Ever since the dawn of humankind, climate has been inextricably tied to human health. A stable climate and receding Ice Age were essential to the rise of modern civilization. From the physiologic stress of excessive heat, to the widespread failure of agriculture, in many and varied ways, the climate crisis is first and foremost an advancing public health crisis.
A hotter, more humid world is already becoming a world of more serious, virulent infectious diseases. West Nile, Lyme disease, dengue fever, Chagas, yellow fever, chikungunya, Rocky Mountain spotted fever, Rift Valley fever, Japanese encephalitis and malaria are just a few of the many infectious diseases attacking more victims and spreading far beyond their previous geographic confines. Global temperatures aren't the only things that broke records in 2015. For example, the number of victims of dengue fever in Brazil reached 1.58 million, an all-time high, up from 78,000 cases in 1990. The Centers for Disease Control and Prevention (CDC) recently concluded that the number of annual cases of Lyme disease in the United States was 300,000 - 10 times higher than their previous estimates - and that the disease is spreading north into Canada.