What is a 'heat associated death'?

 

Answer: Anyone who dies when it is hot and often is classified as a heat associated death. I have spent a lot of time in Pheonix and have seen the deaths in the paper while visiting relatives there. A 90+ year old who dies after taking their dog for a walk in the heat is classified as a heat associated death. 

 

People living in the desert of Arizona are hugely dependent on energy. In the past, the energy has come mainly from dams on the Colorado River. But there is a long-term drought going on right now. Droughts in the desert can go on for a long time. In the last 2000 years, there have been several droughts one of which lasted more than 200 years. 

 

Why are there droughts? 

 

The droughts are associated with long term changes in Ocean currents along the Pacific coast such as the PDO. Typically, they change on a decadal basis - i.e., one or more decades to go from a positive to negative PDO. However, in the past, there are periods when the changes are different. Sometimes other Pacific currents change in various ways - and this causes droughts in Mexico and Central America into the Northern part of South America. Such droughts resulted in the collapse of the Mayan and Aztec civilizations. Depending on exactly the changes in currents like the PDO impacts long term ocean surface temperatures, wind directions and where moisture from the ocean moves over land. The movement of wind and moisture over land impacts whether there is a drought and exactly where it is at. 

 

On living in the high deserts of the Western USA - it is fine unless there is a drought. Then the irrigation water from the Colorado River will be gone or much reduced and the energy from the Colorado River dams will also be reduced or gone. I've always found it kind of strange that there would be a huge population living in the deserts of especially Arizona and Nevada. It has always felt very strange to me to see the hugely dry desert, then the green yards and pools.