June 26, 2014 by Darius
I’m working my way through the Coursera course “The Age of Sustainable Development” taught by Professor Jeffrey Sachs of Columbia. One lecture I just watched dealt with environmental threats to the food supply brought about by climate change and thought the (depressing) information was worth sharing.
- The world is starting to add more meat to its diet. Meat is very inefficient, energy speaking. Up to 10 kilograms of grain are needed to produce one kilogram of beef, for instance. More meat consumption will mean less grain going to people.
- Warming of the climate leads to faster evaporation and thus threatens soil moistures. Lower soil moisture leads to lower crop yields.
- Climate change is also expressing itself in changes in precipitation patterns. The basic theme of these changes is that dry parts of the world will become drier still, while wetter parts of the world will become wetter still. There are already many people who live in areas on the margins of possible agriculture. Less rainfall and a shorter rainy season will put an incredible strain on the marginal areas of crop production.
- Ocean acidification due to carbon dioxide levels in the atmosphere stunts the growth of fish. Already, studies have shown that shellfish, for instance, will not grow to the same size under acidic conditions. Given that millions of people depend on seafood, the fact that there will be less of it, to say nothing of overfishing, is cause for alarm.
- Pesticides and herbicides have increased crop yields on land, but they are also leading to a dangerous drop in biodiversity. They threaten important pollinator species. We don’t know the full impact of the loss of these pollinators.
- Alpine glaciers are melting rapidly, causing an increase in the flow of the rivers that depend on them. As the glaciers melt completely, though, the flow of these rivers will drop precipitously. Hundreds of millions of people depend on glacier-fed water supplies.
- Many rivers, such as the Colorado River in the United States, are so dammed and diverted that they no longer even reach the sea.
- Climate change is contributing to less river flow overall: the Nile, for example, will have a significant decline of flow as a result of climate change. The Yellow River of China is in the same situation. Millions of people depend on these rivers as well.
- Groundwater is being pumped out of aquifers for irrigation and other uses at rates that far exceed the rate of natural replenishment. When aquifers run dry, they are dry and little can be done about it.
Of course, all these challenges come on the backdrop of a rapidly expanding global population. Ouch.