What are greenhouse gases?
Many chemical compounds found in the Earth’s atmosphere act as “greenhouse gases”. These gases allow sunlight to enter the atmosphere freely. When sunlight strikes the Earth’s surface, some of it is reflected back towards space as infrared radiation (heat).
Greenhouse gases absorb this infrared radiation and trap the heat in the atmosphere, and this is often referred to as the Greenhouse Effect1. Over time, the amount of energy sent from the sun to the Earth’s surface should be about the same as the amount of energy radiated back into space, leaving the temperature of the Earth’s surface roughly constant.
Many gases exhibit these “greenhouse” properties. Some of them occur in nature whilst others are exclusively man-made.
What are greenhouse gas emissions?
Many believe that the excess of greenhouse gases emitted over the last century is the cause of global warming via the greenhouse effect. There are natural and man-made greenhouse gas emissions. The primary greenhouse gases thought to be major contributors to global warming are carbon dioxide emissions (CO2), methane & biomethane emissions (CH4), nitrogen oxides (N2O) and fluorinated gases2. Some climate scientists insist that water vapor also belongs to this term.
The primary sources of greenhouse gas emissions from man-made sources include fossil-fuelled power plants, such as natural gas power plants and coal-fired power plants. Other sources of greenhouse gas emissions linked to man-made causes include chlorofluorocarbons, internal combustion engines (fuelled by gasoline and petroleum diesel) and deforestation. Reports show that emissions of carbon dioxide are responsible for 64% of man-made global warming3.
Many people don’t realize that the ocean naturally absorbs as much as 25% of the carbon dioxide emissions. Furthermore, our biosphere absorbs another 25% of the carbon dioxide emissions, i.e. through trees, plants, soil, etc. This leaves about 50% of unabsorbed carbon dioxide emissions remaining in our atmosphere4. As previously stated, carbon dioxide emissions link primarily to the burning of fossil fuels (power plants, cars, trucks, etc.) and deforestation. Greenhouse gas emissions have been on the increase ever since the dawn of the industrial revolution.
The climate crisis is the biggest threat humankind faces today. Individuals, organisations and governments across the globe need to work together in order to prevent the crisis from becoming a catastrophe.
1 What is the greenhouse effect?, https://climate.nasa.gov/faq/19/what-is-the-greenhouse-effect/
2 Overview of greenhouse gases, https://www.epa.gov/ghgemissions/overview-greenhouse-gases
3 Causes of climate change, https://ec.europa.eu/clima/change/causes_en
4 Ocean-Atmosphere CO2 Exchange, https://sos.noaa.gov/datasets/ocean-atmosphere-co2-exchange/