Impacts and Risks of Global Change - Impact of Global Changes on Mountains: Responses and Adaptation - page 45

Although agricultural lands generate very large fl uxes of CO 2 to and from
the atmosphere, the net fl ux of CO 2 is small (Smith et al. 2007).
Methane and nitrous oxides from agriculture contribute about 47 and
58% of total methane and nitrous oxide emissions, with a wide range of
uncertainty, however. N 2 O emissions from soils and CH 4 from enteric
fermentation constitute the largest source, biomass burning, rice production
and manure management account for the rest (Smith et al. 2007, CIPRA
2011: 8).
On the other hand climate change has a strong impact on agriculture.
The effects shown in Fig. 3.6 differ between regions in occurrence,
magnitude and impact.
Figure 3.6. Climate change impacts on agriculture (modifi ed from CIPRA 2011).
Soil erosion is one major impact of climate change. Specifically
mountainous terrain is prone to soil erosion due to its steepness. Excess
water due to intense or prolonged precipitation may cause tremendous
damage to soil. Erosion is projected to aggravate with increases in
precipitation amount and intensity (EEA 2008).
Ecosystems are strongly interlinked with the hydrological cycle
that has already altered over the past several decades. The shrinking of
glaciers, permafrost and snow cover, changes in precipitation patterns and
increasing temperatures and evaporation will increase the competition for
water by different sectors, in particular during the summer months when
precipitation and run-off is reduced. The groundwater level is decreasing,
and irrigation in semi-arid and arid zones is affected. F.i. in the Southern
Alps the groundwater level dropped by 25% over the last 100 years (EEA
2009).
Increasing air temperatures are signifi cantly affecting the duration of
the growing season. In temperate- and cold humid zones the impact on
plants is mainly reported as a trend towards an earlier start of growth of