LIMA - Projected global warming this century has slowed but is still at a severe rate after promises by China, the United States and the European Union to limit greenhouse gas emissions, a scientific study showed on Monday.
The Climate Action Tracker, produced by an independent group of scientists, said temperatures were set to rise by about 3 degrees Celsius (5.6 Fahrenheit) above pre-industrial times by 2100, the lowest since the tracker was set up to monitor promises made by governments in 2009.
The study, issued during UN talks on global warming in Lima, said the rate was 0.2 to 0.4C less than projected after pledges by China, the United States and the European Union in recent weeks to rein in emissions.
Even so, a warming of 3C would cause far more extreme weather such as heatwaves and storms, disrupt food and water supplies and accelerate a thaw of Greenland and Antarctic ice sheets, according to a UN panel of climate scientists.
And it is far above a goal set by almost 200 nations in 2010 of limiting average surface warming to 2C, viewed as a threshold for ever more damaging disruptions to the climate.
Temperatures have already risen about 0.9C since the late 19th century, according to the UN panel of climate scientists.
Still, scientists involved in the tracker said pledges by the top emitters marked progress in the right direction for the talks in Peru, where about 190 nations are working on a deal to rein in emissions to be agreed in Paris in a year's time. "This represents a very important first step," said Bill Hare, of Climate Analytics which compiles the tracker with the Potsdam Institute for Climate Impact Research, Ecofys and the NewClimate Institute.
China promised last month that its emissions will peak around 2030 and the United States agreed to aim to cut greenhouse gas emissions by 26-28 per cent below 2005 levels by 2025.
In October, the European Union said it would cut its emissions by 40 per cent below 1990 levels by 2030. Many other nations have yet to outline their planned cuts as part of the Paris deal.
Niklas Hoehne, of the NewClimate Institute, said there were still many uncertainties - Beijing, for instance,has not indicated the size of its emissions by 2030.