News and Analysis • Volume 13 • Number 1 • March 2009

New Studies Find Climate Change Worse than Predicted

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Participants at a scientific conference held in Copenhagen in March were shocked to hear new, much higher estimates for likely sea-level rise and rainforest loss that could lead to trees emitting more carbon than they store.

Two years ago, the Intergovernmental Panel on Climate Change (IPCC) 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. The conclusions of the new research are alarming: the most likely scenario is a sea-level rise of a metre or more - about twice the amount predicted the IPCC in 2007. The lowest new estimate is at least 50 cm, up from 18 cm two years ago.

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.

From Sinks to Sources?

And the bad news did not end there. 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 2ºC increase above pre-industrial levels would result in a 20-40 percent loss of the rainforest within 100 years. A 3ºC rise, considered a more likely scenario, would see three-quarters of it destroyed by drought and turn the Amazon from a significant carbon sink into a significant source.

The Cost of Inaction

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. In India, climate change has resulted in a 10-percent drop in the productivity of outdoor labourers since 1980, and a further 2ºC temperature rise would mean another 20-percent decline. 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.

Kyoto Protocol or Carbon Tax?

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, while 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. 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,” he said.

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.

While some participants found the idea attractive, others were more sceptical. Daniel Kammen, who teaches economics at Berkeley, noted that enormous investment would be needed to rebuild electricity grids to accommodate a higher proportion of renewables and a carbon price could not achieve that in the necessary time frame. “How many of us would have a cell phone if we had to pay for 20 years of minutes upfront?” he asked.

Message to Climate Summiteers

The International Scientific Congress on Climate Change was organised by a consortium of leading 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. 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 the December climate summit in Copenhagen. The objective of that meeting is the conclusion of a successor treaty to the Kyoto Protocol, which will expire in 2012, but few expect the goal to be met.