The ANU Climate Change Institute had an open day today and its director, Professor Will Steffen gave a talk. I missed most of it but I did pick up a copy of his report entitled Climate Change 2009. Unlike the ANU Reporter which seemed to have nothing but upbeat analysis and positive news in its complimentary Climate Change Edition I found Professor Steffen’s report very alarming if not horrifying. Here are the key points from the executive summary, you judge for yourself. (italics added)
- The climate system appears to be changing faster than earlier thought. Key manifestations of this include the rate of accumulation of CO2 in the atmosphere, trends in global ocean temperature and sea level, and the loss of Arctic sea ice.
- The risk of continuing rapid climate change is focusing attention on the need to adapt, and the possible limits of adaption. Critical issues in the Australian context include the implications of a possible sea-level rise at the upper end of the IPCC projections of about 0.8m by 2100; the threat of recurring severe drought the drying trends in major parts of the country; the likely increase in extreme climatic events like heatwaves, floods and bushfires; and the impacts of an increasingly acidic ocean and higher ocean temperatures on marine resources and iconic ecosystems such as the Great Barrier Reef.
- Climate change is not proceeding only as smooth curves in mean values of parameters such as temperature and precipitation. Climatic features such as extreme events, abrupt changes, and the non-linear behaviour of climate system processes will increasingly drive impacts on people and ecosystems. Despite these complexities, effective societal adaption strategies can be developed by enhancing resilience or, where appropriate, building the capacity to cope with new climate conditions. The need for effective reduction in greenhouse gas emissions is also urgent, to avoid the risk of crossing dangerous thresholds in the climate system.
- Long-term feedbacks in the climate system may be starting to develop now; the most important of these include dynamic processes in the large polar ice sheets, and the behaviour of natural carbon sinks and potential new natural sources of carbon, such as carbon stored in the permafrost of the northern high latitudes. Once thresholds in ice sheet and carbon cycle dynamics are crossed, such processes cannot be reversed by human intervention, and will lead to more severe and ultimately irreversible climate change from the perspective of human timeframes.
In the next chapter Steffen reports that “warming of the climate system is unequivocal” and that the observed increase in global average temperatures since the mid 20th century is “very likely” the result of anthropogenic greenhouse gas emissions, that is, man-made. Furthermore the observations are now pointing to results around the upper limit of IPCC projections, which is what we used to think were worst case scenarios. The potential impact of such climate change is likely to be dramatic in Australia as the south east and south west continues to dry up with serious implications for our food bowls. Then there is the threat of coastal inundation and tidal flooding as well as more extreme bushfire threats and general reductions in drinking water. However the threats to Australia are minor compared to what might happen if the monsoonal system fails in the Indian subcontinent or the Amazon rainforests die or the Greenland ice shelf melts, all of which are implicated if warming continues unabated.
The report says rather plainly that “heat extremes will have increasingly serious implications for food security as they affect the production of food.” Hence the update on the 2001 graph “reasons for concern” shown below. In case the graph is hard to read, the column on the end says that anything over a 1 degree rise means, given all the other indicators, there are now serious grounds for concern, and it should be noted that one degree is very much at the bottom of the range of expectations. Frankly I think concern is putting it mildly…
The report is available here.
