The world can achieve slower climate warming, preventing temperatures from rising by more than 1.5˚C, a global scientific panel says. But time is short.

The good news from the Intergovernmental Panel on Climate Change (IPCC) is that slower climate warming is still within reach. With an enormous and united effort, it says, the world is certainly still capable of keeping global temperatures from increasing by more than 1.5˚C over historic levels (they’ve already risen by over 1˚C). The more worrying findings in the IPCC’s report, described by one scientist as “historic”, show that the impacts of even 1.5˚C of warming are far greater than previously thought, and that the problem is far more urgent than most governments have acknowledged.

The IPCC, set up 30 years ago, assesses the science related to climate change, its impacts and potential future risks, and possible response options, to provide a scientific base to help governments to decide policy. Its conclusions are published in the Panel’s Special Report on Global Warming of 1.5°C, which says limiting global warming to 1.5ºC would require rapid and far-reaching changes in all aspects of society of a sort not yet seen. One British IPCC scientist, Jim Skea, said: “Limiting warming to 1.5ºC is possible within the laws of chemistry and physics but doing so would require unprecedented changes.”

In one cautionary section the report warns that letting the global temperature temporarily exceed 1.5ºC would require more reliance on techniques that remove CO2 from the air to return it to below 1.5ºC by 2100. “The effectiveness of such techniques is unproven at large scale”, it says judiciously. But the report says there is plenty of action that will help. “Every extra bit of warming matters, especially since warming of 1.5ºC or higher increases the risk associated with long-lasting or irreversible changes, such as the loss of some ecosystems,” said Hans-Otto Pörtner of the IPCC’s Working Group II. For instance, the report says, by 2100 global sea level rise would be 10 cm lower with global warming of 1.5°C compared with 2°C. The likelihood of an Arctic Ocean free of sea ice in summer would be once per century with 1.5°C, compared with at least once per decade with 2°C. The 1.5ºC limit was accepted as a goal by 195 governments in 2015 in the Paris Agreement, which committed them to work to keep temperatures “well below” the 2°C previously agreed and to pursue efforts to limit the increase to 1.5°C.

The IPCC’s report has been widely welcomed. Climate Analytics is a global research organisation whose scientists have contributed widely to the literature used by the IPCC and also advise small island developing states and least developed countries on climate change. It says the IPCC has shown that it is “definitely still feasible to hold warming to that level” [1.5ºC].

Hopeful message

Bill Hare, the CEO of Climate Analytics, said: “We welcome the conclusions of this historic report, one that should give the international community not just a wake-up call, but also hope that we can avoid the most devastating impacts of climate change.” He said the report was “very clear in its confirmation that wide-ranging impacts of climate change will be much worse at 2˚C of warming than at 1.5˚C. This report shows the longer we leave it to act, the more difficult, the more expensive and the more dangerous it will be.” The report says renewable energy must make up half of the global energy mix by 2050, and coal needs to be out of the power sector altogether by then. Carbon dioxide emissions must be halved by 2030, and reach zero by 2050. “The advantages of early action are made stark in this report – especially regarding the sustainable development benefits, around poverty alleviation, health and access to clean energy,” said Hare. “It is clear that governments must be preparing now to commit to much stronger 2030 targets under the Paris Agreement that need to be submitted by all governments no later than 2020, and they have to ditch coal.”

Complete CO2 phase-out

Niklas Höhne of the NewClimate Institute is an author of the IPCC ‘s Fourth and Fifth Assessment reports. He says the IPCC report sends a clear message to policymakers: “Act now, because it’s almost too late! Fulfilling the 1.5°C limit is extremely difficult, but not impossible. We have to phase out CO2 emissions completely.” Limiting warming to 1.5 °C is technically and economically feasible and, properly implemented, it can contribute to sustainable development, he says – but only if all join forces. Almost every area of life will have to be turned upside down: how we live, eat, move around, what we consume. Accurately, as regular readers of the Climate News Network will recognise, Professor Höhne points out that the report contains nothing new: it sums up what has already been published. But it does it starkly, in black and white..

The IPCC’s Fourth Assessment Report, published in 2007, and its Fifth (2013) both expected a probable temperature rise by 2100 of up to 4°C. Less than a year ago, one leading climatologist suggested that was too optimistic. Ken Caldeira, an atmospheric scientist at the Carnegie Institution for Science, said there was a 93% chance that global warming would exceed 4°C by the century’s end. The IPCC reminds us that 2100 is really quite close. Even its mix of rigorous science with unambiguous explanation of what it will bring is familiar. We have been here before. But this report leaves us with less room than ever for doubt.

[This article originally appeared on climatenewsnetwork.net]