A boreal ecosystem is an ecosystem with a subarctic climate located in the Northern Hemisphere, approximately between 50° to 70°N latitude. These ecosystems are located in Boreal forests which are commonly known as the taiga, particularly in Europe and Asia. The ecosystems that lie immediately to the south of boreal zones are often called hemiboreal.
The Köppen symbols of boreal ecosystems are Dfc, Dwc, Dfd, and Dwd.
The Boreal Ecosystem-Atmosphere Study (BOREAS) was a major international research field study in the Canadian boreal forest. The main research was completed between the years of 1994-1996 and the program was generously sponsored by NASA. The primary objectives were to determine how the boreal forest interacts with the atmosphere, how climate change will affect the forest, and how changes in the forest affect weather and climate.
Boreal ecosystems display high sensitivity towards both natural and anthropogenic climate change, atmospheric warming due to greenhouse gas emissions ultimately leads to a chain reaction of climatic and ecological effects. The initial effects of climate change on the boreal ecosystem can include, but are not limited to, changes in temperature, rainfall, and growing season. Based on studies from the boreal ecosystems in the Yukon, a territory in northwestern Canada, climate change is having an impact on these abiotic factors. As a consequence, these effects drive changes in forest ecotone as well as marshlands or lakes in boreal ecosystems. This also concerns plant productivity and predator-prey interactions, which ultimately leads to habitat loss, fragmentation, and threatens biodiversity.
In terms of boreal trees, the poleward limit for any given species is most likely defined by the temperature, whereas the equatorial limit is generally defined by competitive exclusion. Basically, as changes in climate occur, change in the corresponding weather variables follows. As climate conditions change, ecosystem alterations involving timing for migration, mating, plant blooming can occur. This can lead to the transition into a different type of ecosystem as the northward shift of plant and animal species has already been observed. Trees may expand towards the tundra; however, they may not survive due to various temperature or precipitation stressors. The rate depends on growth and reproductive rate, and adaptation ability of the vegetation. In addition, the migration of flora may lag behind warming for a few decades to a century, and in most cases warming happens faster than plants can keep up.
Due to permafrost thaw and disturbance alterations such as fire and insect outbreaks, certain models have suggested that boreal forests have developed into a net carbon source instead of a net carbon sink. Although the trees in the boreal are aging, they continue to accumulate carbon into their biomass. However, if disturbed higher than normal amounts of carbon will be lost to the atmosphere.
In some areas, boreal ecosystems are located on a layer of permafrost, which is a layer of permanently frozen soil. The underground root systems of boreal trees are stabilized by permafrost, a process which permits the deeper trapping of carbon in the soil and aids in the regulation of hydrology.  Permafrost is able to store double the amount of current atmospheric carbon that can be mobilized and released to the atmosphere as greenhouse gases when thawed under a warming climate feedback. Boreal ecosystems contain approximately 338 Pg (petagrams) of carbon in their soil, this is comparable to the amount which is stored in biomass in tropical ecosystems.
In boreal ecosystems, carbon cycling is a major producer of ecosystem services essentially timber production and climate regulation. The boreal ecosystem in Canada is one of the largest carbon reservoirs in the world. Moreover, these boreal ecosystems in Canada possess high hydroelectric potential and are thus, able to contribute to the resource-based economy. Through ecosystem assessment, inventory data, and modeling scientists are able to determine the relationships between ecosystem services and biodiversity and human influence. Forests themselves are producers of lumber products, regulation of water, soil and air quality. Within the past decade, the number of studies focusing on the relationships between ecosystem services has been increasing.  This is due to the rise of human management of ecosystems through the manipulation of one ecosystem service to utilize its maximum productivity. Ultimately, this results in the supply decline of other ecosystem services.