Feedback cycles and climate change risks

Another aspect of climate change risks are tied into negative and positive feedback cycles.  [Refresher on negative and positive feedback cycles] For example, we were looking to go apple picking at an apple orchard today (October 8, 2012) and the farmer let us know that for a number of reasons the harvest was only about 80% of normal and they did well in this area – lots of others had significantly less than that.  What happened this year was a warm and early spring and as a result the trees blossomed early and then we had a frost and then these trees almost lost their fruit.  The orchard hired a helicopter to keep the warm air down and that apparently worked pretty well.   Lots of other orchards did lose most of their blooms. Then after the frost, this area had a very dry summer for about 2 months so they were watering their trees about 1000 gallons of water a day for about 2-2.5 months.  He also mentioned that about 80% of the water ended up running off.  Imagine if every summer because of climate change followed a similar pattern of more warmth, less rain and as a result the orchard had to water their trees 1000 gallons per day and then the water table drops and the water is not even available for irrigation.  This is one example of a feedback cycle which may drive the risks of climate change even more.  Another example is the bodies of water that nuclear and fossil fuel fired power plants use for cooling towers and discharge of waters.  Regulations and certifications of approval cover the use of these cooling waters and often there are strict requirements about the receiving waters not exceeding a certain temperature.  During hot summers, as the water temperature rises, power plants will not be able to operate as much to support the A/C needs of the population during summer heat – again a feedback cycle.  This has already been happening in France with nuclear power plants as well as with the Tennessee Valley Authority as well in the summer.

Some solutions which are of course available include drip irrigation and efficient A/C as well as demand side management programs.  These are all being tried and rolled out in various formats in many areas.


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