As worldwide population increases by 40 percent over the next 40 years, sparsely populated Canada, Scandinavia, Russia and the northern United States will become formidable economic powers and migration magnets, Laurence C. Smith writes in “The World in 2050: Four Forces Shaping Civilization’s Northern Future” (Dutton Books), scheduled for publication Sept. 23.

While wreaking havoc on the environment, global warming will liberate a treasure trove of oil, gas, water and other natural resources previously locked in the frozen north, enriching residents and attracting newcomers, according to Smith.