regarding the environment:
http://www.globalwarmingart.com/
googletemperature is rising
averagetemperature is rising
but the problem is:
extrem temperature change
(ETC)
increase in extrem adwerse effects
EPA CCSP NOAA Climate
is defined not simply as average temperature and precipitation but also
by the type, frequency and intensity of weather events. Human-induced
climate change has the potential to alter the prevalence and severity
of extremes such as heat waves, cold waves, storms, floods and
droughts. Though predicting changes in these types of events under a
changing climate is difficult, understanding vulnerabilities to such
changes is a critical part of estimating vulnerabilities and future
climate change impacts on human health, society and the environment. Our
current level of understanding, as summarized in the Intergovernmental
Panel on Climate Change Fourth Assessment Report (IPCC,
2007), is as follows: Since
1950, the number of heat waves has increased and widespread increases
have occurred in the numbers of warm nights. The extent of regions
affected by droughts has also increased as precipitation over land has
marginally decreased while evaporation has increased due to warmer
conditions. Generally, numbers of heavy daily precipitation events that
lead to flooding have increased, but not everywhere. Tropical storm and
hurricane frequencies vary considerably from year to year, but evidence
suggests substantial increases in intensity and duration since the
1970s.In the extratropics, variations in tracks and intensity of storms
reflect variations in major features of the atmospheric circulation,
such as the North Atlantic Oscillation. The
IPCC projects the following likely, very likely, or virtually certain
changes in extreme events and associated effects between now and 2100 (IPCC, 2007): It
is important to understand that directly linking any one specific
extreme event (e.g., a severe hurricane) to human-caused climate change
is not possible. However, climate change may increase the probability
of some ordinary weather events reaching extreme levels or of some
extreme events becoming more extreme. For example, according
to NOAA,
it is probable that heat waves will become more likely and
progressively more intense over the course of decades under current
climate change scenarios. Changes in the frequency and intensity of
heat waves and other extreme events across North America will be
comprehensively assessed in the forthcoming Climate Change Science
Program Synthesis
and Assessment Product 3.3: Climate Extremes. Abrupt
Climate Change Abrupt
climate change has a specific definition and should not be confused
with climate changes that occur slowly or individual extreme events
that affect relatively small areas. Abrupt climate change refers to
sudden (on the order of decades), large changes in some major component
of the climate system, with rapid, widespread effects. The potential
for abrupt climate changes cannot be predicted with confidence;
however, abrupt climate changes are an important consideration because,
if triggered, they could occur so quickly and unexpectedly that human
or natural systems would have difficulty adapting to them (NRC, 2002). Abrupt
climate changes occur when a threshold in the climate system is crossed
– a trigger that causes the climate to rapidly shift from one
state to a new, different one. Crossing thresholds in the climate
system may lead to large and widespread consequences (Schneider et al.,
2007). These
triggers can be forces that are “external” or
“internal” to the climate system. Examples of these
triggers include: More
than one of these triggers can operate simultaneously, since all
components of the climate system are linked. Scientific
data show that abrupt changes in the climate at the regional scale have
occurred throughout history and are characteristic of the
Earth’s
climate system (NRC, 2002).
During the last glacial
period, abrupt regional warmings (likely up to 16°C within
decades
over Greenland) and coolings occurred repeatedly over the North
Atlantic region (Jansen et al., 2007).
These
warmings likely had some large-scale effects such as major shifts in
tropical rainfall patterns and redistribution of heat within the
climate system but it is unlikely that they were associated with large
changes in global mean surface temperature. Our
state of knowledge is not yet sufficient to predict the timing of the
future abrupt climate changes or pinpoint their effects. However, the
National Academies of Sciences did conclude that anthropogenic forcing
could increase the risk of abrupt climate change: …greenhouse
warming and other human alterations of the Earth system may increase
the possibility of large, abrupt, and unwelcome regional or global
climatic events. The abrupt changes of the past are not fully explained
yet, and climate models typically underestimate the size, speed, and
extent of those changes. Hence, future abrupt changes cannot be
predicted with confidence, and climate surprises are to be expected. Changes
in weather patterns can result from abrupt changes that might occur
spontaneously due to interactions in the atmosphere-ice-ocean system,
or from the crossing of a threshold from slow external forcing (as
described above) (Meehl et al., 2007).
In a warming
climate, changes in the frequency and amplitudes of these patterns
might not only evolve rapidly, but also trigger other processes that
lead to abrupt climate change (NRC, 2002).
Examples
of these patterns include the El Niño Southern Oscillation
(ENSO) and the North Atlantic Oscillation/Arctic Oscillation (NAO/OA). Scientists
have investigated the possibility of an abrupt slowdown or shutdown of
the Atlantic meridional overturning circulation (MOC) triggered by
greenhouse gas forcing. The MOC transfers large quantities of heat to
the North Atlantic and Europe, so an abrupt change in the MOC could
have important implications for the climate of this region (Meehl et al., 2007).
However, according to Meehl et al. (2007), the probability of an abrupt
change in (or shutdown of) the MOC is low: “It is very
unlikely
that the MOC will undergo a large abrupt transition during the 21st
century. Longer-term changes in the MOC cannot be assessed with
confidence.” The slowdown in the MOC projected by most models
is
gradual, so the resulting decrease in heat transport to the North
Atlantic and Europe would not be large enough to reverse the warming
that results from the increase in greenhouse gases. The
rapid disintegration of the Greenland Ice Sheet (GIS), which would
raise sea levels 7 meters, is another commonly discussed abrupt change.
Although models suggest the complete melting of the GIS would only
require sustained warming in the range 1.9°C to 4.6°C
(relative
to the pre-industrial temperatures), it is expected to be a slow
process that would take many hundreds of years to complete (Meehl et al., 2007). For
more information on this issue, visit NOAA's Abrupt
Climate Change Web site and
see the National Resource Council report "Abrupt
Climate Change: Inevitable Surprises" (a short
4 page summary is also available (PDF, 4
pp., 714 KB,About
PDF) ) In
addition, visit the CCSP
Web site for
more information about ongoing multi-agency research on abrupt climate
change. An analysis on this topic is underway and will be completed by
2008.Extreme
Events
Related
Links
Projected
Change
Projected
Impacts by Sector
Agriculture,
forestry
Water
resources
Human
health/ mortality
Industry/settlement/society
Warmer/fewer
cold days/nights; warmer/more hot days/nights over most land areas.
Increased
yields in colder environments; decreased yields in warmer environments;
Effects
on water resources relying on snow melt
Reduced
human mortality from decreased cold exposure
Reduced
energy demand for heating; increased demand for cooling; declining air
quality in cities; reduced effects of snow, ice etc.
Warm
spells/heat waves: frequency increases over most land areas
Reduced
yields in warmer regions due to heat stress at key devel. stages; fire
danger increase
Increased
water demand; water quality problems, e.g., algal blooms
Increased
risk of heat-related mortality
Reduction
in quality of life for people in warm areas without air conditioning;
impacts on elderly and very young; reduced thermoelectric power
production efficiency
Heavy
precipitation events: frequency increases over most areas
Damage
to crops; soil erosion, inability to cultivate land, water logging of
soils
Adverse
effects on quality of surface and groundwater; contamination of water
supply
Deaths,
injuries, infectious diseases, allergies and dermatitis from floods and
landslides
Disruption
of settlements, commerce, transport and societies due to flooding;
pressures on urban and rural infrastructures
Area
affected by drought: increases
Land
degradation, lower yields/crop damage and failure; livestock deaths;
land degradation
More
widespread water stress
Increased
risk of food and water shortage and wild fires; increased risk of
water- and food-borne diseases
Water
shortages for settlements, industry and societies; reduced hydropower
generation potentials; potentials for population migration
Number
of intense tropical cyclones: increases
Damage
to crops; windthrow of trees
Power
outages cause disruption of public water supply
Increased
risk of deaths, injuries, water- and food-borne diseases
Disruption
by flood and high winds; withdrawal of risk coverage in vulnerable
areas by private insurers
Incidence
of extreme high sea level: increases
Salinization
of irrigation and well water
Decreased
freshwater availability due to saltwater intrusion
Increase
in deaths by drowning in floods; increase in stress-related disease
Costs
of coastal protection versus
costs of land-use relocation;
also see tropical cyclones above
- National Research Council, 2002References
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