Humans are driving global warming in “unprecedented” ways, a new UN report described as a “code red for humanity” has warned.
Changes to oceans, sea levels and melting permafrost and glaciers are irreversible for decades, centuries or even millennia as a result of past and future warming, the report has found.
The assessment from the UN’s Intergovernmental Panel on Climate Change (IPCC) paints a stark picture of the impact humans are having through activities such as burning fossil fuels – and the future the world faces if it fails to rapidly tackle the crisis.
It found that human-caused climate change is already affecting many weather and climate extremes in every region around the world, while continued warming will drive increases in the frequency and intensity of hot extremes, marine heatwaves, heavy rain, droughts in some regions, the proportion of intense tropical cyclones, and reductions in Arctic sea ice, snow cover and permafrost.
Temperatures are expected to exceed the 1.5C limits set by countries in the Paris climate treaty over the next two decades, county leaders are being warned.
One of the report’s lead authors, Dr Tamsin Edwards from King’s College London, said: “Unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions, the 1.5C target will be beyond reach.”
UN secretary-general Antonio Guterres described the report as a “code red for humanity” and scientists, campaigners and politicians lined up to call for a shift away from polluting fossil fuels and to end deforestation.
He warned: “The alarm bells are deafening, and the evidence is irrefutable: greenhouse gas emissions from fossil fuel burning and deforestation are choking our planet and putting billions of people at immediate risk.
“Global heating is affecting every region on Earth, with many of the changes becoming irreversible.
“The internationally agreed threshold of 1.5C is perilously close.”
He urged countries to urgently step up efforts and set out national plans for cutting emissions this decade ahead of a crucial UN climate summit taking place in Glasgow in November.
He called for an end to coal-fired power plants and fossil fuel exploration, a shift to renewable energy and funding to protect vulnerable communities, and said Covid-19 recovery spending must be in line with climate goals.
As the report was published, Prime Minister Boris Johnson said it was clear the next decade was going to be pivotal to securing the future of the planet.
“We know what must be done to limit global warming – consign coal to history and shift to clean energy sources, protect nature and provide climate finance for countries on the frontline,” he said.
Mr Johnson, whose government is due to publish its strategy on cutting UK emissions to zero overall by mid-century this autumn, but faces concerns over how to fairly pay for the move, added: “The UK is leading the way, decarbonising our economy faster than any country in the G20 over the last two decades.
“I hope today’s IPCC report will be a wake-up call for the world to take action now, before we meet in Glasgow in November for the critical Cop26 summit.”
Speaking at an IPCC press conference on Monday, Inger Andersen, executive director of the UN Environment Programme, warned “it is time to get serious” and that “no-one is safe” during the climate crisis.
The study, which focuses on the physical science of climate change, forms the first part of the IPCC’s sixth assessment report, and is even clearer on the impact humans are having on the planet than the last such analysis in 2013.
It draws on more than 14,000 scientific papers to reach its conclusions and has found it is “unequivocal” that human activity is warming the world.
It suggests that cities are at particular risk as the climate warms, experiencing hotter temperatures in heatwaves and flash flooding from heavy rain.
The study also warns that unlikely events such ice sheet collapses, abrupt changes to ocean circulation – which drives weather patterns – and much higher warming cannot be ruled out.
Professor Ed Hawkins, one of the lead authors of the report from the University of Reading, said a new key aspect of the study was that it showed every bit of warming mattered.
“The 1.5C or 2C goals from the political process, they’re not cliff edges, we don’t fall off a cliff if we go over those thresholds, every bit of warming matters.
“The consequences get worse and worse and worse as we get warmer and warmer and warmer, so every tonne of CO2 (carbon dioxide) matters, and every bit of warming matters,” he said.
Professor Corinne le Quere, a report author from the University of East Anglia, said: “The message could not be clearer, as long as we continue to emit CO2 the climate will continue to warm and the weather extremes – which we now see with our own eyes – will continue to intensify.
“Thankfully we know what to do: stop emitting CO2,” she said.
Alok Sharma, Cop26 president, called on countries to come forward with ambitious 2030 emissions reduction targets and long-term strategies with a pathway to net zero by the middle of the century.
Governments need to take immediate action to end coal power, accelerate the rollout of electric vehicles, tackle deforestation and reduce methane emissions, he urged.
He said: “The science is clear, the impacts of the climate crisis can be seen around the world and if we don’t act now, we will continue to see the worst effects impact lives, livelihoods and natural habitats.
“Our message to every country, government, business and part of society is simple. The next decade is decisive, follow the science and embrace your responsibility to keep the goal of 1.5C alive.”
