Record ocean temperatures around Florida made headlines last month. U.S. government data showed that some buoys around Florida reached temperatures over 100^oF.

According to the National Oceanic and Atmospheric Administration (NOAA), normal water temperatures should be between 73^oF and 88^oF.

However, while Florida made headlines, the seas around Rhode Island were some of the world’s hottest.

The Sea Surface Temperature (SST) is the temperature of the top millimeter of the ocean’s surface. An SST anomaly is a departure from average conditions.

The map below shows the world-wide SST anomaly for Sept. 8, 2023. It shows the temperature relative to the long-term average temperature for September from 1985 through 1997.

Blue shows where temperatures were cooler than average, and red shows where temperatures were warmer than average.

While much of the Southern Ocean and expanses of the southeastern Pacific were anomalously cool (a feature of La Niña conditions), most of the world’s oceans experienced unusually warm temperatures.

This is particularly true for the northwestern Pacific (off Japan) and along the Eastern Seaboard of the United States, including Rhode Island Sound and the Gulf of Maine.

Since the early 1980s, the rate of warming in the Gulf of Maine (0.86°F per decade) has been more than triple that of the world’s oceans (0.27°F per decade).

The causes of the dramatic increase in the region’s SSTs are an area of active research.

Professor Peter Ditlevsen at the University of Copenhagen told BBC News that scientists have warned about a dangerous shift in the Atlantic current, which brings warm water north toward the pole, where it cools and sinks and weakens the Atlantic Current.

“There’s been worries that this current is weakening for as long as we have had measurements of it – since 2004,” he said.

A weakened Gulf Stream could be disastrous for New England. Sea levels would rise even faster along the Northeast coast. Also, the ferocity of nor’easters could be intensified by rising sea levels, increasing storm damage, and making it harder for adaptation efforts to keep pace.

SST Anomalies

Because the ocean covers 71% of Earth’s surface, SST measurements are the basis of many practical applications, including weather prediction, climate and seasonal forecasting, military defense operations, validation of atmospheric models, sea turtle tracking, tourism, and commercial fisheries management.

In coastal areas, anomalous temperatures (either warm or cool) can favor one organism in an ecosystem over another, causing populations of bacteria, algae, or fish to thrive or decline.

SST anomalies more accurately describe climate variability over larger areas than absolute temperatures do. SST anomalies provide more meaningful comparisons between locations and more accurate calculations of temperature trends.

NOAA Coral Reef Watch (CRW)

For more than 20 years, CRW has been helping researchers around the world by delivering the world’s only global early-warning system of coral reef ecosystem environmental changes.

Warm SST anomalies warn where coral reefs may be in danger of bleaching, which has become one of the most visible and damaging marine ecological impacts of persistently rising ocean temperatures driven by climate change.

The Advanced Microwave Scanning Radiometer for EOS (AMSR-E) satellite scans the oceans in near real-time and monitors coral reef environmental conditions worldwide. AMSR-E is managed by the Japanese Aerospace Exploration and can see through clouds, providing an uninterrupted view of the ocean measurements.

NASA processes AMSR-E data, along with data from other instruments, to provide ocean measurements such as sea surface temperature, surface wind speeds, atmospheric water vapor, cloud liquid water, and rain rate.

Roger Warburton, Ph.D., is a Newport resident.