As the world's expanding population burns large quantities of fossil fuels and simultaneously cuts down large expanses of forests worldwide, the concentrations of CO2 and other greenhouse gases are building up in the atmosphere. "The green house effect is the (imperfect) analogy used to explain the atmospheric phenomenon that keeps our planet warm enough to sustain life." There is mounting evidence that this shift in Earth's atmosphere will lead to global changes and potentially major …showed first 75 words of 788 total…

…showed last 75 words of 788 total…to adapt to than a fast one. Uncertainties about global warming are so great that it is not possible now to say whether the net result has been, or will be, beneficial or harmful to forest growth and composition or to the subsequent management and use of forest resources. The only certainties are that: greenhouse gases are accumulating; that the greenhouse effect is real; and that some future global warming is possible as a result.