Understanding Climate Risk

Science, policy and decision-making

Greenhouse 2011 – notsolive blogging1

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I’m at Greenhouse 2011 in rainy Cairns with about 500 delegates attending over the week. I was going to live blog, but the PC widget has just died, so it will be in instalments because I only have access to the internets at my hotel. This part takes on Day 1 to Lunch covering the Hon Greg Combet, Megan Clark and a number of plenary talks summarising recent science.

Minister for Climate Change, Greg Combet, gave us a round-up of the science before moving onto climate policy. He described the opportunities of the new low carbon economy and the speed at which it is emerging. He spoke of Australia’s natural advantages for a low carbon economy, ending with the role of science in underpinning policy and action. How science could cut through the noise of organised denial and opposition to policy. The strong implication was the risk of Australia missing out in the changes underway if policy was left to wither.

His speech was pretty sciency and sober – it wasn’t a political speech at all, but perhaps Greenhouse 2011 isn’t the venue for that. It was maybe hard to engage with the audience because he was telecommuting from Parliament House in Canberra. From this speech and recent discussions that colleagues and I have had with federal politicians (all parties) who accept the risk of climate change believe that climate science has an important, grounding role in the debate on climate policy.

Dr Megan Clark, CSIRO Chief, announced a ‘new’ initiative for CSIRO. Apparently CSIRO is getting into integration. Reduction and specialisation are passé, integration is in, and Australia can be a world leader. I know this sounds cynical, having been a past employee of CSIRO, but frankly, standing up in 2011 and saying the organisation is undertaking integrated assessment and it is ‘new’, is embarrassing. And Australia is as likely to lead the world in integration science as we are in mitigation policy.

On the other hand, it’s a good signal because now complex systems research and modelling may hopefully be better supported than it has been. CSIRO could support this by relaxing the tight top-down project management model they currently operate to allow more open-ended and risky research. The ‘how to’ part of the integrated systems research is not clear, many options need to be tried, with blind alleys, different methods and the development of tools that work on a range of scales. ‘Hard’ mathematical models, and ‘soft’ approaches to social learning need to be be explored in tandem. Clark was talking up a national collaborative program to integrate at the national scale, so cynicism aside, this is welcome news also. Where Australian science is good is not big models where we just don’t have the investment, but is in framing the questions and finding clever ways to do things because we lack the resources to engage in DEEP THOUGHT by computer.

The work picked to demonstrate the current modelling capacity was curious. Carbon farming scenarios showed that marginal land to extensively farmed land in the Murray Darling Basin would almost be taken over as the carbon price increases from range from $1 per tonne to $36 per tonne. As if farmers would be rational adapters based on price alone. Of course, this would mean that grazing and meat production would decline. How would food production respond? Shift to feedlots, soy-lentils or hard biotech food production? In my mind – those questions suggest a need for integration, not single assumption spatial models that cross two disciplines: economics and soil carbon. Ben Preston asked the obvious in question time: how do we ground truth the driving assumptions in these models, e.g., pure market forces running carbon farming models? Dr Clark’s answer concerned the structural assumptions within the model, not the basic assumptions framing the model.

Dr Greg Ayers, head of the BoM, talked about the Lean and Rind (2009) decomposition of natural variability and the global temperature record. This is a very simple empirical model of climate change and variability using observations. ENSO variability, volcanoes and dust and the solar record, combined with the greenhouse forcing record explain 83% of the Hadley Centre global average warming observations. After pulling out the anthropogenic signal, the residual – natural variability – is pretty flat. Pulling out the variability leaves a smooth curve behind that resembles the forcing curve. He reproduced this for Australia and also for the 20th century CMIP runs for climate models used in the IPCC Fourth Assessment Report. Again, a similar result was achieved. Ayers’ example shows what the science community understands well and the broader community not so well, that simple empirical methods can explain a hell of a lot of the more complex science in climate change and is very robust.

Ayers was asked by a News Ltd journalist about how climate science is contributing to the current debate on climate policy – has the situation improved? While giving a pretty conventional answer, he quoted Tony Haymet, formerly of CSIRO and now of Scripps Institution of Oceanography, “Everyone has a right to make up their own mind, but no-one has the right to make up their own data.” This message, and variants of it need to be drummed in.

Dr Sara Mikeloff Fletcher of NIWA in NZ described the carbon budget globally and in the southern hemisphere. Emissions are about 7.7 Pg C per year at the moment. Ocean absorption studies carried out with ocean GCMs estimate uptake at about 2.3 Pg C per year. The rate of intake is influenced by the partial pressure of CO2 in the atmosphere compared to the ocean. As the proportion of CO2 in the atmosphere rises, the rate of absorption into the ocean increases. Terrestrial uptake is about 2.4 Pg C per year but is much more variable and less certain. In the southern hemisphere, NZ net emissions 13.9 Mt CO2e higher than the baseline of 60.8 in 1990. Net afforestation/deforestation 14.4 Mt CO2e. Therefore NZ is meeting its Kyoto obligations through land use changes. Familiar story to us, except these have a real component, not just the hot-air ploy of stopping deforestation. Regional uncertainties in the southern hemisphere carbon budget that may be due to biomass burning in Africa and South America, and total atmospheric column measurements are being used to resolve these. Biomass burning may be under-estimated by a factor of almost 2. So the science is drilling down into regional detail, which is good news.

A similar big to small picture was painted by Prof. Steve Sherwood of UNSW concerning atmospheric feedback uncertainties. New tools for measuring feedbacks include satellite water vapour measured as change per decade, isotope measurements and better cloud measurements. New model tools incorporate more species of aerosol, and include cloud resolving models and satellite-model links. Water vapour feedback is now pretty well understood at the global level. How weather vapour affects weather and climate variability remains poorly known. Recent studies deal with column water vapour giving a better idea of the vertical structure in observations and models. Water vapour in models is well simulated by using isotopes. Relative humidity in the atmosphere (not at the surface) is not so well simulated, and it governs clouds in GCMs which is important.

One reason why clouds give a positive feedback is because clouds are rising in altitude as the troposphere rises. Higher clouds lead to a larger greenhouse effect. This is a robust and high confidence finding. The big spread in models is with low clouds, and low cloud feedbacks remain unknown. Cloud-vapour-circulation interactions are also not so well known – model weather still deficient. GHGs also have a direct effect on clouds which is not yet being modelled.

Dr Scott Power from the Bureau of Met spoke on cyclones and the Walker Circulation. Jeff Callaghan with Scott has put together a database of science, media, news and public sources allowing a homogenous dataset of tropical cyclones in Queensland. The analysis extends from Cairns–Port Douglas to Ballina in NSW, a history of category 3–5 landfall TCs 1872–2010. All landfalls occurred between Dec ember and April 5, with 81% occurring in Jan–Mar. All multiple landfalls in occurred in La Niña years. The take home message is that the rate of landfall of severe cyclones has decreased, but there is high decadal variability, so the recent low count could change very quickly.

The Walker circulation consists of upward moving air over the Pacific Warm Pool that descends in the eastern Pacific returning west as trade winds – most models show a decrease, the model average is ~20%. This makes the climate more El Niño-like but the climatic state of an El Niño like climate may not necessarily produce a semi permanent El Niño. There seems to be a decrease in recent decades but high decadal variability makes attribution difficult.

This is just the morning’s talks. Due to no PC battery power left, I jotted down notes for the afternoon and am not sure whether I will have the time to write out fuller descriptions.


Written by Roger Jones

April 4, 2011 at 9:14 pm

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