Population growth

Human-wildlife overlap is projected to increase across more than half of all lands around the globe by 2070. The main driver of these changes is human population growth. This is the central finding of our newly published study in the journal Science Advances. Our research suggests that as human population increases, humans and animals will share increasingly crowded landscapes. For example, as more people move into forests and agricultural regions, human-wildlife overlap will increase sharply. It also will increase in urban areas as people move to cities in search of jobs and opportunities. Animals are also moving, mainly in response to climate change, which is shifting their ranges. Across most areas, species richness – the number of unique species present – will decrease as animals follow their preferred climates. But because human population growth is increasing, there still will be more human-wildlife overlap across most lands. We also found areas where human-...

Images of orange groves and Spanish-themed hotels with palm tree gardens filled countless pamphlets and articles promoting Southern California and Florida in the late 19th century, promising escape from winter’s reach. This vision of an “American Italy” captured hearts and imaginations across the U.S. In it, Florida and California promised a place in the sun for industrious Americans to live the good life, with the perfect climate. But the very climates that made these semitropical playgrounds the American dream of the 20th century threaten to break their reputations in the 21st century. A postcard illustrates the latest style for Miami beach bathing around 1920. Asheville Post Card Co./Wikimedia In California, home owners now face dangerous heat waves, extended droughts that threaten the water supply, and uncontrollable wildfires. In Florida, sea level rise is worsening the risks...

Leer in español There are questions that worry me profoundly as a population- and environmental-health scientist. Will we have enough food for a growing global population? How will we take care of more people in the next pandemic? What will heat do to millions with hypertension? Will countries wage water wars because of increasing droughts? These risks all have three things in common: health, climate change and a growing population that the United Nations determined passed 8 billion people in November 2022 – double the population of just 48 years ago. In my 40-year career, first working in the Amazon rainforest and the Centers for Disease Control and Prevention, and then in academia, I have encountered many public health threats, but none so intransigent and pervasive as climate change. Of the multitude of climate-related adverse health effects, the following four represent the greatest public health concerns for a growing population. Infectious disease...

At first glance, the connections between the world’s growing population and climate change seem obvious. The more people we have on this planet, the larger their collective impact on the climate. However, a closer look with a longer time horizon reveals relationships between population size and climate change that can help us better understand both humanity’s predicament as the global population hits 8 billion people – a milestone the United Nations marked on Nov. 15, 2022. Looking back to the Stone Age For much of human evolution, our ancestors were exposed to large climatic fluctuations between ice ages and intermittent warmer periods. The last of these ice ages ended about 10,000 years ago. Before the ice sheets melted, sea levels were about 400 feet (120 meters) lower than today. That allowed humans to migrate around the world. Everywhere they went, our ancestors reshaped landscapes, first by clearing forests and then through early agricultural practices...