CLIMATE CHANGE EFFECTS
1. How serious is a warming of a few degrees?
The
Intergovernmental Panel on Climate Change (IPCC) estimates it has warmed 1.2 to
1.4°F (0.7 to 0.8ºC) over the past century and projects a further 3 to 7°F (2
to 4ºC) over the 21st century. The increases may appear minor compared to
short-term weather changes from night to day and winter to summer. In global
climate terms, however, warming at this rate would be much larger and faster
than any of the climate changes over at least the past 10,000 years.
2. Will a warming climate have more positive or negative
effects?
A warming
climate will have both positive and negative impacts. Local impacts are the
most difficult to predict, making it a challenge to know exactly who or what
will be harmed or benefit. Generally, the risk of negative impacts from climate
change increases the faster it warms. More rapid climate change makes adapting
to change more difficult and costly. This is especially true for vulnerable
groups (such as the poor, the very young, and older adults) and fragile
ecosystems which may struggle to adapt to even small changes. The
Intergovernmental Panel on Climate Change (IPCC) suggests that temperature
increases above the range of 3.5 to 5.5°F (2 to 3ºC) over the next 100 years
would dramatically increase the negative impacts of climate change. So a major
aim of climate action is to reduce the risk and likelihood of large, rapid
warming.
3. How will climate change affect ecosystems?
Some
ecosystems have already been affected by changes in climate. As the climate
continues to warm, major changes may occur in ecosystem structure and function,
species’ ecological interactions, and species’ geographic ranges, with
predominantly negative consequences for biodiversity. Warmer temperatures and
precipitation changes will likely affect the habitats and migratory patterns of
many types of wildlife. The range and distribution of many species will change,
and some species that cannot move or adapt may face extinction. In addition,
climate changes such as increased floods and droughts are predicted to increase
the risk of extinction for some plant and animal species, many of which are
already at-risk due to other non-climate related factors.
4. How will climate change affect human health?
Longer,
more intense and frequent heat waves may cause more heat-related death and
illness. There is virtual certainty of declining air quality in cities since
greater heat can also worsen air pollution such as ozone or smog. Insect-borne
illnesses are also likely to increase as many insect ranges expand. Climate
change health effects are especially serious for the very young, very old, or
for those with heart and respiratory problems. Conversely, warmer winter
temperatures may reduce the negative health impacts from cold weather.
5. How will climate change affect agriculture?
The
supply and cost of food may change as farmers and the food industry adapt to
new climate patterns. A small amount of warming coupled with increasing CO2
may benefit certain crops, plants, and forests, although the impacts of
vegetation depend also on the availability of water and nutrients. For warming of more than a few degrees, the effects are
expected to become increasingly negative, especially for vegetation near the
warm end of its suitable range.
6. How will climate change affect polar regions?
Polar regions
are expected to warm more than any other parts of the world. In part, this is
because ice has greater reflectivity (also known as albedo) than ocean or land.
Melting of highly reflective snow and ice reveals darker land and ocean surfaces,
which increases absorption of the sun’s heat and further warms the planet,
especially in those regions. Polar ice sheets (such as those on Greenland and Antarctica) are some of the largest surface features on
our planet. Any changes to them, however small, could have far-reaching
effects. Polar ice sheets potentially will accumulate more snow and ice because
of an increase in precipitation. However, overall melting due to global warming
is expected to reduce the size and extent of the polar ice sheets. Melting of
polar ice and land-based glaciers is expected to contribute to sea level rise.
In addition to the ice sheets, sea ice is also melting. Though the melting of
floating sea ice that covers part of the Arctic Ocean
does not effect sea level, sea ice is important for wildlife and for keeping
the region cool by reflecting sunlight back to space. If the Arctic loses the
reflective surface of ice and then the dark Arctic Ocean
absorbs more heat, the northern regions may warm even more rapidly.
7. How will a warming climate affect precipitation?
Rising
temperatures will intensify the Earth’s water cycle. Increased evaporation will
make more water available in the air for storms, but contribute to drying over
some land areas. As a result, storm-affected areas are likely to experience
increases in precipitation and increased risk of flooding. But areas located
far away from storm tracks are likely to experience less precipitation and
increased risk of drought. In the U.S.,
warming is expected to cause a northward shift in storm tracks, resulting in
decreases in precipitation in areas such as the Southwest
U.S. but increases in many areas to the north and east. However,
these changes will vary by season and depend on weather fluctuations.
8. How will climate change affect sea level?
Sea levels are rising worldwide and along much of the U.S. coast.
Tide gauge measurements and satellite altimetry suggest that sea level has
risen worldwide approximately 4.8-8.8 inches (0.12-0.22 m) during the last century. A significant
amount of sea level rise has likely resulted from the observed warming of the
atmosphere and the oceans. The primary factors driving current sea level rise
include the expansion of ocean water caused by warmer ocean temperatures (warmer
water is less dense), melting of mountain glaciers and small ice caps
(resulting in more water in the oceans and less on land), and - to a lesser
extent - the melting of the Greenland Ice Sheet and the Antarctic Ice Sheet. The Intergovernmental Panel on Climate Change (IPCC)
projects a six-inch to two-foot (0.18-0.59 m) rise in sea level during the 21st
century. Sea level rise may be greater if there are sudden increases in ice
sheet melt. Such increases have already
been observed but their effects have not yet been incorporated into current
projections of sea level rise. The stability of the West Antarctic Ice Sheet is
of particular concern. A sudden collapse of the ice sheet could raise sea
levels 16 to 20 feet (5-6 m). The IPCC is unable to estimate the likelihood or
timing of such a collapse, however, due to incomplete understanding of all the
processes affecting this ice sheet.
9. Will a warming climate make temperatures more extreme?
Most
scientists think that a warming climate will alter the frequency and severity
of extreme temperature events. In general, they expect increases in heat waves
and decreases in cold spells. These effects will vary from place to place.
10. How
will a warming climate affect hurricanes?
Because
warm sea surface temperatures energize hurricanes, a warming climate is likely
to make hurricanes more intense. Hurricanes
in the future will probably have stronger peak winds and increased rainfall. The relationship between sea surface temperatures and the
frequency of hurricanes is less clear. There is currently no scientific
consensus on how a warming climate is likely to affect the frequency of
hurricanes, but research continues.
11. How
will climate change affect water resources?
In a
warming climate, extreme events like floods and droughts are likely to become
more frequent. More frequent floods and
droughts will affect water quality and availability. For example, increases in drought in some areas may
increase the frequency of water shortages and lead to more restrictions on
water usage. An overall increase in precipitation may increase water
availability in some regions, but also create greater flood potential.
12. How
will climate change affect coasts?
If you live along the coast, your home may be impacted by
sea level rise and an increase in storm intensity. Rising seas may contribute
to enhanced coastal erosion, coastal flooding, loss of coastal wetlands, and
increased risk of property loss from storm surges.
13. How
will climate change affect energy?
Warmer
temperatures may result in higher energy bills for air conditioning in summer,
and lower bills for heating in winter. Energy usage is also connected to water
needs. Energy is needed for irrigation, which will most likely increase due to
climate change. Also, energy is generated by hydropower in some regions, which
will also be impacted by changing precipitation patterns.
14. How
will climate change affect recreational opportunities?
Some
outdoor activities may benefit from longer periods of warm weather. However,
many other outdoor activities could be compromised by increased beach erosion,
increased heat waves, decreased snowfall, retreating glaciers, reduced
biodiversity, and changing wildlife habitats
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