Stark warning says we have a decade to avoid catastrophic climate change
World on track to be 3C warmer by mid-century unless radical action taken, say UN climate experts
World leaders have just over a decade to cut emissions and prevent catastrophic climate change.
We are nowhere near reaching the target to limit average global temperature rises to 1.5C above pre-industrial levels, and the world is on track to be 3C warmer.
Cutting emissions from transport, energy and agriculture will require "unprecedented changes" to how we live our lives, the 'Global Warming of 1.5C' report says.
Unless action is taken, more extreme weather events are expected including winter storms and drought, with hundreds of millions of people put at risk of poverty and some small island states facing the prospect of being wiped out as sea levels rise.
It represents the starkest warning yet from the United Nations' Intergovernmental Panel on Climate Change.
The report is based on an analysis of more than 6,000 scientific papers, reviewed by climate scientists from 40 countries. "Every bit of warming matters, especially since warming of 1.5C or higher increases the risk associated with long-lasting or irreversible changes such as the loss of some ecosystems," co-chair of the IPCC Working Group II Hans-Otto Portner said.
"Limiting global warming would also give people and ecosystems more room to adapt and remain below relevant risk thresholds."
Average global temperatures are currently 1C above pre-industrial levels, and are likely to increase 1.5C between 2030 and 2052 under current trajectories, the report says.
The 195 nations which are signatory to the Paris climate deal had committed to keep rises to no more than 2C.
But they asked the IPCC to complete a report on the feasibility to limiting hikes following a request from small island nations. The IPCC said it was possible to limit rises to 1.5C, but that sea levels would still rise, there would be loss of ecosystems and coral reefs, extinction threats would remain for insects, plants and animals and there was also the prospect of lower crop yields, loss marine fisheries and the disappearance of summer sea ice in the Arctic.
"Temperature rise to date has already resulted in profound alterations to human and natural systems, bringing increases in some types of extreme weather, droughts, floods, sea level rise and biodiversity loss, and causing unprecedented risks to vulnerable persons and populations," it says.
But it adds if temperatures rise by 2C, the effects will be more pronounced and more people will be put at risk of poverty and water stress, with higher health risks.
Aid agency Trócaire said the report was a "clear call" for action.
"The world is already experiencing the deadly effects of global warming at 1C," chief executive Caoimhe de Barra said. "Climate change represents a huge risk for all our futures.
"The faster we act, the more we reduce the risk to people everywhere, especially the most vulnerable."
The report says that "rapid, far-reaching and unprecedented" societal changes were needed.
Carbon emissions must fall by 45pc by 2030, reaching "net zero" by 2050. This means any remaining emissions would need to be removed by planting forests, or using carbon capture and storage technology, where emissions from power plants and industry are captured and stored deep underground.
But the report adds: "The effectiveness of such techniques are unproven at large scale and some may carry significant risks for sustainable development."
It also says Government policies are needed to incentivise private-sector investment in low-carbon technologies.
Annual investment of more than €2trn is needed.
The Green Party said the report showed that business as usual was no longer an option. People Before Profit TD Bríd Smith said the "game was up" for fossil fuel companies, and called on the Government to support her bill which would ban fossil fuel exploration in Ireland.