What are the environmental implications of changing household sizes? A recent article by Mason Bradbury, M. Nils Peterson, and Jianguo Liu, published in Population and Environment, analyzes data from 213 countries over 400 years and finds the average number of occupants per home tends to decline as population grows. This dynamic, they write, indicates that accommodating housing could prove to be one of “the greatest environmental challenges of the twenty-first century.” As countries develop and urbanize, “according to convergence theory, household size decreases (often from greater than five to less than three).” Other cultural shifts, like increasing divorce rates, urban sprawl driven by rising affluence, decreasing numbers of multigenerational households, and larger houses (in the United States, homes more than doubled in size between 1950 and 2002, according to the article) compound the issue. As population growth continues in parts of the world, these trends pose critical questions for conservation and environmental sustainability, since “households are the end consumers of most natural resources and ecosystem services.”

Against the stunning backdrop of Marojejy National Park, I recently crossed paths with a conservationist from a very different background, working on the opposite side of Madagascar. But, it turns out, the communities we work with face many of the same challenges, and our meeting spawned a new population, health, and environment (PHE) program.

As policymakers respond to the threat of climate and environmental change, the concept of resilience has found itself at the center of discussion. Few scientists and policymakers, however, can come to a consensus on how to define, evaluate, and build resilience.

Six years after beginning a marine conservation program focused on octopus fishery management in southwest Madagascar, “we can proudly say that we have made a real impact as an organization providing health care,” said Dr. Vik Mohan, medical director of Blue Ventures and a practicing doctor in the United Kingdom.

When Cyclone Haruna swept across Madagascar last February, Blue Ventures, a marine conservation and community health organization, found themselves in a surprising new role. “We went from development, to aid, and back to development, in an integrated way we never expected,” said Medical Director Vik Mohan in an interview at the Wilson Center.

The original version of this article, by Laura Robson and Caroline Savitzky, appeared on Blue Ventures’ Beyond Conservation blog.

The excitement was palpable as we gathered with almost 200 of the world’s finest population-health-environment (PHE) practitioners, researchers, and advocates in Addis Ababa for the International PHE Conference earlier last month! With all of us working on integrated projects encompassing family planning, community health, sustainable livelihoods, and environmental initiatives, there were many ideas and progress updates to be shared.