What causes climate and climate change?
Weather and Climate
Weather is the state of the atmosphere in a region over days and weeks, while climate is the average state of the weather over the longer term – decades, centuries, and millennia. Both are described by temperature, air pressure, cloudiness, moisture, wind speed, and wind direction. Many factors influence climate: the amount of sunlight, the condition of the atmosphere, the oceans, the solid Earth, the great ice sheets, and life itself. It is the complex interaction of all these influences that regulates climate and causes climate change.
Changes in ocean circulation strongly influence climate.
The seasons, which are caused by the tilt of the Earth’s axis, are the most important periodic fluctuations in climate.
The atmosphere is an envelope of gases that surrounds the Earth and is held there by gravity.
The ocean and atmosphere comprise the outer layer of the Earth and are major forces that shape its surface.
Climate changes over time. Twenty thousand years ago, much of Europe and North America was covered with a thick sheet of ice, as Greenland is today.
Coral is a useful indicator of local past climate.
Venus and Earth are about the same size and probably started out with similar atmospheres, but now their atmospheres — and climates — are very different.