Natural environment in the context of climate change adaptation is divided into the following systemic areas:
Climate change may cause shifts in species’ distribution areas. Especially endangered are species at their range boundaries. Changing climate may decrease the adaption ability and viability of species. The changes in species phenology alter interspecific relationships. Climate change can also increase the negative impact of invasive species on biodiversity, causing for example the establishment of new and altered impacts of existing invasive species. Due to shifts in species distribution areas and spread of invasive species, climate change can have negative impact on protected areas. Only few studies about the impact of climate change on protected areas can be found. Increase of extent of protected areas and their coherence is essential to the maintenance of biodiversity.
Terrestrial ecosystems and climate change are inherently linked. Increasing temperature, precipitation and extreme weather events caused by climate change influence the structure and functions of forest ecosystems, altering forest growth, carbon accumulation, and thus the whole nutrient cycle. Changes in the hydrological regime and water table will affect wetlands greenhouse gas balance – carbon dioxide and nitrous oxide emissions generally increase and methane emissions decrease. Soil carbon sequestration in grass- and arable land is affected by increased temperature, plant growth, rainfall, but also by soil obesity, water regime, particle size distribution and concentration of carbonates. Different terrestrial ecosystems are essential for the provision of ecosystem services such as carbon sequestration, protection against floods and soil erosion, and the regenerative and healthy ecosystems provide substantial protection against the effects of climate change. In order to assure sustainability of terrestrial ecosystems benefits and services in changing climate conditions, it is necessary to implement appropriate climate adaptation measures, which are currently missing in Estonia.
There is an increasing need to add climate change adaptation and mitigation measures into watershed management plans. Changing climate will affect freshwater ecosystems mostly by changes in ice regime, ice-free period water temperature, water chemistry and biota. When considering large lakes, Lake Peipsi is most vulnerable to changes in water temperature, Lake Võrtsjärv is strongly affected by water level fluctuations. The most serious threat to small lakes is eutrophication and climate change will affect these lakes in a type-specific manner. Shifts in the water column stratification and mixing patterns are predicted in small lakes. Due to increased water temperature, cyanobacterial blooms are more common in the future. Decrease in snow cover will lead to lower maximum water level and runoff in the watercourses compared to what is seen today. Summer minimum drain period will prolong and high water levels in the autumn can be seen more often. These changes will improve the ecological status of rivers in winter, but make it worse during the summer. Changes in the hydrological regime of watercourses will affect the transport of nutrients and other substances. Climate impacts on freshwaters are difficult to distinguish from the impacts of human activity.
Marine esosystems, incl. the Baltic Sea
Eutrophication is one of the most important environmental issues in the Baltic Sea. Eutrophication along with climate change poses a significant threat for benthic communities and is a direct driver of decreasing marine biodiversity. More frequent disturbances and drifts in seawater circulation, temperature and salinity regime directly affect marine ecosystem stability. Increased water temperature enhances primary production which results in increased eutrophication rate and gradually higher establishment of invasive species. In reality, there is a significant lack of information on marine environment changes in relation to climate change. There is a need to improve the resistance capacity to direct physical stressors and reduce anthropogenic pressures in order for the marine ecosystems to adapt to changing climate conditions.
We have quite a good understanding of different theoretical effects of climate change on different ecosystem services, but there is little data on the actual effects of past extreme weather events. There is plenty of data about various supporting services in Estonia, but the data about the status and scope of regulating and cultural services is insufficient. Climate change adaptation measures are not applied in Estonia, although some measures in place contribute also to better adaptation.