2. On Earth, human activities are changing
the natural greenhouse. Over the last
century the burning of fossil fuels like coal
and oil has increased the concentration of
atmospheric carbon dioxide (CO2). This
happens because the coal or oil burning
process combines carbon with oxygen in
the air to make CO2. To a lesser extent, the
clearing of land for agriculture, industry,
and other human activities have increased
concentrations of greenhouse gases.
3. On average, Earth will
become warmer. Some
regions may welcome
warmer temperatures, but
others may not.
4. Warmer conditions will
probably lead to more
evaporation and
precipitation overall, but
individual regions will vary,
some becoming wetter and
others dryer.
5. A stronger greenhouse
effect will warm the oceans
and partially melt glaciers
and other ice, increasing
sea level. Ocean water also
will expand if it warms,
contributing further to sea
level rise.
6. Meanwhile, some crops and
other plants may respond
favorably to increased
atmospheric CO2, growing more
vigorously and using water more
efficiently. At the same time,
higher temperatures and shifting
climate patterns may change
the areas where crops grow
best and affect the makeup of
natural plant communities.
7. Climate change is a long-term
shift in weather
conditions
identified by changes in
temperature, precipitation,
winds, and other indicators.
Climate change can involve
both changes in average
conditions and changes in
variability, including, for
example, extreme events.
8. The overall effect of human
activities since the
Industrial Revolution has
been a warming effect,
driven primarily by
emissions of carbon
dioxide and enhanced by
emissions of other
greenhouse gases.
9. Climate change can also be caused by
human activities, such as the burning
of fossil fuels and the conversion of
land for forestry and agriculture. Since
the beginning of the Industrial
Revolution, these human influences on
the climate system have increased
substantially. In addition to other
environmental impacts, these activities
change the land surface and emit
various substances to the atmosphere.
These in turn can influence both the
amount of incoming energy and the
amount of outgoing energy and can
have both warming and cooling effects
on the climate. The dominant product
of fossil fuel combustion is carbon
dioxide, a greenhouse gas.
