Table
3-4: Water resource 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 |
Water Resource Effectsc |
Water supply [WGII
TAR Sections 4.3.6 & 4.5.2] |
Peak river flow shifts from spring toward winter in
basins where snowfall is an important source of water (high confidenced).
|
Water supply decreased in many water-stressed countries,
increased in some other water-stressed countries (high confidenced). |
Water supply effects amplified (high confidenced). |
Water quality [WGII
TAR Section 4.3.10] |
Water quality degraded by higher temperatures. Water
quality changes modified by changes in water flow volume. Increase
in saltwater intrusion into coastal aquifers due to sea-level rise
(medium confidenced). |
Water quality degraded by higher temperatures (high
confidenced). Water quality changes modified by changes
in water flow volume (high confidenced). |
Water quality effects amplified (high confidenced).
|
Water demand [WGII
TAR Section 4.4.3] |
Water demand for irrigation will respond to changes
in climate; higher temperatures will tend to increase demand (high
confidenced). |
Water demand effects amplified (high confidenced).
|
Water demand effects amplified (high confidenced). |
Extreme events [WGI
TAR SPM; WGII TAR SPM]
|
Increased flood damage due to more intense precipitation
events (high confidenced). Increased drought frequency
(high confidenced). |
Further increase in flood damage (high confidenced).
Further increase in drought events and their impacts. |
Flood damage several-fold higher than "no climate
change scenarios." |
* Refer to footnotes
a-d accompanying Table 3-1. |