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'No doubt left' about scientific consensus on global warming, say experts

Posted on 29 July 2019 by Guest Author

This is a re-post from The Guardian by Jonathan Watts

The scientific consensus that humans are causing global warming is likely to have passed 99%, according to the lead author of the most authoritative study on the subject, and could rise further after separate research that clears up some of the remaining doubts.

Three studies published in Nature and Nature Geoscience use extensive historical data to show there has never been a period in the last 2,000 years when temperature changes have been as fast and extensive as in recent decades.

It had previously been thought that similarly dramatic peaks and troughs might have occurred in the past, including in periods dubbed the Little Ice Age and the Medieval Climate Anomaly. But the three studies use reconstructions based on 700 proxy records of temperature change, such as trees, ice and sediment, from all continents that indicate none of these shifts took place in more than half the globe at any one time.

The Little Ice Age, for example, reached its extreme point in the 15th century in the Pacific Ocean, the 17th century in Europe and the 19th century elsewhere, says one of the studies. This localisation is markedly different from the trend since the late 20th century when records are being broken year after year over almost the entire globe, including this summer’s European heatwave.

Major temperature shifts in the distant past are also likely to have been primarily caused by volcanic eruptions, according to another of the studies, which helps to explain the strong global fluctuations in the first half of the 18th century as the world started to move from a volcanically cooled era to a climate warmed by human emissions. This has become particularly pronounced since the late 20th century, when temperature rises over two decades or longer have been the most rapid in the past two millennia, notes the third.

The authors say this highlights how unusual warming has become in recent years as a result of industrial emissions.

“There is no doubt left – as has been shown extensively in many other studies addressing many different aspects of the climate system using different methods and data sets,” said Stefan Brönnimann, from the University of Bern and the Pages 2K consortium of climate scientists.

Commenting on the study, other scientists said it was an important breakthrough in the “fingerprinting” task of proving how human responsibility has changed the climate in ways not seen in the past.

“This paper should finally stop climate change deniers claiming that the recent observed coherent global warming is part of a natural climate cycle. This paper shows the truly stark difference between regional and localised changes in climate of the past and the truly global effect of anthropogenic greenhouse emissions,” said Mark Maslin, professor of climatology at University College London.

Previous studies have shown near unanimity among climate scientists that human factors – car exhausts, factory chimneys, forest clearance and other sources of greenhouse gases – are responsible for the exceptional level of global warming.

A 2013 study in Environmental Research Letters found 97% of climate scientists agreed with this link in 12,000 academic papers that contained the words “global warming” or “global climate change” from 1991 to 2011. Last week, that paper hit 1m downloads, making it the most accessed paper ever among the 80+ journals published by the Institute of Physics, according to the authors.

The pushback has been political rather than scientific. In the US, the rightwing thinktank the Competitive Enterprise Institute (CEI) is reportedly putting pressure on Nasa to remove a reference to the 97% study from its webpage. The CEI has received event funding from the American Fuel and Petrochemical Manufacturers and Charles Koch Institute, which have much to lose from a transition to a low-carbon economy.

But among academics who study the climate, the convergence of opinion is probably strengthening, according to John Cook, the lead author of the original consensus paper and a follow-up study on the “consensus about consensus” that looked at a range of similar estimates by other academics.

He said that at the end of his 20-year study period there was more agreement than at the beginning: “There was 99% scientific consensus in 2011 that humans are causing global warming.” With ever stronger research since then and increasing heatwaves and extreme weather, Cook believes this is likely to have risen further and is now working on an update.

“As expertise in climate science increases, so too does agreement with human-caused global warming,” Cook wrote on the Skeptical Science blog. “The good news is public understanding of the scientific consensus is increasing. The bad news is there is still a lot of work to do yet as climate deniers continue to persistently attack the scientific consensus.”

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Comments

Comments 1 to 21:

  1. Wow!  I occasionally peruse Roy Spencer's blog, and he definitely is not on board with the consensus.  His latest post is still beating the "urban heat island" and "it's always cold somewhere else" drums.  I wonder if he and John Christy are all that remains of the "3%"?  It's no surprise the political think tanks like CEI are pushing to not even mention this topic.  As I recall it was one of their key talking points 20 years ago, that scientists are all over the map on AGW. 

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  2. "This paper should finally stop climate change deniers claiming that the recent observed coherent global warming is part of a natural climate cycle."

    I doubt this will silence the critics. When have credible facts ever guided POTUS? I expect the only thing that will move the deniers is evidence outside their windows.

    But hopefully it will move some of the fence sitters into greener pastures.

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  3. This is just a question. How is this different from the famous hocky stick?

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  4. The Consensus on Anthropogenic Global Warming Matters

    http://journals.sagepub.com/doi/abs/10.1177/0270467617707079?journalCode=bsta

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  5. Kuidaskassikaeb... This would just be yet another hockey stick. The first hockey stick was done by Mann, Bradley and Hughes back in 1998/99. It was merely a collection of local and regional temperature data series all combined that stretched back over the past 1000 years to show the changes in global temperature. Since then there have been lots of newer studies with refinements and the same answer comes back: human activities are rapidly warming the planet. And all that is merely a confirmation for what scientists already expected going back through 100+ years of science.

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  6. Even if you believe in catastrophic climate change, no mention is made of the basis for this "consensus." Antropogenic warming of the earth may well be happening but for different reasons than what the IPCC would have us believe........

    The Intergovernmental Panel on Climate Change (IPCC) would have us believe that fossil fuel emissions are the sole reason for climate change. But what about urbanization and deforestation? A study by the UN Department of Economic and Social Affairs states that the urban population rose from 750 million in 1950 to 4.2 billion in 2018. We don’t need the IPCC’S hugely complex computer models to know that cities are hotter. All we have to do is walk from a paved sun-heated street lined with concrete buildings to a grassy park. Rather than reflecting the sun’s rays back to outer space, all that concrete and pavement absorbs the sun rays, creating a giant heat sink. Likewise, deforestation is turning vast tracts of cool African and South American jungles into heat- absorbing barrens. The U. S. EPA summarizes the combined effect, “Processes such as deforestation and urbanization … contribute to changes in climate.” Trying to deal with any problem without considering all possible causes is both a foolish and dangerous strategy.

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    Moderator Response:

    [DB] At Skeptical Science, the onus is on each person posting (in this case, you) to be able to support their statements and assertions with citations to the credible literature.  Please read the Comments Policy and construct future comments to comport more fully with it.

    "Trying to deal with any problem without considering all possible causes is both a foolish and dangerous strategy"

    Scientists already have.  Scientists have evaluated all natural forcings and factors capable of driving the Earth's climate to change and it is only when the anthropogenic forcing is included that the observed warming can be explained.

    Natural vs Anthropogenic Climate Forcings, per the NCA4, Volume 2:

    Forcings

    Changes in the sun's output falling on the Earth from 1750-2011 are about 0.05 Watts/meter squared.

    By comparison, human activities from 1750-2011 warm the Earth by about 2.83 Watts/meter squared (AR5, WG1, Chapter 8, section 8.3.2, p. 676).

    What this means is that the warming driven by the GHGs coming from the human burning of fossil fuels since 1750 is over 50 times greater than the slight extra warming coming from the Sun itself over that same time interval.

    It's not the Sun

    Sloganeering and fake terms snipped.

  7. Hoipolloi... I get the idea that you've never read the IPCC reports because they most certainly do not claim that FF's are the "sole reason" for climate change. There are extensive sections on urbanization and deforestation as well as dozens of other related issues, including changes in solar forcing, volcanic influences, etc, etc.

    You also seem to be under the mistaken assumption that the IPCC does computer modeling. They don't. The IPCC only does a report on all the published science related to climate change. The science cuts across a very wide range of fields of research and their purposes is to pull all that disperate information together into a single report.

    My suggestion for you would be to spend at least an hour purusing through the IPCC reports. I don't even need to post a link. They're very easy to find and they've updated the website to make the reports very easy to navigate.

    Have fun!

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  8. Have you ever tried to argue a creationist out of his point of view.  The most extreme case of cognitive dissonance I have come accross is a geologist I met who was a creationist and argued that a 500 plus series of gravel, sand, clay, gravel sand clay was the result of the great bibical flood.  It is the same with climate change deniers.  No amount of evidence short of a total disastrous flip of the climate is likely to convince them.  The real problem, though, stoping effective action is the financial support of politicians by vested interest.  Sort this one out and we will begin to gain traction on all the things we must do to avoid a disaster. 

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  9. Hoipolloi.., cities are indeed absorbing some solar energy, but they are less than 0.1% of the earths area, so its just not enough energy to account for the vast warming seen in the oceans for example. This is basic stuff to calculate, and is not reliant on computer modelling. 

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  10. "all that concrete and pavement absorbs the sun rays, creating a giant heat sink"

    While urban areas are undoubtedly warmer than surrounding rural areas, this has had little to no impact on warming trends.

    "The Urban Heat Island effect is real. Berkeley’s analysis focused on the question of whether this effect biases the global land average. Our UHI paper analyzing this indicates that the urban heat island effect on our global estimate of land temperatures is indistinguishable from zero."

    http://berkeleyearth.org/faq/#question-15

    "Time series of the Earth’s average land temperature are estimated using the Berkeley Earth methodology applied to the full dataset and the rural subset; the difference of these is consistent with no urban heating effect over the period 1950 to 2010"

    http://static.berkeleyearth.org/papers/UHI-GIGS-1-104.pdf

    "The simple take-away is that while UHI and other urban-correlated biases are real (and can have a big effect), current methods of detecting and correcting localized breakpoints are generally effective in removing that bias. Blog claims that UHI explains any substantial fraction of the recent warming in the US are just not supported by the data."

    For more info:

    https://skepticalscience.com/urban-heat-island-effect-intermediate.htm

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  11. For a less intense introduction to climate change, I often suggest the first IPCC report from 1990. It covers a lot more basics that are simply assumed in later reports.

    https://www.ipcc.ch/report/ar1/wg1/

    In the contents of the Executive Summary, the first section lists:

    What factors determine global climate?

        What natural factors are important?

        How do we know that the natural greenhouse effect is real?

        How might human activities change global climate?

    In the main table of contents, Chapter 1 is titled "Greehouse gases and Aerosols". It covers five specific gases, plus ozone and related trace gases, and then aerosols.

    Chapter 2 is titled "Radiative Forcing of Climate". Its sections cover greenhouse gases, solar radiation, direct aerosol effects, indirect aerosol effects, and surface characteristics.

    So much for the idea that the IPCC does not consider other factors besides fossil fuel emissions. This is so easy to look up.

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  12. As for surface changes, one of the earliest papers I know of is:


    Anthropogenic Albedo Changes and the Earth's Climate

    By Carl Sagan, Owen B. Toon, James B. Pollack

    Science21 Dec 1979 : 1363-1368

    Link to origfinal source is here:

    https://science.sciencemag.org/content/206/4425/1363

    but the full text requires an account. Google Scholar will point you to freely-available copies.

    Short version: climatologists have been aware that surface changes can affect climate for at least 40 years.

    P.S. Don't forget to look at the IPPC 1990 report, too...

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  13. Are you aware of any answer or rebuttal for Uberto Crescenti and his fellow italian scientists declaration ? Would you treat it as was done with the OISM petition?

    This seems to be the original post, but many english translations are suggested on climate skeptiks sites. I assume it is fairly easy to find.

    http://www.opinione.it/cultura/2019/06/19/redazione_riscaldamento-globale-antropico-clima-inquinamento-uberto-crescenti-antonino-zichichi/?altTemplate=Stampa&fbclid=IwAR1YAoqulAKKXJTY-uzRfSEaX-G6NRpVOckp3nVE7iiTAgOQu8DMHGUxRnE

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  14. Sam-qc @13 , 

    what do you consider the Uberto Crescenti's important points which you think might require answer or rebuttal?  It would save much time for readers, if you would pick out 2 or 3 of his points which (maybe) disprove the mainstream climate science.

    The OISM petition was a laughable travesty.  But I (and probably most people) haven't seen the Italian (or English translation) petition you mention.   It doesn't appear to be making worldwide headlines in the news (as one would think it ought to deserve, if it truly overthrows modern science).

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  15. I heard one of Trump's hacks, Myron Ebell. on a video clip parroting all the old discredited rubbish about climate change - there is no consensus, scientists disagree etc. He was pushing Trump's "solution", which he called Energy Dominance.

    This pernicious rubbish will have to be opposed into the 2020s, and maybe even beyond. There is no reason to be smug.

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  16. Sam-qc,

    Crescenti's letter has had little or no impact in Europe. This was the first I heard of it.

    Part of the right and far-right retain climate change denial as part of their DNA, but the recent (relative) success of the Greens in European elections has forced them to dial back. I am not sure if they have the stomach to fight this battle again, which they apparently lost.

    The letter reads like a regurgitation of standard boiler-plate denial. I could have been written by Roy Spencer. The inclusion of the name of Fred Switz and the pre-refuted NIPCC Report is a dead giveaway.

    However, there is no reason to be complacent. We await the stance of the Johnson UK Government on climate change - his cabinet contains "skeptics", and he has been ambivalent in the past.

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  17. I believe that data from the new CO2 measuring sattelite is going to reveal information that will greatly effect existing notions on the sources of atmospheric CO2.  But this will only occur if the data is analized correctly.  For example, NASA has published a description and comments about a Finnish study that purports to isolate the location of CO2 caused by human activity.  However, the map of that CO2 in the United States shows significant correlation with areas of higher vegetation levels while the majority of U.S. large cities show the presence of the lowest level of CO2 presence.  

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    Moderator Response:

    [PS] offtopic. Try again here, but read the article first so you see the evidence. If you reference a study, please provide a link so people can check your interpretation. You expect high vege to emit CO2 so I dont why you think that challenges consensus.

    Please ask yourself if any data will change your mind which is apparently biased toward finding any excuse for inaction of emissions. If you are not prepared to let data form your opionions, then this is not the site for you.

    For anyone responding to billev, please do so on the topic indicated, not here.

  18. Sam-qc @13 , I cant find a list of Italian scientists who signed the document sceptical of human caused climate change. Other similar submissions have always ended up having very few climate research scientists as signatories. I've therefore largely given up reading these sorts of sceptical petitions, because its just going to be more of the same.

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  19. "Discrediting of peer-review" is likely to be an 'increasingly popular' misleading attack on the 'constantly improving climate science consensus in peer-reviewed presentations of research'. (Note: this will be a liberal arts related comment fundamentally based on abductive reasoning used to develop a best explanation for what can be observed to going on in the real world - no statistical mathematics or lab experiments are applied, mainly because social 'experiments-interviews' are difficult to perform in a way that is not open to easy manipulation, mainly because the 'act of observing those things that way' can alter the result of what is observed, like poll results are functions of the way the questions are asked and what order they are asked in)

    The recent Washington Post item "Why we shouldn’t take peer review as the ‘gold standard’" is an example of the subtle ways that the Propaganda Model (PM) developed by Edward S. Herman with support from Noam Chomsky results in twists of the reporting of things (the stories that get told and believed) in ways that are beneficial to developed powerful wealthy interests (The PM was presented in detail in "Manufacturing Consent" published in 1988 and updated in 2002, with further related research and presentations by many others since then, one of the most recent being "Propaganda in the Information Age" compiled by Alan MacLeod as an update on the PM including his recent interview with Noam Chomsky).

    A full reading of the Washington Post article shows it to be a comprehensive presentation that includes pointing out ways that the 'peer-review' concept and label is abused for propaganda purposes, and still supporting the importance of peer-review for the advancement of understanding.

    The Title Banner in particular does not make it clear that "Wealthy powerful harmful interests are abusing the concept of 'Peer-Review' in their propaganda efforts to mislead the general population regarding important new understandings like climate science". The title appears to be deliberately vague, wide open to interpretation by a 'media consumer'. And though the opening statements are critical of an incorrect cliam by the Trump Administration about a specific recent climate science report, the opening statements are vague regarding the rest of climate science reporting. That allows a 'pseudo-skeptic' to accept a perceived to be 'minor criticism' of the Trump Administration while maintaining the belief that climate science claims are all misleading propaganda. And the title implies that, even though the Trump administration was incorrect about the report being 'peer-reviewed', the 'peer-reviewed' report can still be questionable propaganda.

    Herman's PM predicts that pressures from wealthy neoliberal interests will create story presentations that suit their interests as much as possible (as media outlet owners; as advertisers; as sources of pre-packaged "new news content from supposedly reliable sources''; as flak attackers of anyone who is not sufficiently deterred by the first 3 pressures/filters). Note that neoliberals tend to flock to the right-wing parties, but they can also be seen to attempt to influence other parties that are competing for popular support and funding to promote them (neoliberal influence in the US Democrats is the fuel behind unjust but powerful criticism of things like the Green New Deal or single-payer health care insurance)

    In this case the title and opening statements are wide open to the interpretation that peer-reviewed climate science is just a bunch of misleading manipulation. Many people are known to only be seeking confirmation of preferred beliefs, not improved understanding. And many of those easily impressed people only read headlines. And many more only read the headline and opening statements (and news sites like the WP can be seen to present items that way on their home pages for quick consumption).

    The PM model predicts that if the title and opening statements of the article had been more directly correct and critical of the harmful wealthy interests abusing misleading propaganda efforts, the author and editor would have been pressured to 'change it, pragmatically make it more centrist, be 'more balanced (code for compromising actual better understanding)'. And maybe they were. The resulting presentation is incredibly misleading in a way that benefits harmful wealthy interests while allowing them to claim that 'the full story presented is not biased in their favour' even though its presentation undeniably is.

    The PM also predicts that articles like this will be abused in other claims in a propaganda chain trying to discredit the 97% or 99.9% consensus in peer-reviewed presentations by simply referring to the article by its heading knowing that many 'consumers' of the propaganda (enough to make a difference on an election day) will not bother to actually read the full article.

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  20. OPOF @19, the title of the Washinton Post article "we shouldn't take peer review as the gold standard" is indeed very unfortuante and plays right into the hands of the denialists, and is complete nonsense anyway. If peer review is not the gold standard, what is? Clearly peer review is the best thing we have for at least weeding out the science that is fundamentally flawed, and there is no other sensible way I know of that can do this that is not a form of peer review.

    Of course the traditional peer review system has a raft of problems, but rather than trash the system, those should be fixed. There has been much discussion of these problems over the last few years and people will be taking that on board, and modifying how things are done.

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  21. Moderator:  I have investigated, to the best of my ability, as to why I have been "kicked off" this site.  I think I have not received your posts, via email, for about 4 months.  If there is anything you can do on your end to put me back in the "loop", I would appreciate it.  I don't have the proper computer skills to know how to handle it and I am too old to have children who can.  Thank You.

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    Moderator Response:

    [DB]  You are not blocked here, as your comment appearing here attests.  Your last comment was made here on July 6th.  Your account is still set to receive emails.

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