Geo-engineering no Holy Grail - study

[Buster's Uncle]

Geo-engineering no Holy Grail - study
AFP
By Mariette Le Roux  2 hours ago



Sun shines through a forest near Briesen, eastern Germany, on December 13, 2013 (AFP Photo/Patrick Pleul)



Paris (AFP) - Far from offering a simple fix, sci-fi solutions to global warming may in fact make the problem worse, a probe of "geo-engineering" options said on Tuesday.

Once mocked as unscientific, geo-engineering proposals are gaining traction as carbon emissions soar, placing Earth on track for warming of maybe four degrees Celsius (7.2 degrees Fahrenheit) by 2100.

Ideas, mainly experimental or untested, include building mirrors in space to reflect the Sun's rays or growing plankton to boost absorption of heat-trapping carbon dioxide (CO2).

The goal is to buy time to wean the global economy off the cheap but dirty energy sources driving man-made climate change.

But on current emissions trends, these technologies stand little chance of rolling back warming to the UN-targeted 2 C (3.6 F) and may well make matters worse, according to the most comprehensive study yet.

"Climate engineering alone is not a good solution to prevent climate change," said David Keller of the Helmholtz Centre for Ocean Research in Kiel, Germany, who co-authored the paper.

Reporting in the journal Nature Communications, the team devised a computer model to project the impact of five geo-engineering proposals under a scenario of continuing high carbon emissions.

The five schemes entail:

-- planting large forests to absorb CO2 from the atmosphere and store it,

- fertilising the oceans with iron to stimulate the growth of plankton, which would absorb more CO2 from the sea surface through photosynthesis,

-- using long pipes to pump deep, cold, nutrient-rich water to the surface to fertilise plankton,

-- "alkalising" the ocean with limestone to cause a chemical reaction to absorb more CO2 from the atmosphere, and

-- using solar radiation management (SRM): placing reflective particles in the atmosphere or mirrors in space to reflect the Sun's rays.

Even with the technologies combined and applied to the widest extent possible, these options would not prevent mean surface temperatures from rising beyond 2C target if CO2 emissions continue as they are, the simulation found.


- 'Abject stupidity' -

The side effects "could be as bad as the climate change effects that they are trying to prevent," Keller warned.

The study found that SRM was the only method with the potential to swiftly reduce warming.

But it also had some of the largest potential side effects, such as changing rain patterns -- and could never be stopped without instantly warming the planet.

Geo-engineering could also boost sea levels, reduce the surface reflectiveness (albedo) in some regions of the world and cause higher local temperatures, remove oxygen from the ocean, and deplete the ozone layer.

"Our simulations suggest that the potential for these types of climate engineering to make up for failed mitigation may be very limited," said the study.

The UN's Intergovernmental Panel on Climate Change (IPCC) reported last year that SRM, "if realisable", had the potential to offset a global temperature rise -- but would also modify the global water cycle and fail to reduce ocean acidification.

As well as environmental risks, geo-engineering projects carry an unknown economic cost and face legal and political hurdles, previous research has found.

The authors of the study conclude it would be better to focus on curbing emissions, though engineering could "complement" mitigation efforts.

Their simulation was based on the so-called RCP8.5 emissions scenario, the highest used by the UN's climate panel, which expects average warming of 3.7 C by 2100.

Commenting on the new study, University of Bristol natural hazards lecturer Matt Watson said it was clear no single method or technology would solve the climate change problem.

While more research was needed, "the paper sounds a timely warning about the abject stupidity of relying upon climate engineering solutions when reducing our reliance on carbon-based energy systems is the only sensible option," he said.


http://news.yahoo.com/geo-engineering-no-holy-grail-study-180859576.html

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[wistful] But formers are so COOL!

[Buster's Uncle]

Geoengineering Ineffective Against Climate Change, Could Make Worse
LiveScience.com
By Charles Q. Choi, Live Science Contributor  9 hours ago



A diagram of the geoengineering projects people have proposed to combat climate change. The laws surrounding such projects are still uncertain.



Current schemes to minimize the havoc caused by global warming by purposefully manipulating Earth's climate are likely to either be relatively useless or actually make things worse, researchers say in a new study.

The dramatic increase in carbon dioxide levels in the atmosphere since the Industrial Revolution is expected to cause rising global sea levels, more-extreme weather and other disruptions to regional and local climates. Carbon dioxide is a greenhouse gas that traps heat, so as levels of the gas rise, the planet overall warms.

In addition to efforts to reduce carbon dioxide emissions, some have suggested artificially manipulating the world's climate in a last-ditch effort to prevent catastrophic climate change. These strategies, considered radical in some circles, are known as geoengineering or climate engineering.

Many scientists have investigated and questioned how effective individual geoengineering methods could be. However, there have been few attempts to compare and contrast the various methods, which range from fertilizing the ocean so that marine organisms suck up excess carbon dioxide to shooting aerosols into the atmosphere to reflect some of the sun's incoming rays back into space. [8 Ways Global Warming is Already Changing the World]

Now, researchers using a 3D computer model of the Earth have tested the potential benefits and drawbacks of five different geoengineering technologies.


Will it work?

The scientists found that even when several technologies were combined, geoengineering would be unable to prevent average surface temperatures from rising more than 3.6 degrees Fahrenheit (2 degrees Celsius) above current temperatures by the year 2100. This is, the current limit that international negotiations are focused on. They were unable to do so even when each technology was deployed continuously and at scales as large as currently deemed possible.

"The potential of most climate engineering methods, even when optimistic deployment scenarios were assumed, were much lower than I had expected," said study author Andreas Oschlies, an earth system modeler at the GEOMAR Helmholtz Centre for Ocean Research in Kiel, Germany.

One strategy, known as afforestation, would irrigate deserts, such as those in Australia and North Africa, to promote the growth of vegetation that can absorb carbon dioxide. However, this vegetation would also absorb sunlight the deserts currently reflect back into space, thus actually contributing to global warming. That finding supports the results of previous studies.

Another tactic, known as artificial ocean upwelling, would use long pipes to pump deep, cold, nutrient-rich water upward in order to cool ocean-surface waters and promote the growth of photosynthetic organisms that can absorb carbon dioxide. However, the scientists noted that if this strategy were ever stopped, the oceans would rebalance their heat levels, potentially causing disastrously rapid climate change.

One approach, known as ocean alkalinization, would dump lime into the water to chemically increase oceanic absorption of carbon dioxide. Another technique, known as ocean iron fertilization, would dump iron into the oceans to boost the growth of photosynthetic organisms that can absorb carbon dioxide. However, like other geoengineering strategies, the models suggest that both are of little use in reducing global temperatures.

The last method, known as solar radiation management, would reduce the amount of sunlight Earth receives, most likely by pumping reflective sulfate-based aerosols into the atmosphere. The subsequent dimming of sunlight on Earth would cool the planet, but the researchers note that carbon dioxide would continue to accumulate in the atmosphere. This suggests that if this strategy were ever halted, the globe would rapidly warm after the aerosols dispersed.


Possible side effects

All in all, these strategies are relatively ineffective; individually, they reduce global warming by less than 8 percent each, assuming carbon dioxide emission levels continue to remain as high as they are now. In all simulations, atmospheric carbon dioxide levels will still reach more than twice current levels by the end of the century, the researchers found.

Moreover, each geoengineering technique can have potentially severe side effects. For example, solar radiation management would alter patterns of precipitation such as rainfall and reduce total precipitation across the globe.

Altogether, the climate engineering technologies analyzed here are ineffective in reducing carbon dioxide concentrations and in most cases temperature. And this lack of effect "is really striking," said climate scientist Kelly McCusker at the University of Victoria in Canada, who did not take part in this research. McCusker and her colleagues also recently found that a sudden stop in solar radiation management strategies would exacerbate global warming.

"This study nails home the continued importance of reducing our emissions of greenhouse gases," McCusker told Live Science.

The researchers noted they used a moderately complex earth system model, and that more complex models involving a more intricate look at how winds might respond to geoengineering "may give different answers, particularly for precipitation changes," Oschlies said.

Oschlies and his colleagues David Keller and Ellias Feng detailed their findings online Feb. 25 in the journal Nature Communications.


http://news.yahoo.com/geoengineering-ineffective-against-climate-change-could-worse-164200912.html

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Take THAT, GeoModder!