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think the chemistry that ice we can learn about past temperature
and by looking at the air we can actually measure the carbon dioxide
content.
One of the things we learn is that past temperature and carbon dioxide vary
together.
They go up together the go down together
and over the last eight hundred thousand years or so atmospheric carbon dioxide was
never higher than about 280 parts per million.
Until we started adding, carbon dioxide
to the atmosphere and now it's about 390 parts per million
that's about 40 percent higher than it was, when carbon dioxide was only wearing for
natural reasons
now we are headed for 500 parts per million
or more that pace is a hundred to a thousand times greater
and the pace at which things have changed by themselves naturally
the amazing thing to me is that we're already seeing impact because the
change already has been so smart why it's been point eight degrees C
about 1.5 degrees Fahrenheit since 1850 or so
and yet we've seen so much stuff crazy stuff going on already