Future collapse: how optimistic should we be?

Prof. Kelly FRS is optimistic about the chances of avoiding a collapse, but sadly we find his arguments entirely unpersuasive. For example, have Malthus (or we) really been wrong about food security? Roughly 850 million people are seriously undernourished (lacking sufficient calories) today, and perhaps 2 billion are mal-nourished (lacking one or more essential nutrients) [1]. When Malthus lived, there were only about 1 billion people on the planet. We agree that there are many things that could be done to feed today's population of 7.1 billion, or even perhaps over 9 billion in 2050. Many of them (e.g. limiting waste) have been discussed for 50 years with little sign of progress. We do not think any serious analyst doubts that, if it were equitably distributed, today's food production could nourish everyone adequately. Equally, we know of no serious analyst who believes such distribution is likely in the future. The concern is that climate disruption combined with other problems with the agricultural system will make it impossible to feed an ever larger future population, even if equal distribution were achieved. That concern is reinforced by the recent observation that, even before the likely heavy impacts of climate disruption on agriculture appear, production is failing to keep pace with projected needs [2]. There has been an important decline in birth rates in much of the world, but the median projections still foresee an increase of approximately 2.5 billion people by 2050 [3], and recently there have been worrying signs of 'a fundamental change in the well-established negative relationship between fertility and development' ([4], p. 741). Most recently, the UN has revised its projections of future population sizes upward [5], projecting a 2100 population of roughly 11 billion. On the brighter side, there is certainly good reason to think that, with modern contraception and communications, the population trajectory could be changed, leading to reduced fertility in rapidly growing populations if a significant international effort to promote women's rights and family planning in every nation were mounted. Much of Prof. Kelly's criticism of our article is that our treatment of climate disruption, which we discussed first in 1968 [6] and many times subsequently [7– 10] without significant dispute, is mistaken. This is critical, since, for example, the ability to feed people has been dependent on a stable climate, and most other elements of the human predicament have a climate component. We are not …