The disappearance of a tourist submersible off the wreck of the Titanic is now drawing the world’s attention to the depths of the North Atlantic, but for scientists the big story lies on the sea’s surface and they are shocked by what they are seeing. . It’s a much bigger story with potential global climate impacts.
In recent weeks, sea surface temperatures have reached record highs in some parts of the North Atlantic. Unusual warming is occurring over much of the Atlantic.
Satellite data shows that surface waters in some places are 4 to 5°C above normal for this time of year. For example, on June 10th, the average sea surface temperature in the part of the Atlantic Ocean stretching from the equator to latitude 60 degrees north to southern Norway, southern Greenland and the central parts of Hudson Bay in Canada was 22.7°C or 22.7 °C About 1 °C above the 19912020 average. The previous record for the same time of 22.1 °C was from 2010.
An ‘unprecedented’ marine heatwave and intensity is observed off the coast of the UK and Ireland. Overheating oceans pose serious threats to species, scientists warn.
Sea temperatures, particularly off the north east coast of England and the west of Ireland, are several degrees above normal and are breaking records in late spring and early summer. The data shows warmer temperatures in the North Sea and North Atlantic.
The US Ocean and Atmospheric Administration has classified parts of the North Sea as a Category 4 marine heatwave, deemed “extreme”, with areas off the coast of England up to 5C above normal. Off the coast of the United Kingdom, the magnitude of the marine heatwave is peaking on a scale of up to 5. “Beyond the extreme,” summarized British meteorologist Scott Duncan.
By definition “beyond the extreme”.
Ireland and the British Isles are at the epicenter of a major marine heatwave. In modern records we have never seen the North Atlantic like this.
Marine heat waves are divided into categories 1 to 5. There are category 5 hotspots. pic.twitter.com/2lle3hrsGv
— Scott Duncan (@ScottDuncanWX) June 19, 2023
“It’s going to be absolutely incredible. Sea surface temperature anomalies in the North Atlantic set a new record on June 20th, surpassing the previous record set on June 10th. With an average temperature of 23.24°C, or 1.11°C above the 19912020 average, there is a standard deviation of +3.87, or 1 in 18,650,” said Brian McNoldy, senior researcher at the University of Miami.
This is going to be nothing short of incredible… North Atlantic SSTs just set a new record anomaly on June 20th, surpassing the previous one on June 10th. With an average temperature of 23.24 °C, this is 1.11 °C above the mean for the years 19912020 or +3.87 standard deviations. 1 in 18,650. pic.twitter.com/N2OhZwaoMc
— Brian McNoldy (@BMcNoldy) June 21, 2023
Daniela Schmidt, Professor of Earth Sciences at Bristol University, said: “The unprecedented and extreme temperatures show the power of the combination of humancaused warming and natural climate variability such as El Niño.”
“While marine heatwaves occur in warmer seas like the Mediterranean, such anomalous temperatures are unknown in this part of the North Atlantic.” They have been linked to less dust in the Sahara, but also to climate variability in the North Atlantic, which requires more understanding to unravel .”
threat to marine life
Scientists warn that overheating of the oceans could have devastating consequences for ocean species that are used to colder waters and unprepared for warmer waters like today.
“The heat puts a strain on marine organisms, as it does on land. Elsewhere in the world, we have seen massive dieoffs of marine plants and animals from oceanic heat waves, resulting in hundreds of millions of dollars in losses to fisheries, carbon storage, cultural values and habitat loss. Until we drastically reduce emissions, these heatwaves will continue to destroy our ecosystems. However, since this is happening below the surface of the sea, it will go unnoticed,” Daniela said.
ESA
Already Dr. Dan Smale of the Marine Biological Association has been studying ocean heatwaves for over a decade and was surprised by the temperatures. “I always thought they would never have an ecological impact on the cold waters of Britain and Ireland, but this is unprecedented and potentially devastating. Current temperatures are very high, but still not fatal for most species, but stressful for many. If it continues through the summer, there could be mass dieoffs of algae, seaweed, fish and oysters,” he warned.
Piers Forster, Professor of Climate Physics at the University of Leeds, told the Guardian: “Met Office and NOAA sea surface temperature analysis shows temperatures have reached an alltime high.”
What is behind the record warming?
This year’s warmer waters could help strengthen storms that form in the North Atlantic and eventually spawn hurricanes, scientists say. What is causing the unusual warming is not clear. But here’s a summary of several factors that could play a role.
LEON SIMONS
LEON SIMONS
Firstly, there is a shortage of dust in the Sahara. Occasionally huge clouds of dust from the Sahara float over the ocean. The dust is carried by strong winds through a semipermanent highpressure system dubbed the “Azores High” due to its proximity to these islands.
But lately the rallies in the Azores have weakened and shifted towards South West Africa. As a result, the winds that normally pick up dust from the Sahara and carry it west across the North Atlantic are calmer and mostly dustfree, says Michael Mann, a climate researcher at the University of Pennsylvania.
As a result, solar radiation that would normally be scattered back into space by dust reaches the sea surface and warms the water. Should the trade winds pick up, the increasing dust from Africa could help cool the area down a bit.
Second: reducing air pollution. In 2020, new emissions regulations came into effect for longdistance cargo ships that emit highsulphur exhaust plumes. There is speculation that less pollution could lead to more warming. As fewer clouds scatter sunlight back into space, more radiation reaches the ocean’s surface.
However, some studies suggest that the cooling effect of ship plumes may have been less: not only do exhaust plumes have a short lifespan, pollutants can also cause natural clouds to evaporate more quickly, leading to warming rather than cooling.
Three, global warming trends. This year marks the return of El Niño, a weather phenomenon characterized by higher than average sea surface temperatures along the equator west of South America.
Every El Niño has its own story. But in general, El Niño increases average surface temperatures on land and sea around the world. Manmade climate change has done the same. However, there is still a great deal of uncertainty as to how current conditions could affect it.
The exceptionally warm waters of the North Atlantic tend to amplify storm systems that later develop into tropical depressions and then hurricanes. But the El Niño, now strengthening in the equatorial Pacific, could impede their formation by strengthening the upperatmospheric winds that make hurricanes more difficult to form. How active this year’s hurricane season will be depends on which of these forces is dominant: warm water or stronger El Niño wind divergence.