ENSO

Between the record-breaking global heat and extreme downpours, it’s hard to ignore that something unusual is going on with the weather in 2023. People have been quick to blame climate change – and they’re right: human-caused global warming plays the biggest role. The weekslong heat wave that started in June 2023 in Texas, the U.S. Southwest and Mexico would have been virtually impossible without it, one study found. However, the extremes this year are sharper than anthropogenic global warming alone would be expected to cause. September temperatures were far above any previous September, and around 3.1 degrees Fahrenheit (1.75 degrees Celsius) above the preindustrial average, according to the European Union’s earth observation program. July was Earth’s hottest month on record, also by a large margin, with average global temperatures more than half a degree Fahrenheit (a third of a degree Celsius) above the previous record, set just a few years earli...

El Niño is officially here, and while it’s still weak right now, federal forecasters expect this global disrupter of worldwide weather patterns to gradually strengthen. That may sound ominous, but El Niño – Spanish for “the little boy” – is not malevolent, or even automatically bad. Here’s what forecasters expect, and what it means for the U.S. What is El Niño? El Niño is a climate pattern that starts with warm water building up in the tropical Pacific west of South America. This happens every three to seven years or so. It might last a few months or a couple of years. Normally, the trade winds push warm water away from the coast there, allowing cooler water to surface. But when the trade winds weaken, water near the equator can heat up, and that can have all kinds of effects through what are known as teleconnections. The ocean is so vast – covering approximately one-third of the planet, or about 15 times the size...

The Atlantic hurricane season starts on June 1, and forecasters are keeping a close eye on rising ocean temperatures, and not just in the Atlantic. Globally, warm sea surface temperatures that can fuel hurricanes have been off the charts in the spring of 2023, but what really matters for Atlantic hurricanes are the ocean temperatures in two locations: the North Atlantic basin, where hurricanes are born and intensify, and the eastern-central tropical Pacific Ocean, where El Niño forms. This year, the two are in conflict – and likely to exert counteracting influences on the crucial conditions that can make or break an Atlantic hurricane season. The result could be good news for the Caribbean and Atlantic coasts: a near-average hurricane season. But forecasters are warning that that hurricane forecast hinges on El Niño panning out. Ingredients of a hurricane In general, hurricanes are more likely to form and intensify when a tropical low-pressure system encounter...

The official 2023 hurricane season forecasts were just released, and while the Atlantic may see an average storm season this year, a busier-than-normal season is forecast in the eastern Pacific, meaning heightened risks for Mexico and Hawaii. A big reason is El Niño. El Niño typically means trouble for the Pacific and a break for the Atlantic coast and Caribbean. But while this climate phenomenon is highly likely to form this year, it isn’t a certainty before hurricane season ramps up this summer, and that makes it harder to know what might happen. It’s also important to remember that even in quiet years, a single storm can cause enormous destruction. As climate scientists, we study how climate patterns related to the frequency and intensity of hurricanes – information that is used to develop seasonal forecasts. Here is a quick look at how El Niño affects storms and why it tends to cause opposite effects in two basins separated only by a...

There’s an old joke about the fellow who has his left foot in a bucket of ice water and the right in a bucket of hot water, so that his overall temperature is average. That seemed to apply to the climate during 2022’s northern summer of extremes. Global warming is undoubtedly a factor, but just how the increasing extremes – heat waves, droughts and floods, sometimes one on top of the other – are related can be bewildering to the public and policymakers. As a climate scientist, I’ve been working on these issues for more than four decades, and my new book, “The changing flow of energy through the climate system,” details the causes, feedbacks and impacts. Let’s take a closer look at how climate change and natural weather patterns like La Niña influence what we’re seeing around the world today. The June-August 2022 global land and ocean surface temperature was 1.6 degrees Fahrenheit...