3.6.2 Predicted impacts

Climate change tutorial - predicted impacts

How are predictions of climate change and its impacts made?

To predict future climate change and its possible impacts we need:

  • Measured climate data
  • Knowledge of the complexity of climate systems
  • Powerful computers.

Photo © Fitis-Sytske Dijksen
St Ives. Photo © Fitis-Sytske Dijksen
Available climate data and knowledge of the climate system are combined in computer models. These solve complex mathematical equations. The models include many factors such as cloud formation, rainfall, ocean and atmospheric currents, concentrations of greenhouse gases and land cover types. All these and more are known to affect weather and climate.

Several different computer models have been developed. Although they generate different predictions, most indicate warming. Information about modelled projections of the UK's climate was given in the 'Climate Change in the UK' tutorial.

Using different scenarios of future climate it is then possible to predict possible impacts. To do this for a country or region it is necessary to use the appropriate climate model output. This is called 'downscaling'.

Some predicted impacts of climate change

[Source: Government Office for Science]

  • Warming is expected to cause the oceans to expand, glaciers to retreat and parts of ice sheets to melt, increasing global sea level
  • Photo © Elisabeth Raboin
    Photo © Elisabeth Raboin
    Snow and sea-ice cover is predicted to retreat in some areas. Water availability in regions that are supplied by meltwater from major mountain ranges is likely to decrease
  • Rainfall is likely to increase in the tropics and at high latitudes and decrease in the already dry subtropics
  • Photo © Fitis-Sytske Dijksen
    Photo © Fitis-Sytske Dijksen
    Heatwaves are expected to become more frequent as average temperatures rise
  • The number of frost days is expected to decrease at high latitudes, increasing the growing season
  • Some plant species are expected to grow more and/or produce greater yields given the required amounts of nutrients and water, but ...
  • ... expected increases in the frequency and severity of extreme weather events, as well as increased insect outbreaks, are likely to increase crop losses
  • The surface oceans will probably be more acidic (lower pH) than they have been for tens of millions of years. This acidification will happen much more rapidly than in the past, with potentially severe impacts on marine ecosystems, including coral reefs
  • As sea level rises, more people will be at risk of coastal flooding every year. Salt-water incursion could threaten freshwater resources, and it is expected that damage due to floods and storms in coastal areas is likely to increase
  • Increasingly intense and frequent heat-waves are likely to cause more heat-related deaths, particularly amongst the elderly, chronically ill and very young, though the occurence of cold-related deaths is expected to fall.


Uncertainty of predictions

It is important to understand that environmental and biological systems tend to be complex and are affected by many factors that themselves may change over time. This means predicting the impacts of climate change is very challenging. To model the climate and environment it is necessary to make many assumptions and to simplify complexity. These of course lead to uncertainty in the output.

A key aim of researchers is to reduce the amount of uncertainty in our predictions. The more we understand how and why ecosystems change, the more we can improve models and predictions. This is why a long-term monitoring and research programme like ECN is so important.