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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?


Global warming can't be blamed on CFCs – another one bites the dust

Posted on 18 April 2014 by dana1981

A paper published in the International Journal of Modern Physics B by the University of Waterloo's Qing-Bin Lu last year claimed that solar activity and human chlorofluorocarbon (CFC) emissions, not carbon emissions, could explain the observed global warming over the past century.  The journal has now published a rebuttal of that paper by Skeptical Science team members Dana Nuccitelli, Kevin Cowtan, Peter Jacobs, Mark Richardson, Robert Way, Anne-Marie Blackburn, Martin Stolpe, and John Cook.

As I recently discussed, contrarian climate research like this blaming global warming on Anything But Carbon (ABC) tends to receive disproportionate media attention.  Lu's paper was a prime example, receiving substantial media attention when it was published in May 2013.  For example, the paper was trumpeted by a University of Waterloo press release and a Science Daily article, both of which used exaggerated language like "Lu’s theory has been confirmed."  ABC News did a better job covering the paper, talking to climate scientist David Karoly, who expressed appropriate skepticism about a paper which purports to overturn decades and even centuries of well-established physics and climate science in one fell swoop.  Characteristically, The Australian then criticized ABC News for failing to be "fair and balanced" because they interviewed an actual climate expert about the paper.

As we discussed at the time, the paper contained numerous clear fundamental flaws.  For one, the underlying argument was based on "curve fitting" or "overfitting," which is when the variables in a model are arbitrarily scaled to match the observational data.  In this case, Lu took the global energy imbalance caused by CFCs (which are greenhouse gases) and scaled them up dramatically to match measurements of global surface temperatures.

Lu then also had to explain why CFCs would be increasing the greenhouse effect, but carbon dioxide wouldn't.  To accomplish this, he invoked the saturated gassy argument – claiming that increased CO2 can't cause more warming because there is already so much in the atmosphere that its greenhouse effect has become saturated.  This argument was first made by Knut Ångström in 1900, but was conclusively disproved by E. O. Hulburt in 1931 and military research in the 1940s.  Lu misinterpreted several recent papers to revive the argument, but as we showed in our paper, it still remains incorrect.

Ultimately Lu's argument was that global surface warming has slowed in recent years, and his model using CFCs and solar activity could accurately match those observations.  However, Lu used outdated and superseded surface temperature measurements with a cool bias that exaggerated that surface warming slowdown (HadCRUT3).  He also used an extremely outdated reconstruction of solar activity.  We showed that even ignoring the unphysical "curve fitting" in his model, models using current known human climate forcings produced a more accurate fit to up-to-date surface temperature measurements (HadCRUT4) than Lu's model (r2 of 0.81 vs. 0.72).

Nuccitelli et al. (2014) Fig 1

Replication of Lu (2013) Figure 12 using more recent data and a realistic response function. The fit between the anthropogenic forced response (black dashed line) and adjusted temperatures (red squares) is superior to the fit to CFC forcing (green solid line), even allowing for an additional unphysical scaling and lag as in Lu (2o13) (green dashed line).



The consequences of climate change (in our lifetimes)

Posted on 17 April 2014 by Rob Honeycutt

Journalist Peter Hadfield (aka Potholer54) has a new video out on climate change issues. Peter takes his usual effective approach of imploring people to not rely solely on blogs for information. You have to actually read the published scientific literature, which is a proposition even Skeptical Science adheres to. (Authors at SkS are expected to cite references for their claims and we hope our readers take the time to follow through and check those sources.)

It's interesting that Peter is taking on the "in our lifetimes" aspect of climate change, because this is an issue I've often noticed that many people don't grasp. There are far too many people out there who somehow erroneously came to believe that all the predictions in Al Gore's An Inconvenient Truth were going to happen in a few years. 

One of the most deeply complex aspects of climate change is cross generational responsibility. There are definitely impacts that we are already seeing, and we there are more impacts that we are going to see in the coming decades. But the worst is being saved for those who follow us. Our children and grandchildren. 

Peter takes the time to carefully walk us through several aspects of climate change – ice melt, sea level rise, crop production, precipitation and feedbacks – with his engaging wit. And, with appropriate balance, he doesn't hesitate to address errors related to extreme climate impacts that are not scientifically supportable.



Heartland logic: More people have heard of Fidel Castro than Michael Mann, therefore global warming is false.

Posted on 16 April 2014 by Guest Author

This is a guest post from Narahani.


Or is happening and is good for you, or has stopped happening, or is caused by CO2 but only a little, or is about to reverse due to lots of yet-to-be-discovered negative feedbacks, and clouds. And anyhow, peas and water lilies love CO2 so ramping it up to 1000 ppm would be fantastic. The logic is dizzying.  

And yes, Joe Bast repeated his widely criticized statement equating people who support action to limit climate change with "murderers, tyrants, and madmen," declaring that the fact that more people have heard of Fidel Castro than Michael Mann proves his case.

Heartland Institute came to Washington this week to tout their second major effort to discredit the IPCC with a hefty volume ("over 1000 pages!" they keep boasting). This one advertises the benefits of carbon dioxide to plants. The first volume trotted out a long list of well-debunked theories including the old standbys: there is no consensus, "solar cyclicity" is about to cause cooling, and conversely, warming in occurring but will be less than predicted by the IPCC.



2014 SkS News Bulletin #3: IPCC Report (WG III)

Posted on 15 April 2014 by John Hartz

Averting catastrophe is eminently affordable

Catastrophic climate change can be averted without sacrificing living standards according to a UN report, which concludes that the transformation required to a world of clean energy is eminently affordable. “It doesn’t cost the world to save the planet,” said economist Professor Ottmar Edenhofer, who led the Intergovernmental Panel on Climate Change (IPCC) team.

The cheapest and least risky route to dealing with global warming is to abandon all dirty fossil fuels in coming decades, the report found. Gas – including that from the global fracking boom – could be important during the transition, Edenhofer said, but only if it replaced coal burning.

IPCC climate change report: averting catastrophe is eminently affordable by Damian Carrington, The Guardian, Apr 13, 2014



If growth of CO2 concentration causes only logarithmic temperature increase - why worry?

Posted on 15 April 2014 by Marcin Popkiewicz

Because exponential growth of CO2 concentration causes only linear raise in temperature, people sometimes think that subsequent emissions will result in ever slower temperature increases. Well, the most persistent myths are based on technically true statements - that’s true also in this case.

It is true, that for each doubling of CO2 concentration, temperature increases by a constant value. However, at the current level of CO2 content in the atmosphere a good approximate relation is that for each 500 GtC (1833 bn tons of CO2) we can expect equilibrium temperature increase by approximately 1°C. Moreover, because of the continuing exponential growth of CO2 emissions the temperature increase will also accelerate.

Slowing temperature rise as a function of CO2 concentration

When we talk about the temperature increase in response to the growth of greenhouse gases concentration in the atmosphere, we mean the total increase in average temperature which will continue until the Earth’s total energy budget reaches equilibrium. Both numerical simulations using climate models, as well as paleoclimatic research and direct measurements show that in response to doubling of the atmospheric CO2 concentration, (which is equivalent to a radiative forcing of 4W/m2), the Earth’s surface will most probably warm up by about 3°C.
Hence, we can expect a 3°C average temperature increase when the carbon dioxide concentration changes from the pre-industrial level of 280 ppm to 560 ppm. Subsequent temperature increase by another 3°C will require growth of CO2 concentration from 560 to 1120 ppm.

Linear temperature growth as a function of CO2 emissions

Should we therefore draw a conclusion that the rate of temperature increase will steadily drop? Not necessarily, and definitely not if current emissions trends persist in the future. In order to understand key relationships let’s take a look at the connection between our cumulative emissions and the projected temperature increase published in the 5th IPCC report.



Climate contrarian backlash - a difficult lesson for scientific journals to learn

Posted on 14 April 2014 by dana1981

Scientific journals have had a bumpy road trying to learn how to deal with climate contrarians. Poor decisions by journal staff in dealing with contrarians have often led to editors resigning and a damaged reputation in the academic community.

The latest such example is the journal Frontiers and its response to bullying by contrarians over a paper by Stephan Lewandowsky and colleagues. The paper analyzed the conspiratorial psychology of contrarian comments made on public blogs. As I previously documented, Frontiers received a number of complaints from contrarians that this analysis of their public comments was libelous or defamatory, and the journal ultimately caved and decided to retract the paper.

In its investigation, Frontiers had found no academic or ethical problems with the paper, but was concerned about legal liabilities. The journal and paper authors contractually agreed to a retraction statement saying as much. However, perhaps in the face of criticism from the academic community for failing to support academically and ethically sound research, Frontiers later revised its statement to depart from the contractually agreed statement and shift all the blame to the authors, contradicting the contractually agreed upon statement.

This final move backfired and led to the resignation of three of the journal's editors, Ugo Bardi, Björn Brembs, and Colin Davis. Brembs' comments were particularly scathing,

"It is quite clear, why the content of the paper may feel painful to those cited in it, but as long as "conspiracist ideation" is not an official mental disorder, I cannot see any defamation. If you don't want to be labeled a conspiracy theorist, don't behave like one publicly on the internet. Therefore, after reading the paper, in my opinion, Frontiers ought to have supported their authors just as their home institution (UWA) is supporting them as their employees."

Robert Brulle, Professor of Sociology and Environmental Science at Drexel University has also informed me that as a result of the Recursive Fury incident, he has declined to write an article that Frontiers requested, and will no longer write or review for any Frontiers publications. The journal's reputation has undoubtedly taken a serious hit in the academic community for failing to stand behind sound research, and then trying to shift the blame to the authors of that research.

The Frontiers debacle is just the latest in a long history of interactions between contrarians and scientific journals that have not ended well for the latter. Unlike the Lewandowsky case, the previous examples involve the publication of contrarian research that's generally fundamentally flawed in peer-reviewed scientific journals, through one of the four approaches illustrated in the graphic below.

Ways contrarians get papers published in peer-reviewed journals Four ways in which flawed research gets published.



2014 SkS Weekly Digest #15

Posted on 13 April 2014 by John Hartz

SkS Highlights

Roz Pidcock's  IPCC says adapt and mitigate to tackle climate risks garnered the most comments of the articles posted on SkS during the past week. Attracting the second highest number of comments was IPCC issue official rebuttal to more David Rose/Daily Mail nonsense by John Mason.

Toon of the Week

 2014 Toon 15



2014 SkS Weekly News Roundup #15B

Posted on 12 April 2014 by John Hartz

Asgard’s fire

Thorium, an element named after the Norse god of thunder, may soon contribute to the world’s electricity supply

WELL begun; half done. That proverb—or, rather, its obverse—encapsulates the problems which have dogged civil nuclear power since its inception. Atomic energy is seen by many, and with reason, as the misbegotten stepchild of the world’s atom-bomb programmes: ill begun and badly done. But a clean slate is a wonderful thing. And that might soon be provided by two of the world’s rising industrial powers, India and China, whose demand for energy is leading them to look at the idea of building reactors that run on thorium.

Existing reactors use uranium or plutonium—the stuff of bombs. Uranium reactors need the same fuel-enrichment technology that bomb-makers employ, and can thus give cover for clandestine weapons programmes. Plutonium is made from unenriched uranium in reactors whose purpose can easily be switched to bomb-making. Thorium, though, is hard to turn into a bomb; not impossible, but sufficiently uninviting a prospect that America axed thorium research in the 1970s. It is also three or four times as abundant as uranium. In a world where nuclear energy was a primary goal of research, rather than a military spin-off, it would certainly look worthy of investigation. And it is, indeed, being investigated.

Asgard’s fire, The Economist, Apr 12, 2014



Climate imbalance – disparity in the quality of research by contrarian and mainstream climate scientists

Posted on 11 April 2014 by dana1981

A new paper has been published in the journal Cosmopolis entitled Review of the consensus and asymmetric quality of research on human-induced climate change. The paper was authored by John Abraham, myself, John Cook, John Fasullo, Peter Jacobs, and Scott Mandia. Each of the authors has experience in publishing peer-reviewed responses to flawed contrarian papers.

Despite the 97% expert consensus on human-caused global warming supported by peer-reviewed research, expert opinion, the IPCC reports, and National Academies of Science and other scientific organizations from around the world, a large segment of the population remains unconvinced on the issue. A new commentary by Edward Maibach, Teresa Myers and Anthony Leiserowitz in Earth's Future notes that most people don't know there is a scientific consensus about human-caused climate change, which undermines public engagement on the subject.

This 'consensus gap' is in large part due the media giving disproportionate coverage to climate contrarians. In our paper, we sought to evaluate whether that disproportionate media coverage was justified by examining how well contrarian hypotheses have withstood scientific scrutiny and the test of time. The short answer is, not well.

Low climate sensitivity papers by Lindzen and Spencer (open circles) and peer-reviewed rebuttals (closed circles).  Created by John Garrett of Wildomar, CA. Low climate sensitivity papers by Lindzen and Spencer (open circles) and peer-reviewed rebuttals (closed circles). Created by John Garrett of Wildomar, CA.



IPCC issue official rebuttal to more David Rose/Daily Mail nonsense

Posted on 10 April 2014 by John Mason

David Rose. That name rings a bell, huh? This was the guy who last year  manufactured an IPCC crisis meeting in the UK right-wing tabloid the Daily Mail, where he hangs out and writes pages of nonsense about climate science.  At Skeptical Science, as pointed out in the above link, we have previously pre-bunked and debunked and debunked again his articles on the subject of climate change, but he continues to appear oblivious to legitimate criticism of his work or, indeed, facts.

In his latest offering, Rose manages to turn legitimate criticism of Richard Tol into a "green smear campaign" and his co-author Ben Pile accuses the IPCC of "alarmist spin" concerning certain issues in the Final Draft of the contribution of Working Group II to the Fifth Assessment Report, which was released on March 31st 2014. Accompanying graphics accuse the IPCC of "sexing-up" these topics.


more David Rose nonsense



IPCC says adapt and mitigate to tackle climate risks

Posted on 9 April 2014 by Guest Author

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

The front page article of today's Spectator claims the Intergovernmental Panel on Climate Change (IPCC) has "updated" its position on climate change, to accept that "climate change is now a question of adaptation".

Author Matt Ridley suggests that this is such a departure from the UN climate panel's previous findings that its conclusions are now in line with those of climate skeptic lobbyist Lord Lawson.

Lawson stresses "the need to adapt to climate change, rather than throw public money at futile attempts to prevent it", according to Ridley, a fellow skeptic campaigner.

It's worth taking this with a pinch of salt. If the IPCC has said more about adaptation in the last week, it's because its most recent report is specifically about adaptation. That doesn't mean mitigation has been abandoned as Lord Lawson would like it to be - indeed, in a week's time the IPCC will publish another report dedicated to the mitigation he so scorns.

Heavy on adaptation

The crux of Ridley's argument is that adapting to climate change is given more prominence in the latest IPCC report than in past ones.

He says:

"[T]he document itself … emphasised, again and again, the need to adapt to climate change … Whereas the last report had two pages on adaptation, this one has four chapters."



2014 SkS Weekly News Roundup #15A

Posted on 8 April 2014 by John Hartz

2014 El Niño warming up to be a mighty one?

El Niño is a growing threat this year that could play havoc with weather patterns in the United States, forecasters say. 

El Niño, named for the warm waters that occasionally occur in the Pacific Ocean near South America, brings fluctuating weather that includes droughts, flooding and heat waves.

“We have above-normal temperatures in the tropical Pacific Ocean and that often precedes an El Niño because there’s a large volume of above-average water temperature below the surface of the ocean,” Anthony Barnston, chief forecaster for the International Research Institute for Climate and Society, told ABC News. “Volume often tends to come up to the surface; often, but not always.

 “That’s the uncertainty,” Barnston said. “It’s more likely to rise than not.”

2014 El Niño Warming Up to Be a Mighty One? by Danielle Genet, ABC News, Apr 7, 2014



Fox News climate change coverage is now 28% accurate, up from 7%

Posted on 8 April 2014 by dana1981

The Union of Concerned Scientists (UCS) has just published an analysis of 2013 climate coverage by the three major American cable news networks. The report and data are available online, and the results are summarized in the figure below.

Cable news climate coverage accuracy

UCS reviewed nearly 600 segments mentioning "global warming" or "climate change" across the networks' most prominent evening and weekend programs during the 2013 calendar year. Segments that contained any inaccurate or misleading representations of climate science were categorized as misleading; otherwise they were characterized as being accurate.

UCS also put the misleading statements in sub-categories that reveal the problematic tendencies of each network's climate coverage. Aaron Huertas, a science communications officer at UCS who led the analysis said of the difference between network climate coverage,

"Sometimes, it's like the networks are covering different planets. Unfortunately, too many politicians, interest groups, and pundits continue to dispute established climate science and cable shows sometimes give them a platform to do so."

The UCS analysis found that Fox News Channel hosts and guests were the most likely to accuse scientists of manipulating or hiding climate data. Fox hosts and guests often conveyed misinformation about scientific findings, including many false claims that global warming is not occurring.

Types of misleading climate coverage on Fox News



Watch Episode 1 of James Cameron's "Years of Living Dangerously"

Posted on 7 April 2014 by greenman3610

After a long period of development, James Cameron’s terrific and powerful mega-project on climate change, “Years of Living Dangerously”, opens today on Showtime.  The first hour installment of the 9 part series features glimpses of climate change impacts around the planet through the eyes of well known guides.  The first episode is free online and can be watched above.

The series sets a dramatic, powerful urgent tone. The first episode takes the bull by the horns – crisscrossing the planet to take snapshots of climate impacts, and the processes behind them, through the eyes of those impacted.

Don Cheadle explores  drought impacts in the US Southwest. Maybe not so surprising – the very people who are being crushed by the impact of climate change, lower class rural folk in Texas, are unable to make a connection between global climate and their problems. They prefer to believe the problems come from God, or natural cycles.  Climate Scientist Katharine Hayhoe is profiled in her battle against entrenched attitudes and scientific ignorance in that part of the world.



2014 SkS Weekly Digest #14

Posted on 6 April 2014 by John Hartz

SkS Highlights

Howard Lee's Alarming new study makes today’s climate change more comparable to Earth’s worst mass extinction attracted the most comments of the articles posted on SkS during the past week. Earth has a fever, but the heat is sloshing into the oceans by John Abraham garnered the second highest number of comments. Dana's IPCC report warns of future climate change risks, but is spun by contrarians was the third most commented upon.

Toon of the Week

 2014 Toon 14

h/t to I heart Climate Scientists



2014 SkS Weekly News Roundup #14B

Posted on 5 April 2014 by John Hartz

Arctic sea ice falls to fifth lowest level on record

Arctic sea ice remained on its death spiral on Wednesday, with the amount of winter ice cover falling to its fifth lowest on the satellite record, scientists at the National Snow and Ice Data Center said.

The scientists said Arctic sea ice extent for March averaged 14.80m sq km. That's 730,000 sq km below the 1981-2010 satellite average.

The latest findings reinforce a trend that could see the Arctic losing all of its ice cover in the summer months within decades.

Arctic sea ice falls to fifth lowest level on record by Suzanne Goldenberg, The Guardian, Apr 2, 2014



The climate change uncertainty monster – more uncertainty means more urgency to tackle global warming

Posted on 5 April 2014 by dana1981

A new two-part study published in Climatic Change by a team of scientists led by Stephan Lewandowsky examines mathematically what happens to the risks posed by climate change when the scientific uncertainty increases. Part 1 of the study explores two important points.

First, the probable range of climate sensitivity to the increased greenhouse effect isn't symmetrical. Instead, based on the available evidence and research, it's more likely that we'll see a large amount of global warming than a small amount in response to rising carbon emissions. By itself, this means that more climate uncertainty translates into an even bigger risk of painful consequences than relatively benign consequences. More uncertainty means a slightly better chance of the low warming outcomes, but it also means an even bigger chance of the high warming outcomes, because the scientific data have a harder time ruling those out.

The second critical point is that economic models agree that once we reach a certain tipping point, the costs of climate damage increase at an accelerating rate. The models don't agree on exactly where that tipping point lies, but they do agree on the shape of the curve and the acceleration of the climate damage costs once we pass that tipping point (even the 'skeptics' agree on this).



Video: Climate science crash course by Dana Nuccitelli with Citizens Climate Lobby

Posted on 4 April 2014 by dana1981

On March 8th, 2014, I participated in a Faith and Climate Forum near Sacramento, California.  The event was co-sponsored by the Sacramento chapter of Citizens Climate Lobby (CCL), of which I'm a member.  CCL is a non-partisan grassroots organization whose goal is to build the political will to maintain a liveable climate, specifically through a revenue-neutral carbon tax. 

Another Sacramento CCL chapter member, Christine Bailey organized this event, bringing together local faith leaders and CCL members to speak about the importance of addressing climate change.  The event began with local leaders of various religions including Presbyterian, Buddhist, Islamic, and Jewish faiths speaking about the importance of preserving a liveable climate for each of their religions.  I was asked to follow these speakers to talk about the science, and I gave what I called 'a climate science crash course'.  Videographer Brian McKinsey recorded the event, and the whole thing can be viewed on his YouTube page.  My talk can be viewed below, and the Powerpoint slides can be downloaded here (8.5 MB, without Andy Lee Robinson's Arctic sea ice cubes video) and here (16.5 MB with the video).



Earth has a fever, but the heat is sloshing into the oceans

Posted on 3 April 2014 by John Abraham

Much has been made about the Earth's energy imbalance (extra energy absorbed by the Earth). It is clear the Earth is out of balance, in laypersons' terms, it has a "fever". What isn't clear is how bad the fever is. A new study by Dr. Matt Palmer and Dr. Doug McNeall moves us closer to answering this "fever" question.

Matt Palmer and Doug McNeall 

Matt Palmer and Doug McNeall

These scientists used data from the latest group of climate computer models (CMIP5) to look at the relationships between the energy flows at the top of the atmosphere, the surface temperature of the Earth, and changes in ocean energy. They made (in my mind), three important conclusions.



2014 SkS Weekly News Roundup #14A

Posted on 2 April 2014 by John Hartz

4 takeaways from report reveal worsening impacts of climate change

The first installment of the Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report (AR5)—released in September—confirmed the overwhelming scientific consensus that the world is warming, largely due to human activities. The Working Group II (WGII) report, released today, takes this finding a step further: Not only is climate change happening, but every continent on earth is now experiencing its impacts.

Four major takeaways from the report showcase the impacts we’re already seeing, as well as those projected to occur if the world continues to warm. And more importantly, they reveal a critical message: As John P. Holdren, director of the White House Office of Science and Technology Policy, put it, the report “underscores the need for immediate action in order to avoid the most severe impacts of climate change.”

4 Takeaways from IPCC Report Reveal Worsening Impacts of Climate Change by C. Forbes Tompkins and



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