The Impacts and Costs of Climate Change Page: i

                                
The Impacts and Costs of Climate Change
Executive Summary
The effects of global climate change from greenhouse gas emissions (GHGs) are diverse and
potentially very large, and probably constitute the most serious long-term environmental issue
currently facing the world.
This paper is prepared as task 1 of the project 'Modelling support for Future Actions - Benefits and
Cost of Climate Change Policies and Measures', ENV.C.2/2004/0088, led by K.U.Leuven, Katholieke
Universiteit Leuven. The paper provides a rapid review and analysis of the impacts and economic
costs from climate change. The objective is to provide estimates of the benefits of climate change
policy, i.e. from avoided impacts, for support to the Commission in considering the benefits and costs
of mitigation efforts, and to support DG Environment in its report to the Spring Council 2005 and in
future international negotiations on climate change.
Impacts of Climate Change (baseline)
The paper has reviewed the impacts of climate change, looking at potential impacts at a European and
global level. The analysis has identified and prioritised the major effects from climate change. These
are considered to be:
* Impacts of sea level rise, erosion, loss of land/coastal wetlands, and need for coastal protection;
* Effects on agriculture;
* Effects on energy use (including heating and cooling);
* Effects to human health from changes in cold related and heat related effects
* Effects to human health from the disease burden (and other secondary effects);
* Effects on water resources, water supply and water quality;
* Changes to tourism potential and destinations;
* Effects on ecosystems (loss of productivity and bio-diversity);
* Impacts from drought;
* Impacts from flooding;
* Impacts from storm damage and extreme weather (including costs to infrastructure);
* Socially contingent effects (arising from multiple stresses and leading to migration, famine, etc);
* Impacts from major events (e.g. loss of thermo-haline circulation, collapse of West-Antarctic ice
sheet, methane hydrates).
Many of these areas are inter-related. In particular, the major events identified (the potentially
catastrophic effects and major climate discontinuities) will have impacts across all categories. The
risk of avoiding these major effects is highlighted as a specific benefit of future climate change policy,
consistent with the precautionary principle.
Benefits of Different Stabilisation Targets
The review has assessed the potential effects of climate change associated with different stabilisation
targets. These are consistent with specific analysis of CO2 equivalent ppm concentrations, or
temperature changes such as a maximum 2C rise above pre-industrial levels. It has been difficult to
comprehensively assess the impacts associated with different targets, either at a European or global
level. Some initial data highlights that the potential benefits of stabilisation targets could be very
large, and there is increasing information emerging.
The IPCC Third Assessment Report confirms that risks of adverse impacts from climate change

increase with the magnitude of climate change. It considered five causes for concern regarding
climate change risks evolving in the period to 2100. Negative impacts on unique or threatened
systems and risks from extreme climate events occur with a temperature change as small as 1C and
these impacts and risks are projected to become significant and widespread for changes of 2 to 3'C.

AEA Technology Environment, August 2005