Scientists develop mathematically-based
climate models to help predict future climate changes.
Each model uses different assumptions about the future
to predict how atmospheric CO2 levels and temperatures
The variables in each model include:
- Population growth rate
- Economic development
- Energy use
- Efficiency of energy use
- Mix of energy technologies
The graph below shows the results from three climate
models used by the IPCC, with predictions starting in
1990 and ending in the year 2100. In all three, the
global population rate rises during the first half of
the century, then declines.
- The A1B model assumes rapid economic
growth and increased equitythe reduction of
regional differences in per-person income. New and
more efficient technologies are introduced, without
relying heavily on a single energy source.
- The A1F1 model is the same as A1B,
but assumes the continued use of fossil fuel-intensive
- In the B1 model, the world moves rapidly from a
producer-consumer economy toward a service and information
economy. There is a reduction in the use of raw materials,
and an emphasis on clean and efficient technologies
and improved equity.
Other models have been developed, each based upon a
different set of assumptions.
Although differing in degree, these
three climate prediction models show similar trends:
- The projected
rate of global warming in the future is much larger
than the rate of global warming during the 20th century.
rates of global warming are greater than any seen
in the past 10,000 years.
5. Why do scientists develop numerous models rather
than rely on just one?
6. Based upon all the models shown, what
range of temperature increase is expected to occur by