A huge lake in Bolivia has almost entirely disappeared. Lake Poopó used to be the country’s second largest, after Lake Titicaca, and just a few decades ago in its wet season peak it would stretch almost 70km end to end and cover an area of 3,000 sq km – the size of a small country like Luxembourg. Today, the lake is largely a flat expanse of salty mud.
What happened? We’ve looked into this in various scientific studies over the past few years, and the answer is a mix of both climate factors and more direct human factors such as too much irrigation. This does at least provide some hope: Bolivians cannot reverse climate change themselves, but they can do a better job managing their water.
Lake Poopó, is found at nearly 3,700 meters above sea level in the “Altiplano”, a large plateau in the centre of the Andes mountains. It is an endorheic basin: nothing flows out, and water is lost only through evaporation. Since dissolved minerals stick around when water is evaporated, the lake is as salty as the ocean – in some places considerably saltier.
Nonetheless, some decades ago Poopó was home to large communities of plants and animals and was a source of resources for the region’s inhabitants. Nowadays, the situation is drastically different. Water levels have declined over the past two decades, and eventually the lake dried out entirely at the end of 2015 after the extreme weather phenomenon of El Niño.
This was ecological devastation. Many of the lake’s 200 or so animal species disappeared, including reptiles, mammals, birds – it hosts a huge community of flamingos – and of course fish. There was also an exodus of rural people to the nearest big cities. Worst affected of all are the Urus-Muratos, an indigenous community whose entire way of life was based around fishing Lake Poopó.
Throughout Lake Poopó’s history, there have been several periods when water levels were very low but the lake used to recover by itself thanks to the rainy season and water from its main tributary the Desaguadero River, which itself drains Lake Titicaca and flows into the slightly lower altitude Poopó.
But during the past few decades, much of the Desaguadero was diverted for irrigation, so there was less water left to top up the lake. As Poopó is unusually shallow, mostly just a few metres deep, relatively small changes in overall water volume make a big difference to its surface area. Though the lake has partially recovered due to above-average precipitation in the years since 2015, the situation is still dire.
In our most recent study, we analysed satellite data from the Lake Poopó catchment area over the past two decades and found that more water has been gained through precipitation than has been lost through evaporation. This points to poor management of the water resources in the area, rather than climatic variability, as the principle cause of the lake drying up.
This is not to minimise the role of climate variability. In a separate study, we looked at changes in rainfall patterns and how they affected Lake Poopó. We found that, as time goes by, the rainy season is getting shorter but more intense. This will is amplifying the cycle of water storage in the lake, with the lake holding less water at the end of the dry season and more at the end of the wet one. It will become even more necessary to regulate resources, for instance by storing water during the wet season to use when it is dry.
We found the highest increases in water losses took place in the area around the city of Oruro, which lies to the north of the lake. This is an area with lots of human activity, urban growth, new highways, and where river water has been used for mining and agriculture. Bolivia is the biggest producer of quinoa in the world and the crop increased by 45.5% from 1980 to 2011. As quinoa became more popular around the world over the past decade, production increased a further 60% in just five years to meet global demand.
This all highlights how vulnerable a place such as Lake Poopó can be when relationships between land, human politics and cycles of water and people break apart. The ecological disaster is a consequence of not only natural factors but also human activities – but at least this is one reason there is still hope we can reverse the problem.
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What would happen if we cut down the entire Amazon rainforest? Could it be replaced by an equal amount of reforestation elsewhere?
Removing the entire Amazon rainforest would have myriad consequences, with the most obvious ones possibly not the worst.
Most people will first think of the carbon currently stored in the Amazon, the world’s largest rainforest. But the consequences would be far-reaching for the climate as well as biodiversity and ecosystems — and, ultimately, people.
The overall impact of the Amazon’s complete removal is unthinkable and beyond the power of our current predictive tools. But let’s look at some aspects we can describe.
Storing carbon, distributing water
The Amazon rainforest is estimated to harbour about 76 billion tonnes of carbon. If all trees were cut down and burned, the forest’s carbon storage capacity would be lost to the atmosphere.
Some of this carbon would be taken up by the oceans, and some by other ecosystems (such as temperate or arctic forests), but no doubt this would exacerbate climate warming. For comparison, humans emit about 10 billion tonnes of carbon every year through the burning of fossil fuels.
But the Amazon forest does more than store carbon. It is also responsible for the circulation of huge quantities of water.
This image, captured by NASA’s Aqua satellite in 2009, shows how the forest and the atmosphere interact to create a uniform layer of “popcorn” clouds during the dry season. It is during this period, the time without rain, that the forest grows the most.
If the Amazon’s cloud systems and its capacity to recycle water were to be disrupted, the ecosystem would tip over and irreversibly turn into dry savannah very quickly. Estimates of where this tipping point could lie range from 40% deforestation to just 20% loss of forest cover from the Amazon.
Reforestation elsewhere to achieve the same amount of carbon storage is technically possible, but we have neither the time (several hundred years would be needed) nor the land (at least an equivalent surface area would be required).
Another reason why reforestation is not a remedy is that the water the rainforest circulates — and with it the availability of nutrients — would disappear.
Once you cut the circulation of water through (partial) deforestation, there is a point of no return. The water doesn’t disappear from the planet, but certainly from the forest ecosystems, with immediate and powerful consequences for the world’s climate.
Loss of life
Perhaps the most drastic, and least reversible, impact would be the loss of wildlife diversity.
The number of animal species found in the Amazon is even higher, with the largest part made up by insects, representing around 10% of the known insect fauna, as well as a large but unknown number of fungi and microbes.
Once species are lost, they are lost forever, and this would ultimately be the most harmful consequence of cutting down the Amazon. It would possibly be worse than the loss of its role as a massive redistributor and storage of water and carbon.
Last but certainly not least, there are about 30 million people living in and near the Amazon rainforest.
The consequences of losing the forest as a provider of the ecosystem services mentioned above and as a source of food and habitat are unfathomable. The repercussions would reach far into global politics, the global economy, and societal issues.
The Research Brief is a short take on interesting academic work.
THE BIG IDEA: Coyotes are poised to expand their range to a new continent. The North American canine native has now reached the Darién Gap – a dense wilderness on the border of Colombia and Panama, at the very doorstep of South America. If the coyote succeeds, it would be a new chapter in an amazing evolutionary story that’s played out over the past half century.
WHY IT MATTERS: The historical range of the coyote was originally from western Canada to Mexico. But over the past few decades, it has mixed with wolves and dogs, and its adaptability has allowed the species to expand both east and south, making them commonplace everywhere from New York City to Panama City. My colleagues and I study how humans affect the distribution of wildlife on the planet. Usually this is in a negative way – some endangered species are declining because humans are destroying their habitat or hunting them to near extinction. However, some species are quite good at dealing with the changes people bring to the landscape, and coyotes are an example.
WHAT STILL ISN’T KNOWN: If coyotes will actually reach South America, or if jaguars in the Darién will keep them out. Few coyote biologists, including myself, are betting against the coyote. We also don’t know if coyotes, presuming they make it to South America, will have a negative impact on wildlife there. These native species already live with other canine predators in South America, including foxes, so the coyote might not be so bad for native species. People with free-ranging chickens, however, may think that is a different matter!
HOW I DO MY WORK: We set up camera traps, then go back to see what images they captured, and enter everything in a database called eMammal. It’s great to visit a place, see it with your own eyes and speculate about what might be there. Then, a few weeks later, pick up the camera and see all these animals for yourself. Checking the camera memory card is like Christmas every time.
ONE OTHER THING HAPPENING IN THE FIELD: Ricardo Moreno of Yaguara works to save the jaguar in Panama. He is monitoring the Darién to see how the jaguars are doing and working with locals to prevent poaching. He is also running cameras to see if the coyotes move into the Darién.
WHAT’S NEXT FOR YOU: We have just completed #SnapshotUSA, a survey of wildlife across all 50 states, including lots of coyotes! We are in the process of going through the 6 million photos now to identify all the species. We are also working with Wildlife Insights, a data collection site for pictures of wildlife around the world, and Google to develop artificial intelligence to help process all these pictures we get. Maybe this will help us keep an eye on how the coyotes do in Panama.
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With all of the burning and clearing happening in the Amazon rainforest, it was only going to be a short matter of time before a tipping point was reached and now a tipping point appears on the horizon. It would seem only a matter of 1 or 2 years before the Amazon is unable to sustain itself through rainfall. The link below is to an article reporting on the threat posed to the Amazon.