Spooner’s war on climate science
John Spooner of the Melbourne Age used to be a great cartoonist. He’s done whatever cartoonists do whenever they go emeritus or jump the shark – let his emotional beliefs rule the analytical edge that makes satirical comment. As a result he is drawing rubbish cartoons lampooning facts that he finds offensive. When it comes to climate change, Spooner has lost his mojo.
The last Sunday Age (09/07) contained a Spooner anti-climate science cartoon marking the release of the Clean Energy Package. The content came from a paper recently published online in the Proceedings of the National Academy of Science:
Kaufmann RK, Kauppi H, Mann ML, Stock JH Reconciling anthropogenic climate change with observed temperature 1998-2008. Proceedings of the National Academy of Sciences. doi:10.1073/pnas.1102467108
Unfortunately his understanding of the paper came from the science denial blogs (wattsupwiththat was straight onto it) so completely misrepresents its findings.
Caller: Prime Minister, we have news of the latest science from PNAS. New research suggests that sulphide from Chinese coal fired power stations might be calling global cooling
JuliaG: Ok, so we keep exporting coal. What’s the problem?
Caller: Err, well. Global cooling should make the carbon tax and ETS redundant
JuliaG: GET ME GARNAUT NOW!
Caller: But wait, there’s more. It gets worse. There seems to have been no increase during the last decade’s slight cooling.
JuliaG: … and fire Flannery.
So let’s compare that fictional exchange with what the abstract says:
Given the widely noted increase in the warming effects of rising greenhouse gas concentrations, it has been unclear why global surface temperatures did not rise between 1998 and 2008. We find that this hiatus in warming coincides with a period of little increase in the sum of anthropogenic and natural forcings. Declining solar insolation as part of a normal eleven-year cycle, and a cyclical change from an El Niño to a La Niña dominate our measure of anthropogenic effects because rapid growth in short-lived sulfur emissions partially offsets rising greenhouse gas concentrations. As such, we find that recent global temperature records are consistent with the existing understanding of the relationship among global surface temperature, internal variability, and radiative forcing, which includes anthropogenic factors with well known warming and cooling effects.
So Spooner has cited the paper then verballed it. More on Spooner’s exploits with climate science at Deltoid.
Actually, the paper is really interesting. Kaufmann and colleagues have been publishing econometric models combining warming, forcing and emissions for a few years. They are another line of evidence that greenhouse gas emissions are contributing to warming. In this paper, they extend their model to 2008 combining natural and human radiative forcing mechanisms. This is what they look like:
There is a flattening out over the past decade. When the last decade is modelled it looks like this:
The green line is natural forcing and the red line is anthropogenic forcing. The lower temperatures in 2000 and 2008 are interpreted as lying outside the 95th percentile of anthropogenic forcing but this assumes that forcing is converted into global mean temperature on a yearly basis. That, I can’t wear. However, the overall temperature pattern does more closely resemble the natural rather than anthropogenic curve and sits between the two. Alternate hypotheses that the warming was driven by stratospheric water vapour (or black carbon) were rejected. It is possible that the warming hiatus is als affected by climate variability not represented in this model. The energy content of the shallow ocean provides some support for this, but the big picture the paper provides is most likely correct: natural sources are contributing to the recent hiatus.
As to the potential role of Asian (mostly Chinese) sulphate emissions – the plan is to reduce these significantly over the next decade. There may be a post-GFC increase as coal production was increased by the economic stimulus, but this is a temporary departure from longer-term policy.
Figure 1 shows solar, anthropogenic and total forcing since 1950. These show that the warming of the past 60 years is most strongly influenced by anthropogenic forcing. This is another line of evidence independent of climate modelling. The main conclusion I take from this paper? Climate science is developing better explanations for the wiggles and bumps in global temperature. The denialist cherry-picking of short-term trends to supposedly disprove the global warming thesis just produces hot air.