This blog is intended to go along with Population: An Introduction to Concepts and Issues, by John R. Weeks, published by Cengage Learning. The latest edition is the 12th (it came out in 2015), but this blog is meant to complement any edition of the book by showing the way in which demographic issues are regularly in the news.

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Tuesday, January 7, 2014

Does Cold Weather Mean Global Warming is a Hoax?

Global climate change deniers (e.g., FoxNews) have been having a field day with the idea that the very cold weather (a "polar vortex"?) in the US this week means that global warming doesn't exist. But global climate change appears to very real, with one of its side effects being increasing extremes in weather, both hotter and colder at the same time. More importantly, as a report in Nature today points out, it means more problems with water in the future.
To assess what a warmer world might mean for the human race, 30 groups from 12 countries have run thousands of simulations, using a standardized set of scenarios for greenhouse-gas emissions. They made projections of future water availability from a set of global hydrological models in conjunction with five state-of-the-art climate models that combined projections of changes in temperature and precipitation with data on variables such as regional water cycles, river run-off and population.
The multi-model assessment suggests that, in vulnerable regions, climate change will significantly add to the problem of water scarcity that is already arising from population growth. The modellers found that climate-driven changes in evaporation, precipitation and run-off will result in a 40% increase in the number of people worldwide who must make do with less than 500 cubic metres of water per year — a commonly used threshold to signify ‘absolute’ water scarcity.
Regions most at risk from water scarcity include parts of the southern United States, the Mediterranean and the Middle East. By contrast, India, tropical Africa and high latitudes in the Northern Hemi­sphere can expect to receive more water in a warming world.
These are models, of course, because (like population projections) they provide us with the only way of trying to decipher the future. Despite variability in the models, the results consistently point to a future in which weather and water availability will be different. The sooner we own up to that and start planning our responses, the better off we will be. That just seems common-sensical to me.

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