Global emissions of carbon dioxide (CO2) have not decreased enough to meet the critical goal of limiting Earth's warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial levels, according to a new report authored by an international team of more than 100 scientists. In fact, average global temperatures are on track to cross that line within a decade, should warming continue at the current pace.
Achieving net-zero emissions by 2050 would now require annual CO2 decreases as drastic as those seen at the height of the COVID-19 pandemic, when airplane flights were significantly reduced and economies were stalled.
"The emissions of CO2 that cause the planet to warm show no sign of decreasing," said Pierre Friedlingstein, chair of mathematical modeling of climate systems at the University of Exeter in the United Kingdom and lead author of the report. "Actions over the past few years have been nowhere near enough to turn around the trajectory in global emissions," Friedlingstein told Live Science in an email. "Much more needs to be done."
The Global Carbon Budget report, published online Thursday (Nov. 10) in the journal Earth System Science Data, is an annual update that tracks global CO2 emissions. The projections for 2022 are grim, estimating atmospheric CO2 at 417.2 parts per million (ppm) — 51% above preindustrial levels — and global emissions at 40.6 billion tons (36.8 billion metric tons). All figures in the report are projections, as the data cannot account for the final months of 2022.
As ever, the largest contributors are fossil fuels. Global oil use is up 2.2% from last year, largely due to the aviation industry's recovery after a COVID-19 slump. Coal use worldwide is also up 1%, while natural gas use has fallen slightly. But fossil fuel use is not uniform across nations; while emissions went up in the United States and India in 2022, emissions plummeted in China and the European Union, according to the report.
Increases in the U.S. are likely due to industries rebounding after COVID-19 slowdowns, the scientists wrote, while spikes in India are linked to that country's ongoing development. "India has, by far, the most catch-up to do in terms of infrastructure, construction, and energy consumption per capita, all of which means rapid growth in energy consumption that cannot yet be covered entirely by renewable energy," said Jan Ivar Korsbakken, a senior research fellow at the Center for International Climate and Environmental Research in Oslo, Norway, and co-author of the study.
Meanwhile, decreases in fossil fuel emissions from the EU may boil down to an economic slowdown that started in 2021 and only got worse when Russia invaded Ukraine, the study authors reported. Increased interest in solar power also may be playing a role. Similarly, lower emissions in China stem mostly from lingering economic issues in the wake of COVID-19 and a debt crisis in the construction sector, but they also reflect a promising bump in the use of solar and wind power.
Beyond fossil fuels, which make up about 90% of total CO2 emissions, the report highlights other key contributors. "The remaining 10% from land use, such as deforestation, also matters a great deal," Korsbakken told Live Science in an email.
Just three countries — Indonesia, Brazil and the Democratic Republic of the Congo — contribute 58% of the world's "land use emissions," a catchall phrase that describes, among other things, the impacts of deforestation, forest fires, agricultural burning and emissions from livestock. Of particular concern is the increased conversion of carbon-dense forests into rice paddy fields and soybean farms by people in poorer regions. "It is important that richer nations help these countries to develop in ways that do not put their still vast forests and rich ecosystems in further peril," Korsbakken said.
Long-standing carbon sinks — oceans and forests that collectively absorb about half of our fossil fuel emissions — are also strained to the limit. The report suggests that even these last lines of defense may soon be breached. "Warming temperatures and changing weather patterns can weaken this CO2 absorption," Korsbakken said. "We estimate that the climate change in the past decade made the absorption about 10% lower than what it otherwise would have been. This is yet another risk that we are exposing ourselves to by not cutting emissions rapidly."
While the report gives scant cause for optimism, the authors admitted that it's hard to say if 2022 was worse than expected, or how the year might have panned out had we not been simultaneously recovering from a pandemic and living through a war that has placed unusual strain on the European Union. Perhaps climate policies are working, to a degree, but are unable to counterbalance such international upheaval.
"The noise from the pandemic, the energy shortages and supply-chain issues from the recovery, and the chaos wrought by Russia's invasion of Ukraine mean that it is very hard to discern any effect that climate policies might have had," Korsbakken said.
Either way, the authors agree that stronger climate policies are necessary — ideally ones that replace fossil fuels with renewable energy without crippling the global economy. Such goals demand a nuanced approach.
"Energy use and emissions are driven by a myriad of factors in different sectors, each of which play different roles in the global economy and in people's lives, and all of which have various interest groups attached to them," Korsbakken said. "Add politics, and it's not hard to understand why cutting emissions has been so hard."
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Joshua A. Krisch is a freelance science writer. He is particularly interested in biology and biomedical sciences, but he has covered technology, environmental issues, space, mathematics, and health policy, and he is interested in anything that could plausibly be defined as science. Joshua studied biology at Yeshiva University, and later completed graduate work in health sciences at Cornell University and science journalism at New York University.