The number of Canadian adults with low literacy levels will increase 25 per cent in the next two decades, creating a "literacy dilemma" if the problem isn't addressed immediately, a new report says.

By 2031, more than 15 million Canadian adults — three million more than today — will have low literacy levels, the Canadian Council on Learning says in the report released Wednesday.

"Unless some action is taken to reverse this trend, the literacy dilemma we are facing can translate into profound challenges for Canada's social well-being and economic prosperity," the council warned.

With low literacy skills, a person can deal "only with simple, clear material involving uncomplicated tasks," the council said.

Adults who meet the minimum threshold for understanding and using information from text, such as news stories, editorials, poems and fiction, are considered to have low literacy. They aren't considered illiterate. The number of Canadians considered illiterate is "actually very small," the report said, without being specific.

The report cited research showing adults with low literacy levels have more health problems, earn less and live shorter lives than other adults.

"In order to maintain a healthy population and to stay competitive in a global environment, Canada must address these issues today — not 20 years from now," the council said.

The number of adults with low literacy will rise in Vancouver, Toronto, Ottawa and Montreal, the council predicted in the report, titled the Future of Literacy in Canada's Largest Cities.

The rise will be greatest in Ottawa (80 per cent, to 500,000 adults), followed by Toronto and Vancouver (64 per cent, to nearly 3.2 million and 1.3 million, respectively), and Montreal (20 per cent, to more than 1.8 million.)

Although their numbers will increase, adults with low literacy will make up a smaller proportion of the population in Toronto, Ottawa and Vancouver, and a larger proportion in Montreal.

"These new numbers challenge the popular belief that the state of literacy in Canada will improve over time given Canada's growth in post-secondary graduates," said Dr. Paul Cappon, chief executive of the Canadian Council on Learning.

Driving the changes in literacy levels are two growing populations, the report found: low-literacy immigrants and senior citizens, who tend to experience "learning loss as they age."

The CCL, whose mission is "to be a catalyst for lifelong learning across Canada," did not offer specific solutions to the country's literacy levels.