Abstract
In the December 2022 Wilderness & Environmental Medicine Editor’s Note 1 , the author briefly discussed the challenges of delivering healthcare in regions impacted by a changing climate. The author suggested that, due to these burgeoning challenges, the relevance of wilderness and environmental medicine is now arguably greater than ever. Dramatic environmental events such as the profound late spring and summer 2022 flooding in Pakistan caused by heavier than normal monsoon rains and the rapid glacial melt following a severe heat wave are quite likely to become more frequent in and around the mountain regions of Asia. The seemingly inexorable effects of what we have come to term “climate change” has touched us all, and will, without doubt, continue to affect our lives in major ways into the future. Peoples living among the many mountain ranges of Asia—the Himalaya being the largest at approximately 2,400 km in length—and those whose lives are influenced by these great ranges, will clearly not escape the consequences brought by a changing climate.
As Douglas contends throughout his recent comprehensive opus titled Himalaya: A Human History, 2 the combination of altitude and climate is what makes mountain regions such as the Himalaya so remarkable. The natural hazards associated with rapid changes in elevation are complicated and erratic: eg, floods, earthquakes, and landslides. But less obvious dangers abound, such as glacial lakes draining incredibly rapidly and in catastrophic fashion. Variations in climate and environment can be little short of astounding as one moves across the great ranges of Asia. While the monsoon may be the region’s major weather system, local climate, even from one side of a valley to the other, can be surprisingly different.
Thanks to advances in paleoclimatology, we have exquisitely detailed knowledge of how climate has varied over the last few million years. In just the past 3 million years, the earth’s climate has swung between mild states and periods of massive glaciation. Currently, mountain glaciers around the world are receding at an unprecedented rate and have been doing so since the start of the Industrial Revolution. The latest research identifies human-induced climate warming as almost entirely responsible. 3 Another paper published in 2021 provides the most detailed and complete picture to date of glacier wastage over the last 2 decades from over 1 million satellite images and shows how ice loss has been accelerating during this period for most of the 200,000-plus glaciers around the world. 4
Projections based on climate models suggest that the globe will continue to warm another several degrees over the next century. Increasing combustion of fossil fuels has led to carbon dioxide’s (CO2) seemingly relentless climb and now exceeds 400 parts per million, its highest level in at least 3 million years, according to the analysis of gases trapped in ice cores. The present-day temperature increases lag behind the CO2 increase as the climate responds to the unprecedented CO2 rise.
Civilization developed over the last 7,000 years during a period of exceptional climatic stability. 5 Therein lies the heart of the problem. While our distant ancestors had to cope with a sea level rise of about 120 m over a mere 8,000 years or so leading up to the development of civilization, human society has since become finely adapted to the current climate. It has been asserted that a mere 1 m increase in sea level (small by the standards of geologically recent changes) would displace around 100 million people. 5 Agriculture and animal husbandry are also tuned to the present climate, so that comparatively small shifts in precipitation and temperature can exert considerable pressure on governments and social systems whose failure to respond could lead to famine, disease, mass emigrations, and political instability.
A warmer, wetter world will create newly hospitable habitats for tropical and sub-tropical insect vectors and the diseases they carry. Historically, disease-free areas have been protected from becoming hazardous by cold environmental temperatures. With the low temperatures of winter, insect (and in particular, mosquito) populations are decimated. However, as the average global temperature increases, mosquitos will thrive longer and reproduce more successfully at higher latitudes and altitudes. In the northern hemisphere, they are spreading northward and increasing their natural habitat. 6 Vector-borne diseases take an enormous toll on human health. Malaria, dengue, West Nile virus disease, Lyme disease, and Zika virus infection now and increasingly will account for much of the global burden of disease.
In the jungles of northern India, colder seasonal temperatures have historically helped to put an end to the deadly malaria season. However, malaria did not just affect the plains. Douglas 2 quotes the British resident Brian Hodgson’s writing from the mid nineteenth century: “No elevation short of 3,000 to 4,000 ft above the sea suffices to rid the atmosphere of the low Himalaya from malaria.” Villagers would typically build their farmhouses above this line so they could escape the mosquitos, walking down to their lower fields in the morning. Climate change will likely continue to raise the mosquito’s ceiling, creating new problems in remote villages.
Changes in environment at the global, regional, and local levels are often reflected in changes in human health. The human health impacts of climate change are, however, not yet systematically documented. Although based on limited data sets, deductions from Pant et al.
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may be reasonable indicators for many health-related issues that will be encountered in the Greater Himalaya (with dominating local influences and factors) in the not-too-distant future: A warmer environment would lead to increased deaths due to heightened number of heat waves and lack of nighttime cooling. Infectious diseases such a cholera would increase as emerging and reemerging infections take root. Malaria risk would increase in higher altitude mountain and mid-latitude regions. Humidity and temperature range increases with higher frequency of extreme weather variations will produce an undesirable effect on human health. These climate changes are projected to make other mosquito-borne diseases like dengue and Japanese encephalitis more prevalent and widespread. Increased flooding and periods of drought that are anticipated will affect the availability of freshwater and food, making the population more vulnerable to infection because of water-borne diseases and malnutrition.
The hardiness and adaptability of the people living among and around the major mountain regions of Asia is legend and these qualities have served them well for countless generations—a necessity borne of life in an often-extreme environment that reaches to the roots of their culture. But the resilience of subsequent generations will most certainly be tested in the face of the environmental alterations that climate change will invariably bring. Coming to grips with the reality that rapid climate change will offer, at least for the foreseeable future, will mean coming to terms with new challenges to the delivery of health care as well. This will require significant flexibility and improvisation from our traditional systems of care that have often been better known for institutional resistance to change. Some medical-oriented organizations are, undoubtedly, more agile than others in their ability to creatively respond to a rapidly changing healthcare landscape. The Wilderness Medical Society has become well known for an “outside the box” approach to thinking about and delivering care. The Society has an opportunity—also borne of necessity—to lead the way in a century that will see many climate change-related influences on human health.