Climate Change and Future of Health – Human Adaptability
This is a guest article by Pabitra Mukhopadhyay who is an advocate for the indigenous people of the Sunderban wetlands in Bengali, who are fighting a losing battle against aggressive industrialization and the effects of climate change.
So what will it be like in a 1.5 degree warmer world? A world of 450 ppm CO2 in atmosphere? While there is a lot of discussion on bio-diversity loss, sea level rise, melting polar caps, Climate Change is going to affect the health and well being of humanity in a profound way putting adaptability in a test that 100,000 years history of human race has never confronted.
This is not the adaptability that is being discussed in Cancun now, the adaptability and mitigation of Climate Change as a series of planned actions. I am talking about the adaptation on biological scale, one that is associated with Darwinian principle of Natural Selection through evolution.
Humans are formidable adapters. For the last 100,000 years of the present Holocene, Global Climatic Conditions have remained relatively warm but highly variable. Between last 100,000 to 200,000 years (towards the end of Pleistocene and beginning of Holocene, there had been several dramatic periods of cooling and warming that led to major continental glacial advances and retreats. Humans adapted to that and still flourished. There had been migrations and dispersion of human race all the while, winning the climate vagaries each genetic strand by strand. By the last 5000 years, human habitat settled from Arctic to Pacific with a highly credible record of adapting to climate variations, from sub-zero temperatures to tropical heat, from rain forests to desert lands, from coasts and rivers to mountains. That’s a feat for a single species – and humans used all tools available for that. It remains one unique life form that used something beyond dumb biological evolution – societal and cultural evolution with it’s ingenuity and intelligence.
That being the record, why are we so scared about Climate Change, then? We are scared because all that record is for natural Climate Change. What is happening since last Industrial Revolution is anything but natural. We have interfered with the natural climatic cycles in such a huge way that the weather system, which is a fairly delicate system as it is, now shows signs of becoming further unpredictable and chaotic. Most unfortunately, the rate of such ‘forced’ climatic variations and changes are so fast that human prowess of adaption is falling short. Anthropogenic forcings are producing a condition where the earth is now absorbing 0.85+/-0.15 watts per square meter (of earth surface) more energy that it is emitting to space – so we are in a state of positive energy balace – earth is getting warmer every day.
Climate Change and Global Warming are often misconceived as large-scale heat waves or draught. Nothing can be farther from the truth. The worst effects of Climate Change are fast and unprecedented Climate variations. Unexpected rainfalls in places that has no history of such weather (Floods in Pakistan) or heat waves in historically cold places (heat waves in Russia). When incidents as strange and rare as these start to happen, the human biological, societal and cultural adaptability cannot handle it effectively. Research has already shown that warming has a direct correlation with human morbidity and mortality and the most affected are children, sick and old people.
1. Temperature extremes (both hot and cold) appear to increase mortality, although there is disagreement about which sex, age group, or race seems most affected.
2. Low relative humidities in winter appear to be directly related to frequencies of various illnesses and mortality.
3. Winter snowfall accumulations appear to correspond with periods of high mortality.
4. Rapid changes in the weather often induce a series of negative physiological responses from the body, like cardio-vascular constrictions, immune deficiency, asthma and skin problems.
The future of world health will come under 3 critical stresses owing to Climate Change. Health standards and health care of post 2030 will largely be determined by these vectors.
a) Heat Stress: Environmental Heat Stress that will affect humans will be in two categories – hot-wet (high humidity) and hot-dry (low humidity). Hot-wet Heat Stress is basically limitation on evaporative cooling (sweating) which is farther worsened by viral and mosquito carried diseases. Hot-dry Heat Stress on the other hand limits water resources, which links with draughts, famines or low-productivity added with ozone depletion related UV radiation and related skin problems. Heat Stress will increase mortality through dehydration (heat exhaustion), total failure of thermoregulatory system (heat stroke) and stress on cardio-vascular system. Most vulnerable will be very young, very old and people doing physical labor in exposed conditions.
Areas that will come under heat stress are: southeastern and mid-continental US, parts of Europe, southeastern Asia (Indian sub-continent) and most parts of Africa. The future of health care in these areas will require new regimes of work, leisure, physical activities and inoculation programs.
b) Nutritional Stress: One likely effect of Climate Change is movements of iso-thermals towards poles. Warming will be greater in higher latitudes compared to temperate and tropical belts. This will cause shift in agricultural pattern and temporarily some regions may even benefit from it. But Climate Warming is also likely to cause increase in plant pests and diseases. The vulnerability of agricultural crops will increase as new insects and pathogens move into newly warm areas. There is general consensus that Climate Warming will lead to water scarcity in dry areas that are already suffering from water stress (India is one). Crop production will be further reduced in quantity and quality in these areas due to increased soil salinization from irrigation and depletion of aquifer reservoirs. Total arable land will be reduced due to sea level rise. All these factors will influence agricultural production and availability of food both regionally and globally. Human dietary habits and health are deeply correlated; the food habits change much slower than we think. So a nutritional stress will affect world health unless less wasteful feeding luxuries are given up and scarce food stock is intelligently utilized. The heath and dietary adaptation in this low yield food scenario will be completely different from the present. New food cycles with insects as one chief source of protein are one possibility and marine grass is another.
c) Disease Stress: The Heat and Nutritional Stress will indirectly cause many diseases during Climate Warming but one scary aspect of Climate Change is the changes in insects and other disease causing vectors and epidemiology of vector-borne diseases like Malaria, Dengue Fever, Rocky Mountain Spotted Fever, Trypanoso-miasis, Guinea warm, Schistosomiasis and Chagas Disease. Global Climate Change can shift some marginal areas from sporadic epidemic to endemic and other areas from disease free to epidemicity. The disease stress will, in my opinion, have the greatest impact on human health and well being and the genetic scale of adaptive changes denied by rapid Climate Change the average life-span of human will be diminished in the last half of this century.
Global Impacts of Anthropogenic Climate Change on Human Health and Adaptability by Michael A. Little and Ralph M. Garruto
Climate Effects On Human Health by Laurence S. Kalkstein and Kathleen M. Valimont