The current situation shows that only about five percent of the cultivated acreage in Switzerland is irrigated. It is mainly located in alpine dry valley regions and used to the largest extent in grassland, vegetables, vine and fruit production. In contrast, cereals are currently irrigated only to a very small extent (18).

The Swiss Plateau is the major production region for cereals in Switzerland. Changes in climatic conditions in this region are expected to particularly affect the production of spring-sown cereals such as maize. Maize is the most important spring-sown cereal in Switzerland and covers about 12% of the total cereal production acreage (19).

The hot and dry summer of 2003 caused an average yield loss in Switzerland of around 20% relative to the mean for 1991-1999, equivalent to an economic loss of 500 million Swiss Francs (24).

Pests and diseases

In addition to the direct effects of climate variability, climate change indirectly impacts crop yields by altering pest cycles. The first flight of codling moth, a pest of fruit trees, advanced by 10 days between 1972 and 2010 due to a shift to an earlier exceedance of a 15 °C mean threshold temperature in spring (25). Further warming projected by 2045-2075 would increase the likelihood of a second annual generation from 20% at present, to 70-100% (25). Walnut Husk fly, an exotic species that first invaded the Mediterranean region, recently reached Switzerland, likely by crossing the Alpine divide (26). 

The estimated impacts of climate change on maize yields are subject to large uncertainties. Model results suggest that up to around 2050 grain maize yield in Switzerland could either increase or decrease depending largely on the choice of modelling approach and climate model projections, but also depending on local conditions. The range of estimated yield changes for 2050 compared with 1981 – 2010 is within the range of interannual variability. This suggests that the climate in Switzerland will largely remain suitable for grain maize production until (at least) 2050. Future grain maize production may benefit from decreasing radiation deficits and decreasing growth temperature limitations. On the other hand, there may be negative effects due to heat and drought stress, and through accelerated crop development, particularly during vegetative growth, flowering and maturation (23).

Under present conditions, a moderate warming of less than 2 to 3°C would probably have a positive overall effect on Swiss agriculture. The productivity of meadows and the potential crop yield of many cultivated plants will increase as a result of the longer vegetation period, provided that the supply of water and nutrients is sufficient. This will also be beneficial for livestock farming (1,12). Climate change is expected to have small positive effects on winter wheat production, which represents the majority of the Swiss cereal production (17).

Trend analyses for the period 1951–2000 have shown that on average plants bloom 21 days earlier, foliation takes place 15 days earlier and leaves change colour 9 days earlier, while the falling of leaves takes place 3 days later (14). This trend will continue with future warming. Depending on the region, the vegetation period will be extended by about 7 to 10 days per decade (15), which will result in an increase in the potential annual production of pastures. With the decreasing number of frost days, the risk of frost damage decreases as well, although in the case of an early start of the growing season, the danger of late frost damage persists (12).

For Switzerland, the change of crop yield in 2080 referred to 1990 has been estimated based on several combinations of models and scenarios; the outcomes show an increase ranging from 20.2% - 22.8% (5).

If temperature rises by more than 2 to 3°C by 2050, the disadvantages will outweigh the advantages of warming. The increase in heat waves and drought periods is particularly problematic. Thus, high altitude areas will gain in importance as ecological buffers for livestock husbandry (1,2,12).

During the vegetation period water scarcity will become more frequent. Faster plant development will result in harvest losses for cereals and grain legumes. The risk of damage for arable crops and of yield loss in animal feed production will increase. Weeds and insect attacks are expected to occur more often as will damages caused by extreme events. Yield stability in general will be reduced (1,2).

More frequent heavy precipitation events will aggravate soil erosion. In contrast, constraints in agricultural practice due to waterlogged soils may become less in a warmer climate. Additionally, new pests and diseases can occur or persist and changes in the established trophic interactions (e.g. between pests and parasitoids or predators) could take place (1,2). Future temperature conditions in the course of this century can be expected to favour some crop pests, by enabling them to overwinter more easily on the Swiss Plateau, as well as some forest pests, which will likely reach higher elevations (27).

CO2-effect

Provided that all soil nutrients are sufficiently available, an increase in the atmospheric CO2 concentration, in combination with slightly  higher temperatures and sufficient rainfall, means an increase in the potential yield of many agricultural crops. The yield increase caused by CO2 is, however, minor in comparison to long-term cultivation effects, and the positive effect on yield will be weakened by more strongly rising temperatures (16). At the same time, a higher CO2 concentration reduces the protein content of wheat grains, which results in a reduction of the baking quality of the flour (12).

Field workdays

The number of field workdays will increase and the decrease in soil water content will favour the use of bigger agricultural machines. In summer, periods with 2 to 3 consecutive dry days are beneficial to fodder production because insufficient drying impairs the quality of hay and aftermath (12).

Livestock husbandry

Fodder production productivity will increase as a result of climate change at locations with sufficient water supply, and as a result, livestock farming will profit from cheaper, increasingly domestically produced feed. The longer grazing period, as well as new, adapted fodder plant mixtures may increase the potential of animal production. However, negative effects are also to be expected: The increase in heat days will cause problems for livestock husbandry. Furthermore, feed quality may decline and yield security decrease due to more frequent extreme events (12).

From research it was concluded that socio-economic assumptions have a much greater effect on the scenario results of future changes in agricultural production and land use then the climate scenarios (6).

The European population is expected to decline by about 8% over the period from 2000 to 2030 (7).

Scenarios on future changes in agriculture largely depend on assumptions about technological development for future agricultural land use in Europe (6). It has been estimated that changes in the productivity of food crops in Europe over the period 1961–1990 were strongest related to technology development and that effects of climate change were relatively small. For the period till 2080 an increase in crop productivity for Europe has been estimated between 25% and 163%, of which between 20% and 143% is due to technological development and 5- 20% is due to climate change and CO2 fertilisation. The contribution of climate change just by itself is approximately a minor 1% (8).

Care should be taken, however, in drawing firm conclusions from the apparent lack of sensitivity of agricultural land use to climate change. At the regional scale there are winners and losers (in terms of yield changes), but these tend to cancel each other out when aggregated to the whole of Europe (6).

Future changes in land use

If technology continues to progress at current rates then the area of agricultural land would need to decline substantially. Such declines will not occur if there is a correspondingly large increase in the demand for agricultural goods, or if political decisions are taken either to reduce crop productivity through policies that encourage extensification or to accept widespread overproduction (6).

Cropland and grassland areas (for the production of food and fibre) may decline by as much as 50% of current areas for some scenarios. Such declines in production areas would result in large parts of Europe becoming surplus to the requirement of food and fibre production (6). Over the shorter term (up to 2030) changes in agricultural land area may be small (9).

Although it is difficult to anticipate how this land would be used in the future, it seems that continued urban expansion, recreational areas (such as for horse riding) and forest land use would all be likely to take up at least some of the surplus. Furthermore, whilst the substitution of food production by energy production was considered in these scenarios, surplus land would provide further opportunities for the cultivation of bioenergy crops (6).

Europe is a major producer of biodiesel, accounting for 90% of the total production worldwide (10). In the Biofuels Progress Report (11), it is estimated that in 2020, the total area of arable land required for biofuel production will be between 7.6 million and 18.3 million hectares, equivalent to approximately 8% and 19% respectively of total arable land in 2005.

The agricultural area of Europe has already diminished by about 13% in the 40 years since 1960 (6).

The cultivation of land ecosystems will have to adapt to changed environmental conditions (e.g. earlier hay harvest, irrigation of permanent grassland, adjustment of livestock, increased significance of high altitude areas for summer pasture, changes in the choice of tree species). Cultivation of higher altitudes to sustain livestock
will likely become more lucrative again. That means that the alpine region will possibly become more important again as a rediscovered cultivation area as well as a retreat/replacement living space. However, this will only succeed if these areas are kept open by active management and the encroachment of meadows and pastures
is stopped (12).

Maize production

The impact of climate change on the maize production at the eastern Swiss Plateau is expected to be small if simple adaptation options such as shifts in sowing dates and adjustments in the production intensity are taken into account. The expected economic benefits of adopting irrigation will be rather small in the future, particularly if lower crop prices due to market liberalization are taken into account. Analysis shows that the economic benefits of the adoption of irrigation in Swiss maize farming are not only sensitive to changes in climatic conditions but also to the development of output and water prices. Strategic designs and valuations of long-term investments in irrigation facilities and capacities have to simultaneously consider combinations of climate, market and institutional risks (20).

Other adaptation measures at the field and farm level can help farmers to benefit from climate change and to reduce the need for irrigation in Swiss maize production: shifts in sowing dates, production intensity adjustments, changes in fallow and tillage practices, changes and diversifications in cropping patterns. Moreover, higher production and income risks might be covered with farm income diversification and with financial market instruments such as insurances or weather derivatives (21).