Arguments
16 ^ more years of global warming
Posted on 10 January 2013 by Kevin C
Update 21/02/2013: Troy Masters is doing some interesting analysis on the methods employed here and by Foster and Rahmstorf. On the basis of his results and my latest analysis I now think that the uncertainties presented here are significantly underestimated, and that the attribution of short term temperature trends is far from settled. There remains a lot of interesting work to be done on this subject.
Human greenhouse gas emissions have continued to warm the planet over the past 16 years. However, a persistent myth has emerged in the mainstream media challenging this. Denial of this fact may have been the favorite climate contrarian myth of 2012, first invented by David Rose at The Mail on Sunday with an assist from Georgia Tech's Judith Curry, both of whom later doubled-down on the myth after we debunked it. Despite these repeated debunkings, the myth spread throughout the media in various opinion editorials and stunts throughout 2012. The latest incarnations include this article at the Daily Mail, and a misleadingly headlined piece at the Telegraph.
As a simple illustration of where the myth goes wrong, the following video clarifies how the interplay of natural and human factors have affected the short-term temperature trends, and demonstrates that underneath the short-term noise, the long-term human-caused global warming trend remains as strong as ever.
In particular, once the short-term warming and cooling influences of volcanic eruptions, solar activity, and El Niño and La Niña events are statistically removed from the temperature record, there is no evidence of a change in the rate of greenhouse warming. This replicates the result of a study by Foster and Rahmstorf (2011) under slightly different assumptions.
The human contribution to global warming over the last 16 years is essentially the same as during the prior 16 years¹. Human-caused greenhouse warming, while partially hidden by natural variations, has continued in line with model projections². Unless greenhouse gas emissions are brought under control, we will see faster warming in the future³.
Implications:
- The 16-year temperature trend provides no evidence to suggest that human-caused greenhouse warming has slowed.
- The 16-year temperature trend provides no evidence to suggest that the consensus understanding of human-caused climate change is incorrect.
- The temperature record over the past 35 years is consistent with climate change being driven by human greenhouse gas emissions.
- Given that human greenhouse gas emissions are increasing, and that the natural influences do not show a trend on longer timescales, we must expect increasing global warming in the future.
Further Reading:
For details of the method, see the Advanced rebuttal to the myth 'no warming in 16 years'.
The results of this analysis are consistent with a statement by WMO Secretary-General Michel Jarraud:
"Naturally occurring climate variability due to phenomena such as El Niño and La Niña impact on temperatures and precipitation on a seasonal to annual scale. But they do not alter the underlying long-term trend of rising temperatures due to climate change as a result of human activities"
Credits: Video: Kevin C. Voiceover: Daniel Bailey. Advice: The SkS team.
Teaser graphics: What happened next? Does this look like global warming?
Footnotes:
We have attempted to keep the language in this video at the same non-technical level as the media stories it refutes. As a result, it has been necessary to simplify much of the terminology. The following notes are for technically literate readers.
¹ i.e. If a change in gradient is allowed at 1997 then the change in gradient is not statistically significant (even at the 1σ level).
² i.e. Within the envelope of AR4 trend projections.
³ On the basis of both AR4 projections and that global GHG emissions are increasing.
Update 21/02/2013: Troy Masters is doing some interesting analysis on the methods employed here and by Foster and Rahmstorf. On the basis of his results and my latest analysis I now think that the uncertainties presented here are significantly underestimated, and that the attribution of short term temperature trends is far from settled. There remains a lot of interesting work to be done on this subject.
Even as we speak Monckton and his enablers are scheming as how to cherry pick those time windows of time that produce statistically insignificant temperature trends. Unbelievable but true.
So, hopefully this video can be used by the media to educate and inform the public. That way, people will turn a blind eye to ridiculous "skeptic" antics and efforts to obfuscate and the informed public will also be in a position to expose the disingenuous games of fake skeptics whenever they try and push it again.
I sincerely hope that this video goes viral.
Take a bow.
Alexandre @11's comment caused me to go look at all the SkS climate graphics, and it is quite an impressive collection. Don't forget to add this one!
Thanks for the effort, Kevin and Daniel. I hope it gets translated, the same way the Debunking Handbook has been.
Any chance we can get Climate Depot to review the video?
Might have to rework my YT channel and make this video my homepage.
Is it
Which ought to be everyone.
Already done
Indeed using a 2-box model on the whole 130 years and taking into account the CFC reductions after Copenhagen the temperature trend is projected to be very marginally less after the mid 90's. Copenhagen really made a difference.
There are (a few) more details in the advanced rebuttal.
Please can we have more of these short pithy little no-nonsense videos on the other most persistent myths?
Leo Hickman's article is pretty poor IMHO - far too much time devoted to known denial enablers, such as Tisdale or the Daily Fail. Throughout the piece, Hickman demonstrates precious little comprehension of the concept that the change in trend is statistically insignificant, while the long-term trend remains strongly statistically significant. The long-term trend is, in many cases, steeper when you include post-2000 data than it is when you leave it out. Does that sound like a "slowing down"? Remedial stats class required! Armed with this information, Hickman could actually critically evaluate whether the likes of Tisdale or the Mail had anything worthwhile to say, rather than uncritically repeating the nonsense. Leo, if you read this, please do some proper critical analysis before repeating everything you read on the Internet!
A ray in the confusion of the article is the posting of this great video, however.
I assume that the corrections for natural causes depend on indexes? Which indexes have been used and why that index? I have faith that the indexes and values are (largely) correct, but I'm just asking to have answers before the other side of the mirror does...
The "pauses" and "no warming for * years" brigade from been in full cry recently, no doubt hoping to disract from the extreme weather news from around the globe (UK 2nd wettest year ever, Sandy largest exra-tropical cyclone, USA warmest year ever, Australian heat records shattered, Arctic lowest ever ice extent, extreme cold records broken in China and Russia).
Figure 1: Coverage maps for various temperature series. Colors represent mean change in temperature between the periods 1996-2000 and 2006-2010, from +2C (dark red) to -2C (dark blue). Note that the cylindrical projection exaggerates the polar regions of the map.
The other indices don't have good coverage at the poles where, according to GISTEMP, UAH and the NCEP/NCAR reanalysis dataset warming has been fastest over the 15 year period shown.
If my analysis of HadCRUT4 here is correct, then this is particularly serious over the period post 1998, with coverage bias in HadCRUT4 shifting from a warm bias around 1998 to a cool bias now. Of course UAH is the only set of measurements we have for these regions, and probably suffers ground contamination over the antarctic, however the possibility that there is a huge cooling trend over one of the poles which hasn't been picked up by any observations or models is farfetched.
On this basis I think that GISTEMP is the best choice for measuring global trends. I'm working on kriging HadCRUT4 to provide a global version for comparison.
Are you planning more on this front?
Very well done. Bert
As it happens, a total of 19 station record maximum temperatures have been set in Australia over the last week, and a record Australian mean maximum temperature has also been set. But no State records have fallen, and the national record maximum of 50.7 C still stands.
As it happens, over the last few days a total of seven minimum temperature records for individual stations have been set in India. That means currently the world ratio of maximum temperature records to minimum temperature records is 2.71, the third lowest in the last 13 years (including 2013), and well below the average of the last twelve years of 10.39. It is, of course, early days yet.
There does seem to be some debate as to the scaling of the volcanic term to make a forcing - GISS and Isaac Held use the same sort of value (~-20), but the Potsdam value is rather smaller. I adopted the GISS scaling, because it gave the most conservative (lowest trend) result and because gives the best fit in the 2-box model. I'd like to look into the literature on this, but have not had time.
I have a question as well -- has there been any attempt to include in the model the role of increased emission of sulfate aerosols due to the huge increase in coal burning plants in China and the rest of the world? Anything in the published literature? Satellite measurements of increased solar relection for example? Thanks.
I'm not very well read on aerosol measurements, but I think Kaufmann worked his out on the basis of fuel usage. The issues is complicated by the fact that aerosols are not well mixed through the atmosphere and have different effects depending on where they are.
BTW if you look at my post 29 in the thread "IPCC Temperature Projections Have Been Exceptionally Accurate" there is a plot of the averaged ten data sets in our SKS trend feature, but now temp anomaly plotted against log base two (conc/conc 1850). I think present thread is an appropriate place to mention that plot. Dead fit to straight line with probability no correlation abscissa and ordinate less than one in 10,000.
But once again from someone who visits the site constantly thank you all. It is most helpful.
Ultimately, we decided, any video we post will also have a blog post here connected to it. All the people on Youtube (skeptics included) are welcome to post their thoughts and observations here.
Chris Mooney has this recent article out discussing how the tone of a comments section can act to polarize people when commenting goes negative. Youtube is rife with hyper-negative comments threads, especially on the climate issue. We would like to avoid driving people apart. We would prefer that people come here where we can administer our policies of keeping the discussion on topic and about the science, without personal attacks.
My sense is that most of the guys who were commenting on YT will not come here and participate. SkS has proven over and over again that skeptics can participate in discussions, but this is a more challenging atmosphere due to the fact that there are well informed people here and the commenting policies are strictly enforced. Those who are just looking for a fight will do well to keep their commenting limited to YT channels. Those who want to participate in substantive discussions should be more than willing to participate here.
Registering an account here is quick and simple, so that's not a sufficient excuse for anyone who wants to also claim any sort of interest in the discussion. The strategy, while also likely simplifying moderation, might also work to draw in more people like me, who don't have a great degree of knowledge or formal training on climate science. That would be a great thing because SkS, while becoming more and more widely read, still seems to mostly attract commenters who are either quite familiar with the subject or are so invested in their pseudo-scientific ideas (and sometimes conspiracy theories) that they aren't likely to learn much. Maybe a YouTube presence can change the audience for the better.