Our hunter-gatherer future: Climate change, agriculture and uncivilization - ScienceDirect
https://www.sciencedirect.com/science/article/pii/S0016328719303507
In the discussion below, the period two to three centuries in the future is used as a general reference point for the ultimate effects of human-caused climate changes. This long-term view avoids the quagmire of the “immediate collapse” versus the “peak and decline” discussions (2012, Randers, 2008) and also gets us close to the likely ultimate business-as-usual peak of temperature and CO2 levels.
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nevim, jak je tohle presny, ale:
Most projections of global warming focus on either the year 2100 or the effects of a doubling of CO2 (from the pre-industrial level of 275 ppm–550 ppm). The lack of attention to the very long run is a serious shortcoming, since integrated carbon-climate models project that if CO2 from current in situ fossil fuel resources continues to be released into the atmosphere, the peak concentration of atmospheric CO2 could exceed 1400 ppm by the year 2300 and the average global temperature could warm by 8 °C or more (Bala et al., 2005; Kasting, 1998). A CO2 level of 1400 ppm would increase the risk of a rise in temperature as high as 20 °C which will certainly have catastrophic consequences for all life on Earth. It is sobering to consider that current levels of CO2 are higher than at any time in the last 15 million years (World Bank, 2012 p. xiv).
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Agriculture will be impossible in the post-Holocene climate
With the future climate instability already locked into the system by recent human activity we will most likely return to the climate volatility of the Pleistocene. Climate change will adversely affect agriculture in a number of ways including sea level rise, higher average temperatures, heat extremes, changes in rainfall patterns, and the loss of pollinators. Less understood changes include the effects on agricultural pests, soil composition, and the growth response of crops to rising CO2 levels. Fig. 2 shows the possible volatility in climate if the Earth returns to the climate regime of the last few thousand years of the Pleistocene. Future volatility will not, of course, follow exactly the same pattern but Fig. 2 represents a rough guess as to what might occur. Agriculture was impossible in the past because of climate/weather instability and it is likely to again be impossible if similar conditions return.
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Increased climate volatility could occur quite soon. According to Batissti (Quoted in Wallace-Wells, 2017):
By 2050, under a typical middle-of-the-road emissions scenario, you’re looking at a doubling of the volatility for grains in the mid-latitudes. In places like China, the U.S., Europe, Ukraine—the breadbasket countries of the world—the volatility from year-to-year just from natural climate variability at a higher temperature is going to be much higher. The impact on crops is going to be greater and greater.
The ability of agriculture to adapt to climate change will depend on the rapidity of changes as well as their severity. Intensively growing high-tech crops on the massive scale required to support billions more people will be prohibitively expensive just in terms of the energy required. The feasibility of massively moving crops North to avoid warmer temperature is limited because of poor quality soils in places like northern Canada and Russia. Also, temperature fluctuations will be greater toward the poles. Much of the evidence is anecdotal, but there are already indications of climate instability more than offsetting the advantages of longer growing seasons in northern regions, For example, although longer summers in Greenland have increased the growing season by two weeks, they are becoming drier and rainfall has become more unpredictable with adverse effects on crops and livestock (Kintisch, 2016).
Sea level rise will be a major stress factor on agricultural output with the loss of agricultural land and increasing salinity from storm surges. According to Hansen et al. (2016): during the last interglacial, about 140,000 years ago, the earth was about 1 °C warmer than today and sea levels were 6–9 meters higher with evidence of extreme storms. Their modelling implies that a 2 °C warming would cause an eventual shutdown of the North Atlantic current, an ice melt in the North Atlantic and Southern oceans causing increased temperature gradients and more severe storms, and sea level rise of several meters within a very short time span of 50–150 years. Fischer et al. (2018 p. 474) write:
A global warming average of 1−2 °C with strong polar amplification has, in the past, been accompanied by significant shifts in climate zones and the spatial distribution of land and ocean ecosystems. Sustained warming at this level has also led to substantial reductions of the Greenland and Antarctic ice sheets, with sea-level increases of at least several meters on millennial timescales.
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Will the transition to hunting and gathering result from a catastrophic collapse of civilization or a semi-orderly contraction? A strong case can be made for a sudden catastrophic collapse and a massive dieoff of Homo sapiens (Ehrlich & Ehrlich, 2013; Morgan, 2009; Spratt & Dunlop, 2019
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Collapse is not a necessary pre-requisite to a hunter-gatherer future for our species. Our species may avoid collapse and have some sort of semi-orderly contraction of the human population and our impact on the biosphere. One way or another, with the environmental stress on agriculture from future climate change and the inevitable decline in food production, the number of humans on the planet will be drastically reduced over the coming centuries. As human populations shrink, and grain production becomes problematic, state societies as we know them will become increasingly difficult to maintain. This will be good for the planet and for individual human well-being. Scott (2017) makes a strong case that the average person was better off after past state societies collapsed. He argues that the period from the first appearance of states until their complete hegemony some 5000 years later was a “golden age of barbarians.” Barbarians had the autonomy to pursue limited agriculture, foraging and hunting, and they had the opportunity to take some of the spoils of the state through raiding and pillaging
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One can envision a relatively slow decline in food production as climate change becomes more and more pronounced, and a decline in population and economic output. The decrease in economic surplus will increasingly constrain the ability of states to maintain their monopoly on violence and their ability to control the population. It may be unlikely, but if the effects of climate change are gradual enough, a soft landing to a non-agricultural economy may be possible.