The relevant text is: Without prompt aggressive limits on CO2 emissions, the Earth will likely warm by an average of 4°-5° by the century's end.
The source is given in the popup that appears when you hover the mouse over the cartoon, and is given as the latest IPCC Fifth Assessment Report (AR5). That's where XKCD goes wrong.
What is the IPCC projection based on? Computer models. So how are the models tracking climate? Very poorly:
I’ve updated our comparison of 90 climate models versus observations for global average surface temperatures through 2013, and we still see that >95% of the models have over-forecast the warming trend since 1979, whether we use their own surface temperature dataset (HadCRUT4), or our satellite dataset of lower tropospheric temperatures (UAH):The models are simply terrible - two out of 90 are close to the actual recorded temperatures over the last three decades, and they're getting worse over time, not better. In fact, AR5 weakens the case for global warming:
Whether humans are the cause of 100% of the observed warming or not, the conclusion is that global warming isn’t as bad as was predicted. That should have major policy implications…assuming policy is still informed by facts more than emotions and political aspirations.
Figure 1 shows that observations particularly since 2005 are on the low end of the envelope that contains 90% of the climate model simulations. Observations in 2011-2012 are below the 5-95% envelope of the CMIP5 simulations. The trend in the model simulations is substantially larger than the observed trend over the past 15 years.
Emphasis mine. The observed temperatures are no longer within the error bands of the model projections. The idea that this unexplained hiatus will suddenly end and temperatures for the rest of the century will increase even faster than the IPCC projected is certainly novel but is hard to justify.
Figure 1. After expecting an increase of 0.2oC per decade in the early decades of the 21st century from the AR4 statements, the rate of warming over the past 15 years is only ~0.05C.
- The IPCC AR5 bases its projection for the period 2016-2036 of 0.10 to 0.23oC per decade on expert judgment, rather than on the climate model results
- The IPCC does not have a convincing or confident explanation for the hiatus in warming.
And so XKCD disappoints. Wherever we will be in 86 years, it's certainly not going to be where XKCD and the IPCC say we will.
UPDATE 10 June 2014 18:27: Goober opens up a righteous can of whoop-ass on the topic. Recommended.
14 comments:
Yeah, I saw the comic this morning and chuckled a little. I rarely dive into the XKCD forums, but did for this comic. I was a little surprised at the quality of the comments.
And the Asians and Africans aren't going to do anything about it, so anything we would do is moot. waste a whole bunch of money for not one iota of difference.
Funny thing that globalist "Citizens of the UN" think climate change is all about the USA changing the way we live.
I was looking for a reason to stop reading XKCD anyway.
Damn it, Borepatch! I was just writing this exact same thing.
He, like many others, is basing his assumption on model data which has not tracked worth a tinker's damn over the past decades.
Models, as it were, many of which were set up by people who have since been shown to have a pretty serious bias towards warming.
I'm reminded of that scene in Men in Black when he talks about all the totally incorrect things that people used to "know" and asks "imagine what we'll KNOW tomorrow..."
Also, one wonders what a person living in the creataceous era, with palm trees at the poles, as XKCD puts it, would think of how the earth looks now, with huge amounts of fresh water tied up in ice, a massive amount of the globe's land surface almost totally uninhabitable without outside supply, and the sea levels 220 plus feet lower than they are in his time.
It would look like a damned apocalypse, is what it would look like. Yet, that's our normal, so HIS earth looks pretty bad to US.
Makes one pause to think - is the problem really the change, or just our inability to deal with it?
My google-fu is failing me, but a few years ago, some large nanny organization revised the models it used to "predict" climate change. They removed some of the factors in the model, reducing it from 12 to 9, IIRC. The hilarious part was that several of the factors didn't correlate with any observed data, and the ratio of good factors:total factors was, in fact, reduced by their change.
Some fools just don't understand the inherent difficulties in extrapolation and in causation vs. correlation let alone causation vs bravo sierra.
But I'm glad those same fools are writing our regulations and can't be voted out of office.
Yep, truth is screwing up all the models... too bad, so sad...
Erin Palette +1!
I'd thought the uncertainty in the IPCC models was being highlighted, and that the good author was generally in agreement with authorities such as Judith Curry.
I may have to re-read the comic.
The Climate People have been giving the "once and final answer" to "Global Warming" - or "Cooling," as the case may be, for over 30 years.
The Japanese have the final solution. Build atom powered plants all over the place, then stand back and watch earthquakes and typhoons take care of things.
Where do you find the forum for that comic? I'd be interested to read the comments.
I think most of his stuff is funny enough that I'd continue to read it sporadically. I'd just lose a lot of respect if he's serious about this warming thing.
Never mind... GIMF
posted my response over at my place.
The Navier Stokes differential equations describe fluid flow with changes in density and temperature. They are nonlinear, chaotic, with sensitive dependence on initial conditions. No finite set of past states can be sufficient to predict a distant future state. This has been known since the paper "Deterministic Nonperiodic Flow" by Edward Lorenz, he of the Lorenz Butterfly. If anyone attempts to sell a future prediction based on a model built on a record of past temperature and or density measurements, they are either incompetent, or a fraud, or perhaps both. The Navier Stokes also describe some of the fluid flow in the sun, which is much much bigger than the earth, and the sun's behavior is also impossible to model or predict for distant times in the future.
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