In the middle of a summer of fires, floods and heat waves, scientists again reminded on Monday that burning more fossil fuels will rapidly increase the effects of global warming in the decades to come. Only if you pull the emergency brake on greenhouse gas emissions now can the warming of the planet be prevented to dangerous levels by the end of the century, according to the scientists’ report.
The report, Climate change 2021: the physical-scientific basis, is the first edition of the Intergovernmental Panel on Climate Change’s Sixth Assessment Report (AR6), due for completion in 2022. It was approved by 195 member governments of the IPCC on August 6.
The panel’s Working Group I report assesses the physical science of climate change. It found that global warming is exacerbating deadly extremes such as droughts and tropical storms, and affecting every part of the planet.
âWe see this signal in all regions. No region is really spared from climate change, âsaid Sonia Seneviratne, a co-ordinating lead author of the report and a climate researcher ETH Zurichwhere it focuses on climate extremes. The report shows that “immediate reductions in CO2 emissions would be needed to keep the chance of limiting global warming to 2.7 degrees Fahrenheit near the warming target of the Paris Agreement,” she added.
Seneviratne said that while working on the report it had become apparent that many parts of the world were vulnerable to heightened climate impacts, with “extremes of different kinds combined leading to more impacts, such as the coexistence of heat waves and droughts”. . ”
Recent examples include the deadly Pacific Northwest heat wave, which was followed by a wave of forest fires in drought-stressed, dying forests. The warmer the planet, the more likely it is that extreme crop failures will affect different agricultural areas at the same time, she said.
The IPCC report found that with no man-made warming, there is “near zero probability” of some of the deadliest heatwaves of recent history, as well as other extremes such as flood rain. “We see that we have to act immediately if we want to limit the warming to around 1.5 degrees Celsius,” added Seneviratne.
This global climate target, which corresponds to a warming of 2.7 degrees Fahrenheit compared to the pre-industrial level, was set in 2015 as part of the Paris Climate Agreement and is based on the last major climate assessment by the IPCC. The new report confirms that beyond this warming, parts of the climate system, such as the melting of ice sheets that are raising sea levels, could get out of control.
IPCC Vice Chair Ko Barrett, an assistant administrator for the National Ocean and Atmospheric Administration, said the new report provides “unequivocal” confirmation that humans are warming the planet to dangerous levels, causing widespread and rapid changes in it Atmosphere, ocean and cryosphere leads and biosphere in every region of the world and in the entire climate system.
It also reflects “great advances” in understanding how “climate change exacerbates certain weather and climatic events such as extreme heat waves and heavy rain,” said the Co-Chair of IPCC Working Group I ValÃ©rie Masson-Delmotte, Research Director of the French Commission for Alternative Energy and Atomic Energy.
New climate models with more accurate data on critical climate systems like clouds also helped make the most accurate predictions yet about how the climate would react if greenhouse gas emissions were stopped. While there are still some big question marks about how much CO2 permafrost and forests will absorb and release in the future, the report suggests that the climate could begin to stabilize 20 to 30 years after greenhouse gas concentrations have flattened out.
There is also no question that global warming is changing the planet’s hydrological cycle, the report says, bringing with it more intense rainfall and flooding and more intense droughts in many regions. Further north and south, at higher latitudes, rainfall is likely to increase, but is likely to decrease in many already arid subtropical zones.
Since 1990, the panel has published 5 major climate science assessments approximately 5 to 6 years apart, with special reports on specific topics in between. At the global COP26 climate talks in Glasgow in November, the latest scientific assessment provides negotiators with a solid scientific foundation that can empower decision-makers to take critical action.
Steve Cornelius, a former UK government climate negotiator and now chief climate adviser to WWF, said the 2018 IPCC report, which focused on the effects of planetary warming above 1.5 degrees Celsius, was an example of this how science spurs action.
“Policy makers are taking note of the reports from the IPCC,” said Cornelius. âWe have a net zero (carbon dioxide) target in the UK that came about as a direct response to the 2018 IPCC report. That came out, and the government asked the Climate Change Committee to come up with a net zero plan. âWithout the report, it wouldn’t have happened, he said.
But at the global level, the response to the IPCC reports did not do justice to the urgency of the situation, said Saleemul Huq, Director of the International Center for Climate Change and Development in Dhaka, Bangladesh.
“Past IPCC reports served as the basis for pledges to fight global warming,” he said. “The new report, he said, shows” how bad things are getting and why the world needs to accelerate action in line with scientific needs “.
Speaking of tipping points
Stephan Singer, Senior Climate Advisor at the Brussels-based Climate Action Network International, represented environmental and climate activist groups at the recent IPCC meetings. “It was refreshing to see the US back in the caucus of civilized nations,” he said as the government’s scholars and reviewers finalized the report.
He added that the participation of environmental groups helped ensure the IPCC did not deviate from the 1.5 Â° C warming target.
“There were concerns that the 1.5 target might be dropped,” said Singer. âWe wanted to make sure it stayed there as an option. But it’s tough and challenging, and we lose time every day. “
Singer said the environmental groups wanted to “make sure the report highlights the urgent need for action”.
âWe have to do things now to have a chance of reaching net zero,â he said, âand that includes protecting and restoring natural carbon sinks like forests. And people have to understand that this is the only IPCC report that will be released before COP26 and before the United Nations General Assembly, so the language has to be really clear. “
“All the scenarios examined by the IPCC show that global warming is expected to exceed 1.5 degrees Celsius in the next few decades,” said Singer, thus showing how close we are to dangerous threshold values.
“The IPCC speaks strongly of tipping points,” said Singer. âWe can’t rule out significant forest diebacks and ice sheets breaking or other things that can make warming worse. We play Russian roulette with 5 balls in the gun. “
Same message, less “weasel words”
Scott Denning, an atmospheric scientist at Colorado State University, said the new IPCC report hits essentially the same message as all of its 1990 predecessors.
“There are fewer and fewer weasel words in each report, but it’s still pretty much the same message,” he said. “Adding CO2 to the atmosphere warms the world.”
A new element of this latest scientific assessment by the IPCC is a more regional breakdown of the effects of global warming, and some of its conclusions are underscored by current conditions in the western United States. Water supplies in the west are drying up after a 20-year drought, dangerous heat waves last longer and thousands of square kilometers of forest have been burned in recent years.
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Denning said he recently analyzed 40 years of data from a network of 800 snow sensors and found that about half of those locations lost half of their spring snowpack in the past 40 years.
“Holy crap, we’re in trouble when a 1 degree Celsius warming has cost us half of our mountain snowpack,” he said. “We will be upgrading our systems to provide some water, but we cannot support 75 million people in the west without a blanket of snow in the mountains.”
Ida Ploner, a 14 year old activist with Fridays For Future in ViennaAustria said the new science report shows once again the urgency to end carbon emissions now, especially for their generation who will live with the consequences of the choices made today.
“It’s not that it’s just getting a little warmer,” said Ploner, who organizes protests against highway projects that lead to more greenhouse gas emissions. âThat is an existential question. The earth is burning and time is running out. “
The new report could be another wake-up call, she said, but in recent years other landmark reports have done nothing but spark greenwashing campaigns.
“It takes a bit of hope when we see more and more reports and nothing happens,” she said. âAt 14, it shouldn’t be my job to secure a future for myself. That’s why we have leaders, but they don’t, and it’s too important to turn away. We have to show that the whole society is crazy and that we will do something about it. “