Population + Emissions

“Population projections are arguably the backbone of [greenhouse gas] emissions scenarios,” says the Intergovernmental Panel on Climate Change (IPCC).

In its November 2014 report for policy-makers, the IPCC states clearly that “Anthropogenic greenhouse gas emissions have increased since the pre-industrial era, driven largely by economic and population growth, and are now higher than ever. This has led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years. Their effects, together with those of other anthropogenic drivers, have been detected throughout the climate system and are extremely likely to have been the dominant cause of the observed warming since the mid-20th century.”

Meanwhile, a 2010 study published in the proceedings of The National Academy of Sciences of The United States (PNAS) titled “Global Demographic Trends and Future Carbon Emissions” demonstrated that slowing population growth could provide 16-29% of the emissions reductions suggested to be necessary by 2050 to avoid dangerous climate change.

Mitigation strategies, such as alternative energy generation, energy efficiency, and carbon capture and storage are crucial to the planet’s climate future, but programs that address unmet needs for family planning and reproductive health services around the world are also part of a good long-term strategy to reduce global greenhouse gas emissions.

A 2009 study titled “Reproduction and the carbon legacies of individuals,” looked at the relationship between population growth and global warming. It determined that the “carbon legacy” of just one child can produce 20 times more greenhouse gas than a person will save by driving a high-mileage car, recycling, using energy-efficient appliances and light bulbs, etc. The study concluded, “Clearly, the potential savings from reduced reproduction are huge compared to the savings that can be achieved by changes in lifestyle.”

Author Paul Murtaugh also noted that: “In discussions about climate change, we tend to focus on the carbon emissions of an individual over his or her lifetime. Those are important issues and it’s essential that they should be considered. But an added challenge facing us is continuing population growth and increasing global consumption of resources. . . . Future growth amplifies the consequences of people’s reproductive choices today, the same way that compound interest amplifies a bank balance.”

Finally, it is important to remember that emissions negatively impact more then just the Earth’s atmosphere. As the Royal Society noted in their 2012 study titled “People and Planet” (PDF), ocean acidification is another serious predicament created by CO2 emissions. Over the past 200 years the oceans have absorbed at least a quarter of the CO2 emitted by human activities. While the sea’s ability to act as a natural atmospheric scrubber has helped limit the amount of carbon in the atmosphere, this has seriously affected ocean chemistry. The oceans have become more acidic by at least 30% since the start of the industrial revolution — reducing the concentration of carbonate ions that are required for the growth and/or survival of many marine organisms, including coral reefs, most shellfish, and some fish species.

Good population advocacy should promote population stabilization as a necessary part of the answer to anthropogenic global warming, human induced climate-change, and ocean acidification — but not as a silver bullet. It is a necessary and important part of a larger strategy, but population stabilization must be part of much broader overhaul of business-as-usual.

Download a fact sheet about population and emissions.