The Pacific Ocean covers 32% of Earth's surface area, more than all the land combined. Unsurprisingly, its activity affects conditions around the globe. Periodic variations in the ocean's water temperature and winds, called the El Nino-Southern Oscillation, are a major meteorologic force.
Scientists know that human activity is affecting this system, but are still determining the extent. A new study in Nature has revealed that the atmospheric component of this system - called the Pacific Walker Circulation - has changed its behavior over the industrial era in ways that weren't expected.
An international team of scientists - led by two who worked together at Washington University in St. Louis - also found that volcanic eruptions can cause the Pacific Walker Circulation to temporarily weaken, inducing El Nino-like conditions. The results provide important insights into how El Nino and La Nina events may change in the future.
"What happens in the tropical Pacific doesn't stay in the tropical Pacific," said Bronwen Konecky, an assistant professor of earth, environmental and planetary sciences in Arts and Sciences at Washington University. "It impacts vast stretches of the world. The Pacific Walker Circulation is a major driver of variability in global precipitation."
Earth's rotation causes warm surface water to pool on the western side of ocean basins. In the Pacific, this induces more humid conditions in Asia, with low-altitude trade winds blowing west across the sea. The high-altitude easterlies create an atmospheric circulation - the Pacific Walker Circulation - that drives weather patterns in the tropical Pacific, and far beyond.
Konecky said that when one looks at projections for future climate states for the world, "there's an incredibly high model agreement, when it comes to future changes in temperature. There is a whole lot less agreement when it comes to future changes in rainfall."
Climate models generally predict 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 air - introduced by human activity might have the opposite effect.
"We set out to [determine] whether greenhouse gases had affected the Pacific Walker Circulation," said lead author Georgy Falster, a research fellow at the Australian National University and the ARC Centre of Excellence for Climate Extremes. "We found that the overall strength hasn't changed yet, but instead, the year-to-year behavior is different."
Falster worked with Konecky as a postdoctoral fellow at Washington University. Sloan Coats, at the University of Hawaii at Manoa, and Samantha Stevenson, at the University of California, Santa Barbara, are the other authors.
The scientists observed that the length of time for the Pacific Walker Circulation to switch between El Nino-like and La Nina-like phases has slowed slightly over the industrial era. That could exacerbate the associated risks of drought, fire, rains and floods, Falster said.
That said, the authors didn't notice any significant change in the circulation's strength - yet. "That was one surprising result," Stevenson said. "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 the long-term weather patterns of the Pacific over the past 800 years. The scientists combined these datasets with newer observat
ional data, then used statistical methods to build out annually resolved reconstructions of the Pacific Walker Circulation.
"Our study provides long-term context for a fundamental component of the atmosphere-ocean system in the tropics," Coats said. "Understanding how the Pacific Walker Circulation is affected by climate change will enable communities across the Pacific and beyond to better prepare for the challenges they may face in the coming decades."
Volcanoes play a clear role
Among climate scientists, there has been a hot debate over the last few years about what the El Nino system does after a volcanic eruption, Konecky said. The Pacific Walker Circulation is the atmospheric component of that system.
"We have long known that large volcanic eruptions, especially from the tropics, tend to cool the planet off for a few years," Konecky said. "But when it comes to hydroclimate, the impacts are harder to figure out, because rainfall and other hydroclimate variables are so much noisier than temperature. So, it's just hard to tell: was it a little bit wetter this year because a volcano erupted near Fiji, or for some other reason?"
Volcanic eruptions have the power to impact climate on a global scale, but not every volcano has such impact. Previous research has shown that when there is a strong tropical volcano, the world tends to get a bit cooler.
In terms of potential impact on hydroclimate or rainfall, other scientists have been looking at whether volcanic eruptions change ocean temperatures, because the gradient of ocean temperatures across the tropical Pacific can set the stage for El Nino events. This new study tackles the impact of eruptions head-on by focusing on the behavior of the atmosphere, rather than ocean temperatures. The results were striking:
"Following a volcanic eruption, we see a very consistent weakening of the Pacific Walker Circulation," Konecky said.
"This is not happening by chance. It's something that is quite robust," she said. "We see a consistent response in the atmosphere, whereas others have not seen the same response in ocean temperatures. And that's either because the atmospheric response is stronger or it's easier to detect."
Research Report:Forced changes in the Pacific Walker Circulation over the past millennium
Artificial Intelligence Analysis
Defense Industry Analyst:
8/10
This article is highly relevant to defense industry analysts. It provides insight into changes in the Pacific Walker Circulation, which is a major driver of global climate variability, and its potential impacts on regional weather patterns. It reveals that volcanic eruptions can cause the atmospheric circulation to temporarily weaken, inducing El Nino-like conditions. These insights into the El Nino-Southern Oscillation could have implications for defense operations, as regional climate changes could be used to inform strategic decisions.
Stock Market Analyst:
6/10
This article is of moderate relevance to stock market analysts. It discusses changes in atmospheric circulation and their potential impacts on regional climate patterns, but does not directly address any stock market implications. However, the insights into the El Nino-Southern Oscillation could be used to inform investment decisions, as climate changes could impact the performance of companies in certain industries.
General Industry Analyst:
7/10
This article is relevant to general industry analysts. It provides insights into the Pacific Walker Circulation, which affects global precipitation, and its potential impacts on regional weather patterns. It reveals that volcanic eruptions can cause the atmospheric circulation to temporarily weaken, inducing El Nino-like conditions. These insights could help industry analysts better understand the regional climate changes that could impact their businesses, and plan accordingly.
Analyst Summary
:This article discusses the changes in the Pacific Walker Circulation, an atmospheric circulation in the Pacific Ocean that affects global climate variability and regional weather patterns, and its potential implications. It reveals that volcanic eruptions can cause the atmospheric circulation to temporarily weaken, inducing El Nino-like conditions. This has significant implications for defense, stock market, and general industry analysts. For defense analysts, these insights into the El Nino-Southern Oscillation could be used to inform strategic decisions. For stock market analysts, the insights could be used to inform investment decisions, as climate changes could impact the performance of companies in certain industries. For general industry analysts, the insights could help them better understand the regional climate changes that could impact their businesses and plan accordingly.Comparison of article content with significant events and trends in the space and defense industry over the past 25 years:Over the past 25 years, there have been significant advances in space exploration, such as the launch of the International Space Station and the development of reusable spacecraft. In terms of defense, there has been a shift towards increased reliance on technology and automation, with the use of drones and other unmanned systems becoming increasingly common.The articles content does not directly correlate with these trends, as it discusses changes in atmospheric circulation and their potential impacts on regional climate patterns. However, the insights into the El Nino-Southern Oscillation could be used to inform strategic decisions for defense operations, as regional climate changes could be used to inform decisions on deployment of resources.Investigative
Question:
- 1. How might changes in the Pacific Walker Circulation affect global climate variability in the future?
- 2. What other factors might contribute to changes in the El Nino-Southern Oscillation?
- 3.
How could changes in regional climate patterns affect the performance of companies in certain industries?4. What strategies could defense analysts use to adapt to changing climate patterns?
5. What are the potential long-term impacts of changes in the Pacific Walker Circulation?
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