El Niño amid heating oceans: We’re now in uncharted waters

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Source– The post is based on the article “El Niño amid heating oceans: We’re now in uncharted waters” published in the “mint” on 11th May 2023.

Syllabus: GS1- Geography. GS3- Environment

News– The latest spike in ocean temperature matters is a cause of concern.

What are the impacts of rising ocean temperatures?

Huge energy stored– The changes in sea-surface temperatures matters a lot when expressed as energy added to the system that includes our ocean and atmospheres. It is the equivalent of hundreds of millions of atomic bombs.

It’s energy that gets trapped in the system by an increasing concentration of greenhouse gases. That energy can manifest as heat waves or storms.

El-Nino and La-Nina cycles– La Niña has prevailed during the last three years. During this phase, trade winds push warm equatorial water westward from the US across the Pacific, where it piles up by Indonesia.

Every two to seven years, it switches to the El Niño pattern. Warmer water can shift back toward the Americas.

El Niño events can be gentle or fierce. It depends on whether strong westerly winds helps warm water to shift across the Pacific.

El Niño is born in the Eastern Pacific. But, the change in patterns redistributes heat around the planet. It disturbs the entire global atmospheric circulation.

The cycle of El Niño and La Niña has probably been going on for millions of years, since our continents and oceans reached their current configuration.

Now, with rapid overall warming, the Pacific cycle might become even stronger. It is already creating more extreme conditions.

Impact on ocean circulations– There’s more capacity for heat deep in the ocean. But, the water heats up at the surface first. Since cold water is heavier, it can create regions of stillness, where normal circulation stops and oxygen depleted oceans grow.

Scientists are observing alarming dead zones in the Gulf of Mexico, which are made worse by nitrate runoff from farms. It affects the phytoplankton, the zooplankton, the fish, the marine mammals and seabirds.

Warming oceans also lead to marine heat waves. It can destroy kelp forests and grasses that provided a home for fish and marine mammals.

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