UCLA study attributes twice as much of 2024's record rain to warming as to El Niño

Two different 20% figures sit in this story. One is how far the count of heavy-rain days ran above baseline ^[1]. The other is El Niño's share of the explanation, set against 40% for global warming ^[2]. If both shares are measured against the same record increase, together they cover 60% of it and leave 40% ^[10]. The write-up does not define the baseline or say how that remainder divides.

One candidate for the remainder is a rare coincidence of ocean temperatures, and it is the input a 2027 call lacks. Lead author Chad Thackeray said: "Our analysis relied on ocean temperature measurements from December to February each year when El Niño is strongest, so we don't yet know whether that will be a factor this upcoming year." ^[8]

The case for another record is physical. Senior author Alex Hall said a strong winter El Niño "can prime the global atmosphere for elevated extreme precipitation well into the following year" ^[16]. The researchers said Pacific warming appears to be coalescing in the east, a pattern that correlates with rainier seasons than central Pacific El Niños ^[12]. They also cited early scientific estimates that 2027 will likely surpass 2024 as the hottest year on record ^[13].

Hall was explicit about the limit. "We can't say that 2027 will break the 2024 record," he said. "But the ingredients are lining up for another potentially exceptional year for global precipitation extremes." ^[14]

In our view the attribution is the firmer half of the paper, published Oct. 9 in Science Advances ^[6]. It describes a year that has already happened. The 2027 call needs an eastern Pacific event that stays strong, a hot year, and possibly the Atlantic and Indian warmth that Thackeray said cannot yet be assessed. The thing a global count does not tell you is which basins get the rain.