Extreme Weather Frequency


Extreme Weather Frequency. Impacts due to altered frequencies and intensities of extreme weather, climate, and sea level events are very likely to change.

 

Since the IPCC Third Assessment (TAR), confidence has increased that some weather events and extremes will become more frequent, more widespread and/or more intense during the 21st century. Since the TAR, more is also known about the potential effects of such extreme events. A selection of these is presented in the IPCC Extreme Weather Frequency Table below.

Phenomena
and direction
of trend		 Likelihood of future
trend based on
projections for 21st
century using SRES
scenarios		 Examples of major projected impacts by sector
Agriculture,
forestry and
ecosystems		 Water
resources		 Human health Industry/settlement/
Society
Warmer and
fewer cold days
and nights;
warmer/more
frequent hot
days and nights
over most land
areas		 Virtually
certain 		Increased yields
in colder
environments;
decreased
yields in warmer
environments;
increased insect
outbreaks		 Effects on
water resources
relying on snow
melt; increased
evapotranspiration
rates		 Reduced human
mortality from
decreased cold
exposure		 Reduced energy demand
for heating; increased
demand for cooling;
declining air quality in
cities; reduced disruption
to transport due to snow,
ice; effects on winter
tourism
Warm
spells/heat
waves:
frequency
increases over
most land areas		 Very likely Reduced yields
in warmer
regions due to
heat stress; wild
fire danger
increase		 Increased water
demand; water
quality
problems, e.g.,
algal blooms		 Increased risk of
heat-related
mortality,
especially for the
elderly, chronically
sick, very young
and socially isolated		 Reduction in quality of life for people in warm areas without appropriate
housing; impacts on
elderly, very young and
poor.
Heavy
precipitation
events:
frequency
increases over
most areas		 Very likely Damage to
crops; soil
erosion, inability
to cultivate land
due to water
logging of soils		 Adverse effects
on quality of
surface and
groundwater;
contamination
of water supply;
water scarcity
may be relieved		 Increased risk of
deaths, injuries,
infectious,
respiratory and
skin diseases,
post-traumatic
stress disorders		 Disruption of settlements,
commerce, transport and
societies due to flooding;
pressures on urban and
rural infrastructures
Area affected by
drought:
increases		 Likely Land
degradation,
lower yields/crop
damage and
failure; increased
livestock deaths;
increased risk of
wildfire		 More
widespread
water stress		 Increased risk of
food and water
shortage;
increased risk of
malnutrition;
increased risk of
water- and food borne
diseases		 Water shortages for
settlements, industry and societies; reduced
hydro power generation
potentials; potential for
population migration
Intense tropical
cyclone activity
increases		 Likely Damage to
crops; wind throw
(uprooting) of
trees; damage to
coral reefs		 Power outages
cause
disruption of
public water
supply		 Increased risk of
deaths, injuries,
water- and foodborne
diseases;
post-traumatic
stress disorders		 Disruption by flood and
high winds; withdrawal of risk coverage in
vulnerable areas by
private insurers, potential
for population migrations
Increased
incidence of
extreme high
sea level
(excludes
tsunamis)		 Likely Salinisation of
irrigation water,
estuaries and
freshwater
systems		 Decreased
freshwater
availability due
to saltwater
intrusion		 Increased risk of
deaths and injuries
by drowning in
floods; migration related
health
effects		 Costs of coastal protection
versus costs of land-use
relocation; potential for
movement of populations
and infrastructure; also
see tropical cyclones
above



Explanation for the IPCC Table above. Examples of possible impacts of climate change due to changes in extreme weather frequency and climate events, based on projections to the mid to late 21st century. These do not take into account any changes or developments in adaptive capacity. The likelihood estimates in Column 2 relate to the phenomena listed in Column 1. The direction of trend and likelihood of phenomena are for IPCC SRES projections of climate change.

 

Current observations appear to show an increase in ‘extreme weather frequency’. Visit our extreme weather page to see events over the past month.