Monday, May 19, 2014

Do Trees Make It Rain?

Most people have the old diagram of the water cycle (the system of evaporation, cloud formation, and rainfall) that they learned in grade school hidden somewhere in the back of their minds.  In this diagram the sun warms the ocean, water evaporates from the ocean and forms clouds.  These clouds move inland and release their moisture as rain (or sometimes snow or other frozen precipitation). While this picture isn't wrong, it is incomplete.

Trees play a large role in increasing rainfall.  In fact, scientists believe 33-40% of precipitation is due to evapotranspiration from forests.  In the summer in areas, the amount of rainfall originally derived from forests can be as high as 50%.  Evapotranspiration is the process by which trees elevate water from the ground, through their roots up to their canopies and up into the air.  It is remarkably efficient way to liberate ground water and allow it to come down again as rain.  Without trees, most of the ground water would return to the oceans and mix with salt water without ever being used.  Trees can lift up to 100 gallons of water from the ground into the air in one day.

Scientists have long suspected that clouds gain more moisture as they travel over forests, but recent satellite imagery has found "that the more vegetation [forest] the air had traveled over, the more moisture it carried and more rain was produced" (see link below). The fear is that deforestation of the Amazon may lead to drier climates all around.   

We know in many areas summers are getting drier, an a possible cause for this is deforestation.  In Indiana, our rich, productive farmland is almost all cleared forest, as is much of the Eastern United States.  We have also seen our summers getting drier recently. 

A more complete and accurate, if more complicated, diagram of the water cycle from the USGS.  It shows the significant contribution of trees to air moisture and precipitation.  The trees lift water from deep underground using their roots and capillary action to grow.  

There are even questions about whether once successful classical civilizations like the Maya in central America or the Minoans on ancient Crete induced local climate destroying droughts by clearing large forests (for farming in the case of the Maya, for shipbuilding for the Minoans).  

Of course, no society is going to replant productive crop land with trees on a large scale because of risks of decreasing rainfall.  
Planting forests could help drought, but we won't plant forests on good farmland because the farmland itself is so valuable.  So is there anything that can be done?  

Yes!  New technology, designed in Holland to be used in dry areas around the Earth, allows trees to be planted in very dry areas regardless of rainfall.  This technology, called the Groasis Waterboxx, acts a self recharging water battery, filling up with dew and rare rainwater, and slowly channeling this water to the roots of the growing tree.  This forms a column of water beneath the Waterboxx, inducing the tree's roots to reach deep to underground water reservoirs called capillary water (the underground water that would sit stagnant or flow to the sea without the Waterboxx).  The Waterboxx is removed once the tree reaches deeper water stores (evidenced by a growth spurt), and reused up to nine more times.  

The Waterboxx is literally earth changing because it allows trees to be established for profit in areas that have too irregular rainfall to have any other crops.  It works so well that 88% of trees planted with the Waterboxx survived a year in the Sahara, compared to around 11% planted without the Waterboxx but with weekly planting.  This survival rate increases to 99% if two trees are planted per Waterboxx and only the stronger one is kept.  The Waterboxx will allow orchards and timber farms to be established in what was otherwise considered useless land, slowly changing climate.  

Salt cedar trees growing in the Sahara Desert over 3 years with the Waterboxx PlantCocoon® - no water was given to these trees or added to their Waterboxxes at any time after planting!
Clearly no single planting, no orchard, park or forest planted in a current arid area is going to substantially increase rainfall.  But as planting trees with the Waterboxx is profitable, in the future we can reverse the damage we have previously done to our climate by planting large numbers of orchards, parks, timberland on private land.  Their cumulative effect will not just enrich our individual lives and properties, but our world as a whole.  Imagine the entire western Great Plains, from Canada to Texas, an area generally too dry to farm, planted with an uninterrupted swath of trees native to the area.  Imagine parks throughout the eastern U.S. planted with massive trees like sequoias, that recycle huge amounts of water into the atmosphere.   The Waterboxx can allow us to plant trees in dry areas without irrigation and with irregular rainfall.

The Groasis Waterboxx is sold by Dew Harvest LLC in the United States.  Buy the Waterboxx here.  

A schematic view with a cutaway corner of the Groasis Waterboxx PlantCocoon.  Water is collected by the lotus leaf inspired lid, channeled and stored in the green reservoir, and slowly released via a wick to the roots of a growing tree or plant. 
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1 comment:

  1. This is wonderful information. Please let it be known to Panama government that faces drought for letting developers clear forests around Panama Canal.