Climate Change Impacts You Wont Read In The News
“Adaptation and Its Limits”
I recently read portions of the IPCC Fifth Assessment Report in Chapter 4 “Terrestrial and Inland Water Systems” and Chapter 11 “Human Health Impacts” and was extremely disturbed – to put it mildly – by what I learned.
Since then, I had been planning on posting excerpts of 3 absolutely devastating climate change impacts that you won’t see presented in the news or even by environmental groups.
The sections on “Limits to Adaptation” and “Phenology” (Chap. 4) and “Physiological Limits to Heat Tolerance” (Chap. 11) were deeply depressing. Literally the end of the world catastrophic. Read it and support “forest stewardship” and keep on planting that milkweed folks! (that’s snark).
Well today, I am prompted to do so by an email from a stranger requesting that I post her “World Infographic” on a “Day in the Life of Global Warming (hit link to view). So, for those who find those “Infographich” style displays helpful, by all means, hit the link.
And for those who prefer reading a more complex text, here are the 3 absolutely devastating projected climate change impacts you will rarely if ever see discussed: (boldface in original)
Strike 1:
There is a high risk that the large magnitudes and high rates of climate change associated with low-mitigation climate scenarios (RCP4.5 and higher) will result within this century in abrupt and irreversible regional-scale change in the composition, structure and function of terrestrial and freshwater ecosystems, especially in the Amazon and Arctic, leading to substantial additional climate change (medium confidence). There are plausible mechanisms, supported by experimental evidence, observations, and model results, for the existence of ecosystem tipping points in both boreal-tundra Arctic systems and the rainforests of the Amazon basin. Continued climate change will transform the species composition, land cover, drainage and permafrost extent of the boreal-tundra system, leading to decreased albedo and the release of greenhouse gases (medium confidence). Adaptation measures will be unable to prevent substantial change in the boreal-arctic system (high confidence). Climate change alone is not projected to lead to abrupt widespread loss of forest cover in the Amazon during this century a (medium confidence), but a projected increase in severe drought episodes, together with land-use change and forest fire, would cause much of the Amazon forest to transform to less dense, drought- and fire-adapted ecosystems, and in doing so, put a large stock of biodiversity at elevated risk, while decreasing net carbon uptake from the atmosphere (medium confidence). Large reductions in deforestation, as well as wider application of effective wildfire management, lower the risk of abrupt change in the Amazon, as well as the impacts of that change (medium confidence). [4.2.4.1, 4.3.3.1.1, 4.3.3.1.3, 4.3.3.4, Figure 4-8, Box 4-3, Box 4-4]
Strike 2
11.8. Adaptation Limits under High Levels of Warming
Most attempts to quantify health burdens associated with future climate change consider modest increases in global average temperature, typically less than 2° C. However, research published since AR4 raises doubt over whether it will be possible to limit global warming to 2°C above pre-industrial temperatures (Anderson and Bows, 2011; Price Waterhouse Coopers, 2012; Rogelj et al., 2009). It is therefore increasingly important to examine the likely health consequences of warming beyond 2°, including extreme warming of 4-6°C or higher. Predictions of this nature are limited by uncertainty about climatic as well as key, non-climatic determinants of health including the nature and degree of adaptation. Here, we instead focus primarily on physiological or ecological limits that constrain our ability to adapt and protect human health and wellbeing (Section 16.4.1).
It can be assumed that the increase in many important climate-related health impacts at increasingly higher levels of warming will be greater than simple linear increments; that is, that the health consequences of a 4°C temperature increase will be more than twice those of a +2°C world (see Figure 11-6). Nonlinear and threshold effects have been observed in the mortality response to extreme heat (Anderson and Bell, 2011; McMichael, 2013a), agricultural crop yields, as key determinants of childhood nutrition and development (Lobell et al., 2011a; Schlenker and Roberts, 2009), and infectious diseases (Altizer et al., 2006) , for example. These are also briefly elaborated here.
11.8.1. Physiological Limits to Human Heat Tolerance
In standard (or typical) conditions, core body temperatures will reach lethal levels under sustained periods of wet- bulb temperatures above about 35°C (Sherwood and Huber, 2010). Sherwood and Huber (2010) conclude that a global mean warming of roughly 7°C above current temperatures would create small land areas where metabolic heat dissipation would become impossible. An increase of 11-12°C would enlarge these zones to encompass most of the areas occupied by today’s human population.
The above analysis is likely a conservative estimate of an absolute limit to human heat tolerance because working conditions are hazardous at lower thresholds. The U.S. military, for example, suspends all physical training and strenuous exercise when the wet bulb globe temperature (WBGT) exceeds 32°C (Willett and Sherwood, 2012) while international labor standards suggest the time acclimatized individuals spend doing low intensity labor such as office work be halved under such conditions (Kjellstrom et al., 2009a).1 One estimate suggests global labor productivity will be reduced during the hottest months to 60% in 2100 and less than 40% in 2200 under the RCP 8.5 scenario in which global mean temperatures rise 3.4°C by 2100 and 6.2°C by 2200 relative to 1861-1960 (Dunne et al., 2013). It is projected that tropical and mid-latitude regions including India, Northern Australia, Southeastern USA will be particularly badly affected (Dunne et al., 2013; Willett and Sherwood, 2012). (emphasis mine)
- Strike 3:
11.8.2. Limits to Food Production and Human Nutrition
Agricultural crops and livestock similarly have physiological limitations in terms of thermal and water stress. For example, production of the staple crops maize, rice, wheat and soybean is generally assumed to face an absolute temperature limit in the range of 40-45°C (Teixeira et al., 2011), while key phenological stages such as sowing to emergence, grain-filling, and seed set have maximum temperature thresholds near or below 35°C (Porter and Semenov, 2005; Porter and Gawith, 1999; Yoshida et al., 1981). The existence of critical climatic thresholds and evidence of non-linear responses of staple crop yields to temperature and rainfall (Brázdil et al., 2009; Lobell et al., 2011b; Schlenker and Roberts, 2009) thus suggest that there may be a threshold of global warming beyond which current agricultural practices can no longer support large human civilizations, and the impacts on malnourishment and undernutrition described in Section 11.6.1 will become much more severe. However, current models to estimate the human health consequences of climate-impaired food yields at higher global temperatures generally incorporate neither critical thresholds nor nonlinear response functions (Lake et al., 2012; Lloyd et al., 2011), reflecting uncertainties about exposure-response relations, future extreme events, the scale and feasibility of adaptation, and climatic thresholds for other influences such as infestations and plant diseases. Extrapolation from current models nevertheless suggests that the global risk to food security becomes very severe under an increase of 4-6°C or higher in global mean temperature (medium evidence, high agreement) (Chapter 7, Executive Summary).
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