This story was originally published by The Guardian and is reproduced here as part of the Climate Office collaboration.
“It’s unequivocal. These three austere words are the first of the new report of the Intergovernmental Panel on Climate Change. The climate crisis is unequivocally caused by human activities and is already unequivocally affecting every corner of the earth, air and sea on the planet.
The report, produced by hundreds of the world’s top scientists, with the approval of all governments around the world, concludes that it could get worse if the remaining slim chance of avoiding heating above 1.5 degrees Celsius (2 , 7 degrees Fahrenheit) is not immediately captured.
The scientific language of the report is cold and clear but cannot mask the heat and chaos that global warming is unleashing on the world. We have already caused 1 degree C (1.8 degrees F) of heating, approaching dangerously close to the danger limit of 1.5 degrees C agreed to in the Paris climate agreement. Rain showers have accelerated since the 1980s.
Accelerating melting ice has dumped billions of tons of water into the oceans, where oxygen levels are dropping – choking the seas – and acidity is rising. Sea level has already risen by almost 8 inches, and more is now irreversibly cooked.
Greenhouse gas emissions spewed out from the burning of fossil fuels, destruction of forests and other human activities are now clearly destabilizing the mild climate in which civilization began, according to the report. Levels of carbon dioxide in the air are now at their highest level for at least 2 million years.
When was the last time we saw such rapid heating? At least 2000 years ago and probably 100,000 years ago. Such high temperatures? At least 6,500 years old. Are the sea levels rising so fast? At least 3000 years old. So acidic oceans? Two million years.
All of this is already hurting people everywhere, the report says. The heat waves and heavy rains that led to flooding have become more intense and frequent since the 1950s, affecting more than 90 percent of regions around the world, according to the report. Drought is increasing in more than 90 percent of areas for which good data are available. The number of hurricanes and major typhoons is more than 66% likely to have increased since the 1970s.
So what about the future? Some warm-ups are already inevitable. We will certainly reach 1.5 degrees C over the next two decades, no matter what happens to emissions, according to the IPCC. The only good news is that maintaining at 1.5C is not yet impossible.
But that will require “immediate, rapid and large-scale reductions” in emissions, say scientists, of which there are no signs to date. Even the reduction in emissions, but more slowly, leads to 2 degrees C (3.6 degrees F) and much more suffering for all life on Earth.
If emissions do not decrease over the next two decades, then 3 degrees C (5.4 degrees F) of heating seems likely – a disaster. And if they don’t fall at all, the report says, then we’re on track for 4 to 5 degrees C (7.2 to 9 degrees F), which is apocalypse territory.
The report is clear that there is no cliff to the climate crisis. Each tonne of carbon pumped increases the impacts and risks of extreme heat, flooding and drought and therefore every tonne of carbon counts. It will never be too late to act, the report says. Instead, the real question is, just how bad will it get?
For example, extreme heat waves expected once every 50 years without global warming already occur every ten years. With a warming of 1.5 ° C, this will happen about every 5 years; with 2C, every 3.5 years; and with 4C, once every 15 months. More heating also means more disruption to the monsoon rains on which billions of people depend for food.
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More emissions also means the land and oceans become weaker to absorb this carbon pollution, which makes heating even worse. With immediate and rapid reductions, the natural world can still absorb 70 percent of our emissions. Without cuts, that drops to just 40 percent.
One of the more straightforward sections of the report begins: “Many changes due to past and future greenhouse gas emissions are irreversible for centuries, if not millennia. This particularly affects the world’s oceans and ice, which absorb 96% of the world’s heating, meaning the ice will continue to melt and the oceans will rise towards our many overcrowded coastal cities.
The likely range is around 3 to 40 inches, or up to 3.3 feet, by the turn of the century. But it could be over 6.5 feet by then, or over 16 feet by 2150, the report warns. Extreme sea level events, such as coastal flooding, which have only occurred once a century in the recent past, are expected to occur at least once a year in 60% of places by 2100.
“It may seem like a long way off, but there are already millions of children born who are expected to be alive until the 22nd century,” says Professor Jonathan Bamber, University of Bristol, UK, and author of report.
The many scientific advances since the last full IPCC report in 2013 mean better projections for specific regions of the world. He can’t find a safe place. For example, even at 1.5 ° C of heating, heavy rains and flooding are expected to intensify in Europe, North America and most parts of Africa and Asia.
“We can no longer assume that the citizens of richer and more secure countries like Canada, Germany, Japan and the United States will be able to overcome the worst excesses of a rapidly destabilizing climate,” he said. said Katharine Hayhoe, chief scientist at The Nature Conservancy. . “It is clear that we are all in the same boat – facing a challenge that will affect us all in the course of our lives. “
The report is the IPCC’s sixth but the first to thoroughly assess the risk of tipping points. These are abrupt and irreversible changes in critical Earth systems that are having huge impacts and of growing concern to scientists. The collapse of the great Atlantic currents, ice caps or the Amazon rainforest “cannot be ruled out”, warns the report.
“For tipping points, it’s clear that every additional ton of CO2 emitted today pushes us into a minefield of feedback effects tomorrow,” says Dave Reay, professor of carbon management and education at the ‘University of Edinburgh in Scotland.
So what can we do? The last section of the IPCC report discusses how future climate change can be contained. He finds that 2,400 billion metric tonnes (26.5 billion tonnes) of CO2 have been emitted by mankind since 1850, and that we can only leak an additional 400 billion metric tonnes (441 billion tonnes) for have a 66% chance of staying at 1.5 ° C.
In other words, we have already exploded 86% of our carbon budget, although the report says the science is clear that if emissions are reduced, temperatures will stop rising in a decade or two and the increase. extreme fatal events will be severely limited.
“Unless there are immediate rapid and large-scale reductions in greenhouse gas emissions, limiting warming to 1.5 ° C will be out of reach,” said Abdalah Mokssit, IPCC secretary .
“But we never dictate policy to any country – it’s up to governments to make the decisions.”
Scientists have now spoken, louder and more clearly than ever. It is now up to politicians to act.