While the rate of warming of the Earth’s surface has slowed since 1999, ocean temperatures have continued to increase, especially at depth.
The results of a recent study from the University of Washington described here and published in the journal Science, has shown that a slow-moving current in the Atlantic, which carries heat between the two poles, sped up earlier this century to draw heat down almost a mile (1,500 meters) into the ocean.
This current oscillates between warming and cooling periods. During the warming period, faster currents bring more tropical water to to the North Atlantic, warming both the surface and the deep water. The warmer surface water melts ice, slowly decreasing the density of the water. Since salty water is more dense, it sinks and acts as a driver for the current. With less saline water at the surface, the circulation slows and a 30-year cooling phase begins. The current began to draw heat deeper into the ocean around 2000, counteracting human-caused warming at the surface.
From K. Tung / Univ. of Washington. (Top) Global average surface temperatures, where black dots are yearly averages. Two flat periods (hiatus) are separated by rapid warming from 1976-1999. (Middle) Observations of heat content, compared to the average, in the north Atlantic Ocean. (Bottom) Salinity of the seawater in the same part of the Atlantic. Higher salinity is seen to coincide with more ocean heat storage.
Lummi Nation launched the Totem Pole Journey on Sunday, August 17 to bring together tribes across the U.S. and Canada and to expose the environmental and cultural impacts of coal and oil transportation. The Lummi Nation has galvanized resistance to the Gateway Pacific coal export terminal proposed for Cherry Point, WA. The Gateway Pacific Terminal would export 48 million tons of coal a year from the Powder River Basin in Montana and Wyoming. The terminal threatens the Lummi way of life and the area’s ecological integrity. Read more from Grist here..
Listening for the Rain documents the stories of Indigenous communities (four in Oklahoma and two in New Mexico) observing and responding to climate change and variability.