Discovery of North America’s role in Asia’s monsoons offers new insights into climate change

A study published in the journal Scientific advancesIndicates how heating in North America can trigger remote effects in Asia – this could still be exacerbated by anthropogenic global warming and human modification of the North American earth surface.

Study authors claim that their results highlight the importance of global cooperation in the fight against climate change.

Using climatic models, scientists from the University of Bristol and the Research Institute on the Tibetan Plateau (ITP) of the Chinese Science Academy (CAS) have found changes to North America can lead atmospheric models that intensify the influence of the South and East plateau, with an effect almost half as strong as the influence of the Tibetan plate East Asia.

While researchers have long known that the Asian monsoon can influence the climate far beyond Asia, the latter study is the first to reveal that the reverse is also true-that the existence of the North American continent has teleconnections across the Pacific Ocean and strengthens the precipitation of the Eastern and South Summer Mousson.

The main author Linlin Chen, Ph.D. Student in physical geography at the University of Bristol, said: “In recent decades, when people are talking about factors that would lead such a strong monsoon in Asia, they have always watched Eurasian and African continents, in particular the Himalayan and Tibetan region.

“These are indeed great influences. But we know that the climate of the earth is closely linked, and now we have more evidence to show precisely how.”

The authors of the study first modeled an idealized “water” world without continents, then gradually added continents from Eurasia, Africa and India to produce a basic Asian monsoon system. Australia, Antarctica, North and South America, as well as a simplified Tibetan plateau were added separately, to see how the Asian monsoon would react.

Dr. Alex Farnsworth, a main research partner at the University of Bristol, also affiliated with ITP, said: “We initially thought that Australia would surpass, because it is the nearest land mass not considered before. But the results surprised everyone.

“North America turns out to be the most important additional continent which has an impact on the Asian monsoon. It is always exciting when the model reveals something unexpected.”

The team discovered that the North American continent created a heating center in summer. This then creates atmospheric undulation effects, which strengthens the high pressure subtropical system of the North Pacific and widens the northern cell of Hadley.

This improved anticyclone grows more west to the west towards Asia, causing a deeper convection and bringing more humidity of the ocean, thus intensifying precipitation through East and South Asia.

The Tibetan plateau also plays a role but, remarkably, the North American impact is almost half as strong as that of the Tibetan plateau on summer precipitation in East Asia.

Seasonal rains in Asia support more than a billion people. In recent years, the inhabitants of Asia have experienced more extreme floods and droughts, which, according to climatologists, is due to global warming, which then causes more extreme climatic events.

The co-author Paul Valdes, professor of physical geography at the University of Bristol, added: “This study reveals how deeply connected: local changes can trigger global effects. Everyone is responsible for local and global climate change.”