Canada is one of the few developed nations that is a net exporter of energy. Most important are the large oil and gas resources centred in Alberta and the Northern Territories, but also present in neighbouring British Columbia and Saskatchewan. A study undertaken at the University of Calgary suggests that Canada's economy, without the impact of oil and gas, would be reduced to less than half its current size.[citation needed] The vast Athabasca Tar Sands give Canada the world's second largest reserves of oil after Saudi Arabia according to USGS. (Economy of Canada ~ Wikipedia)