Climate scientists have been warning for months about the possible formation of an El Niño phenomenon during the boreal summer, given current conditions in the Pacific Ocean.
The last time El Niño formed was in 2016 and its effects were felt around the world, contributing to record rises in global temperatures, loss of tropical forests, coral bleaching and polar melting.
LThe possibility that in the coming months a powerful El Niño will form It worries scientists, in a context in which a “sudden and unexpected” warming of the oceans has been detected.
All of this, taken together, could push global temperatures to record levels between 2023 and 2024.
To predict the El Niño phenomenon, scientists measure various factors, such as the speed of the trade winds and the temperatures of the ocean waters, both on the surface and in the depths.
In addition, scientists at NASA’s Jet Propulsion Laboratory (JPL) use satellite imagery to study the so-called Kelvin wavesand thus be able to predict with greater certainty the probabilities of the generation of El Niño.
“When we measure sea levels using altimeters in space,” Nadya Vinogradova Shiffer, NASA Sentinel-6 program scientist said in a statement, “we not only see the shape and height of the water, but the movement of waves such as waves. Kelvin”.
But what are these waves that NASA experts have detected in recent weeks and why do they use them to predict phenomena such as El Niño?
Kelvin waves
The waves you see when you go to the beach are caused by the pressure that the atmosphere exerts on the water: increases in pressure cause the water on the surface to compress and expand. In that coming and going, waves are created.
During this wave movement, the warm water on the surface mixes with the colder water from the depths, creating currents.
Kelvin waves -discovered in 1879 by William Thompson, later known as Lord Kelvin-, follow the same principle.
As JPL explains, Kelvin waves are approximately 5 to 10 centimeters high at the ocean surface and hundreds of kilometers wide, moving from west to east.
When they form at the equator, as has been detected in recent weeks, Kelvin waves carry warm water, associated with higher sea levels, from the western Pacific to the eastern Pacific, toward the west coast of South America. .
Kelvin waves that begin in the boreal spring are considered a precursor to El Niño, a phenomenon characterized by higher sea levels and warmer-than-average ocean temperatures along the western coasts of the Americas.
Kelvin waves and El Niño
With more heat in those waters, there is more evaporation, and with more evaporation, there is more precipitation and extreme weather events.
“Kelvin waves are something that we usually see as a precursor to El Niño,” NASA researcher Josh Willis tells BBC Mundo.
“There have been several historic El Niño events in recent years (1996-1997, 2015-2016) and all have seen Kelvin waves before they occurred.”
Through satellite images, scientists can get a clearer visual idea of how temperatures are distributed in the Pacific.
And potentially how strong an El Niño is going to be that is forming.
“I think it’s much more likely that we’ll have an El Niño this year than not,” says Willis, “but whether it’s a big one or a small one, it’s something we’ll have to wait and see.”
What can be said with certainty is that with global temperatures rising due to climate change, any further increases such as El Niño may bring will have significant consequences.
“Satellite data for the period between March and April, showed that by April 24, Kelvin waves had accumulated higher levels of warmer waters off the coasts of Peru, Ecuador, and Colombia,” JPL said in its statement.
These data were reflected, for example, in the historical increases in temperatures that Peru reported during April.
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See original article on BBC