Scientists have known about this transfer of dust for a number of years. But, now, for the first time, experts at Nasa have calculated the precise amount using three-dimensional modelling based on satellite data.
“We know that dust is very important in many ways,” said Hongbin Yu, an atmospheric scientist at the University of Maryland who works at NASA’s Goddard Space Flight Centre. “It is an essential component of the Earth system. Dust will affect climate and, at the same time, climate change will affect dust.”
Mr Yu added: “[To understand those effects] first we have to try to answer two basic questions. How much dust is transported? And what is the relationship between the amount of dust transport and climate indicators?”
Mr Yu and colleagues based their calculation on data collected by NASA’s Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation, or CALIPSO, satellite from 2007 to 2013. The results were published in Geophysical Research Letters, a journal of the American Geophysical Union.
Scientists have measured the amount of dust transported from the Sahara to the Amazon rainforest
The scientists worked out that every year strong winds pick up an average of 182m tonnes of dust and carry it past the western edge of the Sahara. This amount is equivalent to the contents of 689,290 large trucks, Nasa said.
The dust then travels west across the Atlantic ocean. Close to the coast of South America, 132m tonnes remain in the air and around 28m tonnes falls over the Amazon basin. The remainder continues to be transported westwards.
Nutrients from Sahara dust are vital to the life of the Amazon rainforest
Mr Yu said the most valuable dust is that picked up from the Bodélé Depression in Chad, an ancient lake bed where rock minerals composed of dead microorganisms are loaded with phosphorus. Phosphorus is an essential nutrient for plant proteins and growth, which the Amazon rain forest depends on this.
Nutrients – the same ones found in commercial fertilisers – are in short supply in Amazonian soils, Nasa said. Instead they are locked up in the plants themselves. Some nutrients, including phosphorus, are washed away by rainfall into streams and rivers that drain from the Amazon basin.
The project looked at seven year’s worth of data. Experts said it was insufficient to look for long-term trends but crucial for understanding how dusts move across the ocean.
Chip Trepte, project scientist for CALIPSO, said: “We need a record of measurements to understand whether or not there is a fairly robust, fairly consistent pattern to this aerosol transport.”
Mr Yu added: “This is a small world and we're all connected together.”
"Save the rain forest" is a mantra we've all grown up with, and for good reason.
About 17% of the Amazon rain forest has been lost in the last 50 years, according to the World Wildlife Fund. While the annual rate of deforestation has slowed in recent years, cattle ranching and other forms of agriculture remain serious threats to the rain forest.
But another, less talked-about issue the rain forest faces, is the threat of wildfires. While fires are a natural part of many forest life cycles, drier years can lead to particularly severe fire seasons that can damage the forests and threaten the wildlife that lives there. Additionally, human activities related to deforestation and logging can also set destructive fires in the rain forest.
A stunning data visualization from InfoAmazonia shows where forest fires have occurred in the Amazon rain forest between January 2012 and December 2014 using satellite data collected by NASA.
While the full visualization shows a complete timelapse over the past two years, the clip below shows fires in January and February of 2014. The small red and yellow dots popping up show where fires cropped up during this time, with the red dots representing any fires hotter than 116 degrees Fahrenheit and the yellow dots representing particularly high-intensity fires. The static orange and yellow patches on the map show how frequently fires occur — the brighter the yellow, the more frequent the fires.
Typically, this time of the year is relatively quiet with few fires, as you can see in the graphic.
South America’s Amazon Rainforest consists of 2.3 million square miles. That’s quite a bit of territory, roughly equivalent to the combined square miles of the 17 largest US states (AK, TX, CA, MT, NM, AZ, NV, CO, WY, OR, UT, MN, ID, KS, NE, SD, ND).
This vast area, comprising more than half of all the world’s rainforests, covers40% of South America and encompasses parts of nine countries—Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname and Venezuela—though Brazil accounts for up to 60% of the rainforest.
Frequently called “the Earth’s lungs,” the Amazon rainforest absorbs large amounts of the planet’s carbon dioxide and, in turn, sends large amounts of oxygen back into the atmosphere. This amazing feat is due to the trees, upwards of 390 billion of them from some 16,000 species. The trees are essential to making the rainforest a “gigantic hydrological pump that brings humidity of the Atlantic Ocean into the continent and guarantees the irrigation of the region.”
Teeming with life, in the Brazilian portion of the rainforest alone there are an estimated 25 million insect species, 40,000 plant species, and numerous vertebrate species: fish – 3,000, birds – 1,294, reptiles—378, amphibians – 427 and mammals—427. But now the Amazon rainforest is exhibiting alarming signs of drying up, with major negative consequences not just for the region but for the entire planet itself. How and why is this happening and what can be done to reverse it?
Symptoms of decline
Since 2000, rainfall has declined by “up to 25% across a vast swath of the southeastern Amazon,” affecting 69% of the rainforest. Declining rainfall has a dramatic impact on the rainforest’s carbon storage as demonstrated during the major drought of 2005 when “the Amazon lost an estimated 1.6 gigatonnes of carbon, slightly less than Russia’s annual carbon dioxide emissions.”
Decreased rainfall has a direct impact on the tropical savannas, as well, affecting 80% of those areas.
There’s a natural occurrence poetically dubbed, “flying rivers,” which results when clouds of vapor rise from the rainforest, gather together and begin rushing toward central and southern Brazil bringing much rain. The rainforest’s flying rivers are larger than any river on the surface of the earth. This year’s flying rivers did not materialize in January and February, as they should have, due in large part to the overall drying the drought is bringing to the rainforest.
Brazil’s Sao Paulo, home to 20 million people, is particularly hard-hit by the drought and the absence of this year’s Flying Rivers. Sao Paulo’s Cantareira reservoir system is almost tapped out, with water intake pipes pulling water up from the very bottom of the reservoirs. Over 75% of Brazil’s electricity is generated by hydropower reservoirs which are “running critically low in the country’s Southeast region and could prompt emergency rationing next year.” There is also considerable uncertainty about the impact of the drought on this year’s Brazilian soybean crop, the second largest in the world.
Scientists are now able to capture the impact of the drying phenomenon in the Amazon rainforest and its savannas by studying greenness from satellites. Since 2000, 69% of the rainforest itself and 80% of the savannas experienced decreased rainfall, resulting in a noticeable change in plant greenness.
According to the scientists, “if this drying continues, and several studies predict this, it could lead to substantial carbon loss of the Amazon basin.”
There go the planet’s lungs.
Why is the Amazon drying up?
Trees are key to life in the Amazon rainforest and to the weather cycles of the region. The canopy created by the trees doesn’t just protect and sustain the floral and fauna beneath them, but results in “20 billion tonnes of vapour” evaporating daily with moisture spreading to nearby areas.
In contrast to those 20 billion tons of vapor, the Amazon River discharges “17 million tonnes of water . . . each day into the Atlantic.” The great ecological system of the Amazon rainforest is threatened by the disappearance of the canopy as trees are felled, and at an alarming rate.
Deforestation of the rainforest has taken a severe toll already, with over 289,000 square miles of rainforest disappeared since 1978. Sixty-five to 70% of the deforestation has occurred to create large open ranges for cattle. An additional 10% was cleared for large-scale crops, particularly soybeans. Each step in the deforestation process also led to the creation of more roads, pushing ever deeper into the rainforest, an open invitation to legal and illegal loggers and miners, speculators and poor farmers—all threatening the Amazon’s environment and its indigenous communities. Build a road, and the trucks will come.
As trees are felled in the Amazon rainforest, a chain reaction begins. Decreasing the canopy decreases the amount of humidity sent into the air, thus decreasing the Flying Rivers, and ultimately affecting up to “70% of South America’s GDP [which depends on production] in areas fed by precipitation from the Amazon.”
Another danger of loss of canopy and moisture is fire, as sunlight penetrates what used to be forest, exposing the debris from felled trees and dying vegetation which becomes tinder just waiting for a spark and then winds to further the flames. Those fires are in addition to the forest fires deliberately set to clear land.
Whatever the origin, smoke from the fires “introduces too many particles into the atmosphere, dries the clouds, and they don’t rain.”
Overall, in the latter part of the 20th century, there was a shift from traditional indigenous farming in the Amazon to clearing and use of the land for large-scale enterprises, particularly cattle-ranching and soybean farming. Dams were built to channel water for those purposes and for hydroelectric projects, while native habitat was further disturbed and bulldozed by mining and logging activities.
High-resolution satellite images have offered a rare glimpse of the last few people on Earth who live without contact with the modern world – living in remote villages in the Amazonian rainforest, and surviving by hunting.
Satellites have glimpsed distinctive ‘longhouse’ style huts in remote clearings in the Amazonian jungle.
Many of these tribespeople will have had little to no contact with the modern world.
There are dozens of these isolated tribes, but until now, their movements have largely been a mystery.
Researchers are reluctant to fly over in aircraft for fear of frightening the villagers.
Instead, researchers have begun to use hi-res satellite imagery to monitor the villages – and found distinctive clusters of longhouses, dotted through the jungle.
The researchers were able to compare imagery from 2006 and 2013, to see which settlements had grown, and which had shrunk.
One village had cleared forest around it, and begun to farm new fields – a response, the researchers believe, to an influx of other tribespeople fleeing drug gangs and loggers in the area.
The village which expanded, Site H, is now just 24 miles away from a road cut into the jungle.
A team of researchers in the U.S. with another member from Brazil has found that parts of the Amazon rainforest are receiving less rainfall than was received just a couple of decades ago, and because of that are less green. In their paper published in Proceedings of the National Academy of Sciences, the researchers discuss how new satellite technology has allowed for more accurately measuring rainfall amounts in the Amazon river basin which allows for noting changes in rainfall over multiple years.
The Amazon rainforest is a really important piece of Earth's carbon life cycle—scientists believe it's responsible for pulling in up to 25 percent of the total carbon from plants for the entire planet. For this reason, any drop in carbon absorption in the area is cause for concern.
Scientists have suspected for quite some time that the Amazon rainforest is absorbing less carbon dioxide than before, simply because it's not as big as it used to be—humans have cut down the forest in many places. Now it appears that the forest that remains is receiving less rain, which in turn is making it less green which means the trees that are there are pulling in less carbon dioxide from the air around them.
More specifically, the researchers found that the rainforest has received less rainfall starting around the year 2000, than it did before that time—some parts of the southern edges have seen as much as 25 percent less—an area roughly the size of California. That single area, the researchers have calculated, has been accounting for approximately half of the loss of carbon absorption by the rainforest overall.
Even more worrisome is that in normal dry year cycles, generally attributable to El Niño events, the reduction in carbon absorption can be equivalent to the entire amount absorbed by all the plants in Russia in a given year. Some climatologists have predicted that as the planet heats up, super El Niño events are likely to occur which could devastate parts of the rainforest. On the bright side, the same research has shown that La Niña events could have the opposite impact.
Their research is based, the team reports, on new satellite technology that allows for seeing how much green is occurring beneath cloud cover, allowing for better measurements of carbon absorption abilities of the plants below.
Satellite data through the end of July 2013 show that an area half the size of Puerto Rico has been cleared from the Amazon rainforest over 12 months, according to The Guardian. The destruction marks a reversal in restoration gains seen in tree cover there since 2009.
The Brazilian government reports that 5,891 square kilometers of the forest have been cleared in its Amazon regions, up 29 percent from the year before. The largest decreases were seen in Brazil’s Para and Mato Grosso states.
Illegal logging as well as public infrastructure projects are expected to have contributed to the increase in deforestation. Despite the move upward, figures are still not as bad as they were in 2004, when almost 30,000 square kilometers of forest were lost.
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