PoV #6: Turning Up the Heat: Earth's Fever and Its Cascading Effects

This Summer, Earth underwent its hottest month on record, as confirmed by the EU's Copernicus Climate Change Service. But the repercussions of these escalating temperatures go beyond merely breaking records.

The present century is marked by climate alterations, leading to rising global temperatures and more frequently occurring, intense heatwaves. These elevated temperatures strain the human body, exacerbating primary global mortality causes, such as heart ailments, respiratory issues, diabetes, and kidney diseases. Beyond immediate health threats, heatwaves pose challenges to large communities, prompting increased death rates, potential public health emergencies, and subsequent socioeconomic impacts like diminished workforce performance. It's notable how these thermal extremes can compound healthcare challenges, especially when coupled with power outages that can incapacate essential services such as hospitals and public transportation.

?However, there is an evident gap in public awareness concerning the health perils associated with persistent exposure to extreme temperatures. It is imperative for the healthcare realm to recalibrate its approach in response to these escalating thermal challenges. Adopting pragmatic, typically cost-efficient measures at various societal tiers can act as protective buffers against these threats.

?While most acknowledge the impact of heat on infrastructure and agriculture, many underestimate its direct effect on human health. A 2007 survey highlighted this general oversight, despite the evident vulnerability of groups such as children, the elderly, and outdoor workers.

From 2004 to 2018, the U.S. recorded an average of 702 heat-related deaths annually, primarily during the warmer months of May to September. This makes heat the leading weather-related cause of death in the country, outstripping even hurricanes and floods. In 2023 alone, the U.S. faced 15 weather disasters, each resulting in damages exceeding $1 billion. Notably, the August wildfire in Hawaii caused damages nearing $10 billion, marking it as the deadliest wildfire in a century.

Dr. Catharina Giudice, a climate expert from Harvard, states that human-driven climate change has intensified these deadly heatwaves, putting unprepared regions at severe health risks. In light of this, President Biden introduced the inaugural Hazard Alert for heat, designed to protect workers, especially since over 400 workers have died from heat exposure since 2011.

Populations at Risk

Humans are inherently thermal beings, absorbing heat from their environment and generating it through bodily metabolic processes. When there's rapid and excessive heat intake, the body's natural thermoregulatory mechanisms are jeopardized, leading to a spectrum of health issues ranging from heat cramps to grave conditions like hyperthermia and heatstroke.

Interestingly, heat-induced health adversities might manifest immediately or could surface after several days. Particularly during the initial phase of a heatwave, even marginal deviations from regular seasonal temperatures can spike both morbidity and mortality rates. Furthermore, chronic ailments, notably those associated with the heart, lungs, and diabetes, can be aggravated by excessive heat.

Beyond the direct consequences, elevated temperatures can indirectly influence several health parameters. Examples include modifying human behavior, disease transmission dynamics, healthcare provisions, and critical social infrastructures. The exact health outcomes steered by heat are multifaceted, governed by the specific heat event parameters, the community's acclimatization capacity, and the robustness of local infrastructures against extreme temperatures. Interestingly, the temperature threshold for potential health hazards isn't universal; it varies based on regional parameters, including humidity, wind patterns, and preparedness levels.

It's crucial to recognize that certain populations are more vulnerable to extreme heat. This includes children, the elderly, outdoor workers, pregnant individuals, and those with chronic ailments. Disturbingly, racial disparities persist, with communities of color, particularly American Indian, Alaska Natives, and Black individuals, facing higher heat-related mortality rates. Others at risk include those unaccustomed to heatwaves, particularly those without air conditioning, and those on certain medications or abusing substances.

The WMO Report on Air Quality

The World Meteorological Organization (WMO) has spotlighted another concerning dimension of rising heatwaves – their amplification of air pollution. This escalated air pollution affects human health, ecosystems, and even agriculture. Citing the destructive force of wildfires in places like Canada, Hawaii, and the Mediterranean, the WMO underscores the interconnected challenges of climate change, deteriorating air quality, and the critical need for a collective global response.

Oceanic Repercussions

Heatwaves also have underwater counterparts, impacting marine life. A study in Nature Communications documented the responses of marine predators like sharks and whales to these oceanic temperature surges. The findings showed varied reactions, from habitat loss for bluefin tuna and blue sharks during the 2015 heatwave to habitat expansion for sea lions and elephant seals in 2019. With climate change, such oceanic temperature spikes are expected to become more frequent, leading to unprecedented heat stress in regions like the Caribbean Basin and the Gulf of Mexico.

The National Oceanic and Atmospheric Administration (NOAA) has been monitoring these marine heatwaves, which they define as ocean temperatures surpassing the 90th percentile for a specific duration. While these heatwaves can endure for varying periods, their consequences are far-reaching. For instance, the marine heatwave in the Gulf of Mexico, which began early in 2023, has disrupted marine ecosystems, causing phenomena like coral bleaching. Such disruptions also have economic implications, as seen during the infamous marine heatwave "the Blob" from 2013-2016, which led to fishery disasters, including a surge in whale entanglements.

Concluding Thoughts

Whether on land or at sea, the increasing frequency and intensity of heatwaves demand global attention. While experts like Dr. Giudice believe the focus is now more on mitigation than prevention, swift action remains imperative to reduce carbon emissions, safeguard vulnerable communities, and fortify infrastructure against these challenges. The intertwined threats of climate change, air pollution, and heatwaves underscore the need for holistic solutions and international collaboration.