The cost of keeping global warming in check is "relatively modest," but only if the world acts quickly to reverse the buildup of heat-trapping gases in the atmosphere, the head of the UN's expert panel on climate change said.
Such gases, mainly CO2 from the burning of fossil fuels, rose on average by 2.2 per cent a year in 2000-2010, driven by the use of coal in the power sector, officials said as they launched the Intergovernmental Panel of Climate Change's report on measures to fight global warming.
Without additional measures to contain emissions, global temperatures will rise about 3 degrees to 4 degrees Celsius (5 degrees to 7 degrees Fahrenheit) by 2100 compared to current levels, the panel said.
"The longer we delay the higher would be the cost," IPCC chairman Rajendra Pachauri told The Associated Press after the panel's weeklong session in Berlin.
"But despite that, the point I'm making is that even now, the cost is not something that's going to bring about a major disruption of economic systems. It's well within our reach."
The IPCC, an international body assessing climate science, projected that shifting the energy system from fossil fuels to zero- or low-carbon sources including wind and solar power would reduce consumption growth by about 0.06 percentage points per year, adding that that did not take into account the economic benefits of reduced climate change.
"The loss in consumption is relatively modest," Pachauri said.
The IPCC said the shift would entail a near-quadrupling of low-carbon energy, which in the panel's projections included renewable sources as well as nuclear power and fossil fuel-fired plants equipped with technologies to capture some of the emissions.
Coal emissions have declined in the US as some power plants have switched to lower-priced natural gas but they are fueling economic growth in China and India.
