Rising temperatures driven by human activities threaten more than polar bears—they're already impacting human health and well-being, with worse to come. A landmark report published on October 31, 2017, in the prestigious journal The Lancet, authored by international experts including researchers, physicians, and policymakers, outlines the direct and indirect health consequences expected through the next century. We're already seeing effects from increasingly frequent extreme heat episodes.
The number of vulnerable people exposed to intense heat waves has surged +125 million since the early 2000s, reaching 175 million by 2015. Symptoms like dizziness, headaches, and nausea are common, alongside rises in acute myocardial infarction and respiratory failure among those with chronic conditions. Excess mortality from these events also hits children and outdoor workers.
"During France's 2003 heat wave, a third of excess deaths stemmed from hyperthermia or severe dehydration," notes researcher Jean-Pierre Besancenot, author of Climat et santé (ed. Puf). The World Health Organization (WHO) projects around 250,000 additional annual deaths worldwide from climate change alone starting in 2030.
Video of the day:Beyond direct overheating, high CO2 levels impair blood oxygenation in the lungs, as Professor Besancenot explains. Urban pollution worsens too, as heat traps particles under a stagnant air layer. More sunshine means frequent ozone peaks, which inflame airways, trigger asthma, irritate the throat and nose, and strain the heart.
Milder winters and hotter summers supercharge plant growth, extending our exposure. Pollen seasons are longer and more intense—birch pollen now lingers nearly 4 months north of the Loire, up from 10 days in the 1970s. This fuels surges in allergic rhinitis, conjunctivitis, eczema, and hives. Ragweed now yields over 10g of pollen per plant (vs. 5.5g in the 1990s, per ONERC*), with European air concentrations potentially quadrupling by 2050. The WHO warns that by century's end, one in two people could face allergic diseases.
Vector insects are shifting northward with warming temperatures. The tiger mosquito, once limited to the Indian Ocean and Southeast Asia, reached southern France near Nice in 2005 and now infests 34 departments. It transmits chikungunya, dengue, and Zika—isolated local cases emerged since 2010. Without stabilization, 50% of humanity could face dengue by 2085 (vs. 35% if temperatures hold steady). Malaria may decline due to drought, offering some relief.
* www.thelancet.com/climate-and-health
** National Observatory on the Effects of Global Warming
