Natural vs. Human Contributions to Greenhouse Gases and Global Average Temperatures
Above: A graphical representation of a Carbon Dioxide molecule showing one carbon atom and two oxygen atoms.
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Key Takeaways:
Throughout Earth’s history, atmospheric Carbon Dioxide (CO2) levels have waxed and waned, but over time, there has been a long slow drawdown of CO2.1
Recent increases in atmospheric CO2 began around 1850, well before electric power generation and the internal combustion engine were common features of society.
The 1850 start point coincided with the end of the cold period known as the Little Ice Age, suggesting a natural rise in temperature increased global CO2 concentrations from the oceans.
Humans contribute approximately 3.4 percent of annual CO2 emissions today, but only 0.28 percent of the greenhouse warming effect on Earth.
Short Summary:
Greenhouse gases make up no more than 2 percent of Earth’s total atmosphere.2 However, they are critical to making the planet habitable—keeping the Earth from being a freezing rock in space like Mars.3
Carbon Dioxide (CO2) has been directly measured in Earth’s atmosphere since 1958.4 CO2 concentrations are increasing in the atmosphere, in large part due to human activities, such as emissions from the burning of fossil fuels for energy. 5 Computer models project that rising CO2 concentrations will cause an increase in average global temperature through the greenhouse effect.6
The global atmospheric CO2 concentration trend is seen in Figure 1.
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