Land clearing, followed by wetland loss, has been especially rapid in the forest's southernmost region as a result of agricultural expansion. The aspen parkland transition zone and the Peace Parklands have been hardest hit, and present-day conversion rates are likely to increase with growing human populations and a warming climate. In the Alberta parklands, some 200 km2 per year were converted from forest cover to agriculture from 1949 to1995, mostly for small grain crops and improved pasture. Government-owned forestland located on soils suitable for agriculture continues to be sold to farmers for conversion, and the agricultural industry has targeted the WBF for accelerated expansion.
The character of the boreal zone is partly determined by long, cold winters and short summers. Temperatures in central Canada already have warmed at a higher rate than in most of North America. With a doubling of atmospheric CO2 in the next century, average temperatures in the WBF may increase by as much as 4.20 C. This is expected to result in drier average conditions, greater annual climatic variation, melting permafrost, altered surficial hydrology and higher rates of wildfires. Vegetation zones are likely to shift slowly northward and up to 16 million ha of new ground may become suitable for agricultural production. Significant changes in wetland ecology, including food webs that support duck populations, are likely but cannot be predicted with certainty.
Dams for power projects already have altered the hydrology of major boreal wetland systems, most notably the Peace-Athabasca Delta near the Alberta/NT border and the Saskatchewan River Delta on the Manitoba/Saskatchewan border. Many other projects are on the drawing boards. Today, more hydropower projects are proposed for Alaska than for all other states combined. The proposed Rampart Canyon Dam (now on hold) would have caused the inundation of nearly 27,000 km2 of the Yukon Flats.