Scientists have largely attributed this temperature rise to the increase of greenhouse gases, including carbon dioxide and methane, in Earth’s atmosphere since the Industrial Revolution. In the pre-industrial days of the 18th century, the carbon dioxide level in the atmosphere was approximately 278 parts per million (ppm). Today, it’s 420 ppm.

But there are likely other influences on 2024’s temperature rise, too. NASA noted that a particularly strong El Niño — a natural climate fluctuation — that began in fall 2023 likely pushed the average temperature up in 2024. Plus, scientists are still studying the effects of events like the January 2022 Tonga volcanic eruption, which introduced vast quantities of water vapor and sulfur dioxide into the atmosphere.