Sea Surface Temperature & Marine Heatwaves

What is Sea Surface Temperature? What are Marine Heatwaves?

Sea surface temperature (SST) is the temperature near the ocean’s surface. SST, like air temperature, varies by latitude and changes seasonally; the closer to the equator the warmer the temperature. SST measurements are important for climate and marine ecosystem monitoring and forecasting, marine mammal tracking, commercial fisheries management, and tourism.

When SSTs are abnormally high in a specific area for an extended period of time, it is known as a marine heatwave. Marine heatwaves cause stress to organisms in the affected area; thereby, changing the ecosystem by altering habitat, food webs, and species distributions.

In many parts of US Waters, average SST and Marine Heatwave regularity and intensity are increasing.

How do changes to Sea Surface Temperature and Marine Heatwaves affect the ecosystem?

We track SST and Marine Heatwaves because changes to their patterns and intensity can cause:

• Coral Bleaching or Death: High temperatures threaten corals (2023 Florida heat wave; Pacific something)
• Dangerous Toxins: Harmful algal blooms (HABs), which can be caused by high SSTs, occur when algae grow out of control and produce toxic or harmful effects on people, marine/aquatic organisms, and birds. (NOAA HABs; )

• Re-distribution of marine animals: Changing temperatures can mean fewer fish to catch, shortened fishing seasons, changes in migratory patterns for birds and marine mammals, and a lack of food and habitat for marine mammals (Link example [news article])

• “NOAA provides forecasts for seasonal blooms of cyanobacteria (blue-green algae) in Lake Erie, typically from July to October when warmer water creates favorable bloom conditions. Western Lake Erie has been plagued by an increase of HABs intensity over the past decade.”

How could Sea Surface Temperature and Marine Heatwaves affect me?

Warmer SST and more frequent marine heatwaves have noticeable impacts to our daily lives. For example, during Florida’s recent ocean heat wave, SST was as much as 5 degrees above average and caused massive impacts on both marine organisms and humans. Over time, changes to SST and Marine Heatwaves could affect:

• The frequency and intensity of large, dangerous storms like hurricanes
• The quality of recreational activities like whale-watching or snorkeling
• How often you’re able to go to the beach due to closures, or consume shellfish/seafood due to toxicity