温室效应(3/7)

Besides, deforestation also contributes to global warming. Trees use carbon dioxide and give off oxygen in their place, which helps to create the optimal balance of gases in the atmosphere. As more forests are logged for timber or cut down to make way for farming, however, there are fewer trees to perform this critical function. Population growth is another factor in global warming, because as more people use fossil fuels for heat, transportation and manufacturing, the level of greenhouse gases continue to increase. As more farming occurs to feed millions of new people, more greenhouse gases enter the atmosphere. Ultimately, more greenhouse gases mean more infrared radiation trapped and held, which gradually increases the temperature of the Earth's surface and the air in the lower atmosphere.

此外,森林砍伐也会导致全球变暖。树木利用二氧化碳在自己的地方放出氧气,这有助于大气中的气体达到最佳平衡状态。然而随着越来越多的森林被砍了作为木材用或为耕作腾出空间，越来越少的树来发挥这项重要功能了。人口增长是全球变暖的另一个因素。因为越来越多的人将化石燃料使用在高温、运输业和制造业中，温室气体的浓度越来越高。随着越来越多的农业发生养活数以百万计的新人类,越来越多的温室气体进入大气层。最终,更多的温室气体意味着会产生更多的红外辐射,它使地球表面和低层大气中的空气的温度逐渐增加。