According to Accu-Weather, the world's leading commercial forecaster, "Global air temperatures as measured by land-based weather stations show an increase of about 0.45 degrees Celsius over the past century. This may be no more than normal climatic variation...[and] several biases in the data may be responsible for some of this increase."
Satellite data indicate a slight cooling in the climate in the last 18 years. These satellites use advanced technology and are not subject to the "heat island" effect around major cities that alters ground-based thermometers.
Projections of future climate changes are uncertain. Although some computer models may predict warming in the next century, these models are very limited. The effects of cloud formations, precipitation, the role of the oceans, or the sun, are still not very well known and often inadequately represented in the climate models although all play a major role in determining our climate. Scientists who work on these models are quick to point out that they are far from perfect representations of reality, and are probably not advanced enough for direct use in policy implementation. Interestingly, as the computer climate models have become more sophisticated in recent years, the predicted increase in temperature has been lowered |
