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Melting Glaciers Cutting Peru Water Supply
NewYorkCountryLawyer writes "In a story that may repeat itself in all mountainous areas dependent on glaciers for their water supply, the glaciers in Peru's Cordillera Blanca mountain range are melting so quickly (PDF) that the water they supply to the arid region is being threatened 20-30 years earlier than expected. Of the time needed for the region to adapt to the coming water shortages, previously thought to be decades, researchers now believe, 'those years don't exist.'"
How can you know what kind of weather occurred in Peru over the last 150 years? Did someone find Mayan engravings? Or there is this very old guy that can swear that this never happened since he was born? Or maybe it was a Union soldier that got lost and decided to start a weather journal?
Ok, I have some homework for you. Go home and read your textbook on Sedimentology, focussing specifically on lake sediments caused by runoff. Read about how the flows of rivers can be read by drilling sediment cores out of lake beds. Then find your textbook on Glaciology, and read about how cores of ice drilled from long term ice deposits can be used to track snowfall. While you are at it, you can read about how rainfall events leave specific signatures in sand and dirt, including rivulets and specific patterns in the distribution of different sizes of sedimentary particles. I suspect snowfall events could also be inferred with similar observations.
You would be amazed at what geologists and geographers can find out simply by using observation and logic.
This and no other is the root from which a tyrant springs; when first he appears as a protector - Plato (423 to 327 BC)
How can you know what kind of weather occurred in Peru over the last 150 years?
The fact that this Peruvian desert had no precipitation left it as one of the few places on earth with sodium nitrate prior to WWI. Europeans imported it for fertilizer and explosives. Germany had to devise a way to synthesize nitrate for their war efforts.
So yes, many people historically were aware of the lack of precipitation in that Peruvian desert and what the recorded precipitation was by the locals due to it being an extremely rare event.