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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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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?


B.C. lowballing fugitive methane emissions from natural gas industry

Posted on 8 October 2015 by Andy Skuce

This article was first published in the Corporate Knights Magazine.

There is a supplementary article at my blog Critical Angle, that has more detail, links and references, along with an estimation of the GHG emissions (excluding end-use) associated with one liquefied natural gas project and the effect this will have on the feasibility of BC reaching its emissions targets.

There is a further piece at DeSmog Canada, where I compare the situation in BC's gas industry with the Volkswagen emissions reporting scandal, in which a corporation cheats on its emissions tests, with the tacit approval of industry-friendly regulators and governments, only to be exposed by independent researchers performing tests in real-world situations.

The push by British Columbia to develop a new liquefied natural gas (LNG) export industry raises questions about the impact such activities would have on greenhouse gas emissions, both within the province and globally.

One of the single most important factors relates to the amount of methane and carbon dioxide that gets released into the atmosphere, either deliberately through venting or by accident as so-called fugitive emissions. Fugitive emissions are the result of valves and meters that release, by design, small quantities of gas. But they can also come from faulty equipment and from operators that fail to follow regulations.

Photo by Jesús Rodríguez Fernández (creative commons)

According to the B.C. Greenhouse Gas Inventory Report 2012, there were 78,000 tonnes of fugitive methane emissions from the oil and natural gas industry that year. B.C. produced 41 billion cubic metres of gas in 2012. This means about 0.28 per cent of the gas produced was released into the atmosphere.

By North American standards, this is a very low estimate. The U.S. Environmental Protection Agency (EPA) uses a figure of 1.5 per cent leakage, more than five times higher. Recent research led by the U.S. non-profit group, Environmental Defense Fund (EDF), shows that even the EPA estimates may be too low by a factor of 1.5. B.C.’s estimate, in other words, would be about one-eighth of what has been estimated for the American gas industry.

Although the amounts of methane released are small compared to carbon dioxide emissions, methane matters because it packs a much bigger global warming punch. Determining the effect of methane emissions is complicated because molecules of methane only last in the atmosphere for a decade or so and the warming effect from its release depends on the time interval it is measured over. Compared to a given mass of carbon dioxide, the same mass of methane will produce 34 times as much warming over 100 years, or 86 times as much over 20 years.



2015: Still No Let Up in Ocean Warming

Posted on 7 October 2015 by Rob Painting

Ocean warming has made up 93% of global warming in the last 5 decades (IPCC AR5 Chapter 3) and the first six months of ocean heat data for 2015 are now available from the National Centers for Environmental Information (NCEI). Armed with the knowledge that increasing industrial greenhouse gas emissions trap ever more heat in the atmosphere and ocean, it will come as no surprise whatsoever to learn that the strong ocean heating of recent years has continued into 2015. 

Figure 1 - Ocean heat content data up to June 2015 for the 0-2000 meter layer of the global ocean. Image from NOAA's National Center for Environmental Information.   

In contrast to the Northern Hemisphere, the surface area of the Southern Hemisphere is dominated by the ocean and it's therefore the end of Southern Hemisphere summer, when that hemisphere is closest to the sun, that ocean heat uptake is strongest. Loeb et al (2012), however, demonstrated that outgoing longwave radiation (heat loss) from the Earth increases during El Niño, so it will be interesting to see how things pan out over the next 6-8 months given that we have a powerful El Niño still developing in the Pacific Ocean. We may see a temporary reduction in the rate of ocean warming as the El Niño discharges a greater-than-normal amount of tropical ocean heat to the atmosphere. Inevitably, much of this surplus heat will be radiated out to space.  



Skeptical Science reader survey - thanks for your feedback!

Posted on 6 October 2015 by BaerbelW

Thanks a lot to all of you who participated in our reader survey, providing lots of feedback for us to sift through and mull over! We'll share some snapshots of the results in this post and include some of your written comments, selected from those responses where you've given us your consent to share them.

Some statistics

We received 314 filled out surveys over the course of a week with most of them coming in the first 3 days after we posted the link. About 30 different countries show up in the results, with the US, Australia, the UK and Canada listed the most often which also makes English the most often mentioned first language.

Some results

Blog posts


SurveyResultsResearchSelected comments about blog posts:

"It is the first resource I look for comments and discussions about new research."

"i became aware of your site a few years ago, it's a great resource, helped me understand the science."

"it is in the comments where this blog shines. you are doing it right and the community you have nurtured works well and is something i read often"

"The only reason I did not rate blog posts as extremely valuable, is many are available on other blogs I visit regularly. If SKS was my sole source, I would have rated all as extremely valuable. I do have high confidence in what I read at SKS."

"It's tough not to give you folks top marks - Your articles are straight forward and gear towards the intelligent layperson. The links you offer to back up everything described is most excellent. Keep up the good work."

"I find the site very rewarding. Climate change has been a long time interest and to find the wide ranging content is engaging my interest in an ongoing way."


SurveyResultsRebuttalsSelected comments about rebuttals:



The Republican Party stands alone in climate denial

Posted on 5 October 2015 by dana1981

A paper published in the journal Politics and Policy by Sondre Båtstrand at the University of Bergen in Norway compared the climate positions of conservative political parties around the world. Båtstrand examined the platforms or manifestos of the conservative parties from the USA, UK, Norway, Sweden, Spain, Canada, New Zealand, Australia, and Germany. He found that the US Republican Party stands alone in its rejection of the need to tackle climate change and efforts to become the party of climate supervillains.

Republicans would be fringe in any other country

As Jonathan Chait wrote of Republican presidential candidate Jeb Bush’s proposals to eliminate all significant American national climate policies,

In any other democracy in the world, a Jeb Bush would be an isolated loon, operating outside the major parties, perhaps carrying on at conferences with fellow cranks, but having no prospects of seeing his vision carried out in government. But the United States is different. Here in America, ideas like Bush’s fit comfortably within one of the two major political parties. Indeed, the greatest barrier to Bush claiming his party’s nomination is the quite possibly justified sense that he is too sober and moderate to suit the GOP.

So, what’s different about the United States? One factor is the immensely profitable and politically influential fossil fuel industry. However, Canada and Australia serve as useful analogues. With Australian coal reserves and Canadian tar sands, fossil fuels account for a larger share of both countries’ economies. Nevertheless, Båtstrand noted,

The [Republican] party seems to treat climate change as a non-issue ... this appears to be consistent with the U.S. national context as a country with large reserves of coal.



2015 SkS Weekly Digest #40

Posted on 4 October 2015 by John Hartz

SkS Highlights... El Niño Watch... Toon of the Week... Quote of the Week... They Said What?... Poster of the Week... Coming Soon on SkS... SkS Week in Review... and 97 Hours of Consensus

SkS Highlights

Was Broecker really the first to use the term Global Warming? by Ari Jokimäki attracted the highest number of comments of the articles posted on SkS during the past week. Not only is Jokimäki's original research very informative, but the commentary also adds to the body of knowledge. If you have not done so already, you will want to check it out. 

El Niño Watch

African crops, economies at risk as El Nino threatens to scorch and soak by Ed Stoddard, Reuters, Oct 2, 2015

Toon of the Week

 2015 Toon 40

Hat tip to I Heart Climate Scientists



2015 SkS Weekly News Roundup #40

Posted on 3 October 2015 by John Hartz

A chronological listing of the news articles posted on the Skeptical Science Facebook page during the past week.

Sun, Sep 27



Emphasizing co-benefits motivates people to take action on climate change

Posted on 2 October 2015 by John Abraham

A new paper published in the journal Nature Climate Change provides encouragement that people can be motivated to act on climate change. The title of the paper is, “Co-benefits of Addressing Climate Change can Motivate Action Around the World.” Lead author Dr. Paul Bain and his colleagues wanted to know if emphasizing co-benefits when talking about climate change would motivate people to take action. They found that in many cases, the answer is yes.

First of all, what are co-benefits? Pulitzer Prize-winning cartoonist Joel Pett provided some good examples in this cartoon.

Let’s say that you design a city so that there are green spaces and parks in a hope that you will reduce pollution. You might find out that the green spaces and parks cool the city, provide places of recreation and exercise, and generally improve the quality of life beyond merely pollution. These would be called co-benefits; they are extra benefits you get from your action.

The authors of this new study surveyed more than 6,000 people in 24 different countries to find out whether emphasizing co-benefits would make people more likely to act on climate. They classified co-benefits into four categories: development, benevolence, dysfunction, and competence. 

Economic development is an example of a potential development co-benefit. For instance, installing wind turbines would lower greenhouse gas emissions andcreate jobs (jobs are a co-benefit). Benevolence relates to the how caring and moral people are in society and competence relates to whether people are skilled and/or capable. Dysfunction deals with negative effects such as pollution and disease. For instance, decreased disease and airborne pollution are a co-benefits.



Was Broecker really the first to use the term Global Warming?

Posted on 30 September 2015 by Ari Jokimäki

"Global warming" is a term that is most commonly used to describe an increase in global mean surface temperature. Sometimes global warming has been used more broadly to also include temperature evolution in troposphere. In some cases the term has been falsely used in the place of the term "climate change", which has a different meaning. "Climate change" can be any change in climate parameters (for example rainfall or wind) and it doesn't have to be global.

J. Murray Mitchell. Photo from AIP website.

J. Murray Mitchell, Jr. at his home weather station. Photo from Emilio Segrè Visual Archives via AIP website.

The usage of global warming can be traced back at least to 1961 by J. Murray Mitchell Jr. (more on this below). However, NASA has a page by Eric Conway on the terminology which mistakenly claims on the origin of the term global warming:

"Its first use was in a 1975 Science article by geochemist Wallace Broecker of Columbia University's Lamont-Doherty Geological Observatory: "Climatic Change: Are We on the Brink of a Pronounced Global Warming?""

Let us see what earlier papers we can find that used the term. What is interesting, among other things, in Broecker's paper is that it uses both climate change (in the form of climatic change) and global warming in its title. Going further back from the claimed originating year of the term global warming, we somewhat interestingly find Idso (1974):



Is the fossil fuel industry, like the tobacco industry, guilty of racketeering?

Posted on 29 September 2015 by dana1981

ExxonMobil has become infamous for its secretive anti-climate science campaign, having spent $30 million funding groups denying the scientific evidence and consensus on human-caused global warming.

Last week, after an eight-month investigation, InsideClimate News revealed that from the late-1970s to the mid-1980s, scientists at Exxon were in fact at the cutting edge of climate science research.

Exxon documents show that top corporate managers were aware of their scientists’ early conclusions about carbon dioxide’s impact on the climate. They reveal that scientists warned management that policy changes to address climate change might affect profitability. After a decade of frank internal discussions on global warming and conducting unbiased studies on it, Exxon changed direction in 1989 and spent more than 20 years discrediting the research its own scientists had once confirmed.

In an internal September 1982 document, Exxon scientists summarized the expert consensus on human-caused global warming, and the consistency of their own research with that expert consensus.

The consensus is that a doubling of atmospheric CO2 from its pre-industrial revolution value would result in an average global temperature rise of (3.0 ± 1.5)°C … There is unanimous agreement in the scientific community that a temperature increase of this magnitude would bring about significant changes in the earth’s climate, including rainfall distribution and alterations in the biosphere … the results of our research are in accord with the scientific consensus on the effect of increased atmospheric CO2 on climate.

It’s ironic that 33 years ago, the world’s largest oil company accepted and concurred with the scientific consensus on human-caused global warming thatmany people continue to deny to this day.

In another internal company document in November 1982, Exxon scientists illustrated the rapid global warming they expected to occur over the following century due to rising carbon pollution from burning fossil fuels. A year earlier, Exxon scientists were discussing the distinct possibility that the consequences of climate change could become catastrophic in the near future.

exxon temp projections

Exxon’s 1982 projections of how human carbon pollution would cause global temperatures to rise.



Drought stunts tree growth for four years, study says

Posted on 28 September 2015 by Guest Author

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

Trees could take up to four years to return to normal growth rates in the aftermath of a severe drought, a new study finds. 

With the frequency and severity of droughts likely to increase with climate change, we might not be able to rely on forests to absorb as much of our carbon emissions, the researchers say.

Drought stress

Forests hold almost half of the carbon found on the Earth's surface, storing it in their woody trunks and branches. Studies show that forests are sensitive to droughts, causing tress stress and limiting how much they can grow and store carbon.

During the European heatwave in 2003, for example, tree and plant growth fell by 30%. That meant the land surface in Europe actually produced more carbon dioxide than it absorbed that year.

The new study, published in Science, suggests that it takes longer for trees to recover after a severe drought than previously thought.

Tree rings

Using data from the International Tree Ring Data Bank, researchers analysed tree growth at over 1,300 sites across the northern hemisphere countries. The sites are predominantly in North America and Europe, and oak and pine trees make up the majority of the species the researchers considered.

Tree rings provide a handy estimate of how quickly a tree has grown. As a tree grows, it puts on extra layers of wood around its trunk, creating a new ring each year. The quicker a tree grows, the bigger the gap between tree rings from one year to the next. 

800px -tree _rings

Tree rings. Creative Commons 2.5: Arnoldius



2015 SkS Weekly Digest #39

Posted on 27 September 2015 by John Hartz

SkS Highlights... El Niño Watch... Vision of the Week... Quote of the Week... He Said What?... Poster of the Week... Coming Soon on SkS... SkS Week in Review... and 97 Hours of Consensus: Michael Raupach

SkS Highlights

Scientists Respond  To Tol’s Misrepresentation Of Their Consensus Research by Collin Maessen attracted the most comments of the articles posted on SkS during the past week. Climate change set to fuel more "monster" El Niños, scientists warn by Roz Pidcock and Tracking the 2C Limit - August 2015 by Rob Honeycutt each garnered the secondhighst number of comments. 

El Niño Watch

Vision of the Week

2015 Toon 39 

Hat tip to I Heart Climate Scientists



2015 SkS Weekly News Roundup #39

Posted on 26 September 2015 by John Hartz

A chronological listing of the news articles posted on the Skeptical Science Facebook page during the past week.

Sun, Sep 20



Celebrated NASA planet hunter shifts his sights back to climate change on Earth

Posted on 24 September 2015 by dana1981

William Borucki has had an amazing scientific career. One of his first jobs was at NASA Ames Research Center, where he worked on the Apollo moon missions, including helping to develop the heat shield for the space shuttle. After the successful moon landings, Borucki shifted to NASA’s Theoretical Studies Branch in the 1970s, where he developed models of the Earth’s atmosphere to predict the effects of nitric oxides and chlorofluoromethanes on the ozone layer. Both were determined to contribute to the problem of ozone depletion and the hole in the ozone layer.

In the 1980s, Borucki began advocating the development of a space mission that could detect Earth-size planets. He published a paper in 1984 showing that a photometer 1,000 times more precise than any in existence could detect Earth-size planets. Undeterred by rejections of four proposals in the 1990s for a planet-finding mission, Borucki was ultimately appointed Principle Investigator in 2001 for NASA’s new Keppler Mission to discover these planets. During its four years of its operation, the Kepler Mission discovered over 4,600 planetary candidates, confirmed more than 1,000 as planets, and made numerous contributions to stellar astrophysics.

For his work in conceiving and leading the Kepler Mission, Borucki was awarded the Shaw Prize in astronomy. He decided to donate a portion of the award to the Union of Concerned Scientists (UCS) to support the organization’s work in addressing climate change, explaining,



Climate change set to fuel more "monster" El Niños, scientists warn

Posted on 23 September 2015 by Guest Author

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

The much-anticipated El Niño gaining strength in the Pacific is shaping up to be one of the biggest on record, scientists say. With a few months still to go before it reaches peak strength, many are speculating it could rival the record-breaking El Niño in 1997/8.

Today, a new review paper in Nature Climate Change suggests we can expect more of the same in future, with rising temperatures set to almost double the frequency of extreme El Niño events.


Every five years or so, a change in the winds causes a shift to warmer than normal sea surface temperatures in the equatorial Pacific Ocean - known as El Niño.

Together with its cooler counterpart, La Niña, this is known as the El Niño Southern Oscillation (ENSO) and is responsible for most of the fluctuations in global weather we see from one year to the next.

Last week, US scientists confirmed they expect "a strong El Niño" to peak in the next few months. The event brewing in the Pacific is already "significant and strengthening", said the statement from NOAA's Climate Prediction Centre.



Scientists Respond To Tol’s Misrepresentation Of Their Consensus Research

Posted on 22 September 2015 by CollinMaessen

To quote John Reisman, “Science is not a democracy. It is a dictatorship. It is evidence that does the dictating.” It’s this evidence based ‘dictatorship’ that is the basis for a scientific consensus. Based on this ‘dictatorship’ of evidence we know that global warming is real, we’re causing it, and that it’s a problem if we don’t act. This presents a real problem for those denying that there is a problem or want to minimize the consequences.

In science careers are made by overturning existing ideas and findings. This is why a consensus can only arise in science when other scientists cannot find flaws in earlier findings. As Richard Alley has said about showing that global warming isn’t a problem: “Is there any possibility that [among] tens of thousands of scientists there isn’t one of them that got the ego to do that? It’s absurd!

Falsifying a well established scientific theory or concept advances the career and the reputation of a scientist far more than confirming it does.

Attacking the consensus

This is why the paper published in 2013 by Cook et al. that analysed the scientific consensus on human caused global warming in the scientific literature is attacked so much. Finding a consensus of 97% in the scientific literature that we’re causing most of the rise in temperature is inconvenient for them. If they manage to discredit these studies, or sow doubt about them, you’ll prevent the public from acting:

Like Oreskes said, spreading doubt is the most effective strategy a science denier has. This type of attack is crucial to maintain a gap between what scientists agree on and what the public thinks scientists agree on so you can delay action. This tactic is how the tobacco industry successfully delayed action against the harmful effects of smoking for decades.

The consensus gap

A consensus is dangerous for those who deny human caused global warming, or minimize its consequences, as it shows, that they are in the minority. They are a very small percentage compared to the scientists who say, based on the evidence, that human caused global warming is a reality.

That’s why one of the most often used tactics is trying to make the consensus seem tiny. During an interview with me Dana Nuccitelli, one of the authors of Cook 2013, explained how this tactic is used on Cook 2013:



Tracking the 2C Limit - August 2015

Posted on 21 September 2015 by Rob Honeycutt

We ticked up this month over last month on the current 12 month average temperature anomaly in the GISS data. In July we stood at 1.060C and August is now 1.074C. Full size image here.

The Japanese Meteorological Agency is showing very strong, rapid warming with August hitting a new high anomaly. This is likely due to the current El Nino starting to express itself in the surface temperature data.

The weekly ENSO report from NOAA shows that the current El Nino is still going strong, but we're about to move into another downwelling phase (dotted line). But that will probably be followed by yet another upwelling phase (dashed line). Overall, you can see quite a lot of heat coming out of the equatorial ocean over the past 6 months.

Model predictions suggest the current El Nino is going to persist through the rest of the year, and on into the Spring before subsiding again. Bear in mind, there's a 4-6 month delay between the El Nino and when that heat gets expressed in the surface temperature data. 



2015 SkS Weekly Digest #38

Posted on 20 September 2015 by John Hartz

SkS Highlights... El Niño Watch... Toon of the Week... Quote of the Week... He Said What?... SkS in the News... SkS Spotlights... Poster of the Week... Coming Soon on SkS... SkS Week in Review... and 97 Hours of Consensus

SkS Highlights

In a blind test, economists reject the notion of a global warming pause by John Abraham (Climate Consensus-the 97%, The Guardian) drew the most comments of the articles posted on SkS during the past week. Exxon's Own Research Confirmed Fossil Fuels' Role in Global Warming Decades Ago by Neela Banerjee, Lisa Song and David Hasemyer (Inside Climate News) attracted the second highest. 

El Niño Watch

Toon of the Week

2015 Toon 38 

Hat tip to I Heart Climate Scientists



2015 SkS Weekly News Roundup #38

Posted on 19 September 2015 by John Hartz

A chronological listing of the news articles posted on the Skeptical Science Facebook during the past week.

Sun, Sep 13



In a blind test, economists reject the notion of a global warming pause

Posted on 18 September 2015 by John Abraham

Oh how resilient myths can be, even in the face of facts. This past week saw the publication of the third strong refutation of the myth that global warming had somehow stopped a decade or two ago. You would think that with 2014 the hottest year on record and 2015 almost certain to exceed that, and 2016 to potentially set yet another heat record, people would use common sense to conclude that global warming continues. You’d also think with ocean heating breaking records (as discussed here) and loss of ice around the world, any lingering doubts would be put to rest. But alas, for some reason, even more proof is needed.

The first paper, which I covered here looked at the actual temperature trends and found no statistically significant reduction in the rate of warming. The latest paper, just published in the Bulletin of the American Meteorological Society by Stephan LewandowskyJames Risbey, and Naomi Oreskes, looks at the evolution of the terms “pause” and “hiatus.” The authors find that over the past decade or so, there has been a lot of interest in both the scientific community (as judged by papers covering the topic) and by the general public (as determined by web-search statistics). 



Global warming's one-two punch: extreme heat and drought

Posted on 17 September 2015 by John Abraham

As humans emit greenhouse gases into the environment, it causes the Earth to warm, we already know that. What is less certain is how it will cause changes to the weather we experience in our lives. In the past few years, research looking into the connection between a warming planet and more extreme weather has found more conclusive connections.

I have covered extreme weather quite a bit recently, because the science is so compelling and new. But a new paper published in the Proceedings of the National Academy of Sciences by doctoral student Omid Mazdiyasni and his advisor Amir AghaKouchak takes a fresh look at this topic. 

Instead of just looking at heat waves or just looking at precipitation, they looked for concurrent events. Droughts can be caused by reduced precipitation. Hot weather speeds evaporation and damages the environment. But droughts and high temperatures can happen at the same time. These concurrent-event droughts are particularly harmful, they can set in fast and severely.

The authors present results of various heat wave severity (85%, 90%, and 95% events) and for various durations (3 day, 5 day, and 7 day events). Focusing on 1960-2010, they found that the concurrence of all combinations of drought, heat wave intensity, and heat wave durations “have increased substantially in the south, southeast, and parts of the western USA.” 



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