest was the Capitol Power Plant, which supplies steam and chilled water to congressional offices, but more generally its object was coal, which is the world’s leading source of greenhouse-gas emissions. As it happened, on the day of the protest it snowed. Hansen was wearing a trench coat and a wide-brimmed canvas boater. He had forgotten to bring gloves. His sister, who lives in D.C. and had come along to watch over him, told him that he looked like Indiana Jones.

The march to the power plant was to begin on Capitol Hill, at the Spirit of Justice Park. By the time Hansen arrived, thousands of protesters were already milling around, wearing green hard hats and carrying posters with messages like “Power Past Coal” and “Clean Coal Is Like Dry Water.” Hansen was immediately surrounded by TV cameras.

Click here to access the entire article as originally posted on The New Yorker magazine website on June 22, 2009. 

The Climate Expert Who Delivered News No One Wanted to Hear, by Elizabeth Kolbert, Profiles, The New Yorker Magazine, June 27, 2020 Print Edition



How the rise and fall of CO2 levels influenced the ice ages

Posted on 23 July 2020 by Zeke Hausfather

This is a re-post from Carbon Brief

The Earth’s climate has been quite stable over the past 11,000 years, playing an important role in the development of human civilisation. 

Prior to that, the Earth experienced an ice age lasting for tens of thousands of years. The past million years of the Earth’s history has been characterised by a series of ice ages broken up by relatively short periods of warmer temperatures.

These ice ages are triggered and ended by slow changes in the Earth’s orbit. But changing atmospheric concentrations of CO2 also plays a key role in driving both cooling during the onset of ice ages and warming at their end. 

The global average temperature was around 4C cooler during the last ice age than it is today. There is a real risk that, if emissions continue to rise, the world warms more this century than it did between the middle of the last ice age 20,000 years ago and today. 

In this explainer, Carbon Brief explores how the last ice age provides strong evidence of the role CO2 plays as a “control knob” for the Earth’s climate. It also acts as a cautionary tale of how the climate can experience large changes from relatively small outside “forcings”.



Skeptical Science New Research for Week #29, 2020

Posted on 22 July 2020 by doug_bostrom

research stack86 articles

Physical science of global warming & effects

An assessment of Earth's climate sensitivity using multiple lines of evidence

Arctic continental margin sediments as possible Fe and Mn sources to seawater as sea ice retreats: Insights from the Eurasian Margin

Observations & observational methods of global warming & effects

Early‐Warning Signals for Critical Temperature Transitions

Recent anthropogenic curtailing of Yellow River runoff and sediment load is unprecedented over the past 500 y (open access)

Observed Evidence for Steep Rise in the Extreme Flow of Western Himalayan Rivers

Fingerprints for Early Detection of Changes in the AMOC (open access)

Biogenic volatile organic compound ambient mixing ratios and emission rates in the Alaskan Arctic tundra (open access)

Satellite-observed monthly glacier and snow mass changes in southeast Tibet: implication for substantial meltwater contribution to the Brahmaputra (open access)

Comparing methods of uncertainty estimation in optimal fingerprinting

Interdecadal Change in the Effect of Spring Soil Moisture over the Indo-China Peninsula on the Following Summer Precipitation over the Yangtze River Basin

Changes of Compound Hot and Dry Extremes on Different Land Surface Conditions in China during 1957–2018

Harmonised observations of climate forcing across Africa: an assessment of existing approaches and their applicability

Instrumentation of global warming

Spectrally Resolved Fluxes from IASI Data: Retrieval Algorithm for Clear-Sky Measurements (open access)



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