In a report released on Thursday, the U.N. highlighted that the world is currently in "climate crunch time," as greenhouse gases—trapping heat in the atmosphere and driving extreme weather—have reached "unprecedented levels." Labeling this as "one of the most urgent climate warnings to date," the U.N. emphasized that humanity must act within a few years to mitigate the worst consequences of climate change.

"The numbers paint a clear picture," the U.N. stated. To stay below the critical 1.5-degree Celsius target established in the Paris Agreement in 2015, countries must cut emissions by 42% overall by 2030 and achieve a 57% reduction by 2035.

For decades, scientists have emphasized that average global temperatures should not exceed 1.5 degrees Celsius compared to pre-industrial times to prevent deadly weather patterns affecting populations globally. The planet has already warmed since that period, leading to back-to-back heatwaves, droughts, and unprecedented flooding and hurricane events. The impact on agriculture is already evident, with yields projected to decline as temperatures rise between 1.5 and 2 degrees Celsius, potentially causing sea levels to rise by up to 10 feet. Additionally, warmer oceans could result in more powerful hurricanes and threaten vital ecosystems that protect areas from severe weather.

Exceeding the 1.5-degree threshold could lead to the disappearance of entire island nations, more frequent and intense heatwaves, and decreased productivity as extreme temperatures make it increasingly difficult for people to work, according to the U.N. report.

"We're teetering on a planetary tightrope," said U.N. Secretary-General António Guterres. "Either leaders bridge the emissions gap, or we plunge headlong into climate disaster." The report, which assesses nations' climate change efforts, warns that immediate and drastic policy changes are essential; otherwise, achieving a pathway to limit global warming to 1.5°C will become impossible.

Global greenhouse gas emissions reached a record 57.1 gigatons of CO2 equivalent last year, marking a 1.3% increase from 2022 and significantly surpassing the average growth rate of 0.8% per year seen from 2010 to 2019. The primary contributors to this increase are the power, industry, and transportation sectors.

While U.S. emissions declined by 1.4% from 2022, the country still ranks second in global emissions, with China at the top. Notably, U.S. emissions per capita exceed those of China. The report highlights a troubling emissions gap—the difference between current trajectories and the levels necessary to prevent the worst impacts of climate change. There is now a 100% chance of global warming reaching 1.5 degrees Celsius unless all nations fulfill their net-zero emissions pledges; even then, the chance remains at 77%.

If current policies continue, the likelihood of warming reaching 2 degrees Celsius stands at 97%, with a 37% chance of reaching 3 degrees Celsius, according to the report.

"Today's Emissions Gap report is clear: We are playing with fire," Guterres warned. "But there can be no more playing for time. We're out of time."

However, solutions exist that could mitigate these risks. If all countries that signed the Paris Agreement commit to achieving net-zero emissions as soon as possible, the risk of 2 degrees of warming could drop to just 20%, nearly eliminating the risk of 3 degrees. Limiting warming to 1.5 degrees requires a global emissions cut of 7.5% each year until 2035.

Achieving this will largely depend on G20 nations, including the U.S. Increasing the use of solar and wind energy technologies could reduce global emissions by more than a quarter.

"We would need global mobilization on a scale and pace never seen before," said Inger Andersen, U.N. Environment Programme executive director. "Many will say this is impossible. But focusing solely on whether it is possible misses one crucial point: the transformation to net-zero economies must happen, and the sooner this global transformation begins, the better."