Population

A deadly heat wave gripped Asia for weeks in spring 2024, sending temperatures in India’s capital region over 120 degrees Fahrenheit (49 Celsius) in May. Campaigning politicians, news announcers and Indian voters waiting in long lines passed out in the oppressive heat. In June, hundreds of people on the Hajj, a Muslim pilgrimage to Mecca, Saudi Arabia, died in searing heat that reached 120 F (49 C) with high humidity. Most of the planet has suffered the dire effects of extreme heat in recent years. Phoenix hit 110 F (43.3 C) or higher for 31 straight days in summer 2023, and Europe saw unprecedented heat that killed hundreds and contributed to devastating wildfires in Greece. Mexico and neighboring regions were sweltering through a dangerous and long-running heat wave in 2024. Regardless of where or when a heat wave strikes, one pattern has been a constant: Older adults are the most likely to die from extreme heat, and the crisis is worsening....

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...