4.2 What are the regional effects of climate change?

Just as the causes of the enhanced greenhouse effect are not evenly distributed (see Section 3, Anthropogenic causes of global warming), so the effects are also unevenly distributed. This uneven distribution applies both to impacts in different regions of the Earth and over time.

In general, the impacts will be most evident in more sensitive ecosystems, especially those at polar latitudes and those at low latitudes. There are substantial uncertainties in disentangling local management and other factors from climate. Nevertheless, a number of observations have been made that are consistent with the predicted impacts of climate change, leading to the unequivocal conclusion of the IPCC Fourth Assessment Report:

warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level

The website Global Warming: Early Warning Signs usefully recognises two main effects:

  1. Fingerprints – direct manifestations of a widespread and long-term trend toward warmer global temperatures, such as:

    • heat waves and periods of unusually warm weather

    • ocean warming, sea-level rise and coastal flooding

    • glaciers melting

    • Arctic and Antarctic warming.

  2. Harbingers – events that foreshadow the types of impact likely to become more frequent and widespread with continued warming, namely:

    • spreading disease

    • earlier spring arrival

    • plant and animal range shifts and population changes

    • coral reef bleaching

    • downpours, heavy snowfalls and flooding

    • droughts and fires.

The map, compiled by the Union of Concerned Scientists, helps you explore some of the evidence (fingerprints) and likely trends (harbingers) arising from climate change in different parts of the world. It was last updated in winter 2003, so it's a little dated now, but it's still a useful summary of observed trends and likely change.

Additional information can be found in these web-based resources

  • A podcast and animation from NASA shows the declining extent of the Arctic ice cap over the 30 years to 2008.

  • A slide show from the National Academies shows the impact of climate change for North America.

  • The website of the UK Climate Impacts Partnership (CIP) provides an overview of the scenarios and enables you to explore different climate futures for the UK.

  • The UK Marine Climate Impacts Partnership provides a similar service to UK CIP (above), but for marine impacts – see their annual report card.

  • The research report ‘A handbook of climate trends across Scotland’, published by the Scotland & Northern Ireland Forum for Environmental Research, describes likely climate trends and likely impacts for Scotland, based on UK CIP 02 scenarios.

  • The IPCC ‘Fourth Assessment Report Working Group III, Adaptation, Impacts and Vulnerability – Summary for Policy Makers’ discusses the strength of evidence across different regions of the world.

4 The effects of global warming

5 What will more global warming mean later this century?