Based on The Future Climate of Amazonia Scientific Assessment Report.
The world’s rainforests have been called the lungs of the Earth, but it might be more apt to refer to them as its heart.
Recent research indicates that the largest rainforest in the world, the Amazonian forest, has a life-sustaining function for vast areas in South America.
The way it works is surprisingly similar to your own heart.
It works like this:
In the same way that your arteries supply blood to your body, ‘aerial rivers’ provide water to large areas in South America. These invisible rivers consist of condensation which emanates from the forest.
A large tree in the Amazonian forest is, in fact, rather like a geyser. It can pump up 1,000 litres of water through its trunk and transpire this out again, through its leaves, in the course of a day. When billions of trees do the same thing, we are talking about a serious amount of water. To be precise, 20 billion tons every day.
This water returns again as rain over South America’s huge agricultural regions, including those in northern Argentina and southern Brazil.
Just as the veins in your body return the blood back to your heart, the enormous rivers of the rainforest carry fresh water out to sea.
The return of this water to South America is not guaranteed. But the constant evaporation and condensation processes occurring throughout Amazonia influence atmospheric pressure, ensuring that the forest regularly attracts moist air. Amazonia is, therefore, the heart of this circulatory system.
As long as the forest remains, this water pump will continue to function. Just like a heart that goes on beating.
This should make most of South America’s 420 million inhabitants content, given that we humans are entirely dependent on predictable rainfall patterns. We put our trust in the rain to continue coming at the same times and places as usual.
But Amazonia is under attack and has been for a long time now.
In Brazil, 762,679 km2 of forest have been felled over the past 40 years – a figure so high that it is almost incomprehensible.
It may be easier to understand if we think of it in terms of the damage that one individual bulldozer can do.
Picture a bulldozer with a 3 metre wide blade thundering through the rainforest. Thirty-four trees per second. Twenty-four hours a day for 40 years. Help us to stop this bulldozer.
The bulldozer must have worked at this rate, daily for the past 40 years, in order to deforest an area which is double the size of Norway.
If we also include forest that has been damaged, the total area equals more than two million square kilometres. And this is just in Brazil.
This destruction has left permanent scars, severely impairing the forest. But research scientists fear a scenario in which the heart of South America stops completely.
They are afraid the Amazonian ecosystem will collapse entirely.
Is this the future of South America?
Every pilot knows that when a plane takes off, it will reach a speed and a point on the runway where it is no longer possible to land again safely. This is the point of no return.
But do the people chopping down the Amazonian forest know that this same principle also applies there? Do the inhabitants of South America know? Would they take to streets in protest if they did?
Amazonia has a tipping point – a point at which so much of the forest has been cut down that it initiates a chain of destruction.
This is also a point of no return.
A rainforest that is intact will not burn, but a rainforest that is split up into smaller areas will dry out, becoming highly inflammable. In the event that the Amazonian ecosystem collapses, fire and long periods of drought will play a central role. The temperature will rise, and rainfall decrease, in areas where there was once rainforest.
But scientists disagree about the exact magnitude of the consequences. Some studies suggest an average increase in temperature of 1.9 to 2.5⁰ C, with a 10-25% reduction in rainfall.
Others believe that the number of rainy days will be roughly halved (a reduction of 42%), while the biotic pump theory indicates that rain might disappear altogether.
In this event, vast areas of South America would look much like Australia:
An arid core with strips of moist vegetation along the coast.
So, how can we prevent this prophecy of disaster from being fulfilled in Amazonia?
Antonio Nobre, the research scientist specialising in climate change who wrote the report that this article is based upon, suggests the following five practical solutions:
1. The Amazonian effect must become common knowledge.
It is absolutely vital that the scientific facts about how the forest maintains a habitable climate and the threat posed by deforestation are made widely known throughout society.
2. We must cease being patient.
Deforestation in Amazonia has gone on for far too long, and one thing must be absolutely clear: zero deforestation is the ultimate goal. Not merely a little deforestation. There must be no further delay; no one should be satisfied with their efforts until all deforestation has ceased.
3. All intentional lighting of fires must be banned.
The less smoke and soot there is in the atmosphere, the more likely it is that rainclouds will form, helping to keep the rainforest intact. This is why all intentional lighting of fires in and around the forest must be banned.
4. Plant more trees.
Large deforested areas must be returned to their natural state through replanting. By improving the capacity of agricultural production, it will be possible to return farming land back to the forest.
5. Everyone needs to wake up.
In 2008, authorities all over the world responded quickly to the financial crisis, contributing billions of dollars to bail out the banks and avoid a complete melt-down in the financial market. The same level of reaction is required now in Amazonia. Zero deforestation is not a goal we can put off until some point in the distant future.
Is it realistic to think we can achieve this?
The good news is that Brazil has reduced deforestation by 75% since 2004, proving that zero deforestation is not an impossible goal.
The bad news is that deforestation has increased again several times over the past few years.
Saving Amazonia will require decisive, co-ordinated efforts on a number of levels. The first step is to understand what is at stake.
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