Holarctic realm

It includes both the Nearctic zoogeographical region (which covers most of North America), and Alfred Wallace's Palearctic zoogeographical region (which covers North Africa, and all of Eurasia except for Southeast Asia, the Indian subcontinent, the southern Arabian Peninsula).

Many ecosystems and the animal and plant communities that depend on them extend across a number of continents and cover large portions of the Holarctic realm.

Many of the southernmost parts of the Holarctic are deserts, which are dominated by plants and animals adapted to the dry conditions.

These include the brown bear, grey wolf, red fox, wolverine, moose, caribou, golden eagle and common raven.

The brown bear (Ursus arctos) is found in mountainous and semi-open areas distributed throughout the Holarctic.

The grey wolf (Canis lupus) is found in a wide variety of habitats from tundra to desert, with different populations adapted for each.

It has the widest distribution of any terrestrial carnivore, and is adapted to a wide range of habitats, including areas of intense human development.

The caribou, or reindeer (Rangifer tarandus) is found in boreal forest and tundra in the northern parts of the Holarctic.

Golden eagles use their agility and speed combined with powerful feet and massive, sharp talons to snatch up a variety of prey (mainly hares, rabbits, marmots and other ground squirrels).

Leptothorax acervorum is a small red Holarctic ant widely distributed across Eurasia, ranging from central Spain and Italy to the northernmost parts of Scandinavia and Siberia.

Zygiella x-notata is a species of orb-weaving spider with a Holarctic distribution, mostly inhabiting urban and suburban regions of Europe and parts of North America.

During glacial periods, species survived in refugia, small areas that maintained a suitable climate due to local geography.

[5] Their high degree of mobility allowed them to move as the glaciers advanced or retreated, maintaining a constant habitat despite the climatic oscillations.

Brown bears, for instance, moved quickly from refugia with the receding glaciers, becoming one of the first large mammals to recolonize the land.

Another factor contributing to the continuity of Holarctic ecosystems is the movement between continents allowed by the Bering land bridge, which was exposed by the lowering of sea level due to the expansion of the ice caps.

Winter mortality of some insect species drastically decreased, allowing the population to build on itself in subsequent years.

Warming temperatures may also allow pest species to enlarge their range, moving into habitats that were previously unsuitable.

This realm contains most of the world's developed countries, including the United States and the nations of Western Europe.

These mammals, such as brown bears and wolves, require large areas of land with relatively intact habitat to survive as individuals.

Thus, their conservation has direct implications for a wide range of species, and is difficult to accomplish politically due to the large size of the areas they need.

Developed countries who sign this protocol agree to cut their collective greenhouse gas emissions by five percent since 1990 by sometime between 2008 and 2012.

This agreement will aim to build on the successes and failures of Kyoto to produce a more effective method of cutting greenhouse gas emissions (UNFCCC).

If these efforts are successful, the biodiversity of the Holarctic and the rest of the world will see fewer effects of climate change.

Local efforts include creating reserves and establishing safe routes for animals to cross roads and other human-made barriers.

This organization was started in 1997 to help establish a contiguous network of protection for the northern Rocky Mountains, from mid Wyoming to the border between Alaska and Canada's Yukon.

The goal of the Initiative is to create a core of protected areas, connected by corridors and surrounded by buffer zones.