IPCC AR5 WG1

Just in case you aren’t that involved in the climate change/global warming debate, the acronyms in my post title mean Intergovernmental Panel on Climate Change (IPCC) Assessment Report 5 (AR5) Working Group 1 (WG1). The IPCC is in the process of releasing all it’s reports. A couple of days ago, they released the Summary for Policy Makers (SPM) and today they’ve released the final draft of the Working Group 1 (WG1) report. It’s a remarkably long document and I haven’t had a chance to read much (or any for that matter). I’m already impressed by those on Twitter who’ve already managed to find some mistakes (or at least what they think are mistakes). That takes real dedication and commitment.

There was one thing I was going to briefly comment on, and that is the figure below. I have seen it before but that was from a leaked draft of the report, and so I didn’t want to comment until the report was officially released. The figure shows comparisons between observations and model results and includes both regional comparisons and global comparisons. I think it’s a fascinating figure for a number of reasons.

  1. It’s clear that the models are remarkably complicated, and include the atmosphere, land, sea surface, oceans, and sea ice. They are also able to model individual regions as well as producing global comparisons.
  2. Models without anthropogenic forcings (blue lines and blue regions) are clearly unable to reproduce the observed changes. Models including both anthropogenic and natural forcings (red lines and pink regions) do a remarkable job of reproducing the observations (black). This is one of the reasons for the claim that we are now 95% certain that most of the warming since 1950 is anthropogenic. The WG1 document says, when discussing this figure,

    Human influence has been detected in nearly all of the major assessed components of the climate system (Figure TS.12). Taken together, the combined evidence increases the overall level of confidence in the attribution of observed climate change, and reduces the uncertainties associated with assessment based on a single climate variable. From this combined evidence it is virtually certain that human influence has warmed the global climate system.

  3. The models appear to do quite a good job of matching the rise in ocean heat content. Since about 90% of the energy excess goes into the oceans, this would suggest that the models are accurately reproducing the global energy budget.
  4. The main talking point for those “skeptical” of climate change is that the models have not matched/predicted the slowdown in surface warming since the late 1990s. Firstly, the models are still technically consistent with the observations. Furthermore, the models clearly do much more than simply attempt to predict the change in surface temperatures and so focusing on this one thing would, in my opinion, be ignoring all the others aspects of the models that are all relevant to our understanding of global warming/climate change.

So, I think the figure is a really good illustration of how well we understand both the fundamentals and details of global warming. Of course, there may be subtleties that I don’t realise or appreciate. If so, feel free to correct me through the comments.

Detection and attribution signals (decadal averages) in the climate system, at regional scales (top panels) and global scales (bottom 4 panels). Brown panels are land surface temperature time series, blue panels are ocean heat content time series, and white panels are sea-ice time series. Each panel shows observations (black or black and shades of grey), and the 5–95% range of the simulated response to natural forcings (blue shading) and natural and anthropogenic forcings (pink shading), together with the corresponding ensemble means (dark blue and dark red respectively). The observed surface temperature is from HadCRUT4. Three observed records of ocean heat content (OHC) are shown. Sea-ice anomalies (rather than absolute values) are plotted and based on models in Figure 10.16.

Comparison between observations and model results (decadal averages), at regional scales (top panels) and global scales (bottom 4 panels). Brown panels are land surface temperature time series, blue panels are ocean heat content time series, and white panels are sea-ice time series. Each panel shows observations (black or black and shades of grey), and the 5–95% range of the simulated response to natural forcings (blue shading) and natural and anthropogenic forcings (pink shading), together with the corresponding ensemble means (dark blue and dark red respectively). The observed surface temperature is from HadCRUT4.

About these ads
This entry was posted in Climate change, Global warming, IPCC and tagged , , , , , . Bookmark the permalink.

11 Responses to IPCC AR5 WG1

  1. Vinny Burgoo says:

    ‘ I’m already impressed by those on Twitter who’ve already managed to find some mistakes (or at least what they think are mistakes). That takes real dedication and commitment.’

    I read that Twitter exchange. Your ‘dedication and commitment’ came across as implying an unhealthy zeal for error-spotting. But if you have had the dedication and commitment necessary to know your subject very well then you’ll anticipate likely errors/cheats/whatevers and look for them as soon as the full report comes out. That’s presumably what Tol did. Nothing unhealthy. Just someone who knows his subject.

    I have even done it myself, and I’m no expert. One day, sonny, you’ll know enough to do the same.

  2. Pingback: The Climate Change Debate Thread - Page 3209

  3. Dear Old Codger,
    “One day you’ll know enough to” recognise ‘confirmation bias’ (“you’ll anticipate likely errors/cheats/whatevers and look for them …”), ‘conjecture’ (“That’s presumably what Tol did.”), and ‘Dunning-Kruger effect’ (“I have even done it myself, and I’m no expert.”).
    Without reference to data/equations/graphs, you are merely expressing an opinion which is close to writing blank verse poetry (attr. Science of Doom). Now, in my opinion, “sonny” “knows his subject very well”.
    Kindest Regards,
    Sonny-George Montgomery

  4. dbostrom says:

    No fear; what looks like an impossible argument becomes easy with DEET (Dynamic Error Expansion Technology)!

    Nothing fundamentally wrong with WG1? Find a typo or a wrongly placed decimal point then let DEET work its magic to fill the space between your ears with endlessly reverberating spluttering outrage!

    No problem is too picayune for DEET!

  5. dbostrom says:

    I should add that DEET is easily within the means of the average person; indeed, the components of DEET are already found in many households. All that’s required is a serviceable (if greasy) laptop, an Internet connection and an over-active imagination with a bent for conspiracy theories.

  6. Oh dear, Vinny, was my tweet to Richard Tol that transparent? One thing I would dispute is the “Tol knows his subject” claim. Richard Tol is an economist. WG1 is “The Physical Science Basis” so isn’t actually Tol’s subject (at least not specifically). Richard Tol may well be an excellent economist and may well be a leading economist with respect to climate change/global warming. However, he has done nothing to convince me that he knows any more about the science associated with global warming/climate change than one might expect from an economist.

  7. Tom Curtis says:

    You must not underestimate Richard Tol. After all, there is probably no limit to the potential intellectual accomplishments from a man who can squeeze information about raters from data ordered by date and alphabetical order of title ;)

  8. BBD says:

    [...] you’ll anticipate likely errors/cheats/whatevers and look for them [...] I have even done it myself, and I’m no expert. One day, sonny, you’ll know enough to do the same.

    Conspiracist ideation!

    Oh noes!

  9. BBD says:

    Wotts

    However, he has done nothing to convince me that he knows any more about the science associated with global warming/climate change than one might expect from an economist.

    Some economists do seem to get carried away when it comes to “scepticism” about AGW. There’s even a special little club they can join. I believe RT is already a member.

  10. BG says:

    Slight change of direction. Does anyone know off-hand what the cutoff publication date was for papers to be included in the assessment for this report?

  11. Marco says:

    http://www.ipcc.ch/pdf/ar5/ar5-cut-off-dates.pdf
    Note that the “accepted” date is not the same as the publication date. In some fields and journals the difference can be a year.

    Of course, these papers had to be known to the IPCC authors while they were writing.

Comments are closed.