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Reports on leaked IPCC study like a bad game of Chinese whispers

 
Protest Against Carbon Tax in Canberra, Australia

Anti-carbon tax protesters known as The Convoy of No Confidence listen to speeches in front of Parliament House in Canberra on August 22, 2011. The national convoy of disgruntled Australian truck drivers and farmers descended on Canberra to protest government policies including plans for a pollution tax. Photograph: Torsten Blackwood/AFP/Getty Images

 

Powered by Guardian.co.ukThis article titled “Reports on leaked IPCC study like a bad game of Chinese whispers” was written by Graham Readfearn, for theguardian.com on Wednesday 18th September 2013 04.02 UTC

What do you get when cross a game of Chinese whispers, an ideologically-driven section of the press, a failure to check facts and the absence of a time machine?

You get the latest shambles in climate change reporting that has unnecessarily left people confused and misled about the true state of climate change science and the risks of pumping fossil fuels into the atmosphere.

Let’s dive in.

The Rupert Murdoch-owned The Australian, the country’s only national newspaper (besides the business-focused Australian Financial Review), reported in the introduction to a page one story earlier this week that “over the past 60 years the world has in fact been warming at half the rate claimed in the previous Intergovernmental Panel on Climate Change report in 2007.”

Written by the newspaper’s environment correspondent Graham Lloyd, the story did not cite a respected scientist for this central claim, nor did it cite the IPCC itself or a leaked document. Instead, it chose a dubious story in the British conservative tabloid The Daily Mail as its main source.

UK-based Carbon Brief has spoken to several scientists heavily critical of the original Daily Mail story, which had other newspapers first re-reporting and then hastily correcting their stories.

The Daily Mail had made two central claims in its original story (which it has now changed – but more on that in a second). The first was that the IPCC’s 2007 report (known as AR4) had said that the “the planet was warming at a rate of 0.2C every decade”. The second claim was that a leaked copy of the upcoming AR5 put the warming since 1951 at only “0.12C per decade”.

We can check both of these claims.

Firstly, here’s what the 2007 AR4 said about warming since 1951, my emphasis added:

Eleven of the last twelve years (1995–2006) rank among the 12 warmest years in the instrumental record of global surface temperature (since 1850). The updated 100-year linear trend (1906 to 2005) of 0.74°C [0.56°C to 0.92°C] is therefore larger than the corresponding trend for 1901 to 2000 given in the Third Assessment Report of 0.6°C [0.4°C to 0.8°C]. The linear warming trend over the last 50 years (0.13°C [0.10°C to 0.16°C] per decade) is nearly twice that for the last 100 years. The total temperature increase from 1850–1899 to 2001–2005 is 0.76°C [0.57°C to 0.95°C].

So The Daily Mail’s first claim was wrong – 0.13C is not 0.2C.  How about the second claim? As this was based on a leaked draft of a summary of the IPCC’s next report, which is not due out until the end of September, this is harder for people to check. But I have a copy, dated June this year.

Here’s what it says about warming land surface temperatures – bearing in mind that this from a draft copy (apologies to the IPCC for breaking their protocols, but needs must).

Global mean surface temperature trends exhibit substantial decadal variability, despite the robust multi-decadal warming since 1901. The rate of warming over the past 15 years (1998−2012; 0.05 [−0.05 to +0.15] °C per decade) is smaller than the trend since 1951 (1951−2012; 0.12 [0.08 to 0.14] °C per decade).

So when comparing apples with apples, the difference in the warming trend over the last 50 years between the two IPCC reports referred to by The Daily Mail is actually just 0.01C. Bad, bad IPCC.

The Daily Mail also wrote that a finding in the 2007 IPCC report that “hurricanes would become more intense” had “simply been dropped, without mention” in the new report. This is also questionable.

A table from my copy of the upcoming summary report (again, I stress this is a draft dated June so this might have changed) does discuss hurricane activity, saying it was “more likely than not” that there would be more intense cyclones in the latter half of the 21st century, but this wouldn’t happen everywhere. It was “virtually certain” that the North Atlantic had seen increases in intense cyclones since 1970, the report says.

 

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