A new IPCC report says the window to meet UN climate targets is vanishing

THE WINDOW for limiting global warming to relatively safe levels is rapidly closing, according to the Intergovernmental Panel on Climate Change (IPCC). On April 4th the body released a new report, of nearly 3,000 pages. It appeared after two weeks of wrangling by representatives from 195 governments over how best to present the “state of the union” of climate science. Its conclusion is hardly cheering. To meet the goals of the Paris agreement, to limit the average global temperature rise to 1.5°C above pre-industrial levels—and failing that, to below 2°C—will take immediate and unprecedented action from every country.

The IPCC, a UN-backed body, releases a new “assessment report” every eight years or so. Each cycle is a mammoth undertaking, culminating in a trio of reports that comprehensively examines the science of climate change. Hundreds of scientists from around the world plough through thousands of peer-reviewed papers, and then collate their findings into a door-stopping tome.

The latest report is the sixth iteration of the IPCC process. The first part of the latest one, which looked at the physical science of the climate system and was published in August 2021, found that the climate was changing more rapidly than originally anticipated by climate scientists. In February the second volume showed that the consequences of the disruptions to the global climate system are also worse than expected, and evaluated how much humans and the natural world could adapt to them.

The third part lays out the actions that the world can take to stop global temperatures rising beyond certain levels by the end of the century. It also sets out “the consequences of these actions, on the economy and on land use, as well as how people’s behaviours must change, among many other factors.

The new report’s conclusions are stark. To have a 50% chance of avoiding more than 1.5°C of warming throughout the 21st century global carbon emissions will have to reach net zero (where no more carbon is released into the atmosphere than is removed) in the early 2050s. To have a 50% chance of keeping warming below 2°C, global carbon emissions must reach net-zero by the early 2070s. For both, emissions of all greenhouse gases must peak by 2025.

Yet this is far from likely to happen. Despite promises from almost all countries to stop polluting, the IPCC found that the jump in average annual net greenhouse-gas emissions between 2000-09 and 2010-19, was the “highest increase in average decadal emissions on record”. (They do note, though, that the average rate of growth has slowed from 2.1% to 1.3% a year across the same period.)

Pursuing 1.5°C means that global use of coal must decline by 95% by 2050. Oil use must drop by 60% and gas by 45% over the same period. The decreases needed to limit warming below 2°C are not much lower. Under all these scenarios, there is no room for new fossil-fuel projects, and most existing ones will have to be wound down.

The report outlines the ways in which agriculture, travel and most industries will have to be transformed. For the first time, it looks in detail at how individuals might be encouraged to change their behaviour. The potential avenues outlined by the IPCC to limit warming to 2°C all also rely on carbon dioxide being removed from the atmosphere using both natural strategies, such as sequestering it in trees and soils, and new (and unproven) technologies, like capturing carbon directly from the air and storing it underground.

All of this comes at a substantial cost. The report estimates that taking the actions needed to keep temperatures below 2°C could reduce global GDP by 1.3% to 2.7% by 2050, when compared with sticking only to the climate policies that countries have already announced. However, the report points out that these costs do not account for damage caused by climate change or the sacrifices required for adaptation. In other words, not adopting aggressive climate policies brings its own costs. These include lost lives, livelihoods, destruction caused by extreme weather events and lost productivity, to list but a few.

Though they cannot change the underlying science, member governments can influence how it is framed. That process can get contentious. The plenary for the latest report concluded some 40 hours after the deadline. It takes place behind closed doors, but reports from some in attendance suggest that the sticking points echoed those that snarled negotiations at COP26, the UN climate summit that took place in Glasgow in November. Rich countries are reluctant to pay significantly more to help poorer ones. Countries that rely heavily on fossil fuels, such as India and Saudi Arabia, do not want to do away with them: notably, a suggestion that coal use should be scrapped entirely by 2100 was removed from an earlier draft of the summary. These concerns have circulated for years, and are seemingly no closer to being resolved. Meanwhile the time for meaningful action to avert the worst effects of global warming is running out.

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