Note: This program first aired on June 23, 2012.
The late spring and early summer of 2012 has proven to be a
damp one here in Maine. While not as biblical as the spring a few years ago,
when it rained every day for weeks on end, I still hear complaints about the
showers and lack of sun everywhere I go. I admit, I hear them in my own head
and feel them in my own heart as well. And having just returned from a trip to
the desert, where the sky is inevitably blue and sun always shines, the damp
has felt especially insidious.
I’d like to take this time however, and remind us all, how
blessed we are. Water is precious, a fundamental requirement for life on earth,
and increasingly rare. Our physiology demands it at regular intervals on a
daily basis. Modern industry uses (and abuses it) in vast quantities. Our food
supply is critically dependent on fresh water, 70% of all appropriated freshwater
currently goes to irrigation of crops, so where there is water shortage, there
is food insecurity. Over 7 billion people live on this planet, and by 2025,
over half of them will live in areas subject to severe water stress. Millions
of people on the Indian sub continent and in South America rely on glacial melt
water as their primary water supply. With global glaciers in fast retreat and
several projected to disappear in the coming decades where will those people’s
children get water from? Subtropical
regions the world around are already typically desert zones. As climate
instability increases in coming decades, these regions, home to millions of
people, are expected to experience intensified drought. The leading cause of death globally is diarrhea, overwhelmingly
due to lack of access to clean water. When I said we are blessed, I meant it. Clean
water, so necessary for life, literally falls from the sky here.
We primarily get our water (for industry, for drinking and
municipal use), from one of two sources: deep underground aquifers (referred to
as ground water) or surface water (water that is readily available in ponds,
lakes, rivers). Ground water is the form of the vast majority of liquid fresh
water on Earth. According to a UN World Water Development report “Ground water
supplies nearly half of all drinking water in the world” and is crucial for the
well being of people, especially rural poor people, all over the world.
We should (but don’t) think of ground water as a non
renewable resource. Water moves readily through the hydrologic cycle: it
evaporates from the land and ocean surface, and is transpired from vegetation
into the atmosphere. From there it condenses from a gas back to a liquid in the
form of clouds and eventually rain or snow. That precipitation returns the
water to the surface of the Earth, where it infiltrates the soil, or runs off
and returns to surface water reseviors. Much of the water that infiltrates the
surface is taken up by vegetation or simply evaporates back into the
atmosphere. Only a small fraction eventually makes it down into the ground
water aquifer. The rate of recharge depends not only on how much water hits the
land surface, but also on the depth of the saturated layer, and the porosity of
the underlying geological layers the water has to travel through. Many ground
water aquifers are being depleted, due to extraction rates that exceed inflow
or replenishment rates. Basically, we take more water out than is going back in
through natural processes, thus making ground water use unsustainable.
So the next time you are thinking about complaining about
mosquitos or black flies-insects that require water in which to lay their eggs
and provide habitat for their larva, pause and remember: their presence is an
indicator of our good fortune and our richness; abundant clean water that falls
from the sky.
References:
“Environment and Development Challenges: The Imperative to Act” http://www.unep.org/home.asp www.unep.org/pdf/pressreleases/Blue_Planet_synthesis_paper.pdf This is a summary statement from all Blue Planet Award Winners.
“Managing Water under Uncertainty and Risk” United Nations
World Water Development Report 4 http://www.unwater.org/ Cheery reading.
https://www2.ucar.edu/atmosnews/news/2904/climate-change-drought-may-threaten-much-globe-within-decades Report from the National Center for Atmospheric Research
(NCAR).
http://www.ipsnews.net/2011/09/200-million-depend-on-melting-glaciers-for-water/ Excellent 2011 article that provides an overview of the
glacial meltwater issue.
