Vulnerabilities - Terrestrial biodiversity

In Norway, effects of climate change, particularly a temperature increase, have already been observed on terrestrial ecosystems. One has seen earlier arrival in migrating birds, earlier sexual maturation in some animals, higher production and reproduction in both plants and animals, and earlier budding and pollen production. There are also some signs of plant species having expanded northwards or upwards. Satellite-based mapping indicate that the growing season has increased up to 2-4 weeks in parts of Norway since the 1980s. Melting of palsa mires in recent years has been observed (1).

Future climate changes in Norway are expected to lead to migration of species and vegetation shifts to higher altitudes and latitudes, or that species will need to adapt to changed living conditions. … an increase in temperature and/or precipitation is expected to result in the degeneration of the most mar­ginal palsa peatland areas in the course of a few decades (1).

Observations on the distribution and frequency of vascular plants have been performed on 23 mountains situated along a west–east gradient in Jotunheimen, central Norway, where detailed site descriptions and species lists exist from 1930. The sites were resurveyed during the summer of 1998, to examine possible changes in species richness and species distributions along the altitudinal gradient during a 68-year period (2).

Large changes in species richness and altitudinal distributions have occurred during the last 70 years, despite relatively small changes in temperature. … The mean annual temperature has increased by 0.4–1.2°C in the area over the last 100 years (3). … Mean annual precipitation has increased by 5–18% during the period 1896–1997, mainly caused by increased autumn precipitation (4).

Climatic warming may increase the impact of other ecological factors, such as nitrogen deposition (due to more precipitation), grazing and tourism, along with their interactions. It is stated that climatic warming is the major driving factor for the changes observed, and the upward shift of the vegetation belts may continue in the coming decades, especially on the eastern Jotunheimen mountains (2).

With a simple response to warmer climate, high altitude species might be driven upwards, eventually becoming locally extinct, due either to direct temperature effects or to habitat changes and increased competition. In western Jotunheimen, the effects of increased precipitation and rugged topography will probably ensure that refugial habitats for high-altitude, weakly competitive species will remain. In the east, with less increase in snowfall, available refugia are likely to become sparse, especially below 2000 m (2).

Tundra

The concurrent increase in the productivity of the tundra, probably due to longer and warmer growing seasons, will in the long run cause northern boreal forests to invade the tundra, while boreal forests at the southern ecotone are likely to retreat due to increasing drought, insects and more prevalent fires (12). Since the rate of loss at the southern ecotone due to relatively fast processes such as fire is likely to be higher than the rate of gain at the northern ecotone due to the slow growth conditions, the overall effect of these two processes for the boreal forests is likely to be negative during the transient phase, i.e. until a new equilibrium between climate and vegetation is established. However, in equilibrium a general increase in deciduous vegetation at the expense of evergreen vegetation is predicted at all latitudes (13).

Vulnerabilities - Fresh water and wetlands biodiversity

Atlantic salmon is an important species in rivers along the coast of Norway and Norwegian rivers are impor­tant for maintaining Atlantic salmon. In Southern Nor­way predictions are that temperatures will increase and summer precipitation will decrease. This can lead to significant increase in water temperature in rivers in southern Norway during summer. Water tempera­tures in the upper twenties are considered lethal to salmon. This means that rivers in southern Norway in the future may be too warm to maintain self sustain­ing salmon stocks (1).

Increased temperatures of lakes and rivers (by 1-3⁰C during the 20th century) have resulted in decreases in the ice cover by 12 days in average in the last century in Europe. These changes can be at least partly attributed to climate change, and partly to other causes such as freshwater use for cooling processes (e.g. power plants). Lake and river surface water temperatures are projected to increase further with increasing air temperatures (5). The summer stratifica­tion period in lakes will be longer and more distinct, which is likely to favour cyanobacterial blooms(1).

Changes in the timing of phytoplankton and zooplankton dynamics has been observed in a Norwegian lake in the last 4 decades. Trends were different for phytoplankton (later peaks in biomass) vs. zooplankton (earlier peaks). Earlier peaks were nevertheless observed for individual taxa within both groups, possibly due to an increase in spring temperatures (16).

Vulnerabilities - Marine, estuarine and intertidal biodiversity

A rise in the sea temperature will have impact on marine ecosystems. In recent years, distributional changes associated with a warmer climate, have al­ready taken place. In the North Sea there has been a change in plankton communities from cold to warm water species. Arctic species might be replaced by more southern species.

Over the period 1961 to 2003, global ocean temperature has risen by 0.10⁰C from the surface to a depth of 700 m, although lower temperatures have been recorded since 2003 (6). … How large the temperature increase will be in the ocean is uncertain, but an increase of 1-2⁰C in the water layers with highest biological activity has been predicted as fairly likely (7).

Changes in the timing of seasonal biological phenomena (phenology) and in the distribution of marine species have been observed, including earlier seasonal cycles (by 4-6 weeks) and northward movements, of up to 1100 km over the past 40 years, and it seems that these changes have accelerated since 2000. Further, sub-tropical species are occurring with increasing frequency in European waters (5).

The oceans have absorbed approximately 50% (ca. 525 billion tons) of the carbon dioxide (CO2) re­leased to the atmosphere since the beginning of the industrial revolution. When carbon dioxide is absorbed by the oceans it reacts with seawater to form carbonic acid. This has caused an increase in the acidity of about 30%. Present changes are at least 100 times more rapid than similar changes experienced over the past 100,000 years. Acidification gradually will make it more difficult for marine organisms to build calcium carbonate shells and skeletons. Impacts of ocean acidi­fication on biological processes are therefore expected, but their exact nature remains largely unknown and may occur across the range of ecosystem processes. … The acidi­fication of the oceans have potentially large impacts on the biological diversity (8).

Vulnerabilities - Interaction climate change and other factors

Not all expansion of the distribution or invasive plant species can be ascribed to climate change. Land use change and other human interventions associated with the facilitation of species dispersal will promote the spread of alien species. It should therefore be expected that changes in climate and in land use acting in combination will increase the risk of expansion of species (9).

An already important group of alien species that will likely become more prominent are garden plants and plantation trees that have become naturalized (10). Many of the numerous species that are grown in Norwegian gardens and green spaces or in forestry are well adapted to Norwegian conditions and are found in the wild. Some have been grown for a long time and have had good opportunities to spread. Other introductions are comparatively recent, but are basically well adapted to Norwegian conditions. They originate from areas in Asia and North America where the environment is comparatively similar to that in Norway as regards to the climate. New ornamental plants are continually being imported and it is likely that some of these will join the flora of alien species (7).

Species registered or established in neighbouring countries, but that have not been observed in Norway, as well as species that today are found on southern latitudes are expected to spread and expand northwards due to climate changes (11). Such species (“door knockers”) are numerous and the lack of data about the species ecological requirements (both physical and in interaction with other organisms) make predictions about which species may become problematic, challenging (7).

Adaptation strategies

Terrestrial biodiversity

Securing corridors or large habitats with cli­mate gradients and protecting already threatened species, are important measures for securing biological diver­sity. Also stronger regulation preventing the import, spread and establishment of invasive, alien species is important (1).

The Arctic

Given the scale and the magnitude of projected climatic impacts over the arctic, the only adaptation strategy is to protect the resilience of the system, its natural autonomous adaptation capacity. This is done by tackling the stresses that are currently affecting arctic biodiversity. Pollution is one of the major problems. It originates from shipping traffic (oil spills, accidents, chemical), mining, oil and gas development. Also persistent organic pollutants (POPs), heavy metals (mercury, lead, cadmium) and radionuclides are widespread (14).

Overall, the warming will favor an increase of human activities in the Arctic Circle. On land, conditions may be more favorable for people to move north, while the reduced ice cover over the arctic sea will likely increase the shipping traffic, fisheries opportunities and the exploitation of oil and gas reserves. This poses new environmental threats that must be addressed now (15). A potential solution is to identify and designate protected areas before any major industrial plan is put forward. This is part of a broad ecosystem approach that aims at (14):

• Conserving natural resources and services so that they can be the base for long-term sustainable development;
• Protection of key species, habitats and services that have regional and global benefits;
• Identifying and solve possible conflicts between stakeholders in the conservation and development field before major investments are put forward.

References

The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Norway.

1. Ministry of the Environment of Norway (2009)
2. Klanderud and Birks (2003)
3. Hanssen-Bauer and Nordli (1998), in: Klanderud and Birks (2003)
4. Hanssen-Bauer and Fïrland (1998), in: Klanderud and Birks (2003)
5. EEA (2008), in: Gjershaug et al. (2009)
6. Bindoff et al. (2007), in: Gjershaug et al. (2009)
7. Gjershaug et al. (2009)
8. Holmén and Dallmann (2009), in: Ministry of the Environment of Norway (2009)
9. Rosvold and Andersen (2008), in: Gjershaug et al. (2009)
10. Fremstad (2000), in: Gjershaug et al. (2009)
11. Bevanger et al. (2007), in: Gjershaug et al. (2009)
12. Denman et al. (2007); Fischlin et al. (2007), in: Fischlin (ed.) (2009)
13. Fischlin (ed.) (2009)
14. Cenacchi (2008)
15. Rosentrater and Ogden (2003), in: Cenacchi (2008)
16. Moe et al. (2022)