That is the central message of a stark new report from the UN-backed Intergovernmental Panel on Climate Change. The United Nations’ expert panel on climate science on Saturday finished a report on global warming that the UN’s environment agency said offers ”conclusive evidence” that humans are altering the Earth’s climate system.
The document, which combines the findings of three earlier reports, was adopted after all-night talks that went on until 5 a.m. Saturday by the Intergovernmental Panel on Climate Change.
The scientists and government representatives on the panel, who jointly approved the document line by line, then rested for a few hours before resuming the session in Copenhagen to finish the document.
The report is scheduled to be released to the public today.
Apart from discussing the human influence, the report is expected to describe how climate impacts, including melting Arctic sea ice and rising levels, are already happening and could become irreversible unless the world curbs its greenhouse gas emissions.
The IPCC says scientists are now 95 percent certain that the buildup of such gases from the burning of fossil fuels and deforestation is the main cause of warming seen since the middle of the 20th century.
IPCC vice chair Jean-Pascal van Ypersele wrote on Twitter that the report was adopted Saturday afternoon following round-the-clock talks.
The U.N. Environment Program said the report ”offers conclusive scientific evidence that human activities continue to cause unprecedented changes in the Earth’s climate.”
In an interview with The Associated Press, UNEP head Achim Steiner said the world has the technology and capacity to act and needs to do so urgently.
The cost of achieving emissions cuts increases exponentially with each year, Steiner said, ”because you will have to make far more drastic changes in our economy.”
While the IPCC tries to avoid explicitly telling governments what they should do, the report will present scenarios showing that warming can be kept in check if the world shifts its energy system toward renewable sources like wind and solar power and implements technologies to capture greenhouse gases from the atmosphere.
The IPCC urges that by 2050, most of the world’s electricity must – and can – be produced from low carbon sources.
Fossil fuels, without carbon capture and storage (CCS), should be phased out “almost entirely” by 2100.
The short Synthesis Report was published on Sunday in Copenhagen, after a week of intense debate between scientists and government officials.
The report says the world faces “severe, pervasive and irreversible” impacts without effective action on carbon.
“It’s very clear from the report that fossil fuels have had their day,” said Prof Arthur Petersen from UCL and a member of the Dutch government’s team in Copenhagen.
“Of course it is up to politicians to decide which risks they want to take with climate change, so it is not policy prescriptive in saying that these reductions should take place, but it is absolutely clear that the reductions should take place if you want to limit (temperature increases) to 2C.”
Rapid phase out
For electricity production, this would mean a rapid move away from coal and into renewables and other low carbon forms, including nuclear.
The report suggests renewables will have to grow from their current 30% share to 80% of the power sector by 2050.
In the longer term the report states “fossil fuel power generation without CCS is phased out almost entirely by 2100”.
The chair of the IPCC Dr Rajendra Pachauri said that greener electricity is key.
“If the world wants to go on this pathway of keeping temperatures increases below 2 degrees C by the end of the century, then by the middle of the century we will have to treble or quadruple the use of low carbon or zero carbon energy from renewables, and sources like bioenergy, nuclear and carbon capture and storage.”
The Synthesis boils these three into one, with the intention of informing politicians engaged in attempts to deliver a new global treaty on climate by the end of 2015.
It re-states many familiar positions:
- Warming is “unequivocal” and the human influence on climate is clear
- Since the 1950s the observed changes are unprecedented over decades to millennia
- The period from 1983 to 2012, it says, was likely the warmest 30 year period of the last 1,400 years
- Warming impacts are already being seen around the globe, in the acidification of the oceans, the melting of arctic ice and poorer crop yields in many parts
- Without concerted action on carbon, temperatures will increase over the coming decades and could be almost 5C above pre-industrial levels by the end of this century
Politicians have agreed that a rise of 2C is the threshold of danger. In this report the IPCC authors outline a number of routes to keep to that level by the end of the century.
Countries will need to adapt rapidly, but almost all scenarios see near zero emissions by 2100.
“We can’t afford to burn all the fossil fuels we have without dealing with the waste product which is CO2 and without dumping it in the atmosphere,” said Prof Myles Allen from Oxford University, and a member of the IPCC core writing team.
“If we can’t develop carbon capture we will have to stop using fossil fuels if we want to stop dangerous climate change, that is a very clear message that comes out of the IPCC reports.”
The clarity of the language over the future of coal, oil, and gas was welcomed by campaigners.
“What they have said is that we must get to zero emissions, and that’s new,” said Samantha Smith from WWF.
“The second thing is they said that it is affordable, it is not going to cripple economies.”