| |
Figure 3-4: The level of the
sea at the shoreline is determined by many factors in the global environment
that operate on a great range of time scales, from hours (tidal) to millions
of years (ocean basin changes due to tectonics and sedimentation).
On the time scale of decades to centuries, some of the largest influences
on the average levels of the sea are linked to climate and climate change
processes. |
WGI TAR Box TS-2 |
| |
Human Health
|
|
| 3.17 |
Overall climate change is projected to
increase threats to human health, particularly in lower income populations
predominantly within tropical/ subtropical countries. Climate change
can affect human health through multiple pathways, including direct effects
(e.g., reduced cold stress in temperate countries but increased heat stress,
loss of life in floods and storms) and indirect effects that operate through
changes in the ranges of disease vectors (e.g., mosquitoes)5
, water-borne pathogens, water quality, air quality, food availability and
quality (e.g., decreased protein content in some cereals), population displacement,
and economic disruption (medium to high confidence). Some effects
may be beneficial (e.g., reduced cold stress, and reduced disease transmission
in some cases), but the predominant effect is anticipated to be adverse
(see Table 3-1). Actual impacts will
be strongly influenced by local environmental conditions and socio-economic
circumstances, and for each anticipated adverse health impact there is a
range of social, institutional, technological, and behavioral adaptation
options to lessen that impact. Adaptations could, for example, encompass
strengthening of the public health infrastructure, health-oriented management
of the environment (including air and water quality, food safety, urban
and housing design, and surface water management), and the provision of
appropriate medical care.
|
WGII
TAR Sections 5.3, 9.1, 9.5,
& 9.11 |
| |
Biodiversity and Productivity
of Ecological Systems
|
|
| 3.18 |
Diversity in ecological systems is expected
to be affected by climate change and sea-level rise, with an increased risk
of extinction of some vulnerable species (high confidence).
Significant disruptions of ecosystems from disturbances such as fire, drought,
pest infestation, invasion of species, storms, and coral bleaching events
are expected to increase (see Table
3-2). The stresses caused by climate change, added to other stresses
on ecological systems (e.g., land conversion, land degradation, harvesting,
and pollution), threaten substantial damage to or complete loss of some
unique ecosystems, and extinction of some critically endangered and endangered
species. Coral reefs and atolls, mangroves, boreal and tropical forests,
polar and alpine ecosystems, prairie wetlands, and remnant native grasslands
are examples of systems threatened by climate change. In some cases the
threatened ecosystems are those that could mitigate against some climate
change impacts (e.g., coastal systems that buffer the impacts of storms).
Possible adaptation methods to reduce the loss of biodiversity include the
establishment of refuges, parks and reserves with corridors to allow migration
of species, and the use of captive breeding and translocation of species.
|
WGII
TAR Sections 5.2.3, 5.4.1, 16.2,
17.2, & 19.3.2-3 |
| |
| Table
3-1: Human health consequences of climate change if no climate
policy interventions are made. |
| |
2025 |
2050 |
2100 |
CO2 concentrationa
|
405-460 ppm |
445-640 ppm |
540-970 ppm |
| Global mean temperature change from the year 1990b |
0.4-1.1°C |
0.8-2.6°C |
1.4-5.8°C |
| Global mean sea-level rise from the year 1990b |
3-14 cm |
5-32 cm |
9-88 cm |
| Human Health Effectsc |
| Heat stress and winter mortality [WGII
TAR Section 9.4] |
Increase in heat-related deaths and illness (high
confidenced).
Decrease in winter deaths in some temperate regions (high confidenced). |
Thermal stress effects
amplified (high confidenced). |
Thermal stress effects amplified (high confidenced). |
| Vector- and water-borne diseases [WGII
TAR Section 9.7] |
|
Expansion of areas of potential transmission of malaria
and dengue (medium to high confidenced). |
Further expansion of areas of potential transmission
(medium to high confidenced). |
| Floods and storms [WGII
TAR Sections 3.8.5 & 9.5] |
Increase in deaths, injuries, and infections associated
with extreme weather (medium confidenced). |
Greater increases in deaths, injuries, and infections
(medium confidenced). |
Greater increases in deaths, injuries, and infections
(medium confidenced). |
Nutrition [WGII
TAR Sections 5.3.6 & 9.9]
|
Poor are vulnerable to increased risk of hunger, but
state of science very incomplete. |
Poor remain vulnerable to increased risk of hunger. |
Poor remain vulnerable to increased risk of hunger. |
a. The reported ranges
for CO2 concentration are estimated with fast carbon cycle
models for the six illustrative SRES scenarios and correspond to the
minimum and maximum values estimated with a fast carbon cycle model
for the 35 SRES projections of greenhouse gas emissions. See WGI
TAR Section 3.7.3.
b. The reported ranges for global mean
temperature change and global mean sea-level rise correspond to the
minimum and maximum values estimated with a simple climate model for
the 35 SRES projections of greenhouse gas and SO2 emissions.
See WGI TAR Sections
9.3.3 and 11.5.1.
c. Summary statements about effects of climate change
in the years 2025, 2050, and 2100 are inferred from Working Group
II's assessment of studies that investigate the impacts of scenarios
other than the SRES projections, as studies that use the SRES projections
have not been published yet. Estimates of the impacts of climate change
vary by region and are highly sensitive to estimates of regional and
seasonal patterns of temperature and precipitation changes, changes
in the frequencies or intensities of climate extremes, and rates of
change. Estimates of impacts are also highly sensitive to assumptions
about characteristics of future societies and the extent and effectiveness
of future adaptations to climate change. In consequence, summary statements
about the impacts of climate change in the years 2025, 2050, and 2100
must necessarily be general and qualitative. The statements in the
table are considered to be valid for a broad range of scenarios. Note,
however, that few studies have investigated the effects of climate
changes that would accompany global temperature increases near the
upper end of the range reported for the year 2100.
d. Judgments of confidence use the following
scale: very high (95% or greater), high (67-95%),
medium (33-67%), low (5-33%), and very
low (5% or less). See WGII
TAR Box 1-1. |
|
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