When will the Amazon hit a tipping point?

 When will Amazon reach a tipping point in its growth?

Scientists warn that climate change, fires and deforestation could result in the destruction of the world's largest rainforest. The question is when that could happen.

From a viewing tower at the top of the Brazilian Amazon's treetops, you can see the rainforest canopy stretching out to the horizon in an endless sea green. The rainforest canopy looks rich and healthy, but its surroundings can be deceiving. This rainforest, which contains 16,000 tree species, is slowly drying out.

Over the last century, the average temperature has risen by 1-1.5°C. Some areas have seen an increase in dry seasons over the last 50 years. It has gone from 4 months to nearly 5 months. Three severe droughts occurred since 2005. This is all driving a shift of vegetation. In 2018, a study found that trees that thrive best in moist conditions (e.g. tropical legumes) are on the verge of dying. Those that can adapt to drier climates, such as the Brazil nuts tree (Bertholletia magnifica), are thriving.

Large swathes of Amazon rainforest, the world's most extensive, are being deforested and burned. Already, the forest is being reduced by about 15% from its 1970s area of over 6 million square kilometers. Brazil, which has more than half of the forest, has lost more than 19%. Brazil was widely praised in 2000 for its remarkable slowing of forest loss. But, due to political turmoil, and the economic recession, the rate has risen. Brazil's deforestation increased by about 30% to close to 10,000 km2, the biggest loss in a decade. Last August saw international attention due to videos of wildfires raging in the Amazon. The August fires were the largest since an extreme drought in 2010. (See 'Forest Loss'). Many scientists have linked these surges to the anti-environmentalist rhetoric of Brazil's president, Jair Bolsonaro.

Scientists are becoming more worried about the Amazon in the face of an increasing temperature, deforestation, and worsening fires. Some scientists have warned that forest may soon reach a tipping point, where it could become barren scrubland. Others say that there is not enough evidence to predict how long the forest will survive.

A Science Panel for the Amazon was established by a handful of scientists last September. This panel will assess the condition of the Amazon rainforest and recommend actions to preserve it. They plan to have their assessment ready by November for United Nations climate negotiations at Glasgow, UK.

The situation is getting dire, there's no doubt. Eduardo Goes Neves from the University of SaoPaulo, Brazil, says, "It's very difficult moment for people who know, love, and work in Amazonia."

The tipping-point question

The temperature high above the tree canopy, no matter the season is hot enough to make it sweaty even for researchers who climb up the tower. The rainforest ecosystem is sustained by the moist air.

The forest is a vital part of keeping itself alive by recycling water through its trees to create rain. Six times the amount of rain can be caused by a water molecule traveling across the Amazon. A decrease in rainfall may result from reduced vegetation due to fire, drought, or other natural disasters. This might eventually lead to large regions of Amazon becoming more like a Savannah ecosystem, but with less biodiversity. Only the Amazon's western region near the Andes mountains would stay lush. Here, air currents force up the mountains and cause water vapour condense to rain.

Carlos Nobre (University of Sao Paulo climate researcher) raised the alarm in 2018, arguing that Amazon could be closer to a tipping points than scientists believed. Thomas Lovejoy (an environmental researcher at George Mason University, Fairfax, Virginia) wrote an editorial5 in which he stated5 that 20-25% of the rainforest could be cut, and it could reach a tipping points at which the Amazonia's eastern, central, and southern regions would turn to a savannah ecosystem. The pair reiterated the warning last December, calling this a last chance to take action6. Nature told Nobre that if tree mortality continues for another 10-15years, then the south Amazon will become a desert."

This would have a devastating impact on the lives of millions of people and animals living in the area. It could also lead to the emission of billions upon billions of tonnes carbon dioxide into the atmosphere from burning trees and other vegetation. This could result in less rainfall in South America and change in climate patterns. roulette thethropic for beginners and advanced players