Keeling curve
The Keeling curve is a
graph showing the variation in concentration of
atmospheric carbon dioxide since 1958. It shows that human activities are increasing the
greenhouse effect with implications for
global warming.
Charles David Keeling of the
Scripps Institution of Oceanography was the first person to make frequent regular measurements of the atmospheric
carbon dioxide concentration, taking readings atop
Mauna Loa in
Hawaii from 1958 onwards.
These measurements show a steady increase in mean atmospheric CO2 concentration from about 315 parts per million by volume in 1958 to over 380 ppmv by the year 2006 .
Encyclopedia
The
Keeling curve is a
graph showing the variation in concentration of
atmospheric carbon dioxide since 1958. It shows that human activities are increasing the
greenhouse effect with implications for
global warming.
Charles David Keeling of the
Scripps Institution of Oceanography was the first person to make frequent regular measurements of the atmospheric
carbon dioxide concentration, taking readings atop
Mauna Loa in
Hawaii from 1958 onwards.
These measurements show a steady increase in mean atmospheric CO
2 concentration from about 315 parts per million by volume in 1958 to over 380 ppmv by the year 2006 . This increase in atmospheric CO
2 is considered to be largely due to the combustion of
fossil fuels, and has been accelerating in recent years, most likely due to increased fossil fuel combustion and the release of frozen CO
2 from melting ice caps and permafrost. This is supported by measurements of carbon dioxide concentration in ancient air bubbles trapped in polar
ice cores, which show that mean atmospheric CO
2 concentration was between 275 and 280 ppmv for several thousand years but started rising sharply at the beginning of the nineteenth century. Since carbon dioxide is a
greenhouse gas, this has implications for
global warming.
The Keeling curve also shows a cyclic variation of about 5 ppmv in each year corresponding to the seasonal change in uptake of CO
2 by the world's land vegetation. Most of this vegetation is in the
Northern hemisphere, since this is where the majority of the land is located. The level decreases from northern spring onwards as new
plant growth takes carbon dioxide out of the atmosphere through
photosynthesis and rises again in the northern fall as plants and
leaves die off and decay to release the gas back into the atmosphere.
References
