North America has been in the grip of a weird weather pattern that keeps a high atmospheric pressure system locked in place over the Pacific. This blocking ridge of atmospheric pressure disrupts wind patterns and prevents rainstorms from reaching California, while sending warm, dry air up the West Coast and re-routing the rainstorms farther to the north. Meanwhile, cold air has been moving down from the Arctic and across the northeast, keeping temperatures low and bringing higher precipitation across the East Coast.
According to the Globe & Mail (April 3, 2015), “Some climate scientists have suggested that the persistence of such weather patterns is the result of a jet stream that has been weakened by global warming.” A weakened jet stream could have dire consequences for weather patterns worldwide – locking in unusual atmospheric patterns for years.
Scientists call the atmospheric ridge that is currently blocking rain from California “the Triple R” (the Ridiculously Resilient Ridge). Stanford University scientist, Bala Rajaratnam, told Counterpunch.org that such large-scale atmospheric conditions “are far more likely to occur now” because of “large amounts of greenhouse gases” from producing and burning fossil fuels.
The Union of Concerned Scientists recently issued a statement claiming, “This pattern of intense rain and snowstorms and periods of drought is becoming the new normal in our everyday weather as levels of heat-trapping gases in the atmosphere continue to rise.”
But other scientists are factoring in a different dimension of human activity that is contributing to drought (and weird weather) worldwide.
Flying Rivers
Apparently, western scientists have misunderstood the hydrological cycle, long assuming that rain clouds form because of evaporation over water-bodies. Instead, they are now realizing forests and other “greenbelts” are central to rainfall patterns because of “transpiration.”
As water expert Maude Barlow told CBC’s “The Current” (March 3), “the air moving over rainforest carries twice as much rain as air coming over a desert or a cut-down forest. So the forest gives off vapours that are called flying rivers – huge areas of humidity [that] then travel thousands of kilometres. That’s what deposits rain when it’s needed in Sao Paulo [Brazil] and other places. That is the key here.”
Barlow is basing that comment on the work of Brazilian scientist Antonio Donato Nobre and his team of researchers at Brazil’s Earth System Science Centre. Nobre issued a report in October 2014 warning that deforestation of the Amazon is contributing to droughts and extreme weather events through the disruption of the “vegetation-climate equilibrium.”
Nobre reported that the 600 billion trees in the Amazon forest (through transpiration) transfer “20 billion metric tons of water” into the atmosphere DAILY in this “river of vapor that comes up from the forest and goes into the atmosphere” – an amount greater by volume than the entire Amazon River. Nobre calls it “this invisible river running above us.”
But in the past twenty years, the Amazon has lost 763,000 square kilometres of forest – an area the size of two Germanys – and another 1.2 million square kilometres have been degraded. This has decreased forest transpiration and has contributed to the lengthening of dry seasons. It is also likely a factor in the severe drought affecting southeast Brazil, where Sao Paulo (the biggest city in South America) is facing the worst water shortages in a century, with water-rationing affecting some six million residents.
Nobre told The Guardian (Oct. 31, 2014), “Studies more than 20 years ago predicted what is happening with lowering rainfall. Amazon deforestation is altering climate. It is no longer about [computer] models. It is about observation.”
A December 2014 study by scientists at the University of Virginia found that deforestation can disrupt rainfall patterns thousands of miles away.
Global Forest Watch recently reported that the world lost more than 18 million hectares (650,000 square miles) of tree cover in 2013 – with Russia and Canada at the top of the deforestation list. Because of all this forest loss, Nobre says the “vegetation-climate equilibrium is teetering on the brink of the abyss.”
“Vegetative-Climate Equilibrium”
In a 2014 speech, Nobre explained that while he was researching all this, he attended a public declamation given by Davi Kopenawa, a representative of the Yanomami tribe who live deep in the Amazon. As Nobre tells it, Davi Kopenawa basically said, “Doesn’t the white man know that, if he destroys the forest, there will be no more rain? And that, if there’s no more rain, there’ll be nothing to drink, or to eat?”
Nobre says he was astounded by this statement because “we [scientists] are starting to get to this conclusion, which he already knows!”
Nonetheless, Davi Kopenawa’s declamation bothered Nobre at the time because, as he puts it, the Yanomami tribal people have never deforested, so how could they know its effects on rain patterns? The question bugged Nobre until finally he met Davi Kopenawa at another event and asked him, “Davi, how did you know that if the forest was destroyed, there’d be no more rain?” He replied: “The spirit of the forest told us.”
Nobre says “For me, this was a game changer, a radical change.” Nobre is now urging the massive replanting of forests to “reverse climate change, including global warming.”
As Maude Barlow told CBC Radio’s The Current, scientists now understand that the Dust Bowl of the Dirty Thirties was caused by the widespread elimination of trees and perennial vegetation like Prairie grasslands – “the taking down of the grasses created the drought.” Barlow has written elsewhere, “… destroying water-retentive landscapes is in and of itself a major cause of climate change,” but that fact “is not part of the analysis or discussion in climate change circles,” which primarily focus on the burning of fossil fuels.
In BC, thousands of hectares of industrial forest land are waiting to be replanted. Doing this wisely could have multiple benefits, not just for the province but the planet.
The National Gardening Association website states that on a sunny summer afternoon, an average-size backyard maple tree transpires “more than fifty gallons [of water] per hour” into the local climate. All plants transpire, and Antonio Donato Nobre refers in his speech to a colleague in India, Suprabha Seshan, who is involved in rebuilding ecosystems. Her motto, he says, is “Gardening back the biosphere.”
