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This chart shows time on
the bottom, from the Civil War to the present vs concentration of CO2 in ppm.
Since the Civil war, the rates have risen by 30%. The data from 1958 onward
is taken by air samples from Hawaii. Data from 1860 to 1958 are taken from Ice
cores, tree rings and other 'proxy' data. Note some historical events to get
a sense of the timeline
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Atmospheric CO2
Concentrations are Increasing
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As a result of human emissions of greenhouse
gases, the atmospheric level of carbon dioxide, the most important
human-derived greenhouse gas, has increased steadily over the last 140 years
- from 280 parts per million in 1860, the beginning of the Industrial
Revolution, to 370 parts per million in 1998, about a 30% increase.
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CO2 concentration data from before 1958 are
from ice core measurements (tiny air bubbles trapped in ice core samples)
taken in Antarctica. Since 1957, scientists have been making continual
measurements of atmospheric CO2 at an observatory in Mauna Loa, HI. [Annual variation is due to CO2 uptake by
growing plants; the uptake is highest in the northern hemisphere springtime.]
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Over the same time period (from 1860 to
present), levels of other potent greenhouse gases have also increased —
methane concentrations have almost tripled and nitrous oxide concentrations
have risen by about 15%.
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Increases in all of these gases in the
atmosphere last from decades to centuries, so yesterday’s emissions are
today's visible impacts on the climate while today’s emissions will be
affecting the climate well beyond the 21st century. [This is also known as
our commitment to climate change.]
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