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Climate Science

September 1, 2013

Big numbers, geography and land use changes

About 2.4 million pounds per second.

No, this is not the currency in England. No, it is not the weight of water flowing over Niagara Falls. 

This number is the weight of carbon dioxide we were putting into the atmosphere every second in 2011, primarily from the combustion of fossils fuels and land-use changes. Other smaller amounts may come from deep sea vents, volcanoes and other natural events, but most of this amount comes from “us.”

This number is calculated from the amount of fossil fuels we burn on an annual basis. In 2011, the amount of carbon dioxide we pumped into the air was equal to 38.2 billion tons, which is a 3 percent gain over 2010. In 2012, emissions are expected to be 2.6 percent over 2011, based on data reported in Nature Climate Change, December 2012.

The diagram “Where humanity’s CO2 comes from,” published originally in the Proceedings of the National Academy of Sciences, provides an accounting of this gas and reflects scientists’ best understanding of the dynamics of these processes. The top portion shows that about 91 percent of this gas comes from burning fossil fuels and the manufacture of cement (more on that another time), and about 9 percent from land-use changes. The latter includes the loss of tropical rain forests in South America, Africa, Indonesia and elsewhere.

The bottom portion of this diagram indicates that about 50 percent of this gas stays in the atmosphere, about 26 percent goes back into the land (mostly as biomass) and about 24 percent is absorbed into the oceans.

When we talk about the atmosphere, we can see that this is a very thin layer around our planet like the skin on an apple, or, like the membrane one encounters when slicing onions. The sunrise photo was taken from the International Space Station on July 30 and shows the atmosphere as the thin veil over the planets’ surface. About 90 percent of the atmosphere is within 10 miles of Earth’s surface, and a lot of “stuff” goes on in this narrow layer: all of our weather and climate is impacted here. 

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