Is the Earth’s climate changing?
Constantly. It was not so long ago that scientists believed the climate of our planet was more or less constant. The discovery of the ice ages confounded that notion. But even in the current interlude between ice ages, only in the last few decades has the evidence been accumulating to show that the Earth’s climate is in a constant state of change. Today when the public hears about climate change, it is usually in the context of alter ations due to human activities. The planet’s atmosphere, however, has been fluctuat ing since long before Earth was populated by humans. One of the warmest eras ever on Earth occurred during the Cretaceous periods about 100 million years ago. Global temperatures averaged some 18°F warmer than they are today. Ocean levels rose and spilled over onto continents, splitting North America into two land masses.