Climate change and global warming both spend a lot of time in the news, and it is important to distinguish between these two related concepts. Put simply, “climate change” refers to long term shifts in the Earth's climate in which the climate differs radically from the expected norm. “Global warming” is a type of climate change, and the term is usually used specifically to refer to the climate change which began to occur in the 20th century. Both climate change and global warming are topics of interest to scientists, paleontologists, and ecologists.
A number of factors can influence the Earth's climate, causing climate change and global warming, ranging from volcanic eruptions to pollution created by humans. Using archaeological and paleontological evidence, scientists have documented numerous instances of climate change in the Earth's past, and they have examined how, why, and when these changes occurred, using a number of indicators to track these events.
Glaciation is a major indicator of climate change. When the planet experiences cooling, glaciation increases, as it did during the ice ages. With warming trends come a corresponding decrease in glaciation. Dissolved gases in the atmosphere, pollen levels, and rainfall patterns can also provide clues. Estimates about historical shifts in temperature and climate can be arrived at by using evidence such as ice cores along with contemporary reports, such as discussions of unusually warm winters or difficult growing seasons.
The Earth has been experiencing climate change since it was created, and it is clearly a natural process, as demonstrated by the long term trends which have been documented by scientists. Global warming has become an issue because the warming trend appears to be drastically accelerated and more severe than previous documented periods of warming. Some researchers have suggested that human activities have played a role in the global warming trend, and that it may be necessary to modify the human lifestyle in order to prevent additional damage.
The issues of climate change and global warming are both important. Changes in the Earth's climate historically may explain patterns of extinction in some animals, along with human migration patterns and historical events such as famines and plagues. Small variations in temperature, rainfall, and other climactic factors can have a huge impact, as research on climate change and global warming has shown. The difference of only a few degrees can cause serious problems, which is an issue of particular concern in an overcrowded world where shortages of food and decreases in available land could trigger major sociological issues.