Ocean geo-engineering scheme no easy fix for global warming

[OKIsItJustMe]

http://www.noc.soton.ac.uk/index.php?full=1

Ocean geo-engineering scheme no easy fix for global warming

Pumping nutrient-rich water up from the deep ocean to boost algal growth in sunlit surface waters and draw carbon dioxide down from the atmosphere has been touted as a way of ameliorating global warming. However, a new study led by Professor Andreas Oschlies of the Leibniz Institute of Marine Sciences (IFM-GEOMAR) in Kiel, Germany, pours cold water on the idea.

“Computer simulations show that climatic benefits of the proposed geo-engineering scheme would be modest, with the potential to exacerbate global warming should it fail,” said study co-author Dr Andrew Yool of the National Oceanography Centre, Southampton (NOCS).

If international governmental policies fail to reduce emissions of carbon dioxide to levels needed to keep the impacts of human-induced climate change within acceptable limits it may be necessary to move to ‘Plan B’. This could involve the implementation of one or more large-scale geo-engineering schemes proposed for reducing the carbon dioxide increase in the atmosphere.

One possible approach is to engineer the oceans to facilitate the long-term sequestration of carbon dioxide from the atmosphere. It has been suggested that this could be done by pumping nutrient-rich water from a depth of several hundred metres to fertilize the growth of phytoplankton, the tiny marine algae that dominate biological production in surface waters.

The aim would be to mimic the effects of natural ocean upwelling and increase drawdown of atmospheric carbon dioxide by phytoplankton through the process of photosynthesis. Some of the sequestered carbon would be exported to the deep ocean when phytoplankton die and sink, effectively removing it from the system for hundreds or thousands of years.

A previous study, of which Yool was lead author, used an ocean general circulation model to conclude that literally hundreds of millions of pipes would be required to make a significant impact on global warming. But even if the technical and logistical difficulties of deploying the vast numbers of pipes could be overcome, exactly how much carbon dioxide could in principle be sequestered, and at what risk?

In the new study, the researchers address such questions using a more integrated model of the whole Earth system. The simulations show that, under most optimistic assumptions, three gigatons of carbon dioxide per year could be captured. This is under a tenth of the annual anthropogenic carbon dioxide emissions, which currently stand at 36 gigatons per year. A gigaton is a million million kilograms.

One surprising feature of the simulations was that the main effect occurred on land rather than the ocean. Cold water pumped to the surface cooled the atmosphere and the land surface, slowing the decomposition of organic material in soil, and ultimately resulting in about 80 per cent of the carbon dioxide sequestered being stored on land. “This remote and distributed carbon sequestration would make monitoring and verification particularly challenging,” write the researchers.

More significantly, when the simulated pumps were turned off, the atmospheric carbon dioxide levels and surface temperatures rose rapidly to levels even higher than in the control simulation without artificial pumps. This finding suggests that there would be extra environmental costs to the scheme should it ever need to be turned off for unanticipated reasons.

“All models make assumptions and there remain many uncertainties, but based on our findings it is hard to see the use of artificial pumps to boost surface production as being a viable way of tackling global warming,” said Yool.

Original publication:

Oschlies, A., Pahlow, M., Yool, A. & Matear, R. J. Climate engineering by artificial ocean upwelling – channelling the sorcerer’s apprentice. Geophys. Res. Lett. 37, L04701 (2010). DOI:10.1029/2009GL041961.

Links:

http://europa.agu.org/

www.agu.org/pubs/

[RaleighNCDUer]

1. Has anyone looked at the effect of floating plastics in the ocean on its

natural cycles? Do the plastics increase, decrease, or have no effect on surface evaporation? On algae growth? On plankton growth? On light/heat reflectivity?

Any idea?

[OKIsItJustMe]

2. Scientists study 'garbage patch' in Pacific Ocean

http://www.cnn.com/2009/TECH/science/08/04/pacific.garbage.patch/

Scientists study 'garbage patch' in Pacific Ocean

By Shelby Lin Erdman
CNN

(CNN) -- It is a problem of massive plastic proportions -- a giant floating debris field, composed mostly of bits and pieces of plastic, in the northwest Pacific Ocean, about a thousand miles off the coast of California.

...

"I think it's a little misleading to think of it as a great big island that you could practically get out and walk on, but the point is it's a big area of ocean. So even a few pieces of plastic per square meter amounts to a lot of plastic when you add it up over this enormous ocean area."

There has been some previous research on this garbage field, but not much. It's been very poorly studied in a scientific sense. Major questions remain:

...

But the plastic is really the toxic killer. While it slowly degrades, it turns into increasingly smaller bits of plastic. Seabirds mistake it for food and they dive down and eat it.

...

[eppur_se_muova]

3. It seems highly unlikely there would be much effect.

The big danger of plastic articles is ingestion by larger animals (macrofauna). The actual area covered by plastic is a drop in the ocean.

[RaleighNCDUer]

5. It seems to me that if plastic holds heat better than the water it is floating in

that an area the size of Texas that is holding more heat than the rest of the ocean would alter the climate, the way that El Nino affects the worldwide climate even though it covers a relaively small area of the ocean (though El Nino is, admittedly, larger than Texas) becasue of increased evaporation over that area and temp differentials changing wind patterns.

Or maybe not.

Just wondering if anyone has looked into that specifically.

[Nihil]

4. Good.

One dumb programme to support "Business As Usual" down,
a few hundred to go (but every step like this is progress).

:thumbsup:

[The2ndWheel]

6. You can't mold the planet to fit the narrow interests of a single species

without getting caught up in the countless variables which make up existence. If not for that, we could do anything we wanted to.

Sometimes it seems like we're a corporation writing the rules that will regulate it. Privatizing the profits of the planet, and socializing the costs to the rest of life. That doesn't seem to work within civilization, and there is no reason to think it would work on the planet as a whole.