The Unspeakable Connection: Soaring Human Population & Climate Change

These days, we rarely hear about the need to stop soaring human population growth, but clearly this is at the root of many of our problems, such as climate change and biodiversity loss.

In September, the United Nations will update Sustainable Development goals and an international coalition wants universal access to family planning recognized as integral to "climate-compatible development." 

Right now, world population stands at 7.3 billion and while experts used to believe it would level off at an unsustainable 8-9 billion, there now seems to be no end in sight. Projections are for 11-12 billion humans by 2100.  

Many experts believe the Earth’s carrying capacity can’t handle more than 1-2 billion humans.

Obviously, the more crowded the Earth is, the more pressure there is on every resource – from land for farming to  water to drink. As human populations expand, there’s less and less space (and resources) for every other species. It means more economic activity, which brings more greenhouse gas emissions and more intense climate change.

A recent study shows that global temperature rise is in lockstep with population growth – an additional percentage point of human population coincides with an additional 2 degrees Fahrenheit in average global temperatures, according to economist David Rosnick at the Center for Economic and Policy Research.

"There are many warnings of ‘demographic time bombs’ due to population declines in countries like Japan. But lower population growth has many economic benefits; one of the most important is that it reduces the rate of global climate change," he says in The Consequences of Increased Population Growth for Climate Change.

Smaller populations in developed countries would have the most beneficial impact on climate change because of super-sized consumption and emissions. It would have the most beneficial impact on biodiversity in the developing world, where population is growing the most. 

Another recent study estimates that slowing population growth could provide 16-29% of the emissions reductions necessary by 2050.

Estimates of population growth:

"There are many positive economic and social policies that can promote a transition to lower birth rates, including more security in old age; education of girls and women and increased economic opportunities for them, as well as affordable contraception and reproductive choice; lower infant and child mortality; and increased literacy, education levels, and productivity generally."

Indeed, these measures have been priorities for sustainable development groups for decades, and there’s been improvement, but there’s a long way to go.

In Pakistan, for example, just a third of married women use contraception and half of all pregnancies are unintended, according to the Population Reference Bureau, reports Reuters. Ethiopia already includes family planning in its climate action plan. Providing the 222 million women in developing countries with contraception would prevent 54 million unintended pregnancies at a relatively modest cost of $4 billion a year, reports the NY Times.

If women in sub-Saharan Africa had 2.1 children in 2050, down  from 5.4 today, providing food for the region would be much easier. It would spare remaining forests, substantially reducing  carbon entering the atmosphere, while protecting crucial habitat for species like great apes.

"In the past 40 years, we’ve added more than 3 billion people to our population, while wildlife populations have plummeted by half. We can no longer ignore that rampant human population growth and overconsumption are driving species extinct. We can’t continue on this same path and still hope to have a planet that’s ultimately livable for people and wildlife," says Stephanie Feldstein, director of the Population and Sustainability program at the Center for Biological Diversity.

Read, The Consequences of Increased Population Growth for Climate Change: