Source: University of Aarhus, Faculty of Agricultural Sciences (formerly Danish Institute of Agricultural Sciences)

Agriculture must be prepared for the future by adapting to climate changes. In this way it can take advantage of the situation while at the same time limiting the risk of nutrients and pesticides leaching to the aquatic environment.

Every cloud has a silver lining. The same goes for global warming. In some areas, global warming will in all likelihood give rise to problems, while in other areas there will be benefits. Agriculture in Denmark can take advantage of global warming if it learns to adapt to climate changes.

Climate changes are not only on the way; they are already here. There is nothing we can do to alter conditions – at least not in the short run. Instead, agriculture must learn to adapt and take advantage of the benefits that global warming brings, says research professor Jørgen E. Olesen from the Danish Institute of Agricultural Sciences.

Global warming has already announced its arrival and the climate changes will, all things being equal, be amplified in the coming years. This will have a marked effect on agriculture and the environment.

New weather and new agriculture

There will be longer periods in the autumn without crop growth because the grain matures earlier and the winter seed is sown later. Climate changes will, however, generally increase crop yield. Higher yields require higher levels of N-fertilizer, though. Together with the wetter winters and longer periods with bare earth in the autumn, there will also be improved conditions for leaching of nitrogen (N).

The balmy and humid weather is also expected to increase the problems with pests and diseases in crop production. This can lead to an increased need for pesticides. Both nutrients and pesticides risk being leached with the increasing frequency of downpours.

In order to prevent climate changes from leading to increasing pollution of the aquatic environment, and to take advantage of the benefits that the new climate brings to agriculture, agriculture must adapt. This can mean changes in crop production patterns, breeding of varieties that utilise N more efficiently, and establishment or enlargement of zones, borders and other areas that can absorb nitrogen and phosphorus. Areas that risk becoming submerged due to climate changes can advantageously be used as filters instead of being re-drained. Flooding of low-lying areas in a wetter winter climate can thereby be one of the keys to reducing the environmental burden of agriculture.

Sensitive aquatic areas

There are two important reasons for showing an interest in the relation between agriculture and the aquatic environment in precisely Denmark. In the first place, on the European level, Denmark has a very large share of the total intensive farming area, which means use of nutrients and pesticides. Loss of nutrients from agriculture to the aquatic environment gives increased growth of algae, which leads to oxygen depletion. The process is promoted by higher temperatures and less wind.

In the second place, Denmark lies right beside the Baltic Sea, which is the world’s largest brackish water area. Both nitrogen and phosphorus have a great influence on the aquatic environment. The Baltic Sea is layered and is stirred only slightly unless there are strong winds. These conditions produces low oxygen repletion and greater sensitivity to oxygen depletion. With warming of the sea, its sensitivity increases.

- In order to give recommendations to farmers we must undertake analyses that can point out which geographic areas are risk areas and pinpoint when the problems will start. The information must be incorporated into a plan so farmers can alter their production in time, says Jørgen E. Olesen.

Jørgen E. Olesen is studying how climate changes can affect agriculture the next 100 years with regard to yield and nitrogen. He is using climate models based on four different future scenarios prepared by the UN Climate Panel.