| About 50 million years ago, our climate was really warm, caused by a CO2 concentration in the atmosphere of about 1000 ppm (present level is near 386 ppm), the poles were ice free most of the year, and sea levels were about 75 meters above (246 feet) present levels (the icesheets on Greenland and Antartica in effect "remove" water from the ocean, and that results in the present state of affairs). Part of the reason for the high CO2 levels was the movement of the Indian continent northward through the Indian Ocean, and this caused CO2 that had been abstracted from the air/depositied by small lifeforms (algae, plankton, small aquatic lifefoms that had calcium carbonate shells that fell to the ocean floor when they died) to get recycled back into the air. However, the Indian continental plate eventually collided with the Eurasian plate (this gave rise to the Himalayan Mountains - see here for a great description of that event: http://en.wikipedia.org/wiki/H...
It turns out the the ground being thrust upwards at a 5 mm/year rate (yes, Mt Everest is getting taller as we speak) contained a lot of alkaline material, and given the precipitation in the region (for example, Monsoons), a lot of that gets washed into oceans like the Pacific and Indian oceans. Alkalis react with carbon dioxide (CO2) forming carbonate and bicarbonate salts, some of which are not very soluble, and they precipitate and fall to the ocean floor, where they get covered up by sediments. In effect, this pulls CO2 out of the air, and dumps it on the bottom of the ocean as carbonate and bicarbonates, along with the organic compounds (bacteria, algae, plankton, shellfish) in various deceased critters. Lots of gigatons of CO2 has been pulled out of the air in the last 25 million years via this effect, and in the process this has lowered the temperature of the ecosphere and lowered ocean levels via those Greenland and Antarctic icesheets, plus other glaciers (like those on the Himalayan mountains.
It turns out that ocean sediment cores can be used to provide a history of the average global surface temperatures over this period of time. The cores can be accurately dated via radioisotopic methods, so this provides the DATE. And it turns out that oxygen isotope ratios (the ratio of O18 (8 protons, 10 neutrons) to O16 ("normal" oxygen, 8 protons and 8 neutrons) can be used to determine the temperatures of our planet's surface. Then there are other ways that the CO2 concentration in the air can be determined. This system has been extensively tested using ice-cores dating up to 800,000 years in the recent past.
So, what Dr. Hansen and company have assembled is a "paleoclimate history" dating 50 million years, with CO2 concentration and surface temperature recorded versus time. Cool, eh?
It turns out that the earth has small perturbations in its orbit, so that it is a bit further out from the Sun at some times, and closer at others. These lead to times where the solar flux is more intense or less intense, leading to cooling and warming periods. These periods can be exactly tracked, and these can explain a 1 C (1.8 F) change in surface temperatures. During cooler periods, ice tends to form more, this reflects more light, less of the sun's energy is absorbed, and the planet surface tends to get cooler; this is called a feedback mechanism, and it works both ways.
Every once in a while, stuff happens, such as a volvano erupting under the ocean where there could be huge methane-ice clathrates (which became famous due to the Macondo-BP oil disaster in 2011 - see http://en.wikipedia.org/wiki/M... These are only stable solids at high pressure and cold temperatures, and obviously, if a volcano goes off under a big zone of these, the methane bubbles out to the surface. Methane (CH4) is an even more intense infared radiation absorber than is CO2, especially at the wavelength that corresponds to "room temperature" - this wavelength is around 695 cm^-1, or 14.4 microns (red light is 0.7 microns, yellow is 0.52 microns). The methane also gets converted into CO2 in the presence of ultraviolet light and oxygen, which adds to the "greenhouse effect" a bit more. A huge volcanic emanation of CO2 could also spark off a global warming event.
In this paper, the effect is noted - increases in CO2 concentrations (and also possibly via increased CH4 levels) lead to more global warming, and not vice versa. And more global warming melts off and/or leads to the decomposition of the icesheets (sort of like a landslide - very rapid, especially in geological terms). These are the FACTS.
Much of our current electricity generation, almost all of our transportation and residential/commercial/industrial heating needs are fossil fuel sourced, and the by-product of that is CO2 pollution. If our current CO2 concentration in the air was not 386 ppm but more like 216 ppm (dawn of the industrial revolution), that CO2 emanation could rightly be called "emission" instead of "pollution". But since more CO2 is going into the air than is being pulled from the air into the ocean (at a rate of about 2 ppm/yr), it's rightly called pollution. If we want to stop doing this superfluous and dangerous experiment in global warming (CO2 concentration vs global surface temperatures versus time) then we have to stop the advance of CO2 trash dumping into our atmosphere, pure and simple. It's just math....
Of course, when your income depends upon NOT KNOWING something (a famous Upton Sinclair saying), well, people can be stubbornly stupid for a long time. Right now, most think that making and using energy sensibly given the present CO2 concentration, the trends in CO2 concentration and how all those climate feedback loops will behave is going to put a hurt on them financially, socially, or maybe even romantically (it's the car that gets your date for the night in the mood, maybe...). The short term reigns supreme, for now. Unfortunately, it's always the long term that prevails, and in Hansen's most recent paper (he has written a lot of them, including ones correlating CO2 concentrations with ocean levels/icesheet extents) he lays out what will be if we continue this stupid experiment in Global Warming.
It's one of the reasons why you should AT LEAST consider voting with your electricity bill. You can actually select whether your money for the generated portion of your electricity bill (which was about 20% of my Dec 2010 bill, or all of my 2010 electricity bills, for that matter) goes to a polluting electricity source (coal, natural gas, or even nukes, but that's a different kind of pollution other that fossil fuel sourced CO2) of generated electricity. So, use one of the few rights that we seem to have left, and help make the world a slightly better place. Choose non-pollution based electricity, for a change, if you haven't already. |
