Ocean temperatures have been off the charts since mid-March 2023, with the highest average levels in 40 years of satellite monitoring, and the impact is breaking through in disruptive ways around the world.
What’s Going on!
El Niño is partly to blame. This climate phenomenon, now developing in the equatorial Pacific Ocean, is characterized by warm waters in the central and eastern Pacific, which generally weakens the trade winds in the tropics. This weakening of those winds can affect oceans and land around the world. But there are other forces at work on ocean temperatures. Underlying everything is global warming – the continuing rising trend of sea surface and land temperatures for the past several decades as human activities have increased greenhouse gas concentrations in the atmosphere.
The world just came off three straight years of La Niña – El Niño’s opposite, characterized by cooler waters rising in the equatorial Pacific. La Niña has a cooling effect globally that helps keep global sea surface temperatures in check but can also mask global warming. With that cooling effect turned off, the heat is increasingly evident.
Effect Of Atlantic Heat
The warm waters and mild winds across the eastern North Atlantic brought a long stretch of sunny, warm weather in a month when more than 70% of days normally would have been downpours. The whole agricultural sector of Norway is now bracing for a drought as bad as the one in 2018, when yield was 40% below normal. Many scientists have speculated on the causes of the eastern North Atlantic’s unusually high temperatures, and several studies are underway.
Weakened Monsoon
In the Indian Ocean, El Niño tends to cause a warming of the water in April and May that can dampen the crucial Indian monsoon. That may be happening – the monsoon was much weaker than normal from mid-May to mid-June 2023. That can be a problem for a large part of South Asia, where most of the agriculture is still rain-fed and depends heavily on the summer monsoon.
The Indian Ocean also saw an intense, slow-moving cyclone in the Arabian Sea this year that deprived land of moisture and rainfall for weeks. Studies suggest storms can sit for longer over warmer waters, gaining strength and pulling moisture to their core, and that can deprive surrounding land masses of water, increasing the risk of droughts, wildfires and marine heat waves.
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Source: Theconversation
