Since signing the Paris Climate Agreement in 2015, nations around the world have focused on one climate goal: limiting global warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial levels this century. But as greenhouse gas emissions from fossil fuel burning have continued to increase, a new report from the World Meteorological Organization shows global temperatures could temporarily hit that threshold within the next five years.

The WMO stated Monday there is a 50 percent chance that the annual global temperature will hit this mark by 2026. The probability is only increasing with time. In 2015, the chance of temporarily observing 1.5 degrees of warming was zero, underscoring the rapid pace of human-caused climate change.

“A single year of exceedance above 1.5 °C does not mean we have breached the iconic threshold of the Paris agreement, but it does reveal that we are edging ever closer to a situation where 1.5 °C could be exceeded for an extended period,” Leon Hermanson, a researcher at the United Kingdom’s Met Office who led the report, said in a news release.

The projection was calculated by climate scientists across the world and uses “the best prediction systems from leading climate centres,” Hermanson said, but some scientists are wary of the prediction.

“Initialized decadal predictions (such as used here) don’t have a great track record (yet),” Gavin Schmidt, a climate scientist at NASA, wrote in an email. “While I’m happy that research continues the regional predictions are not to be taken too seriously.”

Michael Mann, a climate scientist at Penn State, said that while global temperature readings may temporarily spike to the 1.5-degree threshold in the next several years, the real concern occurs when it is surpassed over a period of many years.

“When we talk about the need to avoid 1.5 degrees Celsius global warming in a climate change context, we’re talking about the long-term trend, not the values for individual years,” he told InsideClimateNews.

Hitting 1.5 degrees Celsius for an extended period may not be far off. The U.N. Intergovernmental Panel on Climate Change concluded last month that the world could blow past the key target within eight years. The assessment of 278 top climate experts wrote that while concerted action could avert this scenario, it “cannot be achieved through incremental change.”

Staying under the threshold, the panel concluded, would involve a coordinated push to expand renewable energy production, revamp transportation networks, extract carbon from the air, and redesign how cities are built and farming is done.

Scientists have long warned about the dangers of 1.5 degrees Celsius of warming on people and the environment. Extreme heat events are more likely to take place and break previous records by large margins, as seen in the Pacific Northwest in June. Hurricanes will unleash more damage, intensifying more rapidly and unleashing more rainfall in a warmer climate. Coral reefs as well as a number of animals species could vanish. Glaciers will continue to melt, raising global sea levels and flooding communities.

Even if the world does not hit 1.5 degrees Celsius in the next five years, the report stated it is “very likely” (a 93 percent chance) that it will post its warmest year on record by 2026, knocking off 2016 from the top ranking. The next five years probably will also be warmer on average than the past five years, which have been some of the hottest on record.

Natural weather patterns will play a key role in determining when annual global temperatures spike to a record level. For instance, the development of a powerful El Niño event, associated with warm waters in the tropical Pacific, helped fuel record temperatures in 2016. The planet’s temperature then shot up to its second highest level in 2019 following a weaker El Niño.

However, La Niña, the cyclical cooling of ocean waters in the tropical Pacific, has put the brakes on warming since then. After El Niño faded and La Niña developed in 2020 and 2021, temperatures plateaued. Those two years ranked as the second (tied with 2019) and sixth warmest on record, according to the National Oceanic and Atmospheric Administration (NOAA).

With the possibility of La Niña extending into a third straight year, NOAA says there’s only about a 40 percent chance 2022 finishes among the warmest five years on record, but it’s “virtually certain” it will still rank in the top 10.

“[W]e are very likely to exceed 1.5ºC in the next decade or so but it doesn’t necessarily mean that we are committed to this in the long term – or that working to reduce further change is not worthwhile!” Schmidt wrote.