By Ed Caryl
The natural CO2 flux to and from oceans and land plants amounts to approximately 210 gigatons of carbon annually. (Note that this is carbon. Multiply the numbers by 3.7 for the total weight of CO2 including the two oxygen atoms.) Man currently causes about 9 gigatons of carbon to be injected into the atmosphere, about 4% of the natural annual flux. There are estimates that about half of man’s emissions are taken up by nature, or 2%. Why only half?
Figure 1 from NOAA and the IPCC, 2001 numbers, here.
The chart above updated to current numbers, implies that 3 gigatons of man’s emissions are absorbed by the oceans and 1.5 gigatons by the rest of the biosphere. If the vegetation on land absorbs 120 gigatons and if rising CO2 improves biosphere production, why isn’t all the excess CO2 also absorbed? It is because the biosphere is being destroyed faster than it can adapt to rising CO2.
About 60 years ago, I read somewhere, probably National Geographic, that the Amazon rain forests were the “lungs of the earth”, the place where CO2 was recycled back to oxygen. This phrase is still widely used, just Google “lungs of the earth” with the quotes and examine the result. One article in particular drew my attention. A quote:
…as recently as 19th century, tropical rain forests in their own right covered around 20% of all the dry land area of the Earth, but this figure was only 7% by the end of the 20th century.”
Image: NASA Jeff Schmaltz, LANCE/EOSDIS MODIS Rapid Response Team, GSFC
The world-wide increase in CO2 is not due to fossil fuel burning, it is due to the destruction of the worlds lungs. Clearing tropical forests for Biofuels production is contributing to that destruction.
Tropical rainforest destruction world-wide runs between 0.5% and 1% by area annually. The world’s lungs are suffering from TB, timber burning. For a horrifying world view of this problem go here, and view the video. Here is a MODIS satellite image of Myanmar on just one day. The red areas are fire.
Sure rainforest is being destroyed, for example to make way for green energy palm oil plantations. And these rainforests, at least what’s left of them, need to be preserved. But a large part of the rainforest destruction was likely compensated for by other forms of biomass, i.e. more grasslands, forests, irrigated land etc. A detailed comparison between today and, say 50 years ago, would be interesting. My gut feeling is that the extra atmospheric CO2 today stems only in part from biomass destruction. The other part comes from naturally warmer oceans and from fossil fuel burning.
You just triggered another article.
I agree that the destruction of rainforest for bio-fuel plantations is disgraceful, but we must get away from the idea that the rainforests are the “Lungs of the World.
Professor Philip Stott, Emeritus Professor of BioGeography at the School of Oriental and African Studies, University of London, wrote this in 2003:
“At the end of the last ice age, only some 12-18000 years ago, the tropics were covered by seasonal savannah grasslands, cooler and much drier than now. There were no rain forests in the Malay Peninsula and much of Amazonia, and, despite the increasing human development of forested space, there are still more rain forests persisting than existed then. As in Europe and North America, the forests came and went as climate changed; there is no Clementsian “long period of control” under one climate. Beneath many rain forests, there are sheets of ash, a testimony in the soil to past fires and non-forested landscapes.”
Check my comment at Rog Tallbloke’s site in May:
http://tallbloke.wordpress.com/2013/05/13/science-press-release-on-rainforests-from-st-james-palace/
Dennis, what you say is all true. During the ice ages, most of the Amazon was grassland. Also during the ice ages, CO2 concentration was very low, so low that many forest species could barely grow. The whole biosphere was suppressed by ice cover, low temperatures, and dryness. Little CO2 was produced so little photosynthesis was needed to recycle CO2 to oxygen and carbohydrates; most of that was probably in the oceans. Now we are at the opposite extreme, warming oceans, burning forests and fossil fuels producing more CO2, but land use is artificially suppressing the biosphere just when we need it most. An ice age world is blue, white, and brown. An interglacial world should be blue and green.
It is an interesting idea. The total flux is so large that there could be something to it. An estimate of the amount of CO2 produced annually by land use change is needed.
Jo Nova just posted a great article that touches on this subject.
http://joannenova.com.au/2013/08/are-forest-fires-evil-polluters/
Have a look. Play the movie there.