Emissions of the main anthropogenic greenhouse gas, CO2, are influenced by:
- the size of the human population,
- the amount of energy used per person,
- the level of emissions resulting from that use of energy.
Similar factors affect the levels of emissions of the other greenhouse gases.
Policies for addressing greenhouse gas emissions are being developed through international negotiation - the development of international environmental policy is traced in the following section.
A variety of technical options are also available which could reduce emissions, especially from use of energy. Reducing CO2 emissions can be achieved through:
- improved energy efficiency,
- fuel switching,
- use of renewable energy sources,
- nuclear power,
-
capture and storage of CO2.
These options are most easily applicable to stationary plant, which is the focus of the discussion below. Another class of measure involves increasing the rate at which natural sinks take-up
CO2 from the atmosphere - for example by increasing the amount of forests.
Reductions in emissions of other greenhouse gases can also be achieved using technology. For example, methods of reducing methane emissions include reductions in leakage and capture of fugitive emissions, with destruction or utilisation of the methane.
Technical responses to climate change deserve serious consideration as means of limiting greenhouse gas emissions whilst continuing to satisfy human aspirations for improved quality of life. The IEA Greenhouse Gas R&D Programme has investigated many of these technologies and the results of some of its assessments are summarised below.