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Comparisons of historical and contemporary aerial photographs provide evidence that Arctic vegetation has already undergone significant shifts in recent decades, foreshadowing changes that are likely to come.  Increased shrub cover has been confirmed in two repeat photography studies in northern Alaska and in a recent study in the Mackenzie Delta region of Canada.  Download press package here

 

These findings are confirmed by data from more detailed ground-based studies and from satellite monitoring.  The area covered by Tundra Climate has been reduced by about 20% since 1980, which reflects an increase in productivity related to the increases in shrub cover and indicate that the length of the growing season is increasing. Spatial variations correspond well to land surface temperature changes, with the greatest changes occurring in Arctic areas that have experienced the most climate warming. For example, expansion of white spruce forests into areas previously occupied by tundra has been documented in numerous locations in Alaska.

 

Together, these data provide strong evidence that tundra productivity is increasing regionally as a direct result of recent climate warming.  Tree line encroachment threatens tundra at its southern margins. Some models predict that by 2100 tree lines will have advanced northward by as much as 500 km, resulting in a loss of 51% of tundra habitat.  A number of experimental warming studies conducted in the Arctic can be used in conjunction with observations and paleo-data to predict how future climate warming will affect tundra ecosystems. An analysis of warming studies found that warming generally increased productivity.

 

Over longer time scales, diversity throughout the Arctic may actually increase, as historically non-Arctic species migrate northwards. However, the loss of endemic Arctic species and landscapes will result in an overall loss of biodiversity at the global scale. 

 

Often experiments and studies are based on short-term responses, which may be poor predictors of longer-term changes in vegetation composition. These uncertainties emphasize the need for more long-term experiments and observational studies in a variety of locations in order to clarify tundra responses to climate warming on greater scales. 

 

Comparisons of historical and contemporary aerial photographs provide evidence that Arctic vegetation has already undergone significant shifts in recent decades, foreshadowing changes that are likely to come. Increased shrub cover has been confirmed in two repeat photography studies in northern Alaska and in a recent study in the Mackenzie Delta region of Canada. These findings are confirmed by data from more detailed ground-based studies and from satellite monitoring. The area covered by Tundra Climate has been reduced by about 20% since 1980, which reflects an increase in productivity related to the increases in shrub cover and indicate that the length of the growing season is increasing. Spatial variations correspond well to land surface temperature changes, with the greatest changes occurring in Arctic areas that have experienced the most climate warming. For example, expansion of white spruce forests into areas previously occupied by tundra has been documented in numerous locations in Alaska. 

 

Together, these data provide strong evidence that tundra productivity is increasing regionally as a direct result of recent climate warming. Tree line encroachment threatens tundra at its southern margins. Some models predict that by 2100 tree lines will have advanced northward by as much as 500 km, resulting in a loss of 51% of tundra habitat. A number of experimental warming studies conducted in the Arctic can be used in conjunction with observations and paleo-data to predict how future climate warming will affect tundra ecosystems. An analysis of warming studies found that warming generally increased productivity. Over longer time scales, diversity throughout the Arctic may actually increase, as historically non-Arctic species migrate northwards. However, the loss of endemic Arctic species and landscapes will result in an overall loss of biodiversity at the global scale.Often experiments and studies are based on short-term responses, which may be poor predictors of longer-term changes in vegetation composition. These uncertainties emphasize the need for more long-term experiments and observational studies in a variety of locations in order to clarify tundra responses to climate warming on greater scales.