IPCC AR5 completed: science has spoken – cut deep, cut soon

The IPCC’s Fifth Report process reached its climax in Copenhagen yesterday with the release of the final “synthesis” report (download here), which pulls together all the strands from the three working group reports on the physical science (Working Group 1), climate impacts (WG2) and how to go about dealing with the problem (WG3). Launching the report, UN secretary general Ban Ki-moon was blunt:

“Science has spoken. There is no ambiguity in their message. Leaders must act. Time is not on our side.”

Given that it’s based entirely on the work done for the underlying reports, there are no surprises the synthesis report for anyone who has been following climate news over the last year, but what is striking is the emphasis on the need for rapid and deep cuts in fossil fuel emissions – and a corresponding steep increase in investment in renewable energy sources. Ban Ki-Moon emphasised the point in a comment aimed at investors:

“Please reduce your investments in the coal- and fossil fuel-based economy and [move] to renewable energy.”

Writing in the Guardian, Bill McKibben notes an increase in the urgency of the language being used:

This week, with the release of their new synthesis report, [scientists] are trying the words “severe, widespread, and irreversible” to describe the effects of climate change – which for scientists, conservative by nature, falls just short of announcing that climate change will produce a zombie apocalypse plus random beheadings plus Ebola. It’s hard to imagine how they will up the language in time for the next big global confab in Paris.

The Guardian’s coverage is – as always – exemplary. In addition to Damian Carrington’s news report, they also give good graph. See also the BBC, and Stuff – who take the AP coverage.

New Zealand’s climate change minister Tim Groser issued a press release to welcome the report:

It is the best scientific assessment of climate issues available. I’m delighted that New Zealand scientists have contributed to this body of knowledge.

If that’s really the case, why is Groser enacting policies which are currently pointing NZ towards a 50% increase in emissions instead of deep cuts? Perhaps he should be listening to Ban Ki-moon when he says “”There is a myth that climate action will cost heavily, but inaction will cost much more.”

Saturday snark: a textbook for Vincent

As Stoat points out, the IPCC has released the reviewers comments on the Working Group One second order draft report. And as you might expect, the IPCC’s favourite inexpert commenter, the New Zealand Climate “Science” Coalition’s very own Vincent Gray was busy reviewing their work. Here’s comment 1-549 from Chapter One (pdf) by Gray:

The records shown are not “observations” and they are not “temperatures”. They are also not “globally averaged. They are a set of multiple averages, subtracted from an overall average, compiled from a vaying non-standardised set of maximum an minimum temperature measurements at varying weather sations and ship measurements. They were previously treated as “Mean Global Temperature anomaly” The uncertainties attached to each figure are very great, individual temperature measurements are rarely accurate to better than one degree, so a claimed “trend” over 100 years of less than one degree has a very low level of statistical significance. [Vincent Gray, New Zealand] (all spelling from IPCC doc)

The response from the editors is a minor classic of its kind:

Rejected – The comment does not reflect the scientific understanding. The errors in individual observations are not additive; we are also doing relative analysis that eliminates many of the concerns about individual errors. The reviewer obviously has a limited understanding of the associated error evaluation for analysis of large datasets. See Chapter 2 for more on the evaluation of these datasets. Or maybe even read a basic textbook. (my emphasis)

For more on accuracy versus precision, and the statistical power of large numbers, this classic post by Tamino is well worth a read.

There are other minor gems to be found as the reviewers deal with Monckton (in the “general” section) and John McLean (seemingly everywhere). In fact McLean’s ubiquity suggests that he may have acceded to Gray’s throne as the man with most comments on a single IPCC report. But don’t expect me to add them all up, I do have a life…

People talkin’ about science (and water)

To kick off a new open thread (biofarmer, that’s you I’m looking at), here’s the IPCC’s new/latest video, in which various lead authors and Working Group 1 luminaries talk about the state of our understanding of the physical science of climate. You may also wish to discuss — anything. Have at it…