Heat Wave!

Yep, it's hot here, with the heat wave that arrived on the East Coast a couple of days ago. The house thermometer reads 90.3, down from 93 earlier, while the Bay weather stations show 89 (Cove Point) or 81 (Gooses Reef). Still not doing much activity, so inside in the AC it is. 

The Bay Journal has this timely article, Marine heat waves create habitat squeeze in the Chesapeake, research shows

Unlike humans, who usually experience heat waves only in the summer, marine life can find itself in hot water, or marine heat waves, throughout the year. While the topic is well-researched in the world’s oceans, little is known at a smaller scale.

The Virginia Institute of Marine Science wrangled 35 years of data to release the first study that analyzes marine heat waves below the first meter of water in an estuary, especially in the Chesapeake Bay. The study found that marine heat waves have seasonal patterns, which could lead to a habitat squeeze for fish and disrupt blue crab migration patterns.

“The only reason that we are able to do [that kind of study] is because of all of the monitoring programs in the Chesapeake Bay,” said Nathan Shunk, who is the lead author of the study. “Everybody really cares about the health of the Bay.”

Marine heat waves occur when water temperatures are warmer than 90% of previous observations for a particular location and time of year. They last 11 days on average in the Bay and can happen throughout the year. Wind, warm water from rivers, ocean currents and a warming atmosphere are all factors that cause this phenomenon.

That strikes me as pretty generous definition of a "heat wave." A deviation higher than 90% of previous values. So in winter when temperatures might typically be in the high 30s or low 40s, a few degrees above those would be a heat wave? Or as we might call it, an unexpected warm spell.

According to the National Oceanic and Atmospheric Association, the world’s oceans absorb 90% of the excess heat associated with global warming. In turn, marine heat waves are becoming warmer.

Water has about 60 time the heat capacity as air, so, yes, heat leaves the atmosphere into the water, so a large increase in air temperature, will generally lead to a much lesser increase in water temperature.  

However, scientists in the field emphasize that marine heat waves are not so frequent and intense that oceans will be caught in a perpetual heat wave. Instead, a warming planet calls for a new definition of “normal conditions” and new thresholds that define heat waves.

“In reality, the impacts associated with global warming, which is a slowly evolving warming of the ocean, are going to be different than the impacts associated with short duration, high-intensity episodic events like marine heat waves,” said Dillon Amaya, research scientist at the NOAA Physical Sciences Laboratory.

Certain studies, like the VIMS research, use a shifting baseline that accounts for ocean warming. That way, marine heat waves remain defined as exceptional and brief events.

And presto! A new field, marine heat waves, is born, another bastard child of the global warming engine in academia.

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