Monday, November 9, 2015

Ocean Heat

Sea Surface Temperatures

Sea surface temperatures were as high as 15.8°C or 60.4°F near Svalbard on November 7, 2015, a 13.7°C or 24.7°F anomaly. Let this sink in for a moment. The water used to be close to freezing point near Svalbard around this time of year, and the water now is warmer by as much as 13.7°C or 24.7°F.

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Above image further shows that sea surface temperature anomalies as high as 6.7°C or 12.1°F were recorded on November 7, 2015, off the coast of North America, while anomalies as high as 6°C or 10.9°F were recorded in the Bering Strait.

NOAA analysis shows that the global sea surface in September 2015 was the warmest on record, at 0.81°C (1.46°F) above the 20th century average of 16.2°C (61.1°F). On the Northern Hemisphere, the anomaly was 1.07°C (1.93°F).

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How did temperatures get so high near Svalbard? The answer is that ocean currents are moving warm water from the Atlantic Ocean into the Arctic Ocean. The ocean is warmer underneath the sea surface and at that location near Svalbard warm water from below the surface emerges at the surface.

Ocean Heat

The oceans are warming up rapidly, especially the waters below the sea surface. Of all the excess heat resulting from people's emissions, 93.4% goes into oceans. Accordingly, the temperature of oceans has risen substantially over the years and - without action - the situation only looks set to get worse.

NOAA's ocean heat content figures for 0-2000 m are very worrying, as illustrated by the image below.


The image below was created with data for January through to March, while adding non-linear trendlines for ocean heat at depths of 0-700 m and 0-2000 m.

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Growth of ocean heat content for 0-700 m appears to follow a polynomial trend, and growth of ocean heat content for 0-2000 m appears to be rising even more strongly, following an exponential trend.

The danger is that, as ocean heat continues to grow, ocean currents will keep carrying ever warmer water from the Atlantic and Pacific Oceans into the Arctic Ocean.

Merely watching temperatures at the surface of the ocean may underestimate the warming that is taking place below the sea surface. At the sea surface, evaporation takes place that cools the water. Furthermore, melting of sea ice and glaciers will make that a layer of cold freshwater spreads at the surface, preventing much transfer of heat from the ocean to the atmosphere, as discussed at this earlier post. The blue-colored areas on the Northern Hemisphere on the top image are partly the result of this meltwater. There is another reason why these areas are relatively cool, i.e. sulfates, as further discussed in the section below.

Aerosols

Particulates, in particular sulfate, can provide short-term cooling of the sea surface. Large amounts of sulfate are emitted from industrial areas in the east of North America and in East Asia. On the Northern Hemisphere, the Coriolis effect makes that such emissions will typically reach areas over the nearby ocean to the east of such industrial areas, resulting in the sea surface there being cooled substantially, until the particulates have fallen out of the sky. Since the sulfate is emitted on an ongoing basis, the cooling effect continues without much interruption.

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This sulfate has a cooling effect on areas of the sea surface where ocean currents are moving warm water toward the Arctic Ocean. Because the sea surface gets colder, there is less evaporation, and thus less heat transfer from the ocean to the atmosphere during the time it takes for the water to reach the Arctic Ocean. As a result, water below the sea surface remains warmer as it moves toward the Arctic Ocean.


Similarly, as illustrated by above image, sulfur dioxide emitted in industrial areas in North America and East Asia can extend over the oceans, cooling the surface water of currents that are moving water toward the Arctic Ocean.

Methane

The image below shows that atmospheric methane levels in 2014 were 1833 parts per billion (WMO data) or 254% the pre-industrial level. WMO data are for 1984-2014 and are marked in red, while IPCC data (AR5) are for the years 1755-2011 and are marked in blue.



The image below shows the rise of methane levels from 1984 created with World Metereological Organization (WMO) data. The square marks a high mean 2015 level, from NOAA's MetOp-2 satellite images, and it is added for comparison, so it does not influence the trendline, yet it does illustrate the direction of rise of methane levels and the threat that global mean methane levels will double well before the year 2040.


The image below illustrates the danger that large amounts of methane will erupt from the Arctic Ocean, particularly in East Siberian Arctic Shelf, where the sea is quite shallow, so much of the methane can reach the atmosphere without being broken down by microbes on the way up through the water column.


The Threat

Ocean heat threatens to increasingly reach the seafloor of the Arctic Ocean and unleash huge methane eruptions from destabilizing clathrates. Such large methane eruptions will then warm the atmosphere at first in hotspots over the Arctic and eventually around the globe, while also causing huge temperature swings and extreme weather events, contributing to increasing depletion of fresh water and food supply, as further illustrated by the image below, from an earlier post.

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Climate Plan

The situation is dire and calls for comprehensive and effective action, as discussed at the Climate Plan.

Below is a radio version of this post, read by Debba Kale Earnshaw at this episode of extinctionradio.org


Sea surface temperatures were as high as 15.8°C or 60.4°F near Svalbard on November 7, 2015, a 13.7°C or 24.7°F anomaly....
Posted by Sam Carana on Monday, November 9, 2015