Atmospheric Carbon Dioxide Concentration, 10,000 BC – 2009 AD. EPA / Climate Change Indicators in the United States

Global atmospheric concentrations of carbon dioxide, methane, nitrous oxide, and certain manufactured greenhouse gases have all risen substantially in recent years.

• Before the industrial era began around 1780, carbon dioxide concentrations measured approximately 270–290 ppm. Concentrations have risen steadily since then, reaching 387 ppm in 2009—a 38 percent increase. Almost all of this increase is due to human activities.

• Since 1905, the concentration of methane in the atmosphere has roughly doubled. It is very likely that this increase is predominantly due to agriculture and fossil fuel use.

• Historical measurements show that the current global atmospheric concentrations of carbon dioxide and methane are unprecedented over the past 650,000 years, even after accounting for natural fluctuations.

Violet: Law Dome, Antarctica, 75-year smoothed:
1010 AD to 1975 AD
Green: Siple Station, Antarctica: 1744 AD to 1953 AD
Orange: Mauna Loa, Hawaii: 1959 AD to 2009 AD
Yellow: Barrow, Alaska: 1974 AD to 2008 AD

Climate Change Indicators in the United States [pdf]

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