sensible people
Guantou wrote - Moving right along...
Sensible people accept the idea that global warming is happening and that it is an anthropogenic effect. The line of reasoning works like this:
(1) CO2, methane and a small handful of other gases have a greenhouse effect - that is, they prevent the heat created by sunlight striking the earth's surface returning to space. Take away greenhouse gases and you lose this greenhouse effect. The dark/night side of Mercury (a planet without atmosphere to carry greenhouse gases) is typically around minus 130 degrees centigrade. The day side is up around 430 degrees. Venus, with high concentrations of CO2 in its atmosphere, is bloody hot pretty much everywhere all the time.
(2) The present atmospheric concentration of carbon dioxide has not been exceeded for the past 650,000 years, and probably not for the last 20 million years - we know this through ice core analysis (very persuasive data) and geological sampling (indicative data). For most of this period (i.e. 20 million years) atmospheric concentrations of CO2 have varied between around 180 parts per million (ppm) and 280ppm. Since the late 18th Century, however, CO2 concentrations have increased to around 380ppm. At presents rates of increase, we should hit 450ppm by the middle of the century.
(3) The cause of this rapid increase in CO2 in the most recent period (i.e. since the start of the industrial revolution) is most likely burning of fossil fuels (coal, oil and gas), and agricultural practices (e.g. land clearing). That is, anthropogenic sources of CO2 emissions are the most obvious source of additional CO2 concentrations in the atmosphere.
(4) There has been an increase in global average temperatures in the scale of 0.7 degrees centigrade over the last 100 years.
Sensible people look at this line-up of facts and causal relationships and conclude that (1) global warming is happening, and (2) people are causing it. This is not an hysterical or uninformed position. We base many other important public and private decisions on much less surity. IMHO, the strength of these conclusions suggests that the burden of proof resides with those who are skeptical about them, rather than those who accept them.
Sensible people accept the idea that global warming is happening and that it is an anthropogenic effect. The line of reasoning works like this:
(1) CO2, methane and a small handful of other gases have a greenhouse effect - that is, they prevent the heat created by sunlight striking the earth's surface returning to space. Take away greenhouse gases and you lose this greenhouse effect. The dark/night side of Mercury (a planet without atmosphere to carry greenhouse gases) is typically around minus 130 degrees centigrade. The day side is up around 430 degrees. Venus, with high concentrations of CO2 in its atmosphere, is bloody hot pretty much everywhere all the time.
(2) The present atmospheric concentration of carbon dioxide has not been exceeded for the past 650,000 years, and probably not for the last 20 million years - we know this through ice core analysis (very persuasive data) and geological sampling (indicative data). For most of this period (i.e. 20 million years) atmospheric concentrations of CO2 have varied between around 180 parts per million (ppm) and 280ppm. Since the late 18th Century, however, CO2 concentrations have increased to around 380ppm. At presents rates of increase, we should hit 450ppm by the middle of the century.
(3) The cause of this rapid increase in CO2 in the most recent period (i.e. since the start of the industrial revolution) is most likely burning of fossil fuels (coal, oil and gas), and agricultural practices (e.g. land clearing). That is, anthropogenic sources of CO2 emissions are the most obvious source of additional CO2 concentrations in the atmosphere.
(4) There has been an increase in global average temperatures in the scale of 0.7 degrees centigrade over the last 100 years.
Sensible people look at this line-up of facts and causal relationships and conclude that (1) global warming is happening, and (2) people are causing it. This is not an hysterical or uninformed position. We base many other important public and private decisions on much less surity. IMHO, the strength of these conclusions suggests that the burden of proof resides with those who are skeptical about them, rather than those who accept them.
posted by david at 10:41 PM
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