Climate Change Impacts Worse than Predicted: Studies

20 March 2009

New studies released at a climate change conference in Copenhagen warn that seas are likely to rise to levels much higher than previously predicted. The studies also suggest that continued deforestation could lead to trees emitting more carbon dioxide than they store.

The findings were presented at the International Scientific Congress on Climate Change, which was held from 10-12 March at the University of Copenhagen. The findings of the Congress are meant to add to the body of knowledge accumulated by the Intergovernmental Panel on Climate Change (IPCC). The Congress will provide a summary of existing scientific knowledge two years after the last IPCC report.

The last IPCC report estimated that sea levels would rise between 18 and 59 centimetres by the end of the 21st century. The group did, however, caution that due to insufficient data, their prediction did not fully reflect the likely effects of melting ice sheets in Greenland and Antarctica.

Since then, scientist have been able develop a new forecasting model based on a much more accurate picture of what is happening in these regions, including the major role played by ice cracking up and sliding into the ocean.

With new estimates suggesting that sea-levels are likely to rise up to a metre or more - about twice the amount predicted by the IPCC in 2007 - environmentalists say the new research is alarming. Some 600 million people, or 10 percent of the earth's population, who live in low-lying areas will be in danger of catastrophic flooding even at the lower end of the new estimates, scientists at the conference said.

Other studies presented at the Copenhagen meeting focussed on other aspects of climate change. A Japanese study showed that while it would cost up to 128 billion yen (US$1.3 billion) to secure the country's ports against more frequent storms, failure to do so could result in the loss of 1.5 to 3.4 percent of Japan's GDP by 2085.

Another study suggests that India has experienced a 10 percent drop in the productivity of outdoor labourers since 1980 due to climate change. The study said this could decline by another 20 percent if a 2 degree temperature rise is realised. The World Health Organisation has estimated that climate change is responsible for some 150,000 deaths a year through increases in crop failures, flooding, malaria and diarrheal diseases.

Increased temperatures accelerate rainforest mortality

David Hilbert of the Australian research organisation CSIRO warned that global warming could turn rainforests from carbon sinks into net emitters. "Most carbon is in living trees, and tree mortality is not included in climate models," he explained. Detailed observations of 117 rainforests sites around the world showed that although trees grow faster with higher temperatures, their mortality goes up too.

According to Dr Hilbert's calculations, every degree centigrade of temperature increase will result in 14 tonnes of carbon emissions per hectare of rainforest, equating to 24.5 gigatonnes of carbon worldwide - two and a half times the world carbon emissions in 2007.

Another study used computer models to investigate how the Amazon would respond to future temperature rises. It found that a 2 degree centigrade increase above pre-industrial levels would result in a 20-40 percent loss of the rainforest within 100 years. A 3 degree rise, which the study says is more likely, would see a 75 percent loss by drought and turn the Amazon from a significant carbon sink into a significant source.

Expert says carbon tax more effective than emissions trading

To avoid the worst effects of climate change, the IPCC has called for a 25-40 percent reduction in global greenhouse gas emissions by 2020. The European Union has committed to a 20 to 30 percent decrease from 1990 levels by 2020. President Obama recently said the US would try to cut its CO2 emissions back to 1990 levels in within the same timeframe. This, IPCC head Rajendra Pauchuri has said, would not suffice for a meaningful post-Kyoto agreement.

Speaking at the Copenhagen scientific congress, Yale economics professor William Nordhaus proposed replacing the ‘inefficient and ineffective' Kyoto Protocol with a global carbon tax. "The developed countries that have emissions reductions targets account for only half of the world's carbon emissions," Nordhaus said. "Our models show that a 50 percent non-participation results in a 250 percent increase in the cost to those who are participating, and this is a huge penalty we can no longer afford."

A carbon tax levied on fossil fuels and transport "would create a reliable carbon price which would create the incentive we need to shift towards a low-carbon economy," professor Nordhaus suggested. Allowing countries to commit to imposing a carbon tax at a minimum level, rather than taking on emissions reductions commitments, would be particularly attractive to small countries.

The Congress was organised by a consortium of universities in Australia, China, Denmark, Japan, Singapore, Switzerland, the UK and the US. Among the event's preliminary conclusions was that the worst-case IPCC scenario trajectories were being realised. Weaker greenhouse gas emissions reduction targets for 2020 would increase the risk of crossing tipping points and make it more difficult to meet the IPCC's 60-percent target for 2050. Participants also agreed that a delay in initiating effective mitigation actions would significantly increase the long-term social and economic costs of both adaptation and mitigation.

A full synthesis report will be published in June and distributed to all participants at December's UN Framework Convention on Climate Change summit in Copenhagen. The objective of that meeting is the conclusion of a successor treaty to the Kyoto Protocol, which will expire in 2012.

ICTSD Reporting

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