Greenhouse gases are molecules in the atmosphere that absorb and re-radiate energy from the Sun, thereby warming the Earth’s surface. Increasing levels of these gases have been caused by human actions and their accumulation is driving the global climate change we are seeing.
The most significant anthropogenic greenhouse gas is carbon dioxide (CO2) which has been increasing rapidly since the Industrial Revolution. Other important anthropogenic greenhouse gases include methane (CH4), nitrous oxide (N2O), hydrochlorofluorocarbons and hydrofluorocarbons (HCFCs and HFCs) as well as black carbon.
Natural processes can also produce greenhouse gases. For example, soils and tundra may release methane, while nitrates and other nitrogen fertilizers are produced by agriculture. Other natural sources of greenhouse gases include biomass burning and fossil fuels combustion.
All greenhouse gases have a unique combination of properties that affect their overall impact on the Earth’s climate, including their radiative efficiency and atmospheric lifetime. These characteristics are summed up into a measure called the Global Warming Potential (GWP) which enables comparisons between different greenhouse gases. The higher the GWP, the more the gas will warm the Earth.
Greenhouse gas emissions can be reduced by avoiding the generation of greenhouse gases through energy efficiency measures in buildings and other public spaces, energy transmission systems and vehicles. Regenerative agricultural practices that support soil health, reduce livestock-related emissions and use cover crops are key to decreasing nitrous oxide and methane releases. These measures can be supported by policy interventions like cap and trade systems.
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