doi.org/10.1126/sciadv.adq0604
Credibility: 989
#Atmosfera
Atmospheric rivers are long, narrow bands of water vapor in the sky that bring heavy rain and storms to the U.S. West Coast and other regions of the world. These “rivers in the sky” are moving toward the poles, and this is changing weather patterns in many parts of the planet.
What are atmospheric rivers”
Atmospheric rivers don`t just appear on the U.S. West Coast. They form in many places around the world and are responsible for more than half of the average annual runoff in regions such as the Southeast and Western U.S., Southeast Asia, New Zealand, northern Spain, Portugal, the United Kingdom, and south-central Chile. In California, for example, up to 50 percent of annual rainfall comes from atmospheric rivers.
When these rivers reach more northern latitudes, they can even melt Arctic ice, affecting global climate. A recent study published in the journal Science Advances by scientists at the University of California, Berkeley, showed that over the past 40 years, these atmospheric rivers have moved about 6 to 10 degrees toward the poles.
Why are these rivers moving
Scientists have found that since 2000, sea surface temperatures in the eastern Pacific Ocean have been cooling, which affects atmospheric circulation around the world. This cooling is often associated with La Niña conditions, which push atmospheric rivers closer to the poles.
This movement of atmospheric rivers is explained as a chain of interconnected processes. During La Niña, cooling in the eastern Pacific causes an air circulation called the Walker circulation to become stronger in the western Pacific, which expands the area of tropical rainfall. These changes in rainfall and winds cause atmospheric rivers to move closer to the poles.
On the other hand, during El Niño, when seawater is warmer, atmospheric rivers do not move as far from the equator.
How does this affect local climates
The change in atmospheric rivers can have big impacts on local climates. In subtropical regions, where these rivers are becoming less common, longer droughts and less water are likely to occur. Places like California and southern Brazil rely on these rains to fill reservoirs and support agriculture. Without this moisture, these areas could face more water shortages, causing problems for communities, farms, and ecosystems.
At higher latitudes, atmospheric rivers that are moving closer to the poles could bring more extreme rainfall, flooding, and landslides to places like the U.S. Northwest, Europe, and even the polar regions. In the Arctic, the arrival of more atmospheric rivers could accelerate the melting of sea ice, contributing to global warming and affecting animals that depend on the ice for survival.
What does this mean for the future
So far, the changes we”ve seen are mostly the result of natural processes, but human-caused global warming also plays a role. As temperatures rise, atmospheric rivers are expected to become more frequent and intense, as a warmer atmosphere can hold more moisture.
How this will continue to change as the planet warms, however, is less clear. Predicting these changes in the future is uncertain, mainly because of the difficulties in predicting the natural variations between El Niño and La Niña, which play a major role in the movement of atmospheric rivers.
As the world continues to warm, atmospheric rivers and the essential rainfall they bring will continue to change course. We need to understand and adapt to these changes so that communities can continue to thrive in an ever-changing climate.
Publicado em 10/27/2024 20h21
Artigo original:
Estudo original: