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Carbon emissions: Catch them if you can

  • Story Highlights
  • CO2 capturing takes emissions out of the atmosphere and into underground 'lakes'
  • Some fear it only encourages fossil fuel use and ignores bigger climate problems
  • Cost and effectiveness of methods are still unproven
  • Other methods to reduce CO2 in atmosphere include production of biochar
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Rachel Oliver CNN
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(CNN) -- Despite plans to slash carbon dioxide (C02) emissions, the world still faces a very basic, and very big, problem.

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Many scientists believe the CO2 "tipping point" has been passed already.

There is already too much C02 sitting in the atmosphere, and put simply, it needs to be somewhere else. That extra carbon has been building up since the advent of the Industrial Revolution and continues to grow apace.

The latest scientific research says that greenhouse gases are now being pumped out faster than at any point during the 1990's, largely because of the continued dominance of fossil fuels.

The problem, however, is that fossil fuels don't look like they are going anywhere anytime soon. Britain's leading economist Sir Nicholas Stern predicts that even with the advances being made now in renewable energies, by 2050 half of the world's energy needs will still be served by fossil fuels.

News like this has effectively boosted interested in carbon capture and storage (CCS) technologies, which boldly promise to prevent 90 percent of power station emissions from reaching the atmosphere.

By employing varying technological means, CCS takes the C02 out of the atmosphere and then puts it deep underground or in underwater "lakes". Not surprisingly, CCS has garnered a great deal of support from the fossil fuel industry.

For this very reason, that has some worried.

CCS looks promising in theory, but some feel it has created a renewed interest in coal-fired power generation.

There are still a number of questions surrounding its efficacy too. No-one knows if burying C02 deep underground is a sensible long-term solution; and some fear the impact of leakages on future generations.

Its supporters however, point out that the very act of trapping C02 underground could make CCS one of the world's first "carbon negative" technologies.

What is an acceptable carbon level?

Among climatologists and environmental scientists there is a debate over what is an acceptable level of CO2 in the atmosphere.

Climate change author Tim Flannery believes, the world's atmosphere contains as much as 200 gigatons (billion metric tons) of excess carbon. And getting rid of that, he and other experts say, is as urgent as "neutralizing" current and future emissions.

Normally, the atmosphere has around 3,000 gigatons of naturally occurring and recycled carbon in it in total. While the human-related contribution to C02 emissions is small in comparison, scientists say it is enough to tip the fine natural balance.

Upset that balance too much a "the tipping point" could be reached, when excess C02 levels in the atmosphere hit critical levels.

Should that happen, scientists are warning, the climate could start rapidly changing in any number of potentially catastrophic ways.

No-one really knows what that number is, but the Intergovernmental Panel on Climate Change has put the maximum amount of C02 levels we should aim for -- and not exceed -- at 550 parts per million (ppm) by 2025.

Others, including NASA's top climate scientist Dr James Hanson think that the figure is much lower -- just 350 ppm if "humanity wishes to preserve a planet similar to that on which civilization developed".

Ways to catch carbon emissions

An impending carbon imbalance has had some of the world's finest minds working overtime. And some of the suggested solutions so far have been fascinating.

Gaia theorist James Lovelock has proposed installing millions of giant pipes into the sea which would pump nutrient-rich water from the sea bed to the surface, allowing the oceans to absorb more C02 than they do normally.

The oceans of the world are natural "carbon sinks," soaking up vast amounts of atmospheric C02 every year. For Lovelock, they are an obvious natural means to sequester carbon on a massive scale.

Carrying on the ocean theme, U.S.-based firm, Planktos dreams of fulfill 1930's 1930's-era theory by British scientist Joseph Hart, to sprinkle vast amount of iron ore across the world's oceans in an attempt to stimulate phytoplankton populations.

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These tiny organisms are amongst the world's most efficient carbon sequesters, soaking up C02 via photosynthesis. Back on land, a professor at Columbia University in New York, has designed a "synthetic tree" which "breathes in" C02 from the atmosphere -- and promises to capture as much as a ton of C02 per tree per day.

But opposition to these plans have been based on a singular objection -- no-one knows what the side effects will be (not to mention what the costs will be).

Opponents of Lovelock's idea are concerned about the consequences of bringing already C02-rich water from the deep to the surface.

Equally, there are very real concerns over the effect of introducing an "iron fertilization" program to the world's seas when nothing of this kind has been tried before.

And while the synthetic trees may be able to suck up C02, the fact that the ultimate home for the emissions is still deep underground means the same concerns dog them as they do other CCS technologies.

And then there is biochar -- the gas and charcoal that arises from a process of burning any form of biomass with the absence of oxygen, called pyrolysis.

Charcoal is one of the most stable forms of carbon known to man. It is also an excellent soil fertilizer.

Biochar in its charcoal form is seen by many, including Flannery, as one of the single most important carbon sequesters in the world -- perhaps even better than reforestation.

Put simply, reforested trees can be cut down, but once charcoal is plowed in the soil, it's there to stay for up to a thousand years.

In order to appease concerns over outcomes, control tests are the next step for all of these ideas, but that means it could take years for this knowledge to be put to any real use, including CCS.

While the world and the corporations behind these technologies wait for them to gather the necessary funding and support, in the meantime, emission levels continue to grow.

All About Global Climate ChangeNature and the Environment

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