Wednesday, May 4, 2011

Handy Guide to CO2

Luboš Motl has a post on his blog The Reference Frame where he notes the range of interesting CO2 concentrations:
It may be useful to summarize some important values of the CO2 concentration:
  • 150 ppm - the minimum concentration below which many plants may face problems to run photosynthesis and stop growing

  • 180 ppm - the concentration during ice ages

  • 280 ppm - the concentration during interglacials, i.e. also the pre-industrial concentration around 1750

  • 391 ppm - the concentration today

  • 500 ppm - the concentration around 2060-2070 (unlikely that before 2050 as they claim)

  • 560 ppm - the concentration around 2080-2110 (the "doubled CO2" relatively to the pre-industrial values) relevant for the calculations of climate sensitivity)

  • 700 ppm - the concentration in an average living room

  • 900 ppm - concentration in an average kitchen

  • 1,270 ppm - the concentration used to double the growth of Cowpea in a famous video

  • 4,500 ppm - the concentration 400 million years ago; see other values in geological epochs

  • 10,000 ppm - sensitive people start to feel weaker

  • 40,000 ppm - the concentration of CO2 in the air we breath out

  • 50,000 ppm - toxic levels at which the animals like us get weaker in hours; the value is 5 percent of the volume
The warming induced by the increase from 391 ppm to 500 ppm is smaller (by about 20%) - because of the logarithmic law - than the warming by the same 109 ppm between 282 ppm and 391 ppm which was about 0.7 °C and pretty much unnoticeable without accurate gadgets and contrived statistical methods.

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