Global climate models

Scientific projections about the future of our climate are developed by running global climate models that are based on scenarios that represent a range of possible future conditions. This includes greenhouse gas (GHG) concentrations in the atmosphere, population size, socio-economic development and technological changes.

These projections are heavily dependent on assumptions about future conditions. However, there is growing agreement within the scientific community that our future climate will be warmer with more extreme climate and weather events.

The climate scenarios mean global temperatures are likely to increase by 0.2ºC per decade for the next two decades.

There is considerable evidence and data to suggest that the climate is already changing.

  • Over the past century, the global mean surface temperature has increased by 0.6ºC (± 0.2ºC).
  • The 1990s was the warmest decade of the past 1,000 years.
  • Sea-ice cover has decreased.
  • Shifts in species distributions have been observed.
  • The global average sea level has increased.
  • The number of heavy precipitation events has increased at northern latitudes and the frequency and severity of drought has also increased.

In addition, continental precipitation has increased by five to ten per cent over the 20th century in the northern hemisphere and has declined in parts of the Mediterranean and Africa.

There are also data to suggest that between 1950 and 2000, the daily surface temperature has decreased over land. Night-time minimum temperatures have also been increasing at twice the rate of daytime maximum temperatures.

There have been more frequent hot days and fewer cold or frost days over the past several decades.

Date modified: