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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Latest Posts


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?


2015 SkS Weekly News Roundup #16B

Posted on 18 April 2015 by John Hartz

2015 hottest year to date, could top 2014 record

By the reckoning of the three main agencies that track global temperature, 2015 has so far been the warmest year in more than a century. Coming immediately after the hottest year on record, the ranking serves as a reminder of how much the globe’s overall temperature has risen thanks to the ever-growing amounts of greenhouse gases in the atmosphere.

With the year only a quarter through, it’s difficult to say definitively how 2015 as a whole will turn out. But with an El Niño event currently in place that could help keep temperatures at record or near-record levels for the remainder of the year, 2015 may be poised to eclipse 2014’s newly minted record, though climate scientists are cautious on such pronouncements.

Land & Ocean Temperature Departure from Average: Jan-Mar 2015

How surface temperatures around the world varied from the 20th century average over the period from January to March 2015. Credit: NOAA

“We expect that we are going to get more warm years, and just as with 2014, records will be broken increasingly in the future. But perhaps not every year,” said Gavin Schmidt, who leads NASA’s Goddard Institute of Space Studies.

2015 Hottest Year to Date, Could Top 2014 Record by Andrea Thompson, Climate Central, Apr 17, 2015



The Rise of Skeptical Science

Posted on 18 April 2015 by CollinMaessen

This is a re-post from Real Sceptic

Everyone at Skeptical Science spends a lot of their time reading the scientific literature and listening to experts. Without that we wouldn’t be able to write all the material that’s published on Skeptical Science. It’s a lot of work, especially when you do this with a critical eye. Our goal, after all, is to ensure that what we write reflects the scientific literature on the subject as accurately as possible.

The materials created by Skeptical Science are used by teachers, politicians, and of course by users on the internet to rebut climate myths. Thanks to this a lot of people have seen materials produced by us, even though they might not know that they have.

The website Skeptical Science wasn’t created overnight, nor was the team behind it assembled instantly. It started small with John Cook starting the website and publishing the first rebuttals to climate myths. As I wasn’t familiar with the story of how Skeptical Science evolved to the website it is today I had the idea to interview John about this.

Despite John constantly saying “I’m just not that interesting” I eventually managed to get him in front of the camera:

This video is longer than usual and is right at the limit of how long I make my videos. But the story of Skeptical Science is an interesting one with a lot of anecdotes of how the team came together and how the website evolved. Well worth your time if you want to know the history of Skeptical Science (plus there’s a fun little bonus if you watch the video till the end).



New Video: The Trouble at Totten Glacier

Posted on 17 April 2015 by Guest Author

This is a re-post from Peter Sinclair at Climate Crocks

The latest “This is Not Cool” video is the third in a trilogy of very important, and sobering, pieces I’ve posted over the last year. I didn’t start with a trilogy in mind, but the developments of the last few months have been jarring and momentous.

Chris Mooney wrote recently in the Washington Post, “A hundred years from now, humans may remember 2014 as the year that we first learned that we may have irreversibly destabilized the great ice sheet of West Antarctica, and thus set in motion more than 10 feet of sea level rise.”
He added, “Meanwhile, 2015 could be the year of the double whammy — when we learned the same about one gigantic glacier of East Antarctica, which could set in motion roughly the same amount all over again.”

The decades-long unfolding of this story – that vast areas of ice once thought to be invulnerable on time scales meaningful to humans, may in fact already be in the process of disintegration – is one that that the vast majority of humanity still does not understand, and that the media has been unwilling to track.  It’s a realization that, one top expert told us, even seasoned ice sheet veterans find “shattering”.

For this video I used in-person interviews from December’s AGU conference, as well as a skype chat with Jamin Greenbaum of the University of Texas, whose recent research on East Antarctic vulnerability has been widely reported. Jamin pointed me to some Australian research from the same area.  There was a huge volume of material, not all of which made it into this video, but which I’ll be posting in coming weeks to flesh out the picture.
The overriding message: we have a problem.



Western Canada’s glaciers could shrink by as much as 95% by 2100, study finds

Posted on 16 April 2015 by Guest Author

This is a re-post from Robert McSweeney at Carbon Brief

The Canadian Rockies, which sit as a backdrop to many a stunning vista, could be almost entirely devoid of glaciers by the end of the century, a new study suggests.

Researchers modelled the impact of rising temperatures on glaciers across western Canada.

The results show widespread ice loss by 2050, and ice all but vanishing a few decades later.

Rising temperatures

Around 27,000 square kilometers of Western Canada is covered by glaciers, an area similar in size to the amount of ice in the Himalayas or the whole of South America.

For the new study, published in Nature Geoscience, the researchers developed a model to see how rising temperatures will affect the volume and area of glaciers in three regions in western Canada. These regions are shown in the map below: the coast (green sections), the interior (pink) and the Rockies (blue).

Clarke Et Al Fig1



2015 SkS Weekly News Roundup #16A

Posted on 15 April 2015 by John Hartz

Britain's fish 'n' chip favourites could dwindle as North Sea warms

The likes of haddock, plaice and lemon sole could find the North Sea a less comfortable place to live as the world's oceans warm up, according to a new study.

The findings suggest that some of our favourite fish species could become less common as they struggle to cope with warming conditions, the lead author tells Carbon Brief.

Britain’s fish ‘n’ chip favourites could dwindle as North Sea warms by Robert McSweeney, The Carbon Brief, Apr 13, 2015



Price on carbon key to Canada tackling global warming, say researchers

Posted on 15 April 2015 by dana1981

65 researchers from provinces across Canada have published a report, Acting on Climate Change, that details how the country can successfully decarbonize its electric grid to slow global warming.


Map of researchers contributing to the Acting on Climate Change report.

The team unanimously endorsed putting a price on carbon pollution as a key strategy. Without a carbon fee, the price of electricity on the market doesn’t reflect its true costs to society. This is a market failure that economists call an “externality,” where the costs associated with a product (in this case, damages incurred via climate change) aren’t captured in its market price. Instead they’re paid by taxpayers in what could be considered a massive subsidy to the fossil fuel industry.

Most economists support putting a price on carbon pollution in order to correct this market failure. Acting on Climate Change notes that this could be accomplished with either a carbon tax or cap and trade system. So far, the province of British Columbia has implemented a highly popular and successful revenue-neutral carbon tax, while the province of Québec has adopted a cap and trade system in coordination with California as part of the Western Climate Initiative, and Ontario has just announced that it will also implement a carbon cap and trade system.

In addition to carbon pricing, some other key policies suggested in the report include,



Hungarian translation of The Debunking Handbook

Posted on 14 April 2015 by Guest Author

This is a guest post by András G. Pintér who is the vice-president of the Hungarian Skeptic Society.

Thanks to the co-operation of a few enthusiastic people, The Debunking Handbook is now available in Hungarian. Although, the translation project was initiated by the Hungarian Skeptic Society about a year ago, the job itself was completed by a supdbh_hungarianporter of our organization by the name Ilona L'Homme, leaving us with only some polishing work to do on the text before sending it back to author John Cook for the final touches on the design.

Many thanks to the authors and the translator who provided Hungarian skeptics with an important tool for the most difficult challenge we tend to take on: correcting erroneous beliefs and mindsets of other people.

Since it fits perfectly into our actions of skeptical activism (lectures, conventions, shows, blogs and social media presence), we are planning to spread the word and make this booklet known to as many people as possible within the Hungarian skeptical movement (and beyond).

It seems like a small thing to do, but far from it: it is a powerful tool, that's now within reach for even those who happen not to have a very strong conduct of English.

We could not be more grateful for this booklet. Let it be translated to all the languages, so that everyone has the chance to use it for the benefit of all.

Note to other translators:

If you'd like to translate the Debunking Handbook into another language, please download the two-column Word document which has the English text in one column and a blank column where you can add the translated text. Email the complete document back to us, and we'll insert it into the existing design. To ensure that no one else is already working on your language, please contact us first by selecting "Enquiry about translations" from the contact form's dropdown menu.



Andy Lacis responds to Steve Koonin

Posted on 13 April 2015 by Guest Author

This is a re-post from And Then There's Physics

I know Eli’s already posted Andy Lacis’s response to Steve Koonin on Judith Curry’s blog, but I thought it worth repeating. It’s a pretty impressive comment in terms of what it covers, so it’s worth reading in it’s own right. I do find myself amazed at what Steve Koonin has been willing to say. Ignoring that much of what he says suggests a woeful lack of understanding of the topic itself, that anyone of his supposed intellectual calibre would construct an argument that essentially goes “look, this number is small, nothing to worry about” is remarkable, and not in a good way. It’s one thing to suffer from hubris, but it’s hard to see why if one’s argument is so obviously silly. Maybe Eli’s right that the best description is beyond contempt.

credit : xkcd

credit : xkcd

Anyway, Andy Lacis’s comment is below (bolds mine).

Physicists should take the time to understand their physics better (Comment: some of us are trying :-) )

Only 1% to 2% . . . that may sound small and insignificant . . . but it isn’t.

It is well known that the normal human body temperature is about 310 K. Furthermore, it is also well known that a seemingly small change (up or down) in absolute body temperature by only 1% (3.1 K, or 5.6 F) would make one sicker than a dog, and, that a 2% change in body temperature (up or down by 6.2 K, or 11.2 F) will virtually guarantee a dead body. From this, it should be sufficiently clear that, when viewed in absolute energy terms, the viable margin between life and death in the Earth’s biosphere is remarkably narrow – so much so that a seemingly insignificant 1% to 2% change in the total energy of the global environment will invariably result in serious disruption of the established infrastructure of life in the biosphere.



2015 SkS Weekly Digest #15

Posted on 12 April 2015 by John Hartz

SkS Highlights

The history of emissions and the Great Acceleration by Andy Skuce generated the highest number of comments of the articles posted on SkS during the past week. Coming in second and third, repectively, were Global warming hiatus explained and it's not good news by Graham Readfearn, and The global warming 'pause' is more politics than science by Dana. 

El Niño Watch

The National Oceanic and Atmospheric Administration (NOAA) is predicting a 60 percent chance that the El Niño it declared in March will continue all year. An El Niño is a weather pattern “characterized by unusually warm ocean temperatures in the Equatorial Pacific.”

There’s A 60 Percent Chance El Niño Could Last All Year by Joe Romm, Climate Progress, Apr 10, 2015 

Toon of the Week

2015 Toon 15 

Hat tip to I Heart Climate Scientists



2015 SkS Weekly News Roundup #15B

Posted on 11 April 2015 by John Hartz

California's new era of heat destroys all previous records

The California heat of the past 12 months is like nothing ever seen in records going back to 1895. The 12 months before that were similarly without precedent. And the 12 months before that? A freakishly hot year, too. 

What's happening in California right now is shattering modern temperature measurements—as well as tree-ring records that stretch back more than 1,000 years. It's no longer just a record-hot month or a record-hot year that California faces. It's a stack of broken records leading to the worst drought that's ever beset the Golden State.  

The chart below shows average temperatures for the 12 months through March 31, for each year going back to 1895. The orange line shows the trend rising roughly 0.2 degrees Fahrenheit per decade, just a bit faster than the warming trend observed worldwide.

 California Avg. Annual Temps: 1900-2014

12-Month Average Temperature (°F), April-March. Source: NOAA / Bloomberg

California's New Era of Heat Destroys All Previous Records by Tom Randall, Bloomberg, Apr 10, 2015



New paper shows how sensitive the ocean biosystem is to climate change

Posted on 10 April 2015 by John Abraham

Changes to the climate have had major impacts on the oceans and the biological systems that live there. A new study sheds more light on how fast these systems respond to changes. What the authors find is that short term climate changes can require 1,000 years for recovery. This means the current harm caused to the deep oceans by the changing climate will last for many centuries to come.

The new study, published in the Proceedings of the National Academy of Sciences by Dr. Sarah Moffitt and her colleagues is novel for a number of reasons. The researchers took core samples from ocean floor regions off the coast of California. The location was chosen in part because of the exceptional synchrony between sediment archives from offshore California and ice core records from the Greenland Ice sheet.

Dr. Sarah Moffitt.  Photo credit: Wayne Freedman Dr. Sarah Moffitt. Photo credit: Wayne Freedman

The authors’ method was novel because they sampled many different types of creatures, not merely the single-celled organisms that are most commonly studied. In fact, the authors included Mollusca, Echinodermata, Arthropods, and Annelida samples (approximately 5,000 fossils). There was major “turnover” in these animals with only small changes to oxygen levels.

Using the ocean sediment core, the authors were able to travel back in time to the last deglaciation. They connected cooling and warming events to increases and decreases in the oxygen contained within the waters. Past events of abrupt warming, which occurred in decades to centuries and were accompanied by subsurface oxygen loss, significantly impacted the types and numbers of animals found within the sediments. Recovery from this abrupt, climate-forced disturbance can take 1,000 years.

Among the changes documented are expansions and intensification of oxygen poor regions. These regions, called “Oxygen Minimum Zones” get larger when the oceans warm. As these oxygen poor zones get larger, there is a predominance of animals that thrive in low-oxygen environments. Animals that need higher levels of oxygen suffer and die off.



Global warming hiatus explained and it's not good news

Posted on 9 April 2015 by Guest Author

You may have heard that global warming has 'paused' but it's only one part of a bigger picture and the search for understanding has equipped climate scientists with better tools than ever.

"It is frustrating," says climate scientist Michael Mann from his office at Penn State University in the United States.

"There certainly has not been a hiatus in global warming — global warming hasn't stopped, even though you still hear those contrarian talking points," he says.

Professor Mann, the director of the university's Earth System Science Centre, is famous for his 'hockey stick' graph that reconstructed 1,000 years of global temperatures showing a dramatic spike towards the end of the 20th century.

The 'pause', also known as the 'slow down' or the 'hiatus', refers to the average rate of warming across the whole planet's surface in the last 15 years or so. The latest major report (pdf) from the United Nations Intergovernmental Panel on Climate Change said the rate of warming between 1998 and 2012 had been about 0.05°C per decade.

This rate, the report said, was "smaller than the rate calculated since 1951" which was 0.12°C per decade.

"The occurrence of the hiatus in global mean surface temperature trend during the past 15 years raises the two related questions of what has caused it and whether climate models are able to reproduce it," the report said (pdf).

This was proof enough for some commentators that computer models of the climate were wrong and that the risks of global warming may have been overblown.



2015 SkS Weekly News Roundup #15A

Posted on 8 April 2015 by John Hartz

Calif. continues to shatter temperature records

The dubious records keep piling up for California, a state wracked by four years of drought brought on by a pernicious weather pattern that has kept rains at bay and exacerbated by human-induced warming. Just one week after the state measured its lowest-ever snowpack, U.S. scientists have announced that the year so far has been the warmest on record, setting expectations for a long, hot, dry year ahead.

“2015 to date has been truly astonishingly warm in California, and we're breaking almost all the temperature records there are to break,” Daniel Swain, an atmospheric science PhD student at Stanford University, said in an email.

Calif. Continues to Shatter Temperature Records by Andrea Thompson, Climate Central, Apr 8, 2015



The global warming 'pause' is more politics than science

Posted on 8 April 2015 by dana1981

The so-called 'pause' in the rate of global warming is false and distracting. It is a politically engineered excuse to avoid taking action on climate change.

Over the past 17 years, the Earth has warmed rapidly, accumulating energy at a rate equivalent to more than four atomic bomb detonations per second. That's over 2 billion atomic bombs worth of heat built up on our planet since 1998.

As discussed in a new book by one of us (Dana Nuccitelli) Climatology versus Pseudoscience, research has shown that much of the heat buildup during that time was deposited in the deep layers of the Earth's oceans, temporarily keeping it from the surface.

A new article co-authored by the other of us (Michael Mann), shows that natural ocean oscillations have recently acted to temporarily slow the warming of the Earth's surface temperatures, in combination with a relatively quiet sun, and active volcanoes.

Despite this temporary masking of some of the surface warming, 2005, 2010, and 2014 each set records for global surface temperature, and 2015 is thus far on pace to break the record once again. Such is the profound nature of human-caused global warming, that it has overcome these many short-term natural cooling influences.

Yet a purported global warming 'pause' (more aptly named the 'faux pause') is often used as an excuse by those who oppose taking action to curb climate change. For example, Republican Senator and US presidential candidate Ted Cruz recently said on American TV:

"Many of the alarmists on global warming, they've got a problem because the science doesn't back them up. In particular, satellite data demonstrate for the last 17 years, there's been zero warming."

This assertion is problematic for several reasons.



The history of emissions and the Great Acceleration

Posted on 7 April 2015 by Andy Skuce

 This is a repost from the Critical Angle blog.

One of my pastimes is downloading data and playing around with it on Excel. I’m not kidding myself that doing this means anything in terms of original research, but I do find that I learn quite a lot about the particularities of the data and about the science in general by doing some simple calculations and graphing the numbers. There’s even occasionally a small feeling of discovery, a bit like the kind that you experience when you follow a well-trodden path in the mountains for the first time:

We were not pioneers ourselves, but we journeyed over old trails that were new to us, and with hearts open. Who shall distinguish? J. Monroe Thorington

Anyway, I downloaded some historical emissions data from the CDIAC site and played around with it. To repeat, there’s nothing new to science here, but there were a few things that I found that were new to me. First, let’s look at historical emissions of CO2 from man-made sources from 1850 to 2010. Note that for all of these graphs there are no data shown for 2011-2015.

What immediately struck me—something I hadn’t fully appreciated before—was how small oil consumption was before 1950. Both world wars were carried out without huge increases in oil use, despite the massive mobilizations of armies, navies and air forces. You can make out some downward blips in coal consumption for the Great Depression (~1930) and around the end of WW2 (~1945).

It wasn’t until after 1950 that fossil-fuel consumption went nuts. Some people have taken to calling this inflection point The Great Acceleration, there’s more on this later.

What do these emissions from different sources look like as a proportion of all human emissions over this time period?



A revealing interview with top contrarian climate scientists

Posted on 6 April 2015 by dana1981

In 1990, University of Alabama at Huntsville scientists Roy Spencer and John Christy created a data set that estimates the temperature of the Earth’s atmosphere by using instruments on satellites (microwave sounding units) that measure microwave radiation in the atmosphere. According to their latestestimates, the Earth’s lower atmosphere has warmed significantly since satellite measurements began in 1979, but not quite as fast as thermometer measurements of temperatures at the Earth’s surface.

Spencer and Christy have also long disputed the degree to which humans are contributing to that warming, and have thus often been called to testify before Congress by policymakers seeking justification to oppose climate legislation. On the 25th anniversary of their satellite data set, interviewed the pairto discuss their science and climate contrarianism. The resulting discussion was quite revealing. 



2015 SkS Weekly Digest #14

Posted on 5 April 2015 by John Hartz

SkS Highlights

Rob Painting's Sea Level Rise is Spiking Sharply drew the highest number of comments of the articles posted on SkS during the past week. Attracting the second highest number of comments was Dana's Global warming and drought are turning the Golden State brown

Toon of the Week

2015 Toon 14 



2015 SkS Weekly News Roundup #14B

Posted on 4 April 2015 by John Hartz

Antarctica’s record high temp bodes ill for ice

The Antarctic Peninsula is one of the fastest warming spots on the planet, but in recent days, a stubborn weather pattern sent temperatures skyrocketing there, setting a record high for the continent.

While the event that set the mercury soaring — called a Chinook, or foehn wind — isn’t unusual for the region, it does seem to be increasing with climate change, as winds around Antarctica become stronger. Scientists are worried that if these sudden warming events become more common or more intense, they could put the already threatened ice of the peninsula in an even more precarious situation, with serious implications for global sea level rise.

The peninsula of Antarctica is a slender arm of land that reaches out from the continent toward South America. It has warmed by about 5°F in the past 50 years, while the globe as a whole has warmed about 1.3°F.

Antarctica’s Record High Temp Bodes Ill for Ice by Andrea Thompson, Climate Central, Apr 1, 2015



We must defend science if we want a prosperous future

Posted on 3 April 2015 by Guest Author

This article was originally published on The Conversation. Read the original article.

Barry Jones, University of Melbourne

Today’s Australians are, by far, the best educated cohort in our history –- on paper, anyway -– but this is not reflected in the quality of our political discourse. We appear to be lacking in courage, judgement, capacity to analyse and even simple curiosity, except about immediate personal needs.

There are more than 1.1 million university students, both undergraduate and postgraduate (about 900,000 of them locals), currently at Australian universities.

Australia also has about 4.5 million graduates (nearly 20% of the population), far more than the total numbers of traditional blue collar workers. Members of trade unions amount to about one million people: 18% of the total work force and about 12% of the private sector.

Inevitably, these numbers will shift our political culture, but the process is occurring slowly.

Australia, like the US, UK, Canada and much of Europe, has undergone a serious decline in the quality of debate on public policy. The British journalist Robert Fisk has called this “the infantilisation of debate”.

In the era of “spin”, when a complex issue is involved, leaders do not explain. They find a mantra (“stop the boats!”) and repeat it endlessly, “staying on message”, without explanation or qualification. The word “because” seems to have fallen out of the political lexicon.

Evidence-based policies and actions should be a central principle in the working of our system and reliance on populism and sloganeering should be rejected, but in reality they are not.



Climate sensitivity is unlikely to be less than 2C, say scientists

Posted on 2 April 2015 by Guest Author

This is a re-post from Roz Pidcock at Carbon Brief

Does the fact that surface temperatures are rising slower than in previous decades mean scientists have overestimated how sensitive the Earth's climate is to greenhouse gases?

It's a question that's popped up in the mediafrom time to time. And the short answer is probably no, according to a new paper in Nature Climate Change.

Using temperature data up to 2011, the authors work out a value of climate sensitivity of 2.5C, comfortably within the range where scientists have suggested the 'real' value lies.

Questions about climate sensitivity are complicated, and won't be solved by any single bit of research. But the new paper seems to contribute to a growing confidence among scientists that climate sensitivity is unlikely to be less than 2C.

A lower limit

Equilibrium climate sensitivity (ECS) is the warming we can expect per doubling of atmospheric carbon dioxide above pre-industrial levels. In 2013, the Intergovernmental Panel on Climate Change (IPCC) estimated the value is likely to lie between 1.5 and 4.5C. This marked a change from previous reports, which put the lower boundary at 2C.

The new paper says lowering of the limit was partly "an effect of considering observations over the warming hiatus". This refers to the last 15 years or so in which surface temperatures have risen slower than in past decades, even though we're emitting greenhouse gases faster.




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