“This IPCC report shows anyone drawing from published papers that there are big differences between 1.5 and 2 degrees warming in both natural and human systems,” Hare said. “Two degrees warming and the tropical reefs have basically no chance – 1.5 degrees, they have a small to modest chance of survival.”
The world is on track to exceed 1.5C of warming unless countries rapidly implement “far-reaching” actions to reduce carbon emissions, according to a draft UN report leaked to Reuters.
The final draft report from the UN’s intergovernmental panel on climate change (IPCC) was due for publication in October. It is the guiding scientific document for what countries must do to combat climate change.
Human-induced warming would exceed 1.5C by about 2040 if emissions continued at their present rate, the report found, but countries could keep warming below that level if they made “rapid and far-reaching” changes.
Under the 2015 Paris climate agreement, almost 200 countries signed up to limit global temperature rises to well below 2C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5C.
Climate scientist and Climate Analytics director Bill Hare said the draft report showed with greater clarity how much faster countries needed to move towards decarbonisation under various temperature situations and that the impacts of climate change greatly increased between 1.5C and 2C of warming.
Necessary actions include making the transition to renewable energy, powering the transport sector with zero carbon electricity, improving agricultural management and stopping deforestation.
“This IPCC report shows anyone drawing from published papers that there are big differences between 1.5 and 2 degrees warming in both natural and human systems,” Hare said. “Two degrees warming and the tropical reefs have basically no chance – 1.5 degrees, they have a small to modest chance of survival.
“There’s a range of commentary that comes out of the report that provides a stronger narrative for us to act than ever before.”
He said it showed that if emissions continued on their present pathway, there was no chance of limiting global temperature rises even to 3C.
Economic modelling in the draft report showed that the dangers for economic growth, particularly in developing countries, were significantly greater at 2C than 1.5C.
The Greenpeace International executive director, Jennifer Morgan, said the moment of truth had come for leaders and the feasibility of achieving the Paris goals was a political choice.
“This choice must be driven by a moral obligation that binds us together. Through international cooperation, real ambition and working with communities, our leaders still have the time to do what they must,” she said.
“That means saying no to fossil fuels and standing up for forest and ocean protection with decisions that prove they understand the urgency. It means cutting down on meat and dairy consumption, and changing the way we produce our food.”
guardian.co.uk © Guardian News & Media Limited 2010