Monthly Archives: September 2013

Main AR5 WG1 Report published

The main body of the AR5 WG1 Report has been published today, Sep 30th, as promised.

This consists of the version of the report written in June 2013, following the second round of review comments, together with a few minor corrections, listed in the document labelled Changes to the Underlying Scientific/Technical Assessment (IPCC-XXVI/Doc.4). These corrections are to make the main report consistent with the SPM released on Friday.

There is a note saying that

The Final Draft Report has to be read in conjunction with the document entitled “Climate Change 2013: The Physical Science Basis. Working Group I Contribution to the IPCC 5th Assessment Report – Changes to the Underlying Scientific/Technical Assessment” to ensure consistency with the approved Summary for Policymakers (IPCC-XXVI/Doc.4) and presented to the Panel at its Thirty-Sixth Session. This document lists the changes necessary to ensure consistency between the full Report and the Summary for Policymakers, which was approved line-by-line by Working Group I and accepted by the Panel at the above-mentioned Sessions.

Unfortunately, the Changes document linked above doesn’t make much sense at all, and seems to contain a lot of mistakes.

It says that

Note that page and line numbers for the SPM and underlying report below are all based on the numbering used in the final drafts as distributed to governments on 7 June 2013.

So to make sense of this you need access to the documents distributed to governments on 7 June – which have not been made public!  However, since the final draft just released is dated 7 June, presumably this is the same thing.

Some mistakes in the changes document:

  • The first change refers to Ch 2 p 2 line 21, which doesn’t exist. I think it means p 4 line 21. Similarly the second entry.
  • The fifth and sixth changes refer to Ch 2 p 2 line 38 and 39.  I think this should be page 38, page 39.
  • Towards the end it refers to SPM tables up to Table SPM.7. But the SPM only has 3 tables and the draft version only had 2.  Perhaps it means figures rather than tables.

I suppose this shows that the stories of IPCC delegates being over-tired and not getting enough sleep were all true.

Picking cherries in the snow

Here is figure SPM3(a) from the IPCC AR5 SPM, captioned “Northern Hemisphere March-April average snow cover extent”.

Here is the corresponding paragraph, in which the IPCC excels in misleading cherrypicking:

There is very high confidence that the extent of Northern Hemisphere snow cover has decreased since the mid-20th century (see Figure SPM.3). Northern Hemisphere snow cover extent decreased 1.6 [0.8 to 2.4] % per decade for March and April, and 11.7 [8.8 to 14.6] % per decade for June, over the 1967–2012 period. During this period, snow cover extent in the Northern Hemisphere did not show a statistically significant increase in any month.

There is so much misleading spin here that it takes some time to unpack it all.
The first thing to note is that the graph does not show much of a decrease, certainly no decrease in the last couple of decades – another indicator of the pause in warming.
The first cherry-pick is that it refers only to the Northern Hemisphere; but this is reasonable since there is so much less land area in the Southern Hemisphere.  Now look at the months selected. Why are ‘March and April’ chosen, and why are they lumped together? (The same thing was done in the AR4 SPM.) And why mention June – a month not generally associated with snow?

Graphs of snow cover for different months can be found at the Rutgers site. (click on ‘Monthly Anomalies’ on the left).

Here is the graph for March. You can see that there has been a decrease, a rather abrupt one in the late 1980s, but since then there has been no decrease. The numbers are all over the place, so to talk of a linear trend per decade is misleading.

What about the winter months, that the SPM doesn’t mention? Well they show either no change, or an increase, for example in this graph for December.  The IPCC wording carefully avoids admitting this by saying there is no ‘statistically significant’ increase in any month.

I wonder if the decrease for March or April, considered separately, would count as statistically significant?

If you look at the ‘Seasonal extent’ graphs at the Rutgers site, you can see that although spring snow cover shows a decline, both the fall and winter graphs show a slight increase. So the IPCC statement claiming very high confidence in decreasing snow cover is not true.

In response to the similar but slightly differently worded claim in the draft SPM, one reviewer wrote “Misleading claim. Rutgers GSL data shows winter snow cover has not decreased.”

“Extremely likely”?

One of the most widely leaked claims in the AR5 SPM is this, in a box on page 12:

This evidence for human influence  has grown since AR4.  It is extremely likely that human influence has been the dominant cause of  the observed warming since the mid-20th century. {10.3–10.6, 10.9}

In the text below the box, this is expressed as “It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together.”

In IPCC-speak, “extremely likely” means at least 95% certain.  We will have to wait until Monday to see what evidence the IPCC has in chapter 10 to support these statements.

Recall that the corresponding statement in AR4 was

Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations

with “very likely” indicating 90% confidence, so there has been an increase in confidence levels between AR4 and AR5. Note however the change of wording from greenhouse gases in AR4 to the broader term “human influence” in AR5, which might include other effects such as deforestation or soot.  I think Roger Pielke Sr will welcome this;  he has argued for many years that the IPCC focus on greenhouse gases is too narrow.

So what could justify the increase in confidence from 90% to 95%, and it what sense has the evidence for human influence grown since AR4 was published in 2007?

Here are some things that have happened since 2007 that might have changed confidence:

  • We’ve had another six years with no warming, that climate scientists failed to predict (in fact they predicted there would be a resumption of warming).
  • Climategate showed the private doubts of climate scientists, plus journal-nobbling and data-withholding.
  • Several new papers from mainstream climate scientists have acknowledged that there is an increasing inconsistency between models and observations.

Yet confidence has increased and evidence grown?

Judith Curry has a good post questioning the 95% claim.  She draws attention to an IAC recommendation  that “Chapter Lead Authors should provide a traceable account of how they arrived at their ratings for level of scientific understanding and likelihood that an outcome will occur.” I look forward to seeing the IPCC’s account of how the 95% figure was derived.

Summary for Policymakers published

The IPCC AR5 WG1 Summary for Policymakers has now been published.  Rumours of a delay proved unfounded and the SPM was posted at the WG1 website at 9am UK time as planned.

Recall that the full report is due to be published on Monday.

Here’s a quick look at some of the points:

  • “It is extremely likely (95%) that human influence has been the dominant cause of the observed warming since the mid-20th century”
  • No best estimate of climate sensitivity, but a likely range given of 1.5 – 4.5C.  The low end  is slightly lower than it was in AR4 (2.0).
  • Misleading graph of ocean heat content
  • Graph of snow cover for March/April only
  • Decadally averaged temperature graph (hide the decline?)
  • Graph of Arctic, but not Antarctic, sea ice.

Each of these issues will be discussed in a separate post.

What other notable points are there?

Behind schedule?

Reports are coming in that the IPCC meeting in Stockholm to finalise the AR5 SPM is running behind schedule and that this might even delay the publication of the SPM expected on Friday morning.

A first hint of this was in a tweet from Met Office climate scientist Mat Collins on Tuesday, “We are not allowed to tweet anything of substance. I can only perhaps say that progress is slow.”

Then on Wednesday, an organisation called IISDRS said in a tweet “Plans to continue discussions well into the night as WGI is very behind the schedule”.  On their web site, which seems to be a semi-official report on the proceedings, they said “From dawn til late into the night on Wednesday, the IPCC Working Group I (WGI) continued line-by-line discussions of the Summary for Policy Makers (SPM)”.  If you’re wondering what the meeting or any of the delegates look like, there are plenty of pictures there.

Now there’s an article in the Guardian, IPCC climate report: last-minute Stockholm talks make slow progress, talking of “fraught negotiations”, “likely to go on all through the night”.

Bryony Worthington tweets: “Hearing there may short delay in publication of climate report tomorrow due to methodical process, not disagreements”. Yes, I’m sure she’s right, there couldn’t possibly be any disagreements, could there.

Now Spiegel is reporting (in German) that the meeting is not going to finish on Thursday evening as planned but will go deep into the night, and it’s not certain that the report will be out on Friday morning as planned. Apparently there are differences between different groups of countries, for example Brazil vs the oil producing Gulf states. Spiegel says there was much debate about the warming pause, and disagreement (sorry Bryony) about the projections.

It would be interesting to be a fly on the wall. It’s tempting to speculate that there’s a battle between the political activists calling for a decisive message and call to action, and the more serious scientists saying we mustn’t exaggerate and must make clear the uncertainties.

David Rose tweets from Stockholm that his hunch is that it will be published on time or only slightly delayed.

Did sceptics take part in the review?

I’ve already commented on the review process for IPCC AR5 WG1, noting that the review took place in two stages (the FOD and the SOD) and that virtually anyone can sign  up to be an “expert reviewer”.  Around 1500 people registered for each round, with 659 submitting comments on the FOD and 800 on the SOD, according to this IPCC fact sheet.   The IPCC has now published a list of all the expert reviewers.  Presumably this list includes those who submitted reviews of the FOD or the SOD or both.

A (possibly) interesting question is whether many of those who take a sceptical view of climate science and the IPCC took part in the review process.  Sceptics are divided on this. On the one hand, some say that the entire process is irretrievably flawed,  that sceptical comments are ignored, and that the IPCC authors will just write what they like in the final version of the report, so engaging in the review is pointless.  Others argue that this is unduly cynical, that one should take part in the review process and that if you don’t, you are on weak ground if you complain later about the content of the report.

After a quick look through the list, here are some names of sceptics (interpreted in a fairly broad sense as those who are known for being critical of the IPCC) who did take part in the review:

  • John Christy – USA – Climate scientist at the University of Alabama in Huntsville
  • Petr Chylek – USA – Climate scientist at Los Alamos
  • Marcel Crok – Netherlands – blogger and author
  • Don Easterbrook – USA – Geologist, Western Washington University (emeritus)
  • Vincent Gray – New Zealand – Chemist (retired), prolific IPCC critic
  • Nicholas Lewis – UK – Independent climate scientist with some published papers
  • Paul Matthews – UK – Who?
  • Ross McKitrick – Canada – Economist, University of Guelph, co-author with McIntyre
  • John McLean – Australia – IT specialist, writes media and web articles
  • Christopher Monckton – UK – Universally acknowledged as a top expert in the field
  • Alec Rawls – USA – Writer, blogger and leaker of the AR5 SOD
  • S. Fred Singer – USA – Environmental scientist, University of Virginia (retired)

Of course there may be many more sceptical reviewers, whose names are not familiar to me. Please let me know if you spot some more.  Notable by their absence are the sceptic bloggers (Andrew Montford, Joanna Nova, Steve McIntyre, Anthony Watts, Judith Curry, Jeff Condon, Lucia Liljegren, Donna Laframboise…).  As previously noted, McIntyre has stated that he was not prepared to agree to the confidentiality agreement, while Watts did register as a reviewer but presumably did not actually submit review comments.

Media and blog coverage

There has of course been a flurry of interest in the media and on blogs about the upcoming IPCC AR5 report. Here is a partial (in both senses) overview.


Newsnight 24th Sept

Overall, a fairly balanced piece.  Paxman said there was a lot that the scientists don’t know, giving ammunition to those who say the whole thing has been overblown. Introduction from Susan Watts said what the report is going to say and mentioned the difficulty over  the slowdown.  In pre-recorded clips, Ed Hawkins insisted that warming had not stopped, using the excuses of volcanoes, the sun and the deep ocean heat, while Myles Allen played with little pieces of coal on a table. Live in the studio, Emily Shuckburgh was given a hard time by Paxman. Tsonis said the science isn’t settled and we need to understand natural variation better.  There’s then an interview with Lord Stern, tedious except for the marvellous Paxman Sneer at 34:09.

BBC News 23rd Sept

This David Shukman item ran on the 6pm and 10pm BBC news.  An oceanographer named Brian King claimed that ocean warming of 1/100th of a degree would have a significant effect on the atmosphere. Unusually for the BBC, a short (27 sec) excerpt with sceptical blogger Andrew Montford was shown.


Starting with three from last Sunday’s papers –

Jonathan Leake, Sunday Times. Don’t Panic. Global warming has shrunk.

Will Hutton, Observer. To fight climate change, we must trust scientific truth and collective action.

Christopher Booker.  The ice is not melting, yet still the scaremongers blunder on.

Spiegel.   Warming Plateau? Climatologists Face Inconvenient Truth

Spectator.  Finally, the IPCC has toned down its climate change alarm. Can rational discussion now begin?

Shari Miller, Mail. Climate scientists insist global warming hasn’t stopped, it’s just on a break as they prepare to release report designed to salvage their reputation.

Matt McGrath, BBC .  Global warming pause ‘central’ to IPCC climate report.

Matt McGrath again.  Five key questions about climate facing the IPCC.

Spiked.  Global warming and the chilling of politics.


Steve McIntyre has come out of apparent semi-retirement to comment on how the IPCC addresses the disparity between models and observations.

Pointman: Armageddon report no 5. I sometimes find it hard to see exactly what Pointman is saying, but he does have a way with words:  “You spin or ignore whatever the tedious coneheads have produced copious volumes of and the summary becomes your bitch.”

Spectator blog: Climatology’s great dilemma. How to talk about the slowdown in warming?

James Delingpole draws attention to the increasing confidence of the IPCC as warming has slowed down.

I’m sure there is loads more. Suggestions?