This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: El Niño and warming in the tropical Atlantic could help provide advance warning of extreme heat in the Amazon, with some signals appearing as much as seven months earlier, new research has found. Researchers from the ARC Center of Excellence for the Weather of the 21st Century and the National Institute of Space Research in Brazil studied how major patterns of natural climate variability influence temperature and rainfall extremes across the Amazon Basin.
Published in the journal Earth's Future, the study found that extreme heat in the Amazon was more likely to follow unusually warm conditions associated with El Niño in the tropical Pacific and warming in parts of the tropical Atlantic. The clearest long-range signal occurred from March to May. Across much of the Amazon, extreme heat during these months was associated with climate conditions observed as much as seven months earlier.
The researchers also investigated whether these large-scale climate patterns could help predict compound hot–dry events, when unusually high temperatures coincide with prolonged rainfall deficits. The results revealed useful early-warning potential in some seasons and regions, particularly in the northern and lower central Amazon. However, predictability was considerably weaker elsewhere.
Associate professor Andrea Taschetto of UNSW, a contributing author to the paper, said, "The main mechanisms that affect the Amazon Basin and are related to the Pacific and Atlantic oceans are well established on the seasonal mean timescale. "But in this study, machine learning techniques allowed us to examine the relationship with extreme compound events, which is much harder. It is quite surprising that heat extremes are linked to conditions in the Pacific and tropical Atlantic oceans observed up to seven months in advance." Compound hot–dry events can increase fire risk, damage ecosystems and threaten human health, food security and water supplies.
They can also weaken the Amazon's ability to absorb carbon dioxide, increasing the risk of large-scale ecological and climatic destabilization. Hot–dry events have become more frequent and intense in recent decades and are expected to become more common and severe as the climate continues to warm. Land-use change may intensify these hazards further, with previous research indicating that deforestation can prolong dry periods and increase temperatures.
Being able to identify heightened risks months or even weeks in advance could help communities, governments and environmental managers prepare for periods of dangerous heat and drought. El Niño is the warm phase of the El Niño–Southern Oscillation (ENSO), a recurring pattern of changing ocean temperatures and atmospheric circulation across the tropical Pacific. During El Niño, unusually warm waters in the central and eastern tropical Pacific alter atmospheric circulation.
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