This year will end as the second hottest year on record, to be surpassed only by 2024. It continues a recent trend of exceptional, unexplained warming. The past three years have been the hottest on record by a wide margin.
In each of the past three years, temperatures have been more than 1.5 degrees warmer than pre-industrial times, putting the world, at least temporarily, in breach of the international goal of limiting warming below that level. in accordance with Copernicus Climate Change Service.
The recent surge in warming, exceeding climate model predictions, has led to puzzled scientists. Experts have examined a number of potential factors, starting with the recent… volcanic eruption in the South Pacific to reduce the amount of sunlight blocking pollution.
Building on recent research on these issues, climate scientist Zeke Hausfather looked at four potential drivers of extreme warming for his recent analysis: published V Carbon summary.
The first was the 2022 eruption of the submarine volcano Hunga Tonga-Hunga Haapai in the South Pacific, which sent a massive plume of heat-trapping water vapor into the upper atmosphere. Secondly, the recent growth in solar energy production. While the timing lines up well with the recent surge in warming, Hausfather believes these factors can explain less than half of the temperature jump.
Average monthly global temperature relative to average temperature from 1850 to 1900. Source: Copernicus Climate Change Service. Yale University Environment 360
A third potential factor was the formation of a powerful El Niño in late 2023, when warm waters pooled in the eastern Pacific Ocean, causing temperatures to rise around the world. But while El Niño can explain the exceptional warmth in 2024, Hausfather shows, it can't explain the jump in temperatures early in 2023.
Finally, the recent sharp decline in sulfur dioxide emissions. The pollutant emitted by coal-fired power plants blocks sunlight, thereby cooling the planet. Its decline contributed to warming. Sulfur dioxide emissions have dropped by 40 percent over the past 18 years as countries, particularly China, have cleaned up pollution from coal burning. Then, in 2020, a new international rule was passed banning the use of sulfur dioxide on cargo ships, leading to a sharp decline in shipping pollution.
Scientists have focused on shipping as an explanation for the sudden surge in warming. Although studies have generally found that reducing pollution from shipping had only a small effect on temperatures, one studyfrom James Hansen, NASA's former chief climate scientist, found that a decline in shipping pollution explains almost all of the recent exceptional warming.
Housefather says all four factors combined could explain the recent surge. But even if they can, he says, questions remain: Is this surge temporary or a sign that warming is accelerating?
