Synthesis Report - Question 3

Climate Change 2001: Synthesis Report

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  Small Islands and Low-Lying Coasts


Populations that inhabit small islands and/or low-lying coastal areas are at particular risk of severe social and economic effects from sea-level rise and storm surges. Many human settlements will face increased risk of coastal flooding and erosion, and tens of millions of people living in deltas, low-lying coastal areas, and on small islands will face the risk of displacement of populations and loss of infrastructure and/or substantial efforts and costs to protect vulnerable coastal areas. Resources critical to island and coastal populations such as freshwater, fisheries, coral reefs and atolls, beaches, and wildlife habitat would also be at risk.

WGII TAR Sections 7.2.2, 17.2, & 19.3.4
3.24 Projected sea-level rise will increase the average annual number of people flooded in coastal storm surges (high confidence). The areas of greatest absolute increase in populations at risk are southern Asia and southeast Asia, with lesser but significant increases in eastern Africa, western Africa, and the Mediterranean from Turkey to Algeria. Significant portions of many highly populated coastal cities are also vulnerable to permanent land submergence and especially to more frequent coastal flooding superimposed on surge heights, due to sea-level rise. These estimates assume no change in the frequency or intensity of storms, which could exacerbate the effects of sea-level rise on flooding risks in some areas.

WGII TAR Sections 6.5.1, 7.2.2, & 17.2.2
  Market Effects

3.25 The aggregated market sector effects, measured as changes in gross domestic product (GDP), are estimated to be negative for many developing countries for all magnitudes of global mean temperature increases studied (low confidence), and are estimated to be mixed for developed countries for up to a few °C warming (low confidence) and negative for warming beyond a few °C (medium to low confidence). The effects of climate change will have market sector effects by changing the abundance, quality, and prices of food, fiber, water, and other goods and services (see Table 3-5). In addition, climate change can have market effects through changes in energy demand, hydropower supply, transportation, tourism and construction, damages to property and insurance losses from extreme climate events, loss of coastal land from sea-level rise, location and relocation decisions for development and populations, and the resource needs and costs of adapting to climate change. Estimates of net market effects from a few published studies, aggregated across sectors and to national or regional scales, indicate losses for most developing countries and regions studied. Both gains and losses are estimated for developed countries and regions for increases in global mean temperature of up to a few °C. Economic losses are estimated for developed countries at larger temperature increases. When aggregated to a global scale, world GDP would change by plus or minus a few percent for global mean temperature increases of up to a few °C, with increasing net losses for larger increases in temperature. The estimates generally exclude the effects of changes in climate variability and extremes, do not account for the effects of different rates of climate change, only partially account for impacts on goods and services that are not traded in markets, and treat gains for some as canceling out losses for others. Therefore, confidence in estimates of market effects for individual countries is generally low, and the various omissions are likely to result in underestimates of economic losses and overestimates of economic gains.

WGII TAR Sections 6.5, 7.2-3, 8.3, 18.3.4, 18.4.3, 19.4.1-3, & 19.5
Table 3-5: Other market sector effects 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
Other Market Sector Effectsc
Energy [WGII TAR Section 7.3] Decreased energy demand for heating buildings (high
Increased energy demand for cooling buildings (high
Energy demand effects
amplified (high confidenced).
Energy demand effects
amplified (high confidenced).
Financial sector [WGII TAR Section 8.3]

  Effects on financial sector amplified. Increased insurance prices and reduced insurance availability (high confidenced).
Aggregate market effectse [WGII TAR Sections 19.4-5] Net market sector losses in many developing countries (low confidenced).
Mixture of market gains and losses in developed countries (low confidenced).
Losses in developing countries amplified (medium confidenced).
Gains diminished and losses amplified in developed countries (medium confidenced).
Losses in developing countries amplified (medium confidenced).
Net market sector losses in developed countries from warming of more than a few �C (medium confidenced).
* Refer to footnotes a-d accompanying Table 3-1.
Figure 3-5: Projected changes in average annual water runoff by the year 2050, relative to average runoff for the period 1961-1990, largely follow projected changes in precipitation. Changes in runoff are calculated with a hydrologic model using as inputs climate projections from two versions of the Hadley Centre AOGCM for a scenario of 1% per year increase in effective CO2 concentration in the atmosphere: (a) HadCM2 ensemble mean and (b) HadCM3. Projected increases in runoff in high latitudes and southeast Asia, and decreases in central Asia, the area around the Mediterranean, southern Africa, and Australia are broadly consistent across the Hadley Centre experiments, and with the precipitation projections of other AOGCM experiments. For other areas of the world, changes in precipitation and runoff are scenario- and model-dependent.
WGII TAR Section 4.3.6

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