The Pacific El Nino phenomenon, which is responsible for recurring extreme weather events worldwide, looks set to be particularly intense as it returns this year after a six-year hiatus.
Climate experts predict that the ocean current pattern, which moves from the West to East Pacific, will have profound environmental and economic effects across the globe.
“The early signs are already there,” French climatologist Professor Benjamin Pohl, of the national CNRS research institute, told FRANCE 24.
“Surface waters are already 0,5°C to 1°C warmer than usual, from which we can predict that they will rise to 2°C above the average as El Nino peaks. This is a considerable rise in temperature.”
The El Nino weather phenomenon translates as “little one” and was named after the baby Jesus by fishermen, as it seemed to peak around Christmas time. Warmer sea currents led to an absence of fish, which prefer cooler nutrient-rich water.
It takes place periodically, in cycles of between two and seven years. The last one happened five years ago.
Scientists predict that the massive warm Pacific currents heading for the Peruvian and Equatorial coasts will be particularly severe this year.
The knock-on effects of the warmer ocean currents are expected to create an upsurge in dense rainclouds that impacts much of North and South America, bringing heavy rain and flooding even in desert regions.
And while this might seem like good news, especially for drought-hit areas such as California, these rain storms are often fast, brutal downpours.
The storms are predicted to be so severe, in fact, that Peru has cancelled the Paris-Dakar rally that had been due to take place there in January 2016.
On the other side of the Pacific, the weather pattern is usually inverted, with lower rainfall and droughts expected as far west as South East Asia, India and West Africa.
“Droughts are especially feared in these countries that are particularly dependent on agriculture,” according to Professor Pohl.
The dry periods are also often the cause of devastating bush fires: the El Nino of 1982-1983 destroyed 335,000 hectares of Australian forest and agricultural land.
Fishing will also be badly affected, the last El Nino events having wiped out 90% of sardine and anchovy stocks on the on the north-west coast of South America.
Across the Pacific, the warmer current will have an irreversible effect on coral reefs. The last big El Nino event, in 1997-1998, caused the worst coral bleaching (where the coral is killed and turns white) on record. The Maldives lost 90% of their coral, and in total 16% or the world’s reefs were wiped out.
The only good news is for the other side of the Americas, where Atlantic hurricanes are normally less severe during an El Nino event.
While El Nino is a naturally-occurring event, with evidence from fossils showing that the weather cycle has been in evidence for at least 10,000 years, “we can see that in the last three decades the phenomenon has become particularly intense”, said Professor Pohl.
“It is likely, even if it hasn’t been proved outright, that global warming linked to human activity is driving these changes,” he said.
This article was translated from the original in French.
Date created : 2015-08-27