Potential impacts of
climate change
Observed climate trends
Trend
in global average surface temperature
The mean global surface temperature has increased by about 0.3 to
0.6°C since the late 19th century and by about 0.2 to 0.3°C over
the last 40 years. |
Precipitation
changes: trend over land from 1900 to 1994
Precipitation has increased over land at high latitudes of the
Northern Hemisphere, especially during the cold season. Decrease
in precipitation occurred in steps after the 1960s over the
subtropics and the tropics from Africa to Indonesia. |
Sea
level rise due to global warming
Over the last 100 years, the global sea level has risen by about
10 to 25 cm. |
Potential impacts of
climate change
Potential
climate change impacts
If greenhouse gas concentrations keep rising, climatic changes are
likely to result. Those changes will potentially have wide-ranging
effects on the environment and socio-economic sectors. |
The
six IPCC scenarios
The projection of future climate change depends partly on the
assumptions made about future emissions of greenhouse gases and
aerosol precursors and the proportion of emissions remaining in
the atmosphere. |
Projected
changes in CO2 and climate: summary of assumptions in
the IPCC 1992 alternative scenarios
Projected anthropogenic CO2 emissions from fossil fuel
use, deforestation and cement production for the six IPCC emission
scenarios. |
Projected
Changes in Global Temperature
Climate models calculate that the global mean surface temperature
could rise by about 1 to 4.5 centigrade by 2100. |
Scenarios
of sea level rise
Models project an increase in global mean sea level of between 13
and 94 cm by the year 2100. |
Sensitivity,
Adaptability and Vulnerability
The potential impacts of climate change on the environment and
socio-economic systems can be understood in terms of sensitivity,
adaptability and vulnerability of the system. |
The
great weather and flood catastrophes over the last forty years
Some reports suggest that increase in climate variability or
extremes has taken place in recent decades. |
Forests
Forest
composition case study in North America
... |
Impact
on mountain vegetation zones
The figure shows a comparison of current vegetation zones at a
hypothetical dry temperate mountain site with simulated vegetation
zones under a climate-warming scenario. |
Cryosphere
Thinning
of the Arctic sea-ice
Ice draft in the 1990s is more than a meter thinner than it was 20
to 40 years earlier. |
Evolution
of the ice-breaking date in the River Torino (Finland)
Winter ice on the Tornio River in Finland has broken up
earlier and earlier since records began in 1693. |
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Changes
in permafrost temperatures at various depths in Fairbanks (Alaska)
Widespread loss of discontinous permafrost will trigger erosion or
subsidence of ice-rich landscapes, change hydrologic processes,
and release CO2 and methane to the atmosphere.
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Oceans and coastal areas
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Great
ocean conveyor belt
The global conveyor belt thermohaline circulation is driven
primarily by the formation and sinking of deep water (from around
1500m to the Antarctic bottom water overlying the bottom of the
ocean) in the Norwegian Sea.
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Potential
impact of sea-level rise on Bangladesh
Bangladesh, one of the world's poorest nations is also the country
most vulnerable to sea-level rise.
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Potential
impact of sea level rise: Nile Delta (today)
The Nile Delta is one of the oldest intensely cultivated areas on
earth. It is very heavily populated, with population densities up
to 1600 inhabitants per square kilometer. The low lying, fertile
floodplains are surrounded by deserts. Only 2,5% of Egypt's land
area, the Nile delta and the Nile valley, is suitable for
intensive agriculture. Most of a 50 km wide land strip along the
coast is less than 2 m above sea-level and is protected from
flooding by a 1 to 10 km wide coastal sand belt only, shaped by
discharge of the Rosetta and Damietta branches of the Nile.
Erosion of the protective sand belt is a serious problem and has
accelerated since the construction of the Aswan dam.
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Potential
impact of sea level rise: Nile Delta (0.5 to 1.0 metres)
Rising sea level would destroy weak parts of the sand belt, which
is essential for the protection of lagoons and the low-lying
reclaimed lands. The impacts would be very serious: One third of
Egypt's fish catches are made in the lagoons. Sea level rise would
change the water quality and affect most fresh water fish.
Valuable agricultural land would be innundated.
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Agriculture
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Changes
on cereal production under three different GCM equilibrium
scenarios
The figure shows change in cereals production under three
different GCM equilibrium scenarios (percent from base estimated
in 2060).
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Impact
of temperature rise on robusta coffee in Uganda
In Uganda, the total area suitable for growing Robusta coffee
would be dramatically reduced with a temperature increase of 2
centigrades.
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Freshwater resources
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Freshwater
stress
Even if the world maintained the pace of the 1990s in water supply
development, it would not be enough to ensure that everyone had
access to safe drinkning water by 2025.
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Population
and freshwater stress
One study suggests that although global water conditions may
worsen by 2025 due to population pressure, climate change could
have a net positive impact on global water resources.
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Human health
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Spread
of major tropical vector-borne diseases
Climate change and altered weather patters would affect the range
(both altitude and latitude), intensity, and seasonality of many
vector-borne and other infectioius diseases.
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Potential
dengue transmission in case of temperature rise
A warmer climate increases occasions of vector borne tropical
diseases. The figure depicts weeks of potential dengue
transmission under current temperature and 2°C and 4 °C warming.
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Malaria.
Plasmodium vivax, with the Anopheles mosquito as a vector, is an
organism causing malaria. The main climate factors that have
bearing on the malarial transmission potential of the mosquito
population are temperature and precipitation.
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source: United
Nations Environment Programme / GRID-Arendal
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