Climate change is a significant and lasting change in the weather patterns over periods ranging from decades to millions of years.
An ice age, or more precisely, a glacial age, is a period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers.
Global warming is increasing an average temperature of the air and sea at Earth's surface. Since the early 20th century, the global air and sea surface temperature has increased about 0.8 °C, with about two-thirds of the increase occurring since 1980. Each of the last three decades has been warmer at the Earth’s surface than any preceding decade since 1850.
Scientists are more than 90% certain that most of global warming is caused by increasing concentrations of greenhouse gases produced by human activities.
The greenhouse effect is the process by which absorption and emission of infrared radiation by gases in a planet's atmosphere warm its lower atmosphere and surface. Without the Earth's atmosphere, the temperature across almost the entire surface of the Earth would be below freezing.
Human activity since the Industrial Revolution has increased the amount of greenhouse gases in the atmosphere. These levels are much higher than at any time during the last 800,000 years, the period for which reliable data has been extracted from ice cores.
Fossil fuel burning has produced about three-quarters of the increase in CO2 from human activity over the past 20 years.