Saturday, 27 June 2015

The drought in Sao Paulo and South America

It’s Not Just Sao Paulo — Much of South America and Caribbean Swelters Under Extreme Drought


26 June, 2015

In Sao Paulo today, a Latin American megalopolis that is now home to 20 million people,public water supplies are cut off for as long as three days at a time. But despite this draconian rationing, the Cantareira Reservoir sits at 9 percent below dead pool. A level so low that utility managers had to install new pipes into the reservoir bottom to tap water supply dregs. A controversial policy due to the fact that drawing water from so low in the pool both results in fish kills and in much more polluted water going into rivers (like the foaming Tiete) and the drinking and bathing supply.

Cantareira Reservoir bone dry
(The Cantareira Reservoir has been bone dry for more than a year and a half now. Severe water rationing has managed to keep levels about steady for the time being. Image source:UOL.)

At least the dramatic cuts in water usage appear to have slowed to a near halt further water declines from the key reservoir. Levels have remained at around -9 percent below dead pool volume ever since the rainy season ended two months ago. But Sao Paulo still has at least four months of dry season ahead. And the weather for Brazil’s largest city, for most of Brazil itself, for Colombia and for the Caribbean remains exceptionally dry.

Drought Extends Over Much of South America, Caribbean

Much attention has been paid to the Sao Paulo drought. This is likely due to the very dire water situation immediately threatening 20 million people with severe water rationing, increased risk of waterborne illness (see Dengue Fever strikes Sao Paulo), and spurring migration to less water stressed regions. But the quiet truth, less widely reported, is that a massive swath of Latin America is also suffering major drought.

Latin American Drought
(South American precipitation deficits and surpluses over the past six months shows widespread, severe drought. Image source: NOAA’s Climate Prediction Center.)

The drought centers over the tree-depleted and human settlement invaded Amazon Rainforest. There half year moisture deficits are in the range of 400 millimeters or greater (16+ inches). A level of extraordinary drought in a region that supplies critical moisture to the surrounding states and nations. Years of clear cutting, slash and burn agriculture, and ramping temperatures due to human-caused climate change have taken a terrible toll on the Amazon. Now its resiliency is compromised with drought a common-place occurrence even as hundreds of wildfires burn away at the forest understory every year.
The warming climate (greenhouse emissions based), the water cycle disrupting clear cutting, and the fires all take their toll, resulting in a declining rainforest health and related moisture levels. The worst years of all are El Nino years — when warming Equatorial Pacific waters enhance drought potentials all throughout the Amazon of Northern Brazil. And the 2015 El Nino is no exception, with worsening drought conditions building at center mass over the Amazon River Basin and its related rainforests.
Prevailing and intensifying drought in the Amazon has far-flung impacts. The region acts as a kind of atmospheric moisture reservoir — sending out streams of flying rivers toward the North, South and East. In this way a healthy Amazon rainforest pumps up the clouds over vast regions, enabling rainfall from Colombia to the Caribbean and throughout Brazil. But an ailing, warming, drought-sweltered and clear-cut rainforest loses its ability to send out flying rivers. Instead, it dries out at its heart.

Amazon Water Vapor
(Often visible from the air, the trees of the Amazon release vast clouds of water vapor into the air. These ‘flying rivers’ are now drying up as the Amazon is warmed by human climate change, burned by understory fires, and clear cut by human development. Image source:Climate News Network.)

For some places in Colombia, this has meant residents suffering through drought for more than three years. In La Guajira, some residents are suffering loss of life due to lack of water and related food stores. The situation is complicated due to the fact that most of the water from depleted aquifer supplies for the region now goes to industrial uses like irrigation-fed international farms or the largest open pit coal mine in the world. This leaves very little water left for residents and what supplies remain are often brackish and polluteа.

In the Caribbean, more than 1.5 million people are now affected by drought with many also facing severe water rationing. Water shortages, withering crops, dead cattle, and disruption to tourism has impacted far-flung island nations from Puerto Rico to St Lucia to Cuba to the Dominican Republic. In the Dominican Republic, the situation is rapidly worsening with civil engineers stating that many of the island nation’s towns have less than thirty days of water left. Reports from other regions like Haiti are more spotty but indications are that these are also heavily impacted (Haiti is terribly deforested and, as a result, has very little resiliency to any form of extreme weather).

With El Nino still ramping up and with global temperatures likely to continue to hit new record highs (due to the heating effect of excessive fossil fuel emissions and CO2 levels hitting above 400 parts per million [above 480 CO2e] for the first time in at least 3 million years) throughout 2015, drought conditions for the Amazon, for Brazil, for Colombia and for the Caribbean will likely continue to worsen for at least the next six months. And to this point it is worth re-stating that crushing drought conditions are not confined to Sao Paulo but instead range from Uruguay through Brazil, Venezuala, Colombia and on into much of the Caribbean Island Chain.

Links:
Hat Tip to Greg
Hat Tip to Colorado Bob


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