Tuesday, May 27, 2014

Climate Change Part 9: Slow Carbon Fast Carbon

Note: This program first aired May 24, 2014.

It should be clear by now, if you’ve been following the show for the past couple of months, that the current global climate change is all about the carbon. Its happened before, in the PETM, and it is happening now. Green house gases are accumulating in the atmosphere, preventing the escape of more and more infrared radiation. This is causing the energy in the climate system to increase, resulting in rising average temperatures and a pattern of climate instability in this period of rapid transition.

We know on a simple level, where the carbon is coming from—out our tail piles and smoke stacks. It comes from the burning of fossil fuels. What I want to look at today is how the carbon got into the fossil fuels in the first place. Were do fossil fuels come from?

For practical purposes, the amount of carbon in our world is fixed. Yes, elements can change form in nuclear reactors, like power plants, and the sun, but for our purposes here on Earth there is a finite amount of carbon, distributed among various reservoirs, or parts of the system where it tends to accumulate. Amazingly over 99% of the carbon on Earth is held in the rock reservoir in the form of limestone and other carbon containing rocks, marine sediments, and fossil fuels. That means that all the changes we are experiencing and that are predicted to occur in the near future are the result in minute changes in surface carbon reservoirs, minute relative to the total amount of carbon on Earth. Surface reservoirs include the atmosphere, the oceans, and all living material-the biosphere. Carbon moves between various reservoirs as a result of various biogeochemical processes; up here on the surface carbon gets taken out of the atmosphere and goes into the living biomass or gets absorbed into the ocean. Carbon can be released from the ocean as well, and when living material biodegrades, it releases carbon back into the atmosphere. These various mechanisms are known as the fast or short term carbon cycle. The cycling of carbon in and out of the rock reservoirs by contrast, happens very slowly, at the bottom of the ocean and any where rock is exposed to the elements, thus, getting carbon into or out of rocks is part of the slow or long term carbon cycle. To summarize, small amounts of carbon cycle rapidly through reservoirs in the biosphere on the surface of the Earth, and larger amounts of carbon move into and out of the rock reservoir very slowly, and in general, the amount that goes in is in balance with the amount that goes out. When the amount of carbon in the system is steady, generally the climate is steady, all other things being equal.

What this means is that the carbon that is building up in the atmosphere right now is carbon that is coming out of the rock reservoir. This is carbon that generally moves very slowly—when that carbon came out of the atmosphere and was sequestered in the rock reservoir during the Carboniferous period about 325 million years ago, it took millions and millions of years to do so. What we are doing is unsequestering that carbon very rapidly, we are moving carbon out of the rock reservoir much faster than normally happens, and much faster than natural processes can move carbon back into the rock reservoir-we’re withdrawing much faster than nature can deposit. That’s where, on a large scale level, the carbon is coming from. It literally is extra carbon in the system, carbon that hasn’t been in the fast, surface carbon cycle for over 300 million years. That’s why we call them fossil fuels.

Is it possible that carbon could exit the rock reservoir this fast naturally? Possibly there is some period in the geologic record where there was extreme weathering or exposed coal burning or some other global event that initiated a sharp decrease in the carbon in the rock reservoir. But whether the carbon imbalance results from some natural event (as may have happened in the geologic past) or from our own insatiable use of this carbon from the rock reservoir, the impact is the same—rapidly changing conditions here on the only place we have to live, the only place we’ve ever had to live. Buckle your seat belts folks. Its going to be a rough ride.

You can find a transcript of this program, as well as contact information and references on our website, head to www.weru.org and look for the Show Notes link. Our music is from Stanley Watson’s Portrait of Don Potter, performed by MDI guitarist Kevin Morse. Thanks for listening, and as always, join us next week for another look at the world around us.


This site from the University of California Berkeley’s Museum of Paleontology is a wealth of information, and resources for teachers:

A good, vetted source for information on climate change, from the American Museum of Natural History: http://www.amnh.org/exhibitions/past-exhibitions/climate-change

Climate Change: The Science of Global Warming and Our Energy Future Dr. Edmond Mathez, Columbia University Press, 2009

The slow carbon cycle, from NASA’s Earth Observatory: http://earthobservatory.nasa.gov/Features/CarbonCycle/page2.php