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Climate and Climate Change
21.1 What Is Climate?
21.2 Climate Zones
21.3 Climate Change
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21.1 What Is Climate?
The climate of a region is its long-term weather. The
two main characteristics of climate are temperature
and precipitation, which can be described by
averages and ranges.
Many other factors act together to determine Earth’s
climate: latitude, elevation, distance from large
bodies of water, ocean currents, topography,
prevailing winds, and vegetation.
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climate controls
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21.1 What Is Climate?
Some climate controls have a greater effect than
others at different locations.
Beijing, China and Valdivia, Chile had the same average
temperature but different climates.
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Climate and Climate Change
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21.2 Climate Zones
Earth has a great diversity of climates. Scientists
categorize Earth’s many climates into zones: polar,
dry, humid tropical, moist mid-latitude with mild
winters, and moist mid-latitude with severe winters.
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Most climate zones are further divided into
subclimates. In mountainous regions, climates can
vary greatly within a small area.
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21.3 Climate Change
Earth’s climate is constantly changing.
Temperature difference (°C)
compared to present
Antarctic Temperatures for Past 420,000 Years
Thousands of years ago
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21.3 Climate Change
Earth’s climate is constantly changing.
Global climate changes can be caused by changes in
Earth’s energy budget and by the interactions among
Earth’s spheres.
Causes for climate change include variations in
Earth’s motions, the location of the continents,
variations in sunspots, and gases and ash ejected
into the atmosphere by volcanoes.
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21.3 Climate Change
Human activities are increasing the amount of
greenhouse gases in the atmosphere, and there is
evidence that the increase is contributing to current
global warming.
Temperature difference (°C)
compared to average for 1951–1980
Global Surface Temperature Change
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21.3 Climate Change
Human activities are increasing the amount of
greenhouse gases in the atmosphere, and there is
evidence that the increase is contributing to current
global warming.
The causes of climate change are complex, so
predicting climate change is difficult.
Scientists study past climate change by analyzing
sea-floor sediments, glacier samples, tree rings, and
other indirect evidence.
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