Silicon Investor (SI) -- The First Internet Community

STOCKTALK

We've detected that you're using an ad content blocking browser plug-in or feature. Ads provide a critical source of revenue to the continued operation of Silicon Investor. We ask that you disable ad blocking while on Silicon Investor in the best interests of our community. If you are not using an ad blocker but are still receiving this message, make sure your browser's tracking protection is set to the 'standard' level.

Politics : Foreign Affairs Discussion Group -- Ignore unavailable to you. Want to Upgrade?

To: Nadine Carroll who wrote (190683)	7/3/2006 12:02:18 PM
From: Wharf Rat	Read Replies (2) \| Respond to of 281500

They measure CO2 levels in ice cores. Samples of air trapped over the centuries in the glacial ice of Greenland show no change in CO2 content until 300 years ago(about the time we started burning coal) Over the last 150 years, carbon dioxide (CO2) concentrations have risen from 280 to nearly 380 parts per million (ppm). You get purty pictures like this . It looks just like the hockey stick graphs without the temperature in the picture. Here is a longer view. Note the slopes mentioned on the right . Historically, the greatest rate of change of concentrations occurred at 0.025 ppm/year ; 1/50 of the current change of 1.18PPM/yr. Carbon dioxide level highest in 650,000 years mongabay.com November 24, 2005 Carbon dioxide levels are now 27 percent higher than at any point in the last 650,000 years, according to research into Antarctic ice cores published on Thursday in Science. Analysis of carbon dioxide in the ancient Antarctic ice showed that at no point in the past 650,000 years did levels approach today's carbon dioxide concentrations of around 380 parts per million (ppm).http://news.mongabay.com/2005/1124-climate.html There is a nice graph there I can't reproduce. Note that it is backwards; today on the left,ancient time to the right. ---------------- It could be much higher than 380, but the planet is still able to buffer some of our production... Careful accounting of the amount of fossil fuel that has been extracted and combusted, and how much land clearing has occurred, shows that we have produced far more CO2 than now remains in the atmosphere. The roughly 500 billion metric tons of carbon we have produced is enough to have raised the atmospheric concentration of CO2 to nearly 500 ppm. The concentrations have not reached that level because the ocean and the terrestrial biosphere have the capacity to absorb some of the CO2 we produce.* However, it is the fact that we produce CO2 faster than the ocean and biosphere can absorb it that explains the observed increase. realclimate.org But that is changing as we speak... Nature 361, 520 - 523 (11 February 1993); doi:10.1038/361520a0 Recent change of Arctic tundra ecosystems from a net carbon dioxide sink to a source Walter C. Oechel†, Steven J. Hastings, George Vourlrtis, Mitchell Jenkins, George Riechers‡ & Nancy Grulke * Systems Ecology Research Group and Department of Biology, San Diego State University, San Diego, California 92182, USA ‡ Statewide Air Pollution Research Center, University of California, Riverside, California 92521, USA§ USDA Forest Service, 3200 Southwest Jefferson Way, Corvallis, Oregon 97331, USA † To whom correspondence should be addressed. ARCTIC tundra has been a net sink for carbon dioxide during historic and recent geological times1-4, and large amounts of carbon are stored in the soils of northern ecosystems. Many regions of the Arctic are warmer now than they have been in the past5-10, and this warming may cause the soil to change from a carbon dioxide sink to a source by lowering the water table11-12, thereby accelerating the rate of soil decomposition (CO2 source)3,13-15 so that this dominates over photosynthesis (CO2 sink). Here we present data indicating that the tundra on the North Slope of Alaska has indeed become a source of carbon dioxide to the atmosphere. nature.com And, as water temperatures increase the solubility of carbon dioxide is reduced and the likelihood of water stratification is increased - both leading to a overall reduction in oceanic carbon dioxide uptake