Amazon drought signals wider dangers

Last year, 2023, was the hottest year on record, with one dataset finding temperatures 1.54ºC hotter than pre-industrial levels. 2023 also brought the harshest drought in the history of the Amazon rainforest; an early sign that we may have triggered a major climate tipping point.

The Amazon is one of the world’s largest terrestrial carbon sinks. Covering an area equivalent in size to the USA, it is estimated to contain 123 billion tonnes of carbon. As the forest dies it releases this carbon further accelerating global heating. A 2021 study in Nature by Luciana Gatti and colleagues found that the Southern Amazon had flipped from carbon sink to carbon source. The drought will further intensify this feedback loop.

The immediate cause of the Amazon drought and a contributing to record temperatures is an El Niño weather event. El Niño occurs every two to seven years as warmer water circulates to the surface of the Pacific. It tends to bring drier, hotter weather to northern South America and wetter weather to the south. This El Niño, supercharged by global heating, has also dried up the Panama Canal, causing disruption to one of the world’s major shipping lanes, while Argentina, Uruguay, Paraguay and southern Brazil experienced severe flooding.

The drought is exacerbated by decades of ecological destruction. As a rainforest, the Amazon plays a role in creating weather conditions for its own flourishing. Rain from the Atlantic falls in Eastern Amazon, is absorbed by trees and transpires. The water cycles in this way several times as the forest spreads West to the foothills of the Andes. About 25-35% of rainfall in the Amazon basin is produced this way and it has a cooling effect on the region.

Deforestation is destroying the rainforests ability to recycle rain. Around 20% of the rainforest has been clear cut to make way for intensive agriculture and mining operations. Brazil’s farmland has expanded by 50% in the four decades in an ever expanding frontier of primary production.

Beef farming is the largest driver. According to the Climate Observatory, Brazil’s 220 million cows have a carbon footprint greater than Japan; 43% of the herd grazes in land that was once the most biodiverse habitats on Earth.

In addition to deforested areas, 40% of the land has been degraded by selective logging. Selective logging operations remove the larger trees — expensive tropical hardwoods - ostensibly to “make room” for new growth. Such practices are branded “sustainable” although 90% of selective logging is done illegally. In reality, it is the largest trees that do most of the heavy lifting of transpiration, pumping out vast quantities of the water into the atmosphere. They are also more efficient at storing carbon than the fast growing softwoods that replace them. A 2023 study found that emissions from degraded forest are equal to and may even exceed those from deforested areas.

Fire

In normal conditions the Amazon is too wet to burn. But the drier, degraded forest is vulnerable to fire. Studies have shown that slash-and-burn by land-grabbers is a major cause of fire in the Amazon. Philip Fearnside, an ecologist at Brazil’s National Institute for Research in Amazonia, says, “Brazil is basically the only country where you can still go into the forest and start clearing and expect to come out with a land title. It’s like the Wild West of North America in the eighteenth century.”

Deforestation went into overdrive under Jair Bolsanoro. Since Lula da Silva’s presidential election tougher enforcement has curbed rates of deforestation. But curbs are not the same as putting an end to this wanton ecocide, still further from restoring farmland to rainforest. A $204 million fund called Arc of Restoration was set up at COP28 to reforest some farmland. But as long as the Amazon’s land and natural resources can be exploited for profit, the destruction will continue.

The speed of these climate events has taken scientists by surprise. Carlos Nobre, who led the research into the Amazon tipping point in 2016 says: “What we were predicting to happen perhaps in two or three decades is already taking place.” Similarly, Gavin Schmidt, director of Nasa’s Goddard Institute for Space Studies was alarmed at the spike in global temperatures: “We are having a real hard time explaining why 2023 was as warm as it was. What happened last year was unprecedented and it’s a concern. This is the first year I’ve been doing this where I’m far less sanguine about my ability to explain what’s happening.”

CO₂ levels are now at levels not seen in over 3 million years when temperatures were 3ºC hotter and sea levels were at least 10 metres higher than today. The speed at which temperatures rise to catch up with CO₂ levels is unknown but capitalist production is adding to atmospheric CO₂ destroy the Earth’s carbon sinks. Unless our productive forces can be brought under social control, the acceleration to hothouse Earth is likely to continue.