Madrid. Volcanic eruptions can cause the Pacific circulation to temporarily weaken, inducing conditions similar to those of The boy.
The results, published in the journal Nature by scientists at Washington University in St. Louis, provide important insights into how weathering phenomena may change in the future. The boy and The girl.
The Pacific Ocean covers 32 percent of the Earth’s surface, more than all the land combined, so its activity affects the conditions of the entire planet. Periodic variations in ocean water temperature and winds, called The boy-Southern Oscillation, are an important meteorological force.
Scientists know that human activity affects this system, but they are still determining its extent. The new study has revealed that the atmospheric component of this system, the Pacific Walker Circulation, has changed its behavior throughout the industrial age in unexpected ways.
“What happens in the tropical Pacific doesn’t stay in the tropical Pacific,” Bronwen Konecky, associate professor of Earth, environmental, and planetary sciences in arts and sciences at the University of Washington, said in a statement. “It affects vast stretches of the world. The Pacific Walker Circulation is one of the main drivers of global precipitation variability.”
The Earth’s rotation causes warm surface water to accumulate on the western side of the ocean basins. In the Pacific, this induces wetter conditions in Asia, with low-lying trade winds blowing west across the sea. High-altitude easterly winds create an atmospheric circulation that drives weather patterns in the tropical Pacific, and far beyond.
According to Konecky, when looking at projections of the world’s future climate states, “there is incredibly high agreement between models when it comes to future temperature changes. There is much less agreement when it comes to future changes in precipitation,” she adds.
Climate models typically predict that the Pacific Walker Circulation will weaken in response to global warming; however, its recent strengthening suggests that aerosols – the suspension of fine solid particles or liquid droplets in the air – introduced by human activity, could have the opposite effect.
“We set out to determine if greenhouse gases had affected the Pacific Walker Circulation,” explains lead author Georgy Falster, a researcher at the Australian National University and ARC Center of Excellence for Climate Extremes. “We found that the global strength hasn’t changed yet, but instead the year-over-year behavior is different.”
The scientists observed that the time it takes for the Pacific circulation to alternate between the phases of The boy and The girl it has slowed slightly over the course of the industrial age. According to Falster, this could exacerbate the associated risks of drought, fire, rain and flooding.
The authors did not observe any significant change in the strength of the circulation yet. “That was a surprising result,” acknowledges Samantha Stevenson of the University of California, Santa Barbara, “because by the end of the 21st century, most climate models suggest that the Pacific Walker Circulation will weaken.”
The team used data from ice cores, trees, lakes, corals, and caves to investigate long-term weather patterns in the Pacific over the past 800 years. The scientists combined these data sets with more recent observational data and then used statistical methods to produce annually resolved reconstructions of the Pacific Walker Circulation.
“Our study provides a long-term context for a fundamental component of the atmosphere-ocean system in the tropics. Understanding how the Pacific Walker Circulation is affected by climate change will allow communities across the Pacific and beyond to better prepare for the challenges they may face in the coming decades,” Coats said.
heated debate
There has been a heated debate among climate scientists in recent years about what the weather system does. The boy after a volcanic eruption, Konecky notes. The Pacific Walker Circulation is the atmospheric component of that system.
“We have known for some time that large volcanic eruptions, especially in the tropics, tend to cool the planet for a few years, but when it comes to hydroclimate, the impacts are harder to figure out, because rainfall and other hydroclimatic variables are so much different. noisier than temperature. So it’s hard to know if it’s been a bit wetter this year because a volcano erupted near Fiji, or for some other reason,” Konecky said.
Volcanic eruptions have the power to influence climate on a global scale, but not all volcanoes have that impact. Previous research has shown that when there is a strong tropical volcano, the world tends to cool down a bit.
Regarding the potential impact on the hydroclimate or precipitation, other scientists have studied whether volcanic eruptions modify the temperature of the oceans, since the oceanic temperature gradient in the tropical Pacific can lay the foundations for the phenomena of The boy.
This new study addresses the impact of eruptions by focusing on the behavior of the atmosphere, rather than ocean temperatures.
“After a volcanic eruption, we observed a very consistent weakening of the Pacific walking circulation,” adds Konecky.
“This does not happen by chance. It’s pretty solid stuff. We see a consistent response in the atmosphere, while others have not seen the same response in ocean temperatures. And that’s because the atmospheric response is stronger or easier to detect.”
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