marine heatwave

A heatwave is a spell of hot weather extending beyond what is considered normal for the season.  We know about the heatwaves we experience on land but they can also occur out at sea. A spell of hot weather at sea is regarded as a heatwave if the temperature is above what is usual for the season and goes beyond five days.  It can be caused by a variety of factors among which are ocean warming producing warm currents of water, and warming from the air, pushed on by winds which increase the degree of heat, and by climate modes such as El Nĩno.  Ecosystems can tolerate a certain degree of warming but a severe heatwave goes beyond such tolerances and puts the ecosystem at risk. With increased ocean warming the number and severity of marine heatwaves (MHWs) will increase.