Human activity is an “unequivocal” driver of the climate crisis that affects every region on Earth, a reality that will have dire consequences for the coming decades but that also reasserts our own power to shape the long-term future of our planet and its inhabitants, according to a highly anticipated new report from the Intergovernmental Panel on Climate Change (IPCC) released on Monday.
The last decade was likely the hottest period that Earth has experienced in 125,000 years, concludes the Sixth Assessment Report from the IPCC, a United Nations body that consists of thousands of scientists and is considered the world’s leading authority on climate change.
Governments have failed to act quickly enough to curb greenhouse gas emissions from fossil fuels, the primary cause of human-driven climate change, which has all but ensured that global temperatures will rise by at least 1.5°C above pre-industrial averages by the 2040s, even in the most optimistic scenarios.
The consequences of this rapid anthropogenic warming are now perennially topical: since June, a severe heat wave killed hundreds of people in the Pacific Northwest, anomalous floods have overwhelmed parts of Europe and China, and unprecedented wildfires are burning in locations as different as Siberia and Hawai’i.
“The world listened, but didn't hear; the world listened, but it did not act strongly enough,” said Inger Andersen, who serves as Under-Secretary-General of the United Nations and Executive Director of the United Nations Environment Programme, in a press briefing about the new report on Monday.
“As a result, climate change is a problem that is here now,” Andersen added. “Nobody is safe, and it's getting worse faster. We must treat climate change as an immediate threat, just as we must treat the connected crises of nature and biodiversity loss, and pollution and waste, as immediate threats.”
The report concludes that the preferred goal to keep global temperatures below 1.5°C, as outlined in the Paris Climate Agreement, is essentially out of reach for the coming decades. It notes, however, that immediate and aggressive decarbonization could lead to temperatures dipping back under this 1.5°C spike by the end of the 21st century. (For reference, humans have already raised global temperatures by about 1.1°C, according to the report).
To that point, it’s important to emphasize the many solutions and mitigation strategies detailed in the report, which provide a much-needed glimmer of hope amid the doom and gloom of the near-term threats of escalating climate change. Human civilization is locked into a certain degree of global warming, including all of its deleterious effects, but the report lays out five “possible climate futures” that will have vastly different impacts on the peoples and ecosystems of the 22nd century and beyond.
In the most optimistic climate scenario, labeled SSP1-1.9, global emissions are reduced to net zero by 2050. In this possible future, temperatures would likely not rise above 2°C and could possibly slip back below 1.5°C by 2100. A certain amount of sea level rise is inevitable in all scenarios, a trend that will exacerbate coastal erosion, hurricane damage, and other disasters, but SSP1-1.9 would limit this effect to about 1.8 feet of rise, at most.
On the other end of the spectrum, a climate scenario called SSP5-8.5 assumes that humans do nothing to curb emissions, leading to a worst-case future that would be especially catastrophic to humans and wildlife. This approach would lead to global temperatures rising by about 3.3°C to 5.7°C by the end of the century, accompanied by a rise in sea levels that could exceed one meter (3.2 feet) by 2100.
The other three scenarios fall between these two hopeful and dire extremes, all of which indicate that the human response to climate change exists on a gradient that could cause a range of possible outcomes in the near and far future.
It is a sad reality that many of the communities most affected by the climate crisis have contributed the least to it, including Indigenous populations and less wealthy nations that lack the resources to respond to escalating climate-related disasters. Though the effort to curb greenhouse gas pollution has to be global, nations such as China, the United States, and India, which are the world’s current leading emitters according to a 2016 study, must assume more responsibility for the problem.
“As citizens and as businesses and as governments, we are well aware of the drama” that is “playing out on the front pages of the newspapers today in terms of climate impacts that we are seeing already,” Andersen said at Monday’s press briefing. “That’s what we need to understand, that the expression of what the science says is exhibited before our very eyes and of course, what this excellent report does is project these scenarios outward.”
“The power is in our hands,” she concluded.