Global Sources

The atmospheric concentrations of the greenhouse gases (GHGs) carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) have all increased since 1750 due to human activity. The graph below illustrates that total anthropogenic GHG emissions have continued to increase over 1970 to 2010 with larger increases toward the end of this period. Despite a growing number of climate change mitigation policies, annual GHG emissions grew on average by 1.0 gigatonne carbon dioxide equivalent (GtCO₂eq) per year from 2000 to 2010 compared to 0.4 GtCO2eq (1.3%) per year from 1970 to 2000 (IPCC, 2015).

Total anthropogenic GHG emissions were the highest in human history from 2000 to 2010 and reached 49 GtCO₂eq/yr in 2010, and the global economic crisis 2007/2008 only temporarily reduced emissions. CO₂ emissions from fossil fuel combustion and industrial processes contributed about 78% of the total GHG emission increase from 1970 to 2010, with a similar percentage contribution for the period 2000–2010 (IPCC, 2015). It is anticipated that the upward trend will continue.

Legend: F-Gases are flourinated gases, N2O is nitrous oxide, CH4 is methane, CO2FOLU denotes forestry and other land use. 

A significant amount of GHGs occur as a result of human activity. Carbon dioxide is the main contributor to the recent surge in GHGs in the atmosphere. This is pricipally due to the burning of fossil fuels and deforestation. The following pages provide more information on the most significant GHGs and their sources in Ireland and globally.