Atmospheric rivers are deviating from their usual trajectory. This phenomenon could profoundly disrupt global precipitation patterns.
These massive streams of suspended water transport enormous quantities of moisture across the globe each year. Stretching over several thousand miles (kilometers), they bring vital rainfall to the lands beneath them.
The atmospheric river dubbed "Rhum Express," forming above the Caribbean and predominantly pouring down here on Portugal, Spain, and France.
Atmospheric rivers originate above tropical oceans. They then move towards higher latitudes, where they release their water as rain or snow when they encounter mountains or coasts. For example, atmospheric rivers are responsible for about half the amount of precipitation on the U.S. West Coast.
According to a recent study from the University of California at Santa Barbara, these moist corridors have shifted towards the poles by approximately 6 to 10 degrees over the past forty years. This shift now affects more northern and southern areas than in the past.
The researchers attribute this displacement to a shift in temperatures in the eastern tropical Pacific. However, the exact mechanisms of this phenomenon remain largely to be elucidated.
The consequences of this shift are already being felt. Regions that were once watered by these rivers may experience more droughts. Areas further from the tropics, on the other hand, risk facing torrential rain. This is already evident in North America and Europe.
Animation of the "Rhum Express"
This shift could also affect ocean currents and their role in global climate regulation. The climate beyond the land may undergo yet unforeseen changes, even impacting marine biodiversity.
Researchers emphasize the urgency of better understanding this phenomenon. Further in-depth studies will be needed to anticipate these variations and protect affected populations.
What is an atmospheric river?
Atmospheric rivers are long, narrow bands of suspended water that circulate in the atmosphere. They carry enormous amounts of moisture over thousands of kilometers (miles), comparable to terrestrial rivers in terms of the volume of water they transport. They play an essential role in global precipitation patterns by moving vast quantities of moisture from the oceans to the continents.
Atmospheric rivers influence the distribution of global precipitation. When they encounter a mountain or coastal barrier, the moisture they carry condenses and falls as rain or snow, nourishing the soil, rivers, and groundwater. Their trajectory is thus important for the water balance of the regions they traverse.
Article by: Cédric DEPOND