Population and Climate Change

In November 2013, the Philippines was hit with what might have been the strongest typhoon in history. Super Typhoon Haiyan left thousands dead and millions homeless. Many of the shelters designated to protect people from the elements were lost in the storm. “We had designated evacuation areas for emergencies like this—the church for our municipality and schools close by. But they were totally destroyed,” said Delfin Sabanal of Leyte province. He, his wife and three children had to cobble together a makeshift shelter from debris.

No single extreme weather event can be blamed entirely on climate change. But scientists agree that climate change can alter weather patterns, which can make storms stronger and recovery more difficult. “Climate change can be seen as a multiplier of already existing risks,” said Alexander Muller of the FAO. “Where people are vulnerable today, they will be even more vulnerable tomorrow.”
Coastal populations—such as those in the Philippines—are particularly sensitive to climate variation. As climate change warms oceans, tropical storms pick up more energy from the ocean, making storms more destructive when they hit land.

Population Growth Makes Adaptation More Difficult

When more people live in regions that are hard hit by climate-related disasters, more people stand to lose their homes, livelihoods, and even their lives. Drought in the Sahel and Horn regions of Africa has made growing enough crops to feed a quickly-growing population increasingly difficult. Countries that experience severe drought and other natural disasters often need food aid to survive. As populations grow, so do food aid requirements. Agricultural sustainability becomes harder and harder to reach.

Developed countries are not immune. “There is disaster risk almost everywhere,” said Christopher Field, a Stanford University professor and leader of an IPCC working group on climate impacts. In 2012, the United States experienced its worst drought in over half a century. About 55 percent of the continental U.S. was under moderate or extreme drought conditions, and one-third of all counties were declared federal disaster areas.

The Population-Carbon Connection

Since 1970, the world’s population has doubled from 3.7 to 7.4 billion. Carbon emissions have followed a similar trend. A 2013 review of data from around the world found that between 1960 and 2005, for every one-percent increase in human population, greenhouse gas emissions increased by slightly more than one percent.

The relationship, however, is complex. Increases in greenhouse gases are driven largely by consumption, which tends to be highest among wealthy populations. In the United States, annual per capita carbon emissions have hovered around 19 tons for decades. However, U.S. emissions have been declining since 2007, with the latest data putting per capita consumption at 17.5 tons. By comparison, the European Union emits approximately 8 tons per capita and most African countries have per capita emissions below 1 ton.

In 2009, President Obama pledged to cut U.S. greenhouse gas emissions 17 percent by 2020 and 83 percent by 2050. He reaffirmed this pledge in his 2013 Climate Action Plan, which aims to cut carbon pollution through strategies such as clean energy and more efficient transportation. This goal would be much easier to achieve if the U.S. population—currently around 323 million—stabilized before reaching the 450 million the UN projects for 2050.

Robert Socolow and Stephen Pacala of the Carbon Mitigation Initiative at Princeton University developed the climate stabilization wedge concept to illustrate which technologies and actions could stabilize annual carbon emissions at 8 billion tons by 2060. Each wedge, or strategy, would reduce carbon emissions by 1 billion tons per year over the next 50 years. Strategies include improving residential and commercial building efficiency and eliminating tropical deforestation.

Slowing population growth would reduce emissions by the equivalent of 1 to 1.5 “wedges,” according to research published by the National Academy of Sciences. And contraception is inexpensive. Averting carbon dioxide emissions through family planning costs only $4.50 per ton, compared to $30 per ton for solar power, and $60 per ton for carbon capture and storage.


“Global warming is too big a problem to be solved by energy experts alone. It’s about people. It’s about how many of us there are and how we choose to live our modern lives,” says Population Connection President, John Seager. “It’s time to open a second front in the battle against global warming by stressing the need for population stabilization—sooner rather than later.”

Paul van Gardingen, professor of international development at the University of Edinburgh, expressed a similar sentiment. “Until we get population dynamics integrated into our understanding of climate change and our responses to it,” he said, “both will be ineffective.”

Facts & Figures

  • The United States accounts for less than 5 percent of the world’s population, yet produces 16 percent of global greenhouse gas emissions.
  • In 2012, China was the leading contributor to global fossil fuel emissions. Chinese emissions make up 29 percent of the global total.
  • All but one of the 16 hottest years on record since the start of the Industrial Revolution have occurred since 2000.

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