Comprehension: The Earth is getting warmer, and the oceans are rising. Why is it happening so? One answer is that it could simply be a part of a natural process. After all, there have been ice ages and long periods of warmth in the past. However, now scientists believe that human activity is the cause. For more than 200 years, human activities have changed drastically (i) (for example, industrial pollution), which have contributed to creating a layer in the atmosphere around the Earth like a giant glass container, affecting the temperatures. Unwariness (ii) of humans may lead to a big global catastrophe in the future, harmful not only to the existence of humanity but to other living and non-living beings too.