With the climate pattern known as El Niño in full force from mid-2023 to mid-2024, 全球气温 连续12个月打破纪录. 作为有史以来最强的厄尔尼诺Niño事件之一, it was likely the main culprit of unprecedented heat, 世界各地的洪水和干旱.
在一个 新的研究 9月出版. 发表在《博彩app推荐》杂志上, a CU Boulder climate scientist and collaborators reveal that the planet could see more frequent extreme El Niño events by 2050 if greenhouse gas emissions continue to increase.
“It’s pretty scary that 2050 is not very far away,” said 佩德罗DiNezio, the paper’s co-lead author and associate professor in the Department of Atmospheric and Oceanic 科学s. “如果这些极端事件变得更加频繁, 社会可能没有足够的时间来恢复, rebuild and adapt before the next El Niño strikes. 后果将是毁灭性的.”
佩德罗DiNezio
多变的风和飙升的气温
El Niño occurs when water temperatures along the equator in the Pacific Ocean rise by at least 0.长时间比平均温度高9华氏度.
The seemingly marginal temperature change can shift wind patterns and ocean currents, 引发全球异常天气, 包括热浪, 洪水和干旱.
当面积 升温3度.比平均水平高6华氏度, scientists classify the El Niño event as extreme. 自从美国.S. National Oceanic and Atmospheric 政府 began collecting data in the 1950s, the agency has recorded three to four extreme El Niño events.
During an extreme El Niño, the impacts on global weather tend to be more severe. For example, during the winter of 1997-98, El Niño brought 加州创纪录降雨量, causing devastating landslides that killed more than a dozen people. 在同一时期，地球 失去了大约15%的珊瑚礁 由于持续变暖.
Last winter El Niño almost reached extreme magnitude, DiNezio said.
“El Niño events are difficult to simulate and predict because there are many mechanisms driving them. This has hindered our ability to produce accurate predictions and help society prepare and reduce the potential damage,他们说.
Prior research suggests that climate change is intensifying and increasing the frequency of extreme weather events, 可能与El Niño模式的变化有关. 然而, 由于数据有限, scientists have yet to confirm whether El Niño will strengthen with warming.
Satellite sea surface temperature departure in the Pacific Ocean for October 2015, where darker orange-red colors are above normal temperatures and are indicative of El Niño. (来源:美国国家海洋和大气管理局)
DiNezio and their team set out to simulate El Niño events in the past 21,000年—since the peak of Earth’s last Ice Age—using a computer model.
模型显示在冰河时期, 那时地球的气候更冷, 极端El Niño事件非常罕见. As the planet warmed since the end of the Ice Age, the frequency and intensity of El Niño have been increasing.
The team validated the model by comparing the simulated data with past ocean temperature data retrieved from fossilized shells of foraminifera, a group of single-celled organisms ubiquitous in the oceans long before human existence. By analyzing the type of oxygen compounds preserved in these fossilized shells, the team reconstructed how El Niño drove ocean temperature fluctuations across the Pacific Ocean for the past 21,000年. The ancient record aligned with the model’s simulations.
“We are the first to show a model that can realistically simulate past El Niño events, enhancing our confidence in its future predictions. We are also proud of the robust technique we developed to evaluate our model, 但不幸的是, 它没有给博彩平台推荐带来好消息,迪内齐奥补充道.
The model predicts that if society continues to pump greenhouse gases into the atmosphere at the current rate, one in two El Niño events could be extreme by 2050.
控制旋钮
尽管El Niño很复杂, the model reveals that a single mechanism has controlled the frequency and intensity of all El Niño events as the planet warmed since the last Ice Age.
When the eastern Pacific Ocean water warms from natural fluctuation, the winds that always blow east to west over the equatorial Pacific weaken due to changes in air pressure above the ocean. 但是在El Niño期间, 减弱的风使温暖的海水向东流动, 温暖的海水进一步削弱了风力, creating a feedback loop known as the Bjerknes feedback.
DiNezio’s research suggests that as the atmosphere warms rapidly from greenhouse gas emissions, the planet experiences a stronger Bjerknes feedback, 导致更频繁的极端厄尔尼诺Niño事件.
最近的El Niño现在已经过去了, DiNezio emphasized that society needs to focus on taking measures to reduce the impact of future extreme El Niño events, including cutting emissions and helping communities, 特别是在发展中国家, 适应极端天气.
“We now understand how these extreme events happen, and we just need the will to reduce our reliance on fossil fuels,他们说. “Our findings emphasize the urgent need to limit warming to 1.5°C以避免灾难性的气候影响.”
