Prerequisites for reindeer husbandry are changing
Climate change affects the quantity and quality of nutrition available to reindeer. Milder winters may make it more difficult for reindeer to find food, which damages their health and reduces the number of calves born. However, the longer growing season increases the availability of food in the summer. Loss of pastureland and the reduced availability of nutrition in the winter are likely to decrease the productivity and profitability of reindeer husbandry.
Reindeer and human – reindeer husbandry is an important form of primary sector production in Northern Finland
The reindeer (Rangifer tarandus tarandus) is a semi-domesticated subspecies of the wild deer found on the Eurasian Arctic tundra and in Subarctic mountain birch forests and northern boreal forests. Reindeer husbandry as a source of livelihood was originally invented by the Fennoscandian Sami but quickly spread among other inhabitants of Northern Finland . Today, reindeer husbandry is not just an important primary or secondary source of income but also a major promoter of continued human settlement and culture as well as a tourist attraction in Northern Finland.
Finland's reindeer herding region includes almost the whole of Lapland and parts of the region of Oulu, and its area accounts for approximately 36 percent of Finland's total area . Habitats vary considerably within the reindeer herding region, from forests to treeless fell tops. The majority of Finland's reindeer live in forests throughout the year. Reindeer husbandry and grazing affect the environment. Large numbers of reindeer cause wear in winter pastures, and reindeer husbandry fights over territory with forestry, construction, tourism, and the mining industry, for example . Due to losses resulting from predation, measures have been taken to restrict the access of large carnivorous mammals to the reindeer herding region.
The structure of reindeer husbandry has changed over the last few decades; the number of herders has decreased but the number of reindeer per herder has increased. In the 2006–2007 season, there were approximately 4,900 reindeer herders in Finland . Reindeer husbandry is an important source of livelihood as well as an integral part of the culture and ethnic identity of the Sami . At the moment, the Sami own almost one third of all reindeer in Finland .
Reindeer are counted every ten years and maximum numbers of reindeer set for each reindeer herding district and each herder by the Finnish Ministry of Agriculture and Forestry. The number of reindeer left alive for the winter has hovered at around 200,000 in the 21st century . The amount of reindeer meat produced in recent years has been between 2.3 and 2.8 million kilograms , with a total value of approximately 37 million euros per year after processing. Including reindeer-based tourism and other products derived from reindeer such as handicrafts and utensils, the estimated turnover from the reindeer industry amounts to between approximately 50 and 60 million euros per year .
Changeable weather conditions and loss of winter pastures among the biggest future challenges for reindeer
Reindeer have adapted well to northern conditions. Their fur is an efficient insulator that keeps them warm even in extremely cold weather. Their hooves adapt to season and help them walk in the snow. Digging for food, which mostly comprises lichen, grasses, and subshrubs, is nevertheless difficult in deep snow.
In the future, winters in the reindeer herding region will become milder, rainfall will increase, and the growing season will become longer. These changes have many implications on reindeer husbandry. If snow cover increases and a crust forms on the snowpack due to repeated melt-freeze cycles, digging for food from under the snow will become harder and force reindeer to use more energy for foraging . On the other hand, harder snow makes it easier for reindeer to walk on top of the snowpack and allows them to eat any lichen that grows on tree branches.
Increasingly changeable weather conditions especially in early winter before a permanent layer of snow has formed affect the quantity and quality of nutrition available for reindeer. If the ground does not freeze properly and snow cover melts in the middle of the winter, the snowpack is more likely to have frozen layers and pastures may become mouldy. Winter rains that cause water to seep through the snowpack all the way to the ground may build a hard layer of ice and snow on top of vegetation . Warm and humid conditions under the snowpack, which may result from lack of ground frost, for example, may increase the likelihood of fungal growth in plants. Some of these microfungi produce compounds that are toxic to reindeer.  
Negative changes in the quality of winter pastures and the availability of nutrition make it considerably more difficult for reindeer to survive over the winter. As suitable pastureland becomes increasingly scarce and competition between the animals increases, pastures wear more quickly and reindeer have to find better grazing areas or supplement their diet with lichen growing on trees, for example. On the other hand, increasing industrial land use in the north and the dwindling availability and fragmentation of suitable pastureland is forcing more and more herders to begin feeding their reindeer. The availability of nutrition in the winter is especially critical for pregnant cows, and the health of cows affects the numbers of calves born and their weight come the following autumn. Increasingly mild winters may have many negative effects on the success of calving and the productivity of reindeer husbandry .
The longer growing season is a benefit, droughts, heat, and parasites a disadvantage
If the spring comes earlier and the growing season becomes longer, more nutrition, such as grasses, sedges, subshrubs, and tree leaves, will be available for reindeer in the summer. An increase in the volume of plant biomass is likely to improve the health of reindeer and accelerate calf growth. A positive correlation has already been found between high numbers of calves born and early melting of snow  . The nutritional value of plants, such as protein and phenol levels, may also either increase or decrease . Reindeer may nevertheless be able to balance their summertime diets thanks to the great variety of plants available, which number as many as two or three hundred .
Rainfall also affects the quality of nutrition available for reindeer. The longer growing season does not improve the food situation as much during dry summers, because plants wilt more quickly and there are no mushrooms, which are an important source of nutrition for reindeer in the autumn. 
Warm summers cause heat stress in reindeer. It forces reindeer to climb to windy treeless fell tops to cool down, which increases energy consumption and reduces the time spent grazing. This lowers the weight of the animals and may increase mortality.  Rising summer temperatures and increasing rainfall also increase the nuisance caused by blood-sucking insects  and may allow new parasites such as deer flies to spread to the reindeer herding region.
Milder winters, on the other hand, create favourable conditions for pests found in mountain birches, such as the winter moth, which may reduce the amount of nutrition available for reindeer. Rising summer temperatures may also increase the likelihood of epidemics caused by a parasitic deer nematode (Setaria tundra) spread by mosquitoes. The parasite causes peritonitis in calves, increases mortality, and lowers the value of reindeer meat. It can also use other species of deer as its host.   The nuisance caused by insects may decrease if dry summers become more common, but dryness also decreases the amount of nutrition available for reindeer .
Advance of the tree line and loss of lichen
Global warming causes vegetation zones and the tree line to move northwards and higher up the slopes of fells. This reduces the area of treeless fell tops, which are important for reindeer both in the winter and in the summer, and may increase competition between reindeer husbandry and forestry over land use. Growth conditions for lichen change as more trees grow and forests become increasingly densely vegetated, and faster-growing plants and species that prefer shade, such as mosses, grasses, and subshrubs, may replace lichen . Signs suggesting that ground-dwelling lichen is decreasing and vascular plants increasing, a trend which may be related to the changed climatic conditions of northern areas, have already appeared across the entire Arctic region .
Forest fires, which may become more common with increasing dryness and windiness, increasing competition over food resources as reindeer are packed into smaller and smaller areas, and overgrazing also damage lichen growth and regeneration . The harmful effects of various different factors reduce the volume of high-quality pastureland suitable for reindeer husbandry. Even if the availability of nutrition for reindeer was to increase in the spring, summer, and autumn, reindeer that winter on natural pastureland still depend largely on the availability of both ground-dwelling and tree-growing lichen. Replacing lichen with herbaceous plants in the reindeer's winter diet usually means less energy and poorer animal health in the winter .
Changing practices, tourism, and predators affect the profitability of reindeer husbandry as a source of livelihood
Loss of pastureland and changes in the availability of nutrition for reindeer affect the productivity of reindeer stock and especially the number and condition of slaughtered animals. On the other hand, supplementing the dwindling winter pasture resources with feeding increases the costs involved in reindeer husbandry and constitutes a major change in the nature of both the animals and the industry. All this affects the profitability and characteristics of reindeer husbandry. Permanent changes in weather conditions, such as increasingly mild winters and long summers, may gradually also affect reindeer husbandry practices. For example, with the icy season becoming shorter each year, reindeer herders may no longer be able to drive their stock across frozen lakes and rivers, which may make rounding up reindeer more difficult . Reindeer husbandry practices need to adapt to the changes; pasture rotation and limiting the number of reindeer in a given area, for example, could help to improve the quality of the remaining lichen pastures .
Revenue generated from reindeer-based tourism may also change in the future: Shorter winters mean shorter tourism seasons. On the other hand, the appeal of Lapland as a winter tourism destination may increase, which may increase demand for reindeer-based products and services such as reindeer sledging and therefore boost supply during the tourism season.
Losses resulting from predators, the time spent looking for dead animals, and the cost of replacing lost animals affect the profitability of reindeer husbandry. At the moment, the Finnish State compensates reindeer herders for predation losses on the basis of the number of reindeer carcasses found during the winter where a kill by a predator is indicated and not according to the number of terrestrial carnivores occurring in the area, which is what is done in the case of the Golden Eagle, for example, and in other Nordic Countries. However, nowhere near all of the reindeer carcasses are ever recovered. With snowy conditions prevailing for a shorter period of time each year, finding reindeer that have been killed by predators becomes less and less likely, which means less compensation for reindeer herders, although reindeer herding districts are currently paid compensation for calf losses even when no carcass can be demonstrated.