Table
3-3: Agricultural 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 |
Agricultural Effectsc |
Average crop yieldsg [WGII
TAR Sections 5.3.6, 10.2.2,
11.2.2, 12.5,
13.2.3, 14.2.2,
& 15.2.3] |
Cereal crop yields increase in many mid- and high-latitude
regions (low to medium confidenced).
Cereal crop yields decrease in most tropical and subtropical regions
(low to medium confidenced). |
Mixed effects on cereal yields in mid-latitude regions.
More pronounced cereal yield decreases in tropical and subtropical
regions (low tomedium confidenced). |
General reduction in cereal
yields in most mid-latitude
regions for warming of more than a few °C (low to medium confidenced).
|
Extreme low and high temperatures [WGII
TAR Section 5.3.3] |
Reduced frost damage to some crops (high confidenced).
Increased heat stress damage to some crops (high confidenced).
Increased heat stress in livestock (high confidenced). |
Effects of changes in extreme temperatures amplified
(high confidenced). |
Effects of changes in extreme temperatures amplified
(high confidenced). |
Incomes and prices [WGII
TAR Sections 5.3.5-6] |
|
Incomes of poor farmers in developing countries decrease
(low to medium confidenced). |
Food prices increase relative to projections that
exclude climate change (low to medium confidenced). |
* Refer to footnotes
a-d accompanying Table 3-1.
g. These estimates are based on the sensitivity of
the present agricultural practices to climate change, allowing (in
most cases) for
adaptations based on shifting use of only existing technologies. |