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Future predictions
The IPCC (Intergovernmental Panel on Climate Change) has considered 177 models predicting future emission levels and corresponding increases in both temperature and sea levels.
In order to stabilise the concentration of greenhouse gases in the atmosphere, emissions will need to peak and decline thereafter. The majority of models predict that emissions will peak in 2060 and as a consequence:
- The average global temperature will increase to between 3.2°C and 4°C higher than the pre-industrial equilibrium.
- The average sea level will be between 0.6 metres and 2.4 metres higher than the pre-industrial level.
- The concentration of greenhouse gases in the atmosphere will be between 60% and 90% higher than in the year 2000.
In addition
- There is a consensus that warming of at least 2°C is now inevitable.
- Achieving a target of 3°C will require stringent mitigation, with emissions peaking in 10 years. Developed countries as a group would need to reduce their emissions significantly by 2020 (10-40% below 1990 levels) and to still lower levels by 2050 (40-95% below 1990 levels).
- With no change in energy policy the energy mix used to run the global economy will remain unchanged, with more that 80% of energy supply based on fossil fuels. Under this scenario the corresponding average global temperature increase is expected to be much higher than 3°C.
- The most pessimistic model predicts a worst case temperature increase of 6°C by the end of this century. The implications of this would be catastrophic, with sea level rises of up to 3.7 metres.
Predicting the growth of emissions and the impact of those emissions on the climate is complex. Assumptions need to be made about key drivers such as population growth, economic development and technological development. CO2.
So far however, models have proved to be reasonably accurate: since the first report by the IPCC (Intergovernmental Panel on Climate Change) in 1990, the average global temperature increase has been 0.2°C - this compares to projected increases of between 0.15°C and 0.3°C.
The full range of model predictions is summarised here (click to open).
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Climate Change 2004: IPCC AR4 Synthesis Report.
Regional temperature increases
The largest temperature increases are expected to be over land at high latitudes in the Northern hemisphere, with the maximum increase in the Arctic. The smallest increases are over the Southern Ocean and parts of the North Atlantic Ocean.
The chart below shows surface temperature increases across the globe expected by the end of this century, assuming a world of very rapid economic growth, a global population that peaks in mid-century and rapid introduction of new and more efficient technologies.