Climate Change and Disaster Risk Reduction
ISDR
Briefing Note
01
Geneva, September 2008
Climate Change and Disaster Risk Reduction
Weather, climate and climate change
Defining climate change For most people, the expression “climate change” means the alteration of the world’s climate that we humans are causing, through fossil fuel burning, clearing forests and other practices that increase the concentration of greenhouse gases (GHG)1 in the atmosphere. This is in line with the official definition by the United Nations Framework Convention on Climate Change (UNFCCC) that climate change is the change that can be attributed “directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods”.2 However, scientists often use the term for any change in the climate, whether arising naturally or from human causes. In particular, the Intergovernmental Panel on Climate Change (IPCC) defines “climate change” as “a change in the state of the climate that can be identified ... by changes in the mean and / or the variability of its properties, and that persists for an extended period, typically decades or longer”.3 Each of these two definitions is relevant and important to keep in mind.
1 Greenhouse gases (GHGs) “are those gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and emit radiation at specific wavelengths within the spectrum of thermal infrared radiation emitted by the Earth’s surface, the atmosphere itself, and by clouds.” The primary greenhouse gases include H2O, CO2, N2O, CH4 and O3. IPCC Fourth Assessment Report, Working Group I, Glossary of Terms: http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Annexes.pdf. 2 UNFCCC Article 1, Definitions: http://unfccc.int/essential_background/convention/background/ items/1349.php. 3 IPCC Fourth Assessment Report, Working Group I, Glossary of Terms: http://ipcc-wg1.ucar.edu/wg1/ Report/AR4WG1_Print_Annexes.pdf.
Briefing Note
01
Geneva, September 2008
Climate Change and Disaster Risk Reduction
Weather, climate and climate change
Defining climate change For most people, the expression “climate change” means the alteration of the world’s climate that we humans are causing, through fossil fuel burning, clearing forests and other practices that increase the concentration of greenhouse gases (GHG)1 in the atmosphere. This is in line with the official definition by the United Nations Framework Convention on Climate Change (UNFCCC) that climate change is the change that can be attributed “directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods”.2 However, scientists often use the term for any change in the climate, whether arising naturally or from human causes. In particular, the Intergovernmental Panel on Climate Change (IPCC) defines “climate change” as “a change in the state of the climate that can be identified ... by changes in the mean and / or the variability of its properties, and that persists for an extended period, typically decades or longer”.3 Each of these two definitions is relevant and important to keep in mind.
1 Greenhouse gases (GHGs) “are those gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and emit radiation at specific wavelengths within the spectrum of thermal infrared radiation emitted by the Earth’s surface, the atmosphere itself, and by clouds.” The primary greenhouse gases include H2O, CO2, N2O, CH4 and O3. IPCC Fourth Assessment Report, Working Group I, Glossary of Terms: http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Annexes.pdf. 2 UNFCCC Article 1, Definitions: http://unfccc.int/essential_background/convention/background/ items/1349.php. 3 IPCC Fourth Assessment Report, Working Group I, Glossary of Terms: http://ipcc-wg1.ucar.edu/wg1/ Report/AR4WG1_Print_Annexes.pdf.
Cited: in the Stern Review, Report on the Economics of Climate Change (2006): http://www.hm-treasury.gov.uk/independent_reviews/stern_review_ economics_climate_change/stern_review_report.cfm.