Climate mitigating energy production

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The IPCC report “Climate Change 2014: Impacts, Adaptation, and Vulnerability” ranks the risk of death, injury, ill-health, or disrupted livelihoods in low-lying coastal zones and small island developing states and other small islands, due to storm surges, coastal flooding, and sea-level rise as the number one threat posed by climate change.

 

Stefan Rahmstorf notes in a RealClimate post What makes sea-level rise? “The causes of global sea level rise can be roughly split into three categories: (1) thermal expansion of sea water as it warms up, (2) melting of land ice and (3) changes in the amount of water stored on land.”

 

Each of these causes is mitigated with technology that produces as much energy as is currently derived from fossil fuels as outlined in the Natural Analogies section of this site.

 

The heat accumulating in the oceans due to climate change excites the water molecules causing an increase in their average separation and thermal expansion. This effect however  is not manifest at a constant rate throughout the depths of the ocean. The greatest expansion occurs at the surface and then decrease to a depth of 1000 meters, beyond which it slowing increases again until at 8000 meters the rate returns to close to what it is at the surface.

 

The greatest potential for sea level rise exists in the polar icecaps, which if melted entirely would raise the oceans by a total of 68 meters. About 61 meters of this rise would come from Antarctica, where the average temperature  is -37°C, so it seems unlikely all of this will melt. It is estimated however that warming will occur at a rate 2.5x greater in Antarctica than the tropics and 4x greater in the Arctic where the ice is floating and will not effect sea levels when it melts.

 

Greenland on the other hand would add 7 meters to ocean levels if all of  its ice melts. Since it is closer to the equator than Antarctica, the temperatures are higher and there is a greater  likelihood this will happen.

 

The question is, how fast will any of this occur?

 

The following schematic shows how heat is typically added, is mixed, and is lost in the major oceans.

 

 

Near the equator heat warms the ocean’s surface, with some of the heat mixing to deeper water, while the rest migrates towards the poles. There heat is radiated back to the atmosphere and space, and the chilled water, which becomes denser as it gets colder, sinks and circulates back towards the equator as part of the Thermohaline circulation that governs much of the global climate. 

 

Global warming is the trapping of more heat than is being radiated back to space by greenhouse gases in the atmosphere.        

The latest work of James Hansen and 16 of his colleagues adds a troubling wrinkle to the cycle pictured above and to global warming in general. Hansen et al. think that increased melting of ice around the coasts of Greenland and Antarctica will create a fresh water blanket that will flow over the warm layer moving towards the poles. This blanket prevents the loss of heat to the air and the trapped heat then works on the underside of the ice shelves and glaciers; increasing their melt rate and sea level rise.

 

This accumulating cold water on the surface will also shut down the Thermohaline with the result tropical waters will get warmer and produce stronger storms, while higher latitudes will be cooled by the melt water on the surface.

 

Effectively the oceans are experiencing a greenhouse effect of their own which has ramifications for the calls by Hansen and others for nuclear power as the remedy for global warming.

 

If the potential for waste heat, which are as high as twice as much as the energy produced,  from thermal sources like nuclear power to radiate into space is impaired then it probably shouldn't be produced at all since it will primarily increase the melting of the icecaps.

 

While the Hansen group says the icecaps are being eroded from below, another current study by a team lead by Samuel Doyle of Aberystwyth University, says the melting of the Greenland ice sheet is being amplified by rainfall on the ice surface driven by late-summer cyclones. Since this too will produce the effects Hansen notes, including stronger storms that will in turn produce more late summer rainfall in Greenland, this doubly negative feedback will likely produce far greater and faster sea level rise than is currently anticipated?  

 

In a Nature article, “Model estimates of sea-level change due to anthropogenic impacts on terrestrial water storage”, Yadu Pohkrel et al. postulates, “climate-driven changes in terrestrial water storage and the loss of water from closed basins have contributed a sea-level rise of about 0.77 mm yr−1 between 1961 and 2003, about 42 percent of the observed sea-level rise.”

 

As drought conditions persist in regions like California the pumping of aquifers, which have taken thousands of years to fill in many cases is being increasingly relied on because the alternative for many farmers is to stop producing crops.

 

It is a stark proposition, starve or contribute to the inundation of the land.

 

These sea level consequences are addressed with energy production that moves the heat accumulating due to global warming though a heat engine to produce energy.

 

Sea Level