FUTURE CLIMATE CHANGE

Greenhouse gas concentrations in the atmosphere will increase during the next century unless greenhouse gas emissions⁸ decrease substantially from present levels. Increased greenhouse gas concentrations are likely to raise the Earth's average temperature, influence precipitation and some storm patterns as well as raise sea levels. The magnitude of these changes, however, is uncertain.

As noted in the Climate Change Technology Program Strategic Plan⁹ (PDF, 16 pp., 172 KB, About PDF¹⁰): "…stabilizing greenhouse gas concentrations, at any atmospheric concentration level, implies that global additions of greenhouse gases to the atmosphere and global withdrawals of greenhouse gases from the atmosphere must come into a net balance. This means that growth of net emissions of greenhouse gases would need to slow, eventually stop, and then reverse, so that, ultimately, net emissions would approach levels that are low or near zero."

The amount and speed of future climate change will ultimately depend on:

• Whether greenhouse gases and aerosol concentrations increase, stay the same or decrease.

• How strongly features of the climate (e.g. temperature, precipitation and sea level) respond to changes in greenhouse gas and aerosol concentrations.

• How much the climate varies as a result of natural influences (e.g. from volcanic activity and changes in the sun ’s intensity).

The following pages provide a summary of the projected changes in the atmosphere and climate over the next century based on the current state of knowledge:

• Future Atmosphere Changes in Greenhouse Gas and Aerosol Concentrations¹

• Future Temperature Changes²

• Future Precipitation and Storm Changes³

• Future Sea Level Changes⁴

References

• National Research Council (NRC), 2001. Climate Change Science: An Analysis of Some Key Questions. National Academy Press, Washington, DC