I’m not sure where I have dismissed anything, except to question your comment that this is “a risky gambit that will have disastrous consequences”. This idea is at far too preliminary a stage to form such a definitive conclusion. I would not want to wave away any concerns - apologies if I give that impression. A while ago I had a thread on
Insolation and Global Warming. As here, I used that as an opportunity to research scientific information.
In that case my interest was primarily to understand if natural levels of insolation are rising or falling. The conclusion, from the orbital dynamics of Milankovitch cycles, was that the interplay of obliquity and precession means that the low point of June insolation at the equator occurred in 1296 AD when the solstice passed the aphelion in its 21646 year cycle.
Due to shifting obliquity, this low point has not yet occurred at the north pole, and will not happen until about 2700 AD. The interesting thing is that due to the midnight sun, the summer solstice insolation is highest at the poles, as shown at
Insolation over the next million years all latitudes which shows summer solstice north pole insolation at 530 watts per square metre, and south pole the highest solstice figure at 562 w/m2. By comparison, the summer solstice figure at 60° and 30° averages just under 500 w/m2, whereas the equator figure is about 400 throughout the year. Of course at the poles the figure declines to zero in winter.
The Economist special report on the Arctic leads with a view that the Arctic is warming twice as fast as the rest of the planet. It goes on to explain that albedo from sea ice previously reflected incoming solar light to space, but the rapid melt allows this heat into the water.
The link I provided last week shows there was less sea ice in June than in any previous recorded year.
A good starting point is
Climate Change in the Arctic which states “Scientists are studying possible causal factors such as direct changes resulting from the greenhouse effect as well as indirect changes such as unusual wind patterns, rising Arctic temperatures, or shifting water circulation … Reduction of the area of Arctic sea ice means less solar energy is reflected back into space, thus accelerating the reduction."
The cause of the warming in the Arctic is anthropogenic emissions, transmitted through a range of mechanisms. As the maps previously linked show, rising temperatures have led to much lower summer ice area. The question I am raising is not so much whether the measured warming of the Gulf Stream is the only transmission mechanism for a warming Arctic, but rather whether intervention to cool the Gulf Stream might be the most effective way to slow the loss of summer ice. The North Atlantic Current and Gulf Stream is a warm current that brings heat from the equator to the pole. Most of the heat dissipates along the way. But in the summer, insolation in the polar region means the current stays warmer for longer.
You are asking if placing a reflective plastic sheet over the current, and raising cold water from the deep to the surface layer above the sheet, would heat or cool the water below the sheet. It would cool the water below the sheet for the same reason that removing the Arctic sea-ice blanket causes warming of water, that it allows energy from the sun to enter the water instead of reflecting to space. In the algae production sheet, convection from the colder top layer would also cool the current beneath. Despite the simplification, the available charts are correct regarding the bulk northerly flow of the main current. More detailed charts are available such as this
chart of currents in the Norwegian Sea. It should be relatively easy to place interventions to maximise cooling of the bulk flow.
The objective is not to get warm water to depth, but to maximise cooling of the current that reaches the pole. Warmed outlet water could be taken to coastal areas or dissipated in south flowing currents. If sending warm water to depth is the most efficient solution then that should be investigated.As I mentioned earlier, the apparatus would be sunk or rolled up on the approach of hazards such as storms and icebergs, although ice is not present in the Norwegian Sea in summer.
My idea is that the constant depth of the sheet would be maintained by buoys tied to the sheet. When barometric pressure falls below a storm approach threshold, these buoys would automatically deflate allowing the system to sink to depth of say 20 metres, or whatever the minimum safe depth is. The buoys would then be reflated by wave pumping when calmer weather returns. If the plastic is rated to a life of ten years the system would survive ocean conditions long enough to be profitable from fish sales, and would be dismantled and recycled before it begins to break up.
Rain and normal swell are not hazards. The sheet is flexible and becomes part of the swell.
Shipping is likely to be a primary concern, but there are many other similar marine hazards which are marked and avoided. If the algae reefs become productive fishery sources then shipping concerns can be readily addressed.
Sea birds are likely to be a hazard, requiring surface level bird netting to deter them from diving through the sheet.If the sheets are each one acre in size, and aim to cover a total of 1% of the current flow, they just become a set of reefs, and will be easy for fauna to deal with, enriching the marine ecosystem.
Dr Jonathan Trent of NASA’s Offshore Membrane Enclosure to Grow Algae project has given a TED talk in which he emphasises the role of plastic algae structures as reefs that will support additional marine life. Fish cages beneath the reef could allow small fish to leave while keeping big fish in place, to pay for the system from fish sales. My view is that eventually algae production would become a bigger earner than fisheries.This ‘toxic tide’ alarm is something that Lovelock discussed in his original Gaia book. It really is not a risk. My suggestion is that constant monitoring of algae produced and feedback of the best output into the inlet will force adaptation towards higher yielding varieties. Such varieties would be adapted to flourish in this system and would not compete in the open sea where nutrient and warmth is less.Yes, but harmful algae blooms are caused by lack of management of the ecosystem, and the alterations you describe are about taking something away, not improving natural conditions. Putting systems like this at the Mississippi mouth would fix the dead zone. In the Great Barrier Reef it would cool the water and could aim to reduce acidification.The rating of plastic to survive at sea would require field testing. I would very roughly estimate $20 per square metre for the reflective plastic, or about $80,000 for an acre field, plus buoys, inlet pipe, barometer system, tether, fish cage, output feedback system, etc for total cost per acre about $200,000. Plastics is an extremely large world industry, producing about 200 billion kilograms per year. Components for an acre size field would be transported to site by container. Manufacture and installation costs could readily be quantified in a pilot research stage, depending on the rating and type of plastics to be used.That is exactly the question that field research would answer. There is little point suggesting not to conduct research because you do not yet precisely know what the research will show. My estimate is that the algae produced, the sunlight reflected, and the current cooled would reduce anthropogenic warming by far more than any production activities would increase it.
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Originally Posted by Ara Pacis
