Who's to BLAME

How are humans responsible for global warming?
              Deforestation and burning fossil fuels are chief culprits
Scientists have closed the case: Human activity is causing the Earth to get hotter.

How? Primarily by two actions: Burning fossil fuels, with a smaller contribution from clear cutting forests, known as deforestation.

Greenhouse gases trap heat

When we extract and burn fossil fuels such as coal or petroleum, we cause the release of carbon dioxide and other heat-trapping “greenhouse gases” into the atmosphere.

Though natural amounts of carbon dioxide have varied from 180 to 300 parts per million (ppm), today’s levels are around 400 ppm. That’s 40% more than the highest natural levels over the past 800,000 years.

We also can tell that the additional carbon dioxide in the atmosphere comes mainly from coal and oil because the chemical composition of the carbon dioxide contains a unique fingerprint.

Losing forests makes it worse

Clearing forests also releases large amounts of carbon dioxide. On top of that, plants and trees use it to grow. Worldwide deforestation means we don’t have as many trees to absorb the extra carbon dioxide.

This means more of it stays in the atmosphere, trapping more heat.

Scientists are more confident than ever that humans are responsible.

Ilissa Ocko
Climate Scientist

/www.edf.org/climate/human-activity-is-causing-global-warming

Global Warming is Human Caused
Scientists have concluded that most of the observed warming is very likely due to the burning of coal, oil, and gas. This conclusion is based on a detailed understanding of the atmospheric greenhouse effect and how human activities have been tweaking it. At the same time, other reasonable explanations, most notably changes in the Sun, have been ruled out.

The atmospheric greenhouse effect naturally keeps our planet warm enough to be livable. Sunlight passes through the atmosphere. Light-colored surfaces, such as clouds or ice caps, radiate some heat back into space. But most of the incoming heat warms the planet's surface. The Earth then radiates some heat back into the atmosphere. Some of that heat is trapped by greenhouse gases in the atmosphere, including carbon dioxide (CO2).
Human activity--such as burning fossil fuels--causes more greenhouse gases to build up in the atmosphere. As the atmosphere "thickens" with more greenhouse gases, more heat is held in. Fossil fuels such as oil, coal and natural gas are high in carbon and, when burned, produce major amounts of carbon dioxide or CO2. A single gallon of gasoline, when burned, puts 19 pounds of carbon dioxide into the atmosphere.


The role of atmospheric carbon dioxide (CO2) in warming the Earth's surface was first demonstrated by Swedish scientist Svante Arrhenius more than 100 years ago. Scientific data have since established that, for hundreds of thousands of years, changes in temperature have closely tracked with atmospheric CO2 concentrations. Since the Industrial Revolution, the burning of coal, oil and natural gas has emitted roughly 500 billion tons of CO2, about half of which remains in the atmosphere. This CO2 is the biggest factor responsible for recent warming trends.

https://www.nwf.org/Wildlife/Threats-to-Wildlife/Global-Warming/Global-Warming-is-Human-Caused.aspx