World could cross red line for planetary warming by decade's end, study finds

The release of planet-heating chemicals into the atmosphere is set to hit a record high in 2024 — with “no sign” of a peak in sight, a new study has found.

This year, fires and smokestacks around the world will have released a billion tons more carbon dioxide than the already-record levels in 2023, according to projections by the Global Carbon Budget in the journal Earth System Science Data.

Those emissions will drive further heating and extreme weather for decades or centuries to come, magnifying the effects already seen in today’s worsening heat waves, flash droughts and hurricanes.

And they are on track to rise further in 2025, the global team of 120 researchers found in their paper, which has not yet been peer-reviewed.

At current rates of emissions, that means the world has a coin-toss chance of being consistently above 1.5 degrees Celsius of warming by the end of the decade, the study found — a level scientific consensus holds as a red line above which more dangerous impacts of climate change will begin to be felt.

The preliminary findings are being released amid the 29th United Nations climate conference (COP29), where world leaders are seeking to find ways to slow the global heating that is undermining the key planetary systems on which human civilization rests.

There is some good news in the data: In 2024, the world’s richest economies showed signs that they had approached the peak of their emissions. 

China, the world’s largest economy and a country responsible for nearly a third (32 percent) of global emissions, saw its contribution to planetary heating go flat.

Meanwhile, the U.S., responsible for about one-eighth (13 percent), saw a slight decrease (about half of 1 percent), and the European Union reduced its releases of carbon dioxide and methane by about 5 percent.

Even as those numbers go down, however, the total amounts of those compounds in the atmosphere are increasing. 

Despite the decrease in levels of fossil fuels burned by wealthy nations since 2023, overall global levels are still increasing — in part because of the continued rise in fossil fuel burning across the rest of the world.

For example, India’s emissions, which are projected to be about equal to those of the EU this year, will increase by about 5 percent over their 2023 levels. And the amount of methane and carbon dioxide rising from the rest of the world — which accounts for roughly the same share of global emissions as China and the EU combined — is on track to rise by about 1 percent.

These countries may simply be a bit behind wealthier nations when it comes to cutting emissions, and their historic contributions to climate change is far lower than that of the U.S., China and the EU, whose economies put into the atmosphere most of the planet-heating chemicals responsible for present-day climate disruption.

The researchers found signs that the current wave of climate disasters, exacerbated by those countries’ historic burning of fossil fuels, was accelerating natural processes that are warming the climate further.

For example, the researchers found that emissions from wildfires, which are made worse by the heat and drought caused by climate change, have been above average since 2003 — spiking with the past two years’ wildfires in Canada and Brazil.

Researchers also found that while the rate of deforestation has slowed in the past decade, the impact of land-clearing, drought and fires mean that it is on track to rise again in 2024.

That rise, too, comes on top of a long-term pattern of forest loss that, whether it speeds up or slows down, has never stopped, let alone reversed.

The fossil fuel industry has for the past decade touted its ability to use carbon reduction and carbon capture tools to reduce — and ultimately reverse — the implacable rise in temperatures. 

The researchers found, however, that the carbon captured or reduced by such projects accounts for just one-millionth (0.0001 percent) of the chemicals released by the burning of fossil fuels.