It seems that scarcely a day goes by without another meeting, conference or report on climate change. The title of this post comes from a recent report by Will Steffen (pdf), Executive Director of the ANU’s Climate Change Institute, with the assistance of and published by the Department of Climate Change. The report reviews recent scientific literature on climate change with particular reference to Australia.
From Penny Wong’s press release is generally supportive and from what she said you’d think it might put a burr under the Government’s saddle. You’d be wrong.
When the ABC picked up on the report Wong used it to beat up on the Opposition over passing the CPRS. The ABC was mostly interested in what it said about the big dry over Southern Australia and the Murray-Darling Basin. More of that soon. I found a number of interesting talking points.
Steffen updates an earlier graph from Rapauch et al to fill in the 2007 values for world emissions:
There is simply no way the 3.3% pa increase will be sustained. By using the rule of 72 emissions would double every 20 years or so. If continued over 100 years that would mean an increase of 32 times. Ain’t going to happen. I’d make three points about the trend. First, even if the GFC brings the 2010 or 2011 values below the red line they would still be way above what are given as the 450ppm and 650ppm stabilisation paths. Pure madness.
Second, the emissions in recent years no doubt reflect the rapid expansion of coal-fired power generation capacity in China, India and elsewhere. As I keep saying, Ken Caldeira tells us:
We did a calculation that actually the average coal-fired power plant cools the Earth for about the first 7 years because it’s sulphate emissions have a cooling influence more than the CO2. But then after seven years the CO2 accumulates enough to overwhelm that sulfate cooling, and then of course the CO2 levels remain high in the atmosphere for many thousands of years.
Third, as far back as the Stern Review anyone paying attention has known that 450ppm gives us a 50% chance of exceeding 2C. See the first figure in this post, and that is taking into account short-term feedbacks only.
Section 2.1 has an interesting section on sea-level rise which I think is quite conservative. He goes for a “more plausible” 0.8m by 2100 based on Rahmstorf’s linear projections, but says an outcome towards 1.5m cannot be ruled out. I would suggest that 2m is quite possible, as in this post where I concluded:
My feeling is that sea level rise is going to turn non-linear at some point and that point could easily be before the century is out. I’d tentatively suggest that Hansen’s notion of two metres by 2100 is more likely than 80cm which seems to me the minimum.
Steffen does pick up the vulnerability of the West Antarctica ice sheet, but nothing in advance of what we found in looking at the Andrill project.
We’ve also talked about the threat from the “disproportionately large
increase in the frequency of extreme sea?level events associated with high tides and storm surges” from a modest sea level rise.
A 0.5 m rise in mean sea?level could cause such extreme events to occur hundreds of times more frequently by the end of the century (ACE CRC 2008; Figure 9); an event that now happens once every hundred years would be likely to occur two or three times per year.
This map is quite disturbing:
Progress has been made in sorting out what is happening with the climate in Australia. The shorter story is that there is a clear climate change signal in the drying pattern in south-west Australia in recent decades and in the lower edge of the Murray-Darling Basin. There is some evidence of a climate change signal in the drying trend in Victoria and the lower half of South Australia. In Northern NSW and Queensland it is too early to say. There is evidence of increased rainfall in the north-west from the Asian brown cloud. There is no clear pattern yet of changes in El Nino. The following graphs are a worry:
It should be noted that heat by itself will reduce runoff, with 1C said to cause a 15% reduction.
On ocean acidity a study of the Southern Ocean shows:
an intense minimum in carbonate ion concentration in winter, suggesting that conditions deleterious for the growth of important calcifying plankton species could occur as early as 2030 in winter (McNeil and Matear 2008; Figure 19), and more generally by 2050–60 (Orr et al. 2005).
On the Great Barrier Reef a study of the coral Porites shows a decline in the rate of calcification of 14% since 1990.
Climate sensitivity is the long-term increase in surface temperature flowing from a doubling of CO2 levels from the pre-industrial, ie. to 560ppm. There are three points to note here. The first is that through studies on the Vostok ice cores the IPCC value of 3C has been confirmed with greater certainty for short-term feedbacks. Whereas the IPCC gave a plus or minus uncertainty of 1.5C Hansen in his Bjerknes Lecture (see entry of 20 December, 2008) puts the uncertainty at plus or minus 0.5C.
Second, with long-term feedbacks climate sensitivity is doubled to 6C.
Third, and very interesting, is that climate models do not include long-term feedbacks.
The models should be OK for a century or two, but importantly we just don’t know when the long-term feedbacks cut in with “rapid, sustained radiative forcing.” It hasn’t been done before in the manner we humans are doing it now, not in a billion years.
A further worry is the aerosol masking effect. A study has found that:
even if greenhouse gas concentrations could be fixed at their 2005 levels, the additional warming caused by cleaning up aerosol pollution and reaching atmosphere–ocean equilibrium would be 1.6°C.
If we stopped all emissions yesterday and cleaned up the aerosols we’d probably end up with a temperature rise of 2.4C above pre-industrial.
In view of this the updated “burning embers” diagram which Steffen uses in the Executive Summary and at Figure 28 is interesting. I prefer the version from the Copenhagen Synthesis Report (Figure8) with the 2C guardrail marked:
The temperature base is 1990, so 2.4C would equate to 1.8C on the diagram.
Now this graph showing the effect of carbon sinks I find really interesting:
There has been an assumption in Stern and the IPCC that there is a ‘safe’ level where emissions are benignly absorbed by the ocean and land. Stern put this at 5gt of carbon or 18.35gt of CO2e. Monbiot in 2006, writing a little before Stern, noted a study suggesting that by 2030 sinks would be reduced to 2.7gt or about 10gt of CO2e. I understand that Caldeira thinks that anything above pre-industrial levels is a problem for ocean acidity.
There’s more of interest in the report, including a southern hemisphere version of the hockey stick. It should shake the complacency of the Government and Opposition alike, but there has been no sign of that to date.