The Washington Post reports:

Ocean temperatures along the East Coast are near or above their warmest levels on record for this time of year, and they are not only drawing in unusual sea creatures but also helping to fuel the busiest Atlantic hurricane season on record to date.

Now, Hurricane Isaias is poised to draw energy from these abnormally toasty waters as it rides up the East Coast and, depending on its course and speed, the consequences could be severe from Florida to Maine.

Much of the Eastern Seaboard, from the Georgia coast to southern Maine, is in the midst of what scientists define as a marine heat wave. They occur when ocean temperatures are abnormally warm (in the 90th percentile of available data) for an extended period (at least five days).

Marine heat wave intensity is categorized from moderate to extreme. While the waters off the Southeast coast are mostly in a moderate heat wave, the intensity becomes strong along pockets of the Mid-Atlantic coast before swelling to strong to severe off the shores of Massachusetts and southeast Maine.

Temperatures off the Northeast coast are 5.4 to 7.2 degrees above normal, said Andrew Pershing, chief scientific officer at the Gulf of Maine Research Institute, in an email.

Due to human-caused buildup of greenhouse gases in the atmosphere, marine heat waves have increased dramatically in frequency, size and severity in recent decades. They’ve altered fisheries and killed seabirds in the North Pacific and Bering Sea, and damaged or killed parts of the Great Barrier Reef, a World Heritage site.

A study published in December warns that by late this century there may be “a permanent marine heat wave state” in many parts of the ocean because of continued warming. The oceans are absorbing the vast majority of the extra heat pumped into the climate by the highest levels of greenhouse gases in human history, and marine heat waves and altered ocean currents are just some of the consequences. [Continue reading…]