Satellite pictures show that large areas of Antarctic ice are already disappearing. The evidence available suggests that a warming has taken place. This fits the theory that carbon dioxide warms the earth.
However, most of the fuel is burnt in the northern hemisphere, where temperatures seem to be falling. Scientists conclude, therefore, that up to now natural influences on the weather have exceeded those caused by man. The question is: Which natural cause has most effect on the weather?
One possibility is the variable behavior of the sun. Astronomers at one research station have studied the hot spots and cold spots (that is, the relatively less hot spots) on the sun. As the sun rotates, every 27.5 days, it presents hotter or colder faces to the earth, and different aspects to different parts of the earth. This seems to have a considerable effect on the distribution of the earths atmospheric pressure, and consequently on wind circulation. The sun is also variable over a long term: its heat output goes up and down in cycles, the latest trend being downward.
Scientists are now finding mutual relations between models of solar-weather interactions and the actual climate over many thousands of years, including the last Ice Age. The problem is that the models are predicting that the world should be entering a new Ice Age and it is not. One way of solving this theoretical difficulty is to assume a delay of thousands of years while the solar effects overcome the inertia (惯性) of the earths climate. If this is right, the warming effect of carbon dioxide might thus be serving as a useful counter-balance to the suns diminishing heat.
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