Posted by From Yale Environment 360, more questions about future UN population projections:
For now, we can indeed be highly confident that world population will top 7 billion by the end of this year. We’re close to that number already and currently adding about 216,000 people per day. But the United Nations “medium variant” population projection, the gold standard for expert expectation of the demographic future, takes a long leap of faith: It assumes no demographic influence from the coming environmental changes that could leave us living on what NASA climatologist James Hansen has dubbed “a different planet.”
How different? Significantly warmer, according to the 2007 assessment of the Intergovernmental Panel on Climate Change — as much as 10 degrees Fahrenheit more than today on average. Sea levels from two to six feet higher than today’s — vertically, meaning that seawater could move hundreds of feet inland over currently inhabited coastal land. Greater extremes of both severe droughts and intense storms. Shifting patterns of infectious disease as new landscapes open for pathogen survival and spread. Disruptions of global ecosystems as rising temperatures and shifting precipitation patterns buffet and scatter animal and plant species. The eventual melting of Himalayan glaciers, upsetting supplies of fresh water on which 1.3 billion South Asians and Chinese (and, of course, that number is rising) depend for food production.
And that’s just climate change, based on the more dramatic end of the range the IPCC and other scientific groups project. Yet even if we leave aside the likelihood of a less accommodating climate, population growth itself undermines the basis for its own continuation in other ways. Since 1900, countries home to nearly half the world’s people have moved into conditions of chronic water stress or scarcity based on falling per-capita supply of renewable fresh water. Levels of aquifers and even many lakes around the world are falling as a result. In a mere 14 years, based on median population projections, most of North Africa and the Middle East, plus Pakistan, South Africa and large parts of China and India, will be driven by water scarcity to increasing dependence on food imports “even at high levels of irrigation efficiency,” according to the International Water Management Institute.
The world’s net land under cultivation has scarcely expanded since 1960, with millions of acres of farmland gobbled by urban development while roughly equal amounts of less fertile land come under the plow. The doubling of humanity has cut the amount of cropland per person in half. And much of this essential asset is declining in quality as constant production saps nutrients that are critical to human health, while the soil itself erodes through the double whammy of rough weather and less-than-perfect human care. Fertilizer helps restore fertility (though rarely micronutrients), but at ever-higher prices and through massive inputs of non-renewable resources such as oil, natural gas, and key minerals. Phosphorus in particular is a non-renewable mineral essential to all life, yet it is being depleted and wasted at increasingly rapid rates, leading to fears of imminent “peak phosphorus.”
Definitely read the whole thing. I expressed similar doubts when the UN released its revised population predictions earlier this year, suggesting that yet again, the UN has failed to take environmental limitations fully into account.
The Yale piece places very little emphasis on energy resources, even though those have an enormous impact on a whole host of factors that support population – distribution of food through global networks is an obvious one, the economy another obvious one (whether correlation or causation, oil shocks tend to be accompanied by significant recessions), but also assumptions that the tide of HIV deaths in Africa will be stemmed depend on fragile, oil-dependent distribution and production of drugs. One certainly hopes that drug distribution will be a priority with extant resources, but it may not be.
Neither Yale nor the UN has fully grasped the degree to which energy and population are linked and approaching a crisis point. This deserves more attention and analysis than it has received – we know that many oil dependent systems can be replaced by long-term sustainable systems. For example, we know that we can make much better use of phosphorous and nitrogen, How many people this can support and for how long is another question all together. Even bigger than that, however, is what we will choose to do – because acting or not acting, either way, we’re making a choice.
In _A Nation of Farmers_ Aaron Newton and I came roughly to the conclusion that were the planet to make feeding people in a low energy system its main priority, we could do so – but that this would require an attendence to equity and food justice not currently supported by the mainstream culture of the Global North, and we couldn’t do it forever, or at low environmental cost, and that there’s no evidence we *WILL* do such a thing, even if we can.
The UN population projects are used to make all sorts of decisions at the international level – they should and must take into account the world we’re actually facing to be useful and relevant.
Sharon
October 16, 2011
October 16, 2011
October 16, 2011
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October 17, 2011
(just in case that was a bit too subtle to get through to most people 
October 18, 2011