What effects will the new episode of La Niña that is developing in the Pacific have?
The World Meteorological Organization announces that this new La Niña episode will likely have a cooling effect on the world
A new episode of La Niña is developing in the Pacific Ocean and is expected to be “moderate to intense,” announced the World Meteorological Organization (WMO).
The phenomenon, which occurs naturally, causes large-scale cooling of the ocean surface temperature.
This episode, which will last until the first quarter of 2021, will likely have a cooling effect on global temperatures.
But it won’t prevent 2020 from being one of the warmest years on record.
La Niña is described as one of the three phases of the climate pattern known as El Niño-Southern Oscillation (ENSO).
This includes the warm phase called El Niño, the coldest (La Niña) and a neutral phase.
La Niña develops when winds blowing over the Pacific push warm surface water west toward Indonesia.
Instead, colder waters from the deep ocean rise to the surface.
This causes major climate changes in different parts of the world.
Normally, La Niña means that countries like Indonesia and Australia can get much more rain than usual, and a more active monsoon occurs in Southeast Asia.
More storms are likely in Canada and the northern US, often leading to snowy conditions.
At the same time, the southern states of the United States may be affected by drought.
The last time an intense event unfolded was in 2010-2011.
The WMO says there is now about a 90% chance that tropical Pacific temperatures will remain at La Niña levels for the rest of this year.
There is a 55% chance that conditions will persist into the first quarter of next year.
While a La Niña event typically has a cooling effect on the world, this is unlikely to have much of an impact in 2020.
“La Niña normally has a cooling effect on global temperatures, but this is offset by the heat trapped in our atmosphere by greenhouse gases,” said WMO Professor Petteri Taalas.
“Therefore, 2020 remains on track to be one of the warmest years on record and 2016-2020 is expected to be the hottest five-year period on record,” he said.
“The La Niña years are now warmer even than the years in the past with intense El Niño events,” he explained.
WMO says it is announcing La Niña now to give governments the opportunity to start planning in key areas such as disaster management and agriculture.
An important aspect of La Niña is the effect it could have on the remainder of the Atlantic hurricane season.
A La Niña event reduces wind shear, which is the change in winds between the surface and upper levels of the atmosphere.
This allows hurricanes to grow.
Hurricane season ends on November 30, and there have been 17 named storms so far out of the 19-25 that were forecast by the US National Oceanic and Atmospheric Administration (NOAA).