Dramatic change

The changes to our climate that are happening now are attributed to a very steep rise in the concentration of a number of gases in the air. Concentrations of these gases, known as greenhouse gases (GHGs), have risen steeply since the industrial revolution c. 1750 and so human activity - how we live our lives - is the cause.

These gases are called greenhouse gases (GHGs), because they let sunlight pass through the atmosphere to reach the earth but then trap the outgoing energy from the heated surface, which is similar to what happens in a greenhouse.

These increases were initially triggered by the change from an economy based on manual labour to one based on machine manufacture, and have continued to grow as all aspects of our lives have become mechanised.

Major GHG trends

CO2 emissions per region over 1750 –2010, including emissions from fossil fuel combustion, cement production, and gas flaring (IPCC, 2015)

The graph above from the IPCC's AR5 (2015) illustrate the evidence for the upward trend in GHG levels. Fossil CO2 emissions have grown substantially over the past two centuries and emissions over 2002–2011 were estimated at 30  GtCO2/yr. Emissions in the 2000s as compared to the 1990s were higher in all regions, except for Economies In Transition, and the rate of increase was largest in Asia. The increase in developing countries is due to an industrialization process that historically has been energy-intensive; a pattern similar to what the current OECD countries experienced before 1970.

The figure also shows a shift in relative contribution. The OECD-1990 countries contributed most to the pre-1970 emissions, but in 2010 the developing countries and Asia in particular, make up the major share of emissions (IPCC, 2015).  Overall, this shows a clear and dramatic increase since 1750, which lends urgency to the development and implementation of mitigation and adaptation measures on a global scale.

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