Issues Magazine

Risks from Climate Change

By Dr Kathleen McInnes

The Intergovernmental Panel on Climate Change has released a summary of its Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation.

In November the Intergovernmental Panel on Climate Change (IPCC) released a summary of its key findings from its Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation.

It is the first comprehensive assessment that has focused solely on extreme events – extreme rain, cyclone, flood, heatwave, sea level – and how these events interact with society and ecosystems to cause natural disasters.

Overall, the effects of climate change will be felt most acutely through extreme weather and climate events such as temperature, rainfall, sea levels, tropical cyclones, droughts and floods.

The IPCC’s confidence in changes for some extremes, such as temperature, is higher than for other extremes, such as floods.

For Australia, it is very likely that there has been an overall decrease in the number of cold days and nights and an overall increase in the number of warm days and nights.

There is low confidence that any observed long-term (i.e. 40 years or more) increases in tropical cyclone activity are robust, after accounting for past changes in observing capabilities.

It is likely that there has been an increase in extreme coastal high water related to trends in mean sea level in the late 20th century.

The report states that:

• it is likely that human influences have led to warming of extreme daily minimum and maximum temperatures on the global scale;

• there is medium confidence that human influences have contributed to intensification of extreme rainfall on the global scale;

• it is likely that there has been human influence on increasing extreme sea levels via mean sea level contributions; and

• there is low confidence that human influences have contributed to changes in tropical cyclone activity.

The report stresses that an assessment of low confidence in observed changes or their causes does not exclude the possibility that changes have occurred or that there is a causal relationship, but rather the evidence is not sufficient at this stage to make a stronger assessment.

The report states that it is virtually certain we will see increases in the frequency and magnitude of warm daily temperature extremes and decreases in cold extremes through the 21st century, and that it is very likely that the length, frequency and/or intensity of warm spells, including heat waves, will continue to increase over most land areas.

Australia’s 1-in-20-year daily maximum temperature is projected to increase in frequency to once every 1–8 years towards the end of the century, and it is likely that the frequency of heavy rainfall or the proportion of total rainfall from heavy falls will increase in the 21st century over southern Australia.

The report provides guidelines for effective preparation for changing risks of climate extremes and disasters. These include “low regrets” options such as early warning systems, risk communication, education, sustainable land use management, ecosystem management and restoration, which have benefits now and lay the foundation for future adaptation.

Other options include ongoing monitoring of response strategies, adopting a range of actions for dealing with risks, and integrating local knowledge with external scientific information.

The full report will be released by the IPCC early in 2012.