Greenhouse gas (GHG) emissions

Greenhouse gases (GHG) are those compounds in the atmosphere that prevent infrared radiation from the Earth surface to escape to the outer space, sending the radiation back to surface. The consequence is an increment in the temperature in the lower atmosphere that has major impacts in both the people and environment.

Without greenhouse gases (GHG), there would be no life in the planet. The temperature would be around -17.5 C.

GHG are natural components of the planet’s system, however human activities are also adding GHG to the atmosphere, those are called anthropogenic emissions.

The most abundant GHG is water vapour, followed by CO₂, the second largest GHG in the atmosphere part of the carbon cycle. CO₂ is the product of oxidation of carbon in organic matter either through combustion or decay.

Anthropogenic GHG, synthetic gases such as HFCs, PFCs, SF₆ and NF₃ have a global warming potential much higher than natural GHG such as CO₂, CH₄, N₂O.

The global concentration of GHG in the last 150 years has increased leading to a rise on the global temperature of almost 1C. Predictions say that if we continue with this trend, temperatures might raise in the next 50 years causing profound and severe climate changes as: sea level rise, desertification, flooding, extreme weather events (cooler winters, hotter summers), more hurricanes, tsunamis, loss of biodiversity and epidemics.

Sources of GHG emissions

Natural sources of CO2 include respiration, volcanic activity, fires and exchange in the oceans.  The oceans are the single source that emits and absorbs the largest amount of GHG. However, human activities are breaking the equilibrium and we are adding more GHG to the atmosphere, such as CO₂, CH₄, N₂O, HFCs, PFCs, SF₆ and NF₃ These are called Anthropogenic gases.

The main anthropogenic sources of CO₂ are fossil fuel combustion, deforestation, land use change. For CH₄ is the product of decay from landfills, wetlands, wastewater treatment, natural gas transportation, distribution, diesel combustion and ruminant animals. N₂O is produced by fertiliser, animal waste, fossil fuel combustions and industries. HFCs and PFCs are man made compounds (produced synthetically) used in industrial production (semi-conductors, refrigeration and foam-blowing for insulation and aluminum) and its global warming contribution is much higher than natural GHG (CO_{2, CH4, N2O)}