Forecasts may be too rosy: study

UN projections of how much current climate policies and national pledges to cut carbon pollution will slow global warming are more uncertain than widely assumed, researchers reported Monday.

Leading into this month's COP26 summit, the UN said existing policies would see Earth's average surface temperature rise a "catastrophic" 2.7 degrees Celsius above preindustrial levels by 2100.

Renewed pledges from large emitters such as India would have a negligible effect on warming this century, the UN said during COP26, and were still worlds away from the Paris Agreement temperature goal of 1.5C of warming.

But the apparent precision of these estimates is misleading, according to a new study, written by several contributors to the UN reports it calls into question.

Seven different climate modelling groups assessed how voluntary pledges under the Paris treaty running to 2030 -- known as nationally determined contributions -- would play out by 2100.

Their estimates, published in Nature Climate Change, ranged from 2.2C to 2.9C, roughly in line with the UN figures. What stood out, however, was the lack of certainty.

"If you take the low end of that range, it may sound like we are really close to meeting the Paris goals," Peters told AFP. "But it is equally likely that the outcome could be up around 3C, in which case much stronger policies would be needed."