Ocean surface heat is at record levels. Temperatures started to rise in mid-March and skyrocketed over the course of several weeks, leaving scientists struggling to figure out exactly why.
Temperatures have dropped from their peak in April – as they naturally do in spring – but are still higher than ever at this time of year.
“It’s remarkable,” said Gregory C. Johnson, an oceanographer for the National Oceanic and Atmospheric Administration, who calculates ocean surface temperatures using a network of ships, buoys, satellites and floats.
While this is still preliminary data, if it persists, he said, “this is another milestone.”
The record may not seem huge – it’s nearly two-tenths of a degree higher than the previous record in 2016 – but considering the amount of heat required to heat this massive body of water, “it’s a huge amount of energy,” Matthew England, professor of ocean dynamics and climate at the University of New South Wales in Australia, told CNN .
What is behind this rapid increase is still not entirely clear. “These temperatures have skyrocketed, people haven’t had a chance to decipher everything,” Johnson said.
Some scientists are concerned that the scale of these new records could mark the start of an alarming trend. Others say record temperatures like these are always worrying but expected given the man-made climate crisis.
Everyone agrees that the consequences are likely to be significant. Warmer oceans bleach corals, kill marine life, accelerate sea level rise and make the ocean less efficient at absorbing planet-warming pollution – the warmer the oceans get, the more the planet warms.
The return of El Niño
One of the main drivers of the heat is believed to be the approaching – and potentially strong – El Niño, a natural climate fluctuation associated with warming in the tropical central and eastern Pacific Ocean, which has a global warming effect.
The world has just emerged from a 3-year La Niña, the cooler counterpart to El Niño, which helped to mask the full impact of global warming. Since La Niña ended in March, ocean temperatures appear to be recovering, scientists say.
“It’s like we opened the freezer door for a while and that helped cool the planet,” Johnson said. But even with the freezer open, background temperatures continued to rise. Now the freezer is closed, everything is warmer than before.
The World Meteorological Organization said on Wednesday that there is about an 80% chance of an El Niño developing between July and September. But part of what has intrigued scientists is that temperatures rose long before it even arrived.
Some are concerned that this suggests that climate change may be progressing in ways that climate models did not predict.
“An El Niño event is brewing, but it’s probably too early to blame this as the cause,” Professor Mike Meredith, scientific lead at the British Antarctic Survey, told the CNN .
“It is vital that we find out what is causing [o pico na temperatura da superfície do oceano] and let’s understand if this is an isolated extreme high or the beginning of an even more worrying trend”.
Deepest ocean heat
Surface temperatures tell a story about what is happening to the world’s oceans.
But to understand where the world is going in the long term, it’s important to also look at deeper ocean temperatures, said Sarah Purkey, an assistant professor at the Scripps Institution of Oceanography.
Thousands of floaters in the world’s oceans measure their heat content, analyzing the temperature from the surface to the deep waters, feeding back the data.
“The heat content of the ocean has been increasing a lot, sometimes accelerating,” Purkey told CNN because of man-made global warming.
Oceans absorb about 90% of the excess heat the world produces, as well as about 25% of carbon pollution.
In 2022, the oceans were the warmest on record for the fourth consecutive year.
A study published in April found that heat in the climate system is accelerating, which spells bad news for the oceans.
He found that the rate of change in how much heat Earth has accumulated has more than doubled over the last two decades – and most of that is going to the ocean.
“There’s a really urgent need to understand this because if it’s part of a long-term trend, it’s highly concerning,” said Karina von Schuckmann, an oceanographer at Mercator Ocean International in France and a co-author of the study.
One surprising reason could be the reduction of aerosols in the atmosphere. In 2020, regulations were introduced to limit the amount of sulfur in fuel used by ships – a policy aimed at combating air pollution.
While air pollution has a significant impact on human health, it also acts as an artificial sunscreen and reflects sunlight away from the Earth. One theory is that the absence of aerosols could have added to the heat, von Schuckmann said.
Worrying impacts of ocean warming
Whatever the reasons behind the increase in ocean heat, the impacts are potentially catastrophic if temperatures continue to rise.
The oceans protect us from all the impacts of the climate crisis.
“We have the ocean to thank for soaking up most of what we’ve done to the climate system, otherwise we’d be seeing effects that are actually 100 times greater than what we’re seeing now,” Purkey said.
But this buffering role comes at a high cost.
Warmer oceans cause coral reefs to bleach and are linked to toxic algal blooms, which can suck oxygen out of the water and suffocate marine life, sometimes forcing fisheries to close.
Warmer waters are also less effective at absorbing carbon, meaning more is left in the atmosphere, which in turn fuels more global warming.
Sea levels rise as water warms – not just from melting ice sheets, but water also expands as it warms.
Surface warming supercharges cyclones and hurricanes.
Scientists are particularly concerned about the impact of warming on meridional currents, oceanic “conveyor belts” that push surface water into the deeper ocean and play a key role in regulating the planet’s energy balance.
“It’s probably the most important thing to monitor,” Purkey said.
The strength of currents will determine how efficiently the ocean absorbs the excess heat humans are producing, she said.
And, for example, if the current in the Atlantic Ocean weakens, or even collapses, the consequences could be dire – including very cold winters in Western Europe, rapid rise in sea levels and disruption of tropical monsoons.
For now, ocean surface temperatures have started to drop, even though they remain high for this time of year.
As scientists continue to analyze the reasons for record warming of the oceans, it is clear that records will continue to be broken as the climate crisis intensifies.
“This is kind of a wake-up call, I hope, for everyone across the world that this warming trajectory that we’re on is not going to stop until we get our emissions back to zero,” England said.
Source: CNN Brasil
Bruce Belcher is a seasoned author with over 5 years of experience in world news. He writes for online news websites and provides in-depth analysis on the world stock market. Bruce is known for his insightful perspectives and commitment to keeping the public informed.
