Why recent water temperatures in the North Atlantic have scientists buzzing

It is well documented that ocean temperatures have increased around the world in recent decades.

But what’s been happening in recent weeks with warming waters in the North Atlantic has left the scientific community buzzing.

Temperatures in the North Atlantic Ocean are rising to new record levels this spring, based on data collected by NOAA satellites and produced by the University of Maine.

In early June, sea surface temperatures in the North Atlantic were as warm as 0.5 degrees above the previous record and more than a degree above the 1982-2011 average.

The reason for this recent record heat of 2023 is still under investigation.

Climate scientists agree that climate change and the continued warming of our oceans are undoubtedly a contributing factor. However, they also agree that it is much more likely that multiple factors are at play at this point.

Blockade pattern in the North Atlantic

One of the most likely factors is the recent atmospheric setup over the North Atlantic. Over the past few weeks and months, you’ve no doubt heard me talking during my predictions about the ongoing blockade pattern over the Labrador Sea, Greenland, and Iceland.

This pattern has led to the long spells of cooler and wetter weather we experienced this spring in Atlantic Canada, especially last week when parts of the Maritimes saw more than 100mm of rain in just five days.

This blocking arrangement in the high latitudes of the North Atlantic means there is higher-than-normal pressure in that region. This also usually leads to lower-than-normal pressure near Bermuda and the Azores, which was the case this spring.

A weaker subtropical high corresponds to weaker easterly trade winds. These winds increase the upwelling of cooler water from below the surface. Without those strong trade winds, there’s a better chance for the tropical Atlantic to bake in the late spring sun.

As a result, one of the areas with the greatest variations in sea surface temperature is currently in the “main development region” in the tropical Atlantic. This area, which is critical to tropical development, is already reaching temperatures not normally seen until August and September.

Sahara desert dust

Another possible factor is that there is currently much less dust than usual over the Atlantic Ocean.

Weaker trade winds from the east mean that fewer dust clouds blow from the Sahara to the North Atlantic.

These dust clouds generally have a cooling effect at this time of year as they reflect the sun’s rays that warm the ocean waters.

a 2021 NASA study predicted less dust from the Sahara in the coming years, largely due to warming ocean temperatures in the North Atlantic.

Consequences for the hurricane season

Regardless of the causes, this record heat in the North Atlantic is not good news for hurricane season.

Warmer tropical waters of the Atlantic typically lead to more tropical storms and hurricanes, with more fuel available for developing systems.

But as discussed in the hurricane forecast a few weeks ago, a rapidly developing El Niño could help counteract any storms that develop in the tropical Atlantic.

El Niño events typically lead to stronger wind shear in the tropical Atlantic. This wind shear can suppress the development and growth of tropical storms.

The atmospheric battle of the warming Atlantic versus the ongoing El Niño will be one to watch all summer and fall.