CO2 - Carbon Dioxide - Reduction and Sequestration to Mitigate Global Warming

A Different Way of Looking at Atmospheric Carbon Dioxide

Almost no doubt remains today in anyone's mind that CO2 is building up in the atmosphere, that this build-up is causing atmospheric warming, and that human activity, especially the burning of fossil fuels, is a major factor in the carbon build-up. Indeed, there now appears to be enough agreement amongst governments around the world for them to begin agreeing upon and implementing measures to mitigate these effects.
     Most of the measures proposed act to reduce greenhouse gas emissions caused by human beings, employing such measures as:

a. Increasing auto efficiency.
b. Removing carbon from coal before using it to generate electricity.
c. Improving household and commercial energy efficiency.
d. Substituting fuel cells for internal combustion engines.
e. "Capping" carbon emissions by law and encouraging trading in carbon credits so the free market will select the best ways to achieve improvements.

These are only a few of the more ambitious proposals. There are many more. And they are mostly worth pursuing, as no single program can possibly achieve the desired outcome.
     Some efforts encourage planting trees to increase absorption of CO2, rather than reducing its emission. But few participants in the discussion offer a full perspective on this approach, partly (we suspect) to keep human beings focused on what they can and should do themselves.
     For a change, here is a "macroscopic" look at the biosphere's CO2 and its capacity to help out:

1. Global energy emissions are in the area of 8 billion tons of CO2 per year
2. The terrestrial biosphere emits about 100 billion tons and absorbs about 103 billion tons of CO2 each year, absorbing 3 billion tons, net.
3. The oceans also emit and absorb billions of tons of CO2 per year, with a net absorption of about 3 billion tons.
4. Thus the net annual increase in the atmosphere amounts to about 2 billions tons.

These data beg the following question: is it easier to change the balance of the terrestrial biosphere by 4 per cent OR to cut global energy-related emissions by 50 per cent? Changing the ocean's ability to absorb more carbon is another possibility. Of course, no need to pick one or the other, but increasing absorption clearly has to be considered as a possible major contributor to solving the problem.
     Biologists are working hard to develop plants whose capacity for capturing carbon from the atmosphere is genetically improved. And burning sections of the rain forest is being recognized as offering very little usable land when compared to the atmospheric damage it causes. If we humans can find and use genes that will conquer cancer, surely we can develop and grow plants that will help us redress the imbalance caused by fossil fuel consumption.
     And the ocean, which we know suffers from acidification and coral reef losses when it absorbs CO2, is also capable, with human intervention, of harboring greatly increased biomass to perform photosynthesis (absorb carbon). Such microorganisms, in addition to fighting acidification, will produce more edible food for larger sea creatures, potentially enhancing food sources for human beings.
     Craig Venter, of human genome project fame, is currently circling the globe on his own research vessel "Sorcerer" gathering samples of oceanic microorganisms along the way . He is discovering that the diversity of life in the sea is far greater than anyone previously believed, and that therefore we have many more existing organisms to work with to give the ocean a helping hand in growing more food and absorbing more carbon.
     Many will not find it appealing to harness the land and/or the ocean as partners in the fight against greenhouse gases, but it certainly offers tremendous potential, if carefully pursued and monitored.      - DLA

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A (Stronger) Wind Blows No Good:

Oceans May Be Losing Ability to Absorb CO2

It appears that the southern oceans on the planet may not be able to absorb as much atmospheric carbon dioxide as expected, according to a study just published on the web site of the journal Science.
     Oceans, plants, and soil absorb about half of all carbon dioxide emitted by industry, cars, and other human sources. The southern oceans on the planet take up about 15% of total absorbed carbon dioxide.
     The study indicates that the southern oceans became 30% less efficient at absorbing carbon dioxide between 1981 and 2004, and that the capacity of these oceans to absorb will continue to decline over the next 25 years. The basic thrust of the study is that since the 1950s (1) the depletion of the ozone layer and global warming have (2) caused atmospheric temperature changes which (3) increased windiness over these oceans, which thereby (4) caused more vertical ocean water mixing, which in turn (5) brought more carbon-dioxide rich water up from the ocean depths to the surface, which (6) increased the carbon-dioxide level of surface water and thus (7) reduced the capacity of the surface water to absorb additional carbon dioxide from the atmosphere.
     The study's lead author, Dr. Corinne Le Quere at the University of East Anglia, England, said the study suggests that over next 25 years the oceans' capacity to absorb carbon dioxide will continue to decline as a result of increasing windiness, thereby increasing atmospheric levels of carbon dioxide over whatever levels they otherwise would have been.      - KEM

Does Soot in the Arctic Outpace CO2 in Melting the Icecap?

Every day we learn something new about what is happening in the climate change field.
     Scientists at the University of California, Irvine, have calculated the warming effect of soot on Arctic snow. The result is surprising: in the Arctic, dirty snow may be responsible for more warming than greenhouse gases.
     "It turns out that nothing is more efficient at increasing the Earth's temperature than soot in snow," said Charles S. Zender, a professor of Earth system science at the university.
     Soot, from coal burning, inefficient cook stoves and forest and agricultural fires, falls in the Arctic, darkening snow. Dark colors absorb more sunlight than lighter colors and generate more heat as a result.
     Previous studies had looked at this effect and found that it contributed to regional warming. "But they had probably underestimated the impact," Dr. Zender said.
     The new work, published in The Journal of Geophysical Research, takes a more detailed look at the effects of soot. Among other things, Dr. Zender says, it accelerates the "aging" of snow, as fine crystals turn into larger grains and the snow turns darker. (City dwellers are familiar with this phenomenon, as a bright white blanket turns to gray within days.)
     With this and other effects built into their model, researchers found that over the past 200 years, dirty snow has been responsible for 0.5 to 1.5 degrees Celsius of warming in the Arctic. Over all, the region has warmed 1.6 degrees in that time.
     Dr. Zender said that several steps could be taken to reduce the impact. One is a matter of timing. If farmers must burn fields, for example, it's better to do it in the late summer and fall, when the impact on the snow cover is less.
     More efficient cook stoves for villagers across Asia would also help. By burning cleaner, they would produce less soot. Conversely they would produce more carbon dioxide, "but in this case emitting CO2 would be the lesser of two evils," Dr. Zender said.       - DLA

Science Body Reports:

Climate Change Models Do Not Exaggerate

T hose who disagree that humans have contributed to climate change — or even say there has been no climate change — often scoff at the validity of computer-based climate models. But a report in "Science" magazine tells us that scientists in Germany, France, Australia, USA, and the UK have compiled observed climate trends for the past sixteen years of (1) carbon dioxide concentration, (2) global mean air temperature, and (3) global sea level. They then compared these trends to previous model projections of these variables contained in the 2001 assessment report of the Intergovernmental Panel on Climate Change (IPCC). The magazine is a publication of the American Association for the Advancement of Science.
     Although the short time period must be emphasized, the data indicates that the climatic system, and particularly global sea levels, may be changing more rapidly than the models predicted. For the past twenty years sea levels have been rising 25% faster than the rate of rise in any 20 year period in the previous 115 years. This rise has been caused principally by thermal expansion and melting from non-polar glaciers. Although the contribution of ice sheet melting has been small, early indications are that this component is increasing rapidly.
     Overall, the data in all three dimensions highlight concerns about climate change. Previous IPCC projections have not exaggerated these expected changes but may actually have understated them, particularly for sea level.
      - KEM

Terra Preta — A Gift From the Past

Could an Ancient Amazonian Technique Show Us How to Make Carbon Useful?

Who would imagine that Native Americans, living in the Amazonian rain forest 4,000 to 5,000 years ago would develop anything that would help us in the 21st Century deal with a serious and growing threat to the environment?
     Well, it is possible that they did, and growing attention is being paid to Terra Preta, or the black earth that was created by groups of early people living in the Amazon area. Rain forests are well known for creating soil conditions on the ground that are very poor for cultivation of plants for food. The early inhabitants of the area solved this problem by cutting down a few trees (with stone axes, no less, which meant that each tree would take days to fell) and then smoldering the wood and starving the fire of oxygen in a way that prevented full combustion, so that what remained were large amounts of "char" (or charcoal). Mixing the char in with the soil to concentrations of as much as 20 times the normal carbon content of good soil, and then mixing in massive quantities of pottery shards as well, produced Terra Preta, which was remarkably fertile and productive for long periods of time.
     All over the Amazon Basin are large concentrations of ancient Terra Preta, which are harvested, bagged and sold by local entrepreneurs as potting soil for gardeners throughout the continent. Sometimes the deposits are four and five feet deep, and they even seem to have the ability to regenerate, if left alone for long periods of time. Accordingly, the locals harvest perhaps 20% of the deposit and then stop and wait for it to regenerate.
     It is not yet fully understood why this soil is so productive. It is known that high concentrations of carbon seem to attract needed plant nutrients and release them slowly over long periods. The role of the pottery shards is not yet determined, but study is taking place at the University of Georgia to learn these secrets, as well as learn how to reproduce the soil reliably in large amounts.

Why is this important now?

Intensive farming in the US makes heavy use of nitrogen fertilizer that is made from natural gas, a scarce hydrocarbon that releases CO2 into the atmosphere when it is burned or converted into fertilizer. Furthermore, tilling the soil after fertilizing it releases CO2 that would otherwise be trapped in the soil if "no till" agriculture were practiced. Enter Terra Preta, which requires no fertilization and no tilling. So, for example, corn could be grown for ethanol production that would not deplete the soil so completely and would therefore be more competitive with other forms of ethanol like that made from cellulosic biomass.
     So, an invention from ancient South America might allow us to slow the trend towards global warming and move closer to energy independence.
     And the final dividend would be if we could figure out how to strip the carbon from the CO2 that we will be removing from coal before it is burned in electric power plants. We could then use it for manufacturing massive amounts of Terra Preta. That would avoid the need for costly CO2 sequestration below ground or in the deep ocean. But, don't hold your breath. The process that separates carbon from CO2 is called photosynthesis, and it took Mother Nature billions of years to figure out how to do that with water, energy from the Sun and CO2.
     Stay tuned for updates on the Terra Preta story.      - DLA