FEEDBACK EFFECTS    

Carbon Dioxide in our air is has clearly reached 385 parts per million, and is growing steadily. This is a historically excessively high figure. ^*1 Most of this is due to anthropogenic (human) activity. Scientists estimate that a RUNAWAY FEEDBACK EFFECT will kick in at approximately 425 to 450 parts per million of atmospheric carbon dioxide. In 2005, scientists estimated that the time left for humanity to achieve , NOT PLAN FOR , a significant reduction in atmospheric carbon was 10 years or less.

A positive "FEEDBACK EFFECT " is where an increase in temperature causes other changes, which in turn increase further changes in temperature. A runaway positive feedback effect with respect to climate change implies a runaway situation that can no longer be minimized by human effort. There are several feedback effects listed below:

 

ICE FEEDBACK

As the earth warms, ice covering the surface of the earth melts. Most of this ice is in mountain glaciers and near the poles. Normally, ice reflects 90% of the sun's radiation so its energy is reflected back into space. However, if the melting ice results in water, then that water will absorb 90% of the sun's energy, thus further warming the earth. This feedback effect is mostly seen near the poles where the ice was initially found. Our ice is now melting quickly.

 

METHANE HYDRATES     [to Top]

Methane is a very powerful greenhouse gas (over 20x more powerful than carbon dioxide). Large deposits of methane lie on the ocean's bottom in the form of a white solid material called a methane hydrate. As the oceans warm, these solids transform from solids to methane gas, which will bubble into the atmosphere, causing extremely rapid heating. Scientists believe that the last time this happened, 55 million years ago, even the temperature at the normally cool North Pole reached 23°C when more than 90% of all species went extinct.. (Hansen 2006b - see "Avoiding Catastrophe, pg 6"). Imagine what that means for humanity, for your children.

 

PERMAFROST

In the once fully frozen northern hemisphere lay vast tracts of ground made up primarily of fully frozen dead plants. As the globe is warming this material is thawing, and bacterial activity is now causing the the plants to decay. As they decay the plants release methane. Each molecule of methane traps over 20 times as much heat than a molecule of carbon dioxide. This creates more global heating.

 

PHYTOPLANKTON

Phytoplankton live on the top most layer of the ocean's waters. This plankton is responsible for approximately half of the photosynthesis on this planet. Photosynthesis is also the process used by other marine and terrestrial plants, and by trees. Photosynthesis provides us with oxygen and acts as a carbon sink by absorbing and chemically converting carbon dioxide. With phytoplankton this process essentially locks carbon dioxide into their shells. When the plankton die they sink to the bottom of the ocean where that carbon is stored for thousands of years. Scientists have found that as the surface of the ocean warms it "stratosphies" and prevents important nutrients from colder layers below from reaching the phytoplankton in the warmer layer above. The nutrients are vital for the phytoplankton, and without them the phytoplankton dies, which in turn reduces the absorption of the CO2 from the atosphere. This causes a feedback look because with less plankton, there is less CO2 removed, More CO2 builds in the atmosphere, the globe warms further and the ocean surface warms to repeat the process.

SOILS

Plant matter in the ground is decaying all the time. This process of decay releases about 7 times as much carbon dioxide than burning fossil fuels. These emissions are usually offset by a delicate balance with new plant growth. As soils warm this decay process is accelerating.

Our biosphere is a net absorber of carbon dioxide at the present time, however, it is projected that global warming will cause it to become a net emitter towards the end of the century.

Wikipedia: Positive feedback and runaway greenhouse effect
Real Climate: Runaway Tipping Points of No Return (.pdf)