Climate change as a result of global warming is predicted to be most pronounced at high latitudes. It is known from experimental studies that Sphagnum species respond to enhanced UV radiation by decreasing their growth (Huttunen et al. 2005). Some polar bryophytes reproduce sexually and form sporulating sporophytes, e.g., Polytrichum hyperboreum on the Svalbard tundra. Antarctic mosses tend to reproduce sexually more often at higher Antarctic latitudes (Lewis-Smith & Convey 2002). Simultaneously, increased emissions of nitrogenous air pollutants cause increased nitrogen deposition over the northern hemisphere (Bouwman et al. 2002).

Mires, i.e., wetlands actively accumulating organic material, are believed to play an important role in the global biogeochemical carbon cycle, potentially serving as major long-term carbon sinks. Vegetation structure, however, strongly influences the carbon sink capacity of mires (Malmer & Wallén 2005). In general, carbon accumulation is greater in Sphagnum-dominated mires than in sedge-dominated mires (Dorrepaal et al. 2005).

Graminoid dominance, however, leads to increased methane (CH4) emissions, due both to increased root exudation of precursor compounds for CH4 formation and to plant-mediated transport of CH4 to the atmosphere through aerenchyma tissue, bypassing oxidation in the acrotelm. Because of such feedbacks on global carbon budgets, investigations of vegetation dynamics in response to ongoing pollution and warming are crucial for estimates of future scenarios of global change (Wiedermann et al. 2007).

There is great uncertainty in the estimations of the impacts and possible outcome of global climate changes.