Lim is a first-year student at McGill and a climate activist, and the harsh public pledge she took this week was meant to jolt federal politicians into aggressive action on global warming. But her birthing boycott is just as much of a wake-up call about demographics and the workforce as it is about the environment.

Canada needs kids, and lots of them. Not just because they’re fun and cuddly, but also because they need to be born right about now in order to grow up and support the rest of us in our old age.

Canada also needs their young parents to be fully engaged in the workforce, helping companies deal with looming labour shortages and driving the economy.

So it’s no coincidence that the political parties are at least tinkering with social and economic policies that would ease the way for families, encourage parents to work, and bolster support for seniors.

But the proposals so far are timid compared to the challenge at hand.

New population projections from Statistics Canada that cast out to 2068 across the country and by province show that immigration is the main force sustaining population growth. That’s been the case for a while, and it’s becoming far more pronounced. Statscan’s medium growth projection sees today’s population of 37 million rising slowly to 55 million in 50 years in which 94 per cent of the net growth comes from immigration.

The problem for public policy however, is that the population is projected to become rapidly much older. By 2068, for every 100 people of working age (15 to 64 years old), there will be 25 children and 43 seniors, according to a middle-of-the-road, medium-growth scenario compiled by StatsCan.The over-80 crowd is growing even more quickly, as the baby boom ages. In 2018, there were 1.6 million people over 80. By 2068, there will be between 4.7 million and 6.3 million. The trends are more extreme in Atlantic Canada and rural areas more generally, where populations are expected to age more quickly and shrink outright.

It means the dependency ratio — the portion of people too young or too old to work, compared to those of working age — will climb steeply. In 2018, for every 100 people between 15 and 64 years old, there were 50 people younger or older than them, dependent on those working people for their work and their tax revenues to pay for social programs. By 2068, that ratio will rise to anywhere between 63 and 73.

Successive federal and provincial governments have put many supports in place. Already, seniors receive the lion’s share of social services to the cost of tens of billions every year. Researcher John Stapleton compiled all the $189 billion in income support payments in Canada and figured out who got what by age. He found that in 2016-2017, seniors made up 16.4 per cent of the population but received 52.1 per cent of that money. Children made up 19.6 per cent of the population and received 14.5 per cent of the income support. And working age adults made up 64 per cent of the population but received 33.4 per cent of the government transfers.

Those proportions are poised to become starker. All the party leaders are in the midst of promising more transfers to seniors. Justin Trudeau this week offered to top up Old Age Security for those over 75 years old, and to negotiate with the provinces an increase in survivors’ benefits under the Canada Pension Plan. Two days later, Andrew Scheer proposed an increase in the age credit that seniors can claim at tax time. Jagmeet Singh is committed to extending the reach of seniors’ benefits and bolstering long-term and home care.

At the other end of the dependency ratio, income support aimed at children is ramping up too. The Liberals want to raise the Canada Child Benefit for the first year of a child’s life, create more daycare spots for primary school kids and enrich parental leave benefits. The Conservatives are also proposing better tax treatment for parental leave, and tax breaks for kids enrolled in artistic or sports activities. The NDP wants to put $1 billion into child care in 2020 alone.

It’s all done in the name of affordability and poverty alleviation. But there’s a broader reality underlying the need to support children and seniors: working-age Canadians and immigrants need to pile into the workforce, all of them, and work as hard as they can in order to maintain the income supports that we already have, and that make Canada a great place to live. The more people in the workforce, the easier that becomes.

So when the likes of Lim threaten to withhold their ability to make babies, they have Canada snookered. And they may have a point on climate change too.

Heather Scoffield is an economics columnist based in Ottawa.