IPCC more certain on warming

IPCC more certain on warming


THE hottest days in Australia will increase in temperature by up to 6 degrees and higher than previously predicted sea-level rises could decimate the Northern ­Territory's Kakadu wetlands, according to an international ­scientific report to be released today.


THE hottest days in Australia will increase in temperature by up to 6 degrees and higher than previously predicted sea-level rises could decimate the Northern ­Territory's Kakadu wetlands, according to an international ­scientific report to be released today.

The latest findings from the Intergovernmental Panel on Climate Change on the science of climate change, on which The Australian Financial Review has been briefed, are expected to upgrade the likelihood that man-made activity is causing global warming to 95 per cent.

It is now "unequivocal" Earth has warmed since the start of the 20th century by 0.89 degrees. In contrast, in 2001 the probability of this being the case was only 66 per cent.

The release of the report is set to intensify domestic political debate about the future of the carbon price scheme and the credibility of the Abbott government's Direct Action policy in reducing emissions. A summary will be released in Stockholm tonight around 7pm Australian eastern standard time.

To keep temperature increases below 2 degrees, the report finds global greenhouse gas emissions will need to be cut by 10 per cent a year.

But there is less confidence than the last report in 2007 that global drought or hurricane activity has increased. The new report also reduces the minimum possible temperature increase from 2 degrees to 1.5 degrees if atmospheric greenhouse gas concentrations double.

Importantly, the report responds to the slowing of temperature increases over the past decade. The slowing has been seized upon by critics of the IPCC as evidence man-made climate change is not occurring.

The IPCC says the slowdown is partly explained by an increase in aerosols – fine atmospheric particles – and the storage of heat in lower levels of the ocean has slowed surface warming.

It finds temperature increases will rapidly resume as a result of strict air quality measures. Further, the top-ten warmest years on record have occurred since 1997, and 2005 and 2010 were tied for the warmest year.

"It will certainly show there is no ­reason to think this [stabilisation] will continue," said one of the lead authors of the report, Dr Pep Canadell of CSIRO.

"Global warming will resume in the future because the loading of greenhouse gases in the atmosphere has not stalled and if anything has accelerated."

The report is the fifth by the IPCC and was written by a group of 831 scientists from 85 countries. The body does not conduct its own research but provides an overview of all existing research on climate change. The summary has been approved and modified by governments. The full report will be released on Monday.

A key difference between the report in 2007 and the new version is a change in the scenarios to project future climate change. In 2007, scenarios were based on assumptions about factors driving emissions such as population growth and economic growth. All but one of the 2007 scenarios drastically underestimated the growth in emissions from China.

As a result, the latest report adopts a different approach. It uses scenarios based on how much extra energy the earth will retain as a result of human activity and the concentrations of greenhouse gases in the atmosphere based on them.

Under only one of the four new scenarios will it be possible to keep global warming to 2 degrees – a target agreed to by countries in 2009. This target would require an annual cut in emissions of 10 per cent.

In contrast, warming above 4 degrees by 2100 is likely in the most pessimistic scenario, under which emissions continue to rise at the current rate. "In order to be able to stay under the 2 degrees the enormity of the challenge is very large," Dr Canadell said. "It is possible. It is just what is required is very large and unless policy matches that enormity of the challenge it will be very difficult."

According to regional findings by the IPCC, temperatures have increased between 0.4 degrees and 1.25 degrees in Australia, with the most warming in the centre of the country. Over the medium-term (2046 to 2065), temperatures will increase by 2 degrees and by 2100 they will increase by between 3 degrees and 4 degrees. The warmest daily maximum temperature is projected to increase by 5 to 6 degrees.

Longer dry periods are projected in south-west Western Australia and an increase of floods and droughts is very likely in Australia's agricultural ­production areas. A loss of snow in mountainous regions is also predicted.

Some of the major findings in the report relate to sea-levels. It finds global sea level has risen by 19 centimetres over the last century, mainly as a result of melting ice and sea water expanding as it warms. Sea levels rose almost twice as fast from 1993 to 2010 than from 1901 to 2010. It is now at least 66 per cent certain global sea levels will rise between 0.29 and 0.82 metres higher than from 1986 to 2005; higher than predicted in 2007 when the range given was 0.18 to 0.59 metres. Glaciers and ice sheets are also melting faster; with continuing high emissions the Arctic is expected to be nearly ice-free in summer by 2050.


From the front page

Sponsored by