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Climate change 2 - the Keeling Curve

The Keeling Curve is a measurement of the carbon dioxide level in the world's atmosphere which has been made continuously since the 1950's, and provides a clear indicator of how humanity is doing in relation to carbon emissions. It is measured at an observatory on the Hawaiian island of Mauna Loa in the middle of the Pacific Ocean, a spot chosen to minimise interference from man-made sources.

It is available at various scales, such as this one which gives the full 60 year record:


and this one showing the past two years:

The curve wobbles up and down on a yearly cycle because more CO2 is absorbed when it is summer in the Northern Hemisphere and more released in the winter (the Northern Hemisphere dominates because it has a larger land mass and more vegetation). However as you can see from the 60 year graph the overall trend is up, and it's rising at an accelerating rate. This is happening despite all the international conferences, protest marches, energy efficiency, development of renewables and everything else that's being done. Until the Keeling curve starts to come down we're losing the battle.

Why does it keep rising? It could be that despite all the progress, human emissions are still increasing. It could also be that human emissions are falling but biological sources of carbon dioxide have taken over.  There is evidence that the Amazon rainforest has switched from being a net absorber to an emitter of carbon dioxide, and the sasme could be said for the oceans, or the Arctic permafrost.

The message here: if anyone tells you that we're getting climate change under control, don't believe them until the Keeling curve starts to fall.

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