When new reports from Berkeley Earth landed on researchers’ desks, they confirmed what many had feared but few expected to see so soon: the past three years of global temperatures have blown past earlier expectations of a slow, steady rise. Scientists who once trusted that climate models had the broad arc of global warming “solved” were suddenly staring at a spike that looked less like a gentle curve and more like a step change. Those three “insane” years are not a freak event. They are a stress test that exposed blind spots in how we understand and manage a heating planet.
The core story is simple. Human activity has been loading the atmosphere with greenhouse gases, and the planet has been responding with steady warming. Then 2023, 2024 and 2025 arrived. El Niño, a modest La Niña, and shifts in air pollution pushed temperatures into new territory. Now the question is whether this burst was a one‑off jolt or the start of a new climate regime that will shape the rest of our lives.
The three-year heat shock
Over the past three years, global temperature records have fallen in rapid sequence, turning what used to be once‑in‑a‑generation events into something closer to a new normal. According to Berkeley Earth’s global analysis, 2024 ranked as the hottest year on record, 2023 came in second, and 2025 was third. Their data show that each of these years rose well above 1.4 degrees Celsius above preindustrial levels, and monthly averages in 2023 and 2024 crossed 1.5 degrees for many weeks. That kind of back‑to‑back ranking is not just a statistic. It is a sign that the climate system is spending more time in territory that used to be considered extreme.
New data from the Tyndall Centre confirm that 2025 was the third warmest year ever recorded and the third year in a row exceeding 1.4 degrees Celsius above preindustrial levels. Several international climate reports released in January describe this run of heat as part of a longer pattern of relentless human‑caused warming, not a brief flare‑up that will quickly fade. One of those assessments notes that the recent stretch has pushed global averages over 1.5 degrees for at least 46 consecutive months. Taken together, these findings suggest that the last three years were not just hot. They were a warning that the climate is moving into a different gear.
El Niño, La Niña and a broken script
For decades, scientists have treated El Niño and La Niña as the main rhythm of year‑to‑year temperature swings. El Niño tends to push global temperatures higher, while La Niña usually brings a slight dip. Berkeley Earth’s 2025 report notes that 2023 and 2024 were El Niño years, which helps explain part of the surge. But 2025 began and ended with a modest La Niña event that, in theory, should have cooled the planet a bit. Instead, 2025 still landed as the third warmest year on record. That outcome shows that the background warming trend is now so strong that even a cooling phase in the Pacific cannot pull global averages back toward older baselines.
Several climate reports released in January describe the recent heat as an “unprecedented run” rather than a simple El Niño bump, tying the pattern to relentless human‑driven warming that continued through 2025. One assessment points out that global temperatures have been above the 1.5‑degree mark for about 698 days in, a streak that would have been hard to imagine a decade ago. When a La Niña year like 2025 can still rank in the top three, the old mental model of a gentle staircase of warming, with natural cycles adding small wiggles, starts to break down. A better image now is a moving escalator that has sped up, with El Niño and La Niña only adding bumps on top of a much steeper climb.
The aerosol “mask” comes off
Natural cycles are only part of the story. One of the most striking changes in recent years has happened in a place most people never see: the smokestacks of giant shipping liners. In 2020, new rules sharply limited the sulfur content of marine fuels. A technical review from Berkeley researchers explains how these rules have cut the sulfur in ship exhaust that once helped brighten clouds and reflect sunlight back to space, acting like a thin, temporary shield. Their analysis of aerosols argues that this “mask” was hiding some of the warming caused by greenhouse gases, and that its removal lines up in time with the recent jump in global temperatures.
Climate scientist Zeke Hausfather and colleagues estimate that the rapid drop in shipping pollution may have added a few tenths of a degree to recent sea‑surface temperatures in some busy ocean corridors. While he stresses that nearly all long‑term warming still comes from greenhouse gases, the timing of the aerosol cuts matters. In a PBS interview, Berkeley Earth’s Robert Rohde said that almost all global warming is from human‑caused emissions of carbon dioxide, methane and other gases, but that the last three years were extreme even against that backdrop. A separate assessment in Eos put it bluntly, stating that “the magnitude of this recent spike suggests additional factors have amplified recent warming beyond what we would expect from greenhouse gases and natural variability alone.” That Eos commentary is a clear nod to rapid aerosol reductions and other short‑term amplifiers that older climate expectations did not fully capture.
Scientists split on what is “driving” the spike
Behind the scenes, there is a real debate over how to describe the cause of the recent jump in temperatures. On one side, Rohde and other researchers argue that nearly all of the warming comes from human‑caused emissions of greenhouse gases, especially from burning coal, oil and natural gas. In the PBS discussion, he treats El Niño, La Niña and aerosol changes as modifiers that add year‑to‑year noise on top of a human‑forced signal that has been building for decades.
On the other side, the authors of the Eos article argue that the size of the recent spike suggests that extra factors have amplified recent warming beyond what we would expect from greenhouse gases and natural variability alone. They point to rapid aerosol cuts, unusual ocean heat patterns and possible feedbacks that may not be fully captured in older models. These positions are not truly in conflict. Greenhouse gases set the baseline, and new policies and natural swings decide how quickly the world feels the heat that has already been locked in. The real mistake was ever thinking that a single driver, or a single number like 1.5 degrees, could fully capture the risks we face.
From “solved” models to moving targets
Part of the shock of the last three years comes from how they collide with older expectations. A decade ago, many climate briefings framed warming as a gradual climb that would play out over generations. One summary from 2019 reported that the 2010s were the warmest decade ever recorded, with 2019 the second warmest year in history and 2018 helping make the last five years the warmest on record. That earlier coverage was alarming at the time, but it now reads like an early warning that did not fully prepare the public for how quickly records could fall again.
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*This article was researched with the help of AI, with human editors creating the final content.
