We're getting warmer.
Throughout the course of the Earth's history, the global climate has undergone many significant changes, including a period of global cooling known as the Ice Age, which left its mark in the valleys and magnificent natural formations left by retreating glaciers. In more recent years, however, many leading scientists have become concerned that the Earth's global temperature may be climbing steadily, due to an increase in human emission of greenhouse gases, of which carbon dioxide is a major component.
While the Earth's average temperature has only risen 1°F over the past century, this trend could eventually have many negative consequences for life on Earth, from melting ice caps and rising ocean levels to major changes in the Earth's weather patterns that could have a negative impact the world's food supplies. Because this recorded change coincides with the industrialization of the planet, it is believed that the increased levels of carbon dioxide from the use of fossil fuels may play a role in global climate change.