Global warming leads to continuous destruction of ecosystems

Published on 08/15/2021 06:00

(Source: Jonathan Nakstrand / AFP – 17/8/19)

Eleven years ago, one of the world’s most important climate scientists, Tim Linton of the University of Exeter in England, warned that without ambitious policies to contain carbon dioxide emissions, the planet would approach a series of inflection points – when pulled by warming, beyond temperature, which leads to irreversible accelerating effects. Few listened to him.

At the time, the world was preparing to negotiate the document that would succeed the Kyoto Protocol, with commitments to reduce emissions, and there were high expectations for that year’s United Nations Conference of the Parties on Climate Change (COP), in Copenhagen. The warnings by Linton’s team did not have the effect they should have had, and the agreement signed in Denmark did not advance.

More than a decade later, the Intergovernmental Panel on Climate Change (IPCC), a group of scientists from around the world providing input to COPs, has confirmed, based on recent studies, that human-caused global warming is driving the Earth system to collapse. wide range. The resulting phenomena could take thousands of years to reverse, in the case of melting glaciers. “We are now seeing evidence that more than half of the inflection points have already been triggered,” says Linton, director of the Global Systems Institute at the University of Exeter.

The Earth is an interconnected system, and unrelated facts seem to affect the entire globe. As with the domino effect, the fall of a piece in Antarctica or Greenland, for example, would cause the collapse of islands in the Pacific Ocean, swallowed up by rising sea levels. California will burn more, because melting causes fresh water to flow into the Atlantic Ocean, and this, in excess, interferes with an important regulatory chain for global climate.

In turn, the liberalization of the so-called South Atlantic inversion (Amoc) cycle, of which the Gulf Stream is a part, will affect the Indian monsoon to tropical precipitation. The result for Brazil will be a drier Amazon. Without this important carbon sink, the world could expect to emit tons of greenhouse gases into the atmosphere, something that is already starting to happen, because due to record deforestation, the forest has recently reached the point of releasing more stored gases. Carbon Dioxide.

The latest research by Tim Linton’s team has identified nine tipping points that are already active or very close to them: the Amazon rainforest, Arctic sea ice, Greenland ice sheet, boreal forests, permafrost, South Atlantic inversion circulation and the Atlantic ice sheets. West Antarctica, parts of East Antarctica and hot water coral.

The most worrying thing, according to the scientist, is that these systems are already threatened by an increase of 1.1 ° C relative to the temperature of the pre-industrial period, in the nineteenth century. Since the economy based on fossil fuels will not be extinct before 2050, it is expected that within three decades, the Earth will cross the 1.5°C barrier. By the end of the century, a worst-case scenario predicts a temperature rise of 3°C.

“We may have already crossed the threshold of a series of interconnected inflection points. However, the rate of progress, and thus the risks it poses, can be reduced by lowering our emissions,” notes Linton, urging policymakers not to delay the adoption of truly ambitious measures.

Models

The domino effect caused by critical temperatures was also the subject of a study by the Postdam Institute for Climate Impact Research (PIK) in Germany. The researchers performed a risk analysis and simulated, in computer models, the effects of melting glaciers on temperature increases between 1.5°C and 2°C over Greenland, the Gulf Stream, Antarctica, and the Amazon rainforest. This is the maximum growth range for thermometers, in relation to pre-industrial levels, set by the Paris Agreement, at COP-21, in 2015.

“Although it’s a risk analysis, not a prediction, our results are concerning,” says Ricarda Winkelmann, head of the PIK Laboratory of Earth’s Resilience in the Anthropocene. “We’ve found that the interaction of these four elements can make them more vulnerable globally due to long-term mutual destabilization,” he says.

A third of simulations already show a domino effect with global warming of up to 2°C – the IPCC report, released on Monday, highlighted that in a low emissions scenario, in two decades, the planet would be 1.5°C warmer . from the 19th century. The document also states that, with few effective measures, the century would end 3°C above pre-industrial levels.

The four elements studied “are the parts of the Earth system that, once in a critical state, can undergo significant and potentially irreversible changes in response to perturbations,” Winkelman recalls. It can appear stable until a critical threshold is crossed. In the IPCC document, scientists showed a particular interest in melting glaciers, which, according to the text, will take centuries or thousands of years to recover.

“This is just one example of the many complex interactions between the changing elements of climate: if there were significant melting of the Greenland ice sheets releasing fresh water into the ocean, it could slow the rotation of the South Atlantic inversion, which is driven by differences in degrees of heat, salinity and the transfer of large amounts of heat from the tropics to the mid-latitudes and polar regions,” explains Nico Wunderling, also of the Potsdam Institute.

This in turn could lead to global warming in the Southern Ocean and thus, in the long run, to the destabilization of parts of the Antarctic ice sheet. This phenomenon contributes to sea level rise and increased water at the edges of the ice sheets in both hemispheres, which contributes to increased mutual destabilization.”

On the edge of the abyss

In the report of the Intergovernmental Panel on Climate Change (IPCC) of the United Nations, scientists expressed serious concern about the Amazon rainforest. Although it has not yet reached the tipping point, the world’s largest rainforest may cross that threshold sooner than previously thought, with 40% of the biome shifting to savannah, according to a study published in Nature Communications.

Tropical forests are very sensitive to changes that affect prolonged rainfall, says Ari Stahl, a researcher at the Copernicus Institute at Ultrecht University in the Netherlands and lead author of the study. “In about 40% of the Amazon rainforest, precipitation is now at a level where the forest can turn into a savanna,” he says. According to him, the results are worrying because parts of the Amazon receive less rain than expected, and this trend is expected to worsen with increasing heat, due to greenhouse gas emissions.

This scenario is exacerbated by deforestation. In 2018, climate scientist Carlos Nobre, of the University of São Paulo (USP) and American researcher Thomas Lovejoy, of the University of Fairfax, published an editorial in Science Advances, warning of a 20% to 25% forest loss, the inflection point of the biome, which Irreversible for at least a hundred years, it will arrive in the next ten or fifteen years. The analysis was based on satellite observations from the North American Space Agency (NASA).

According to the National Institute for Space Research (Inpe), 17% of the biome has been deforested. Since 2019, deforestation rates have seen record increases, and from January to June 2021, the forest lost an area of ​​4,014 square kilometers, the largest recorded in the first semester in a decade. (dust)

Welcome to Brasilia, hell on earth

Young people may not believe it, but the weather in Brasilia was once nice. As a kid in the ’80s, we were taught at school about the “high tropical” climate with cold nights, and having a fan in the house was unimaginable. Four decades later, I admit without any pride that I bought the fourth air conditioner.

Climatology confirms the old people’s perception that the capital has improved a lot. From 1975, when you were born, until the past decade, the city has gained about an extra month a year with maximum temperatures exceeding 32 degrees Celsius, according to a New York Times compilation in the app How Hot Is Your Hometown.? The number of hot nights annually, those with temperatures over 20 degrees Celsius, has increased tenfold (that’s right, tenfold) since the city was founded, according to a compilation prepared by the National Institute of Meteorology. The number of extremely dry days has also increased. According to meteorologist Morgana Almeida, of Enmet, Brasilia has warmed an average of two degrees Celsius in the past 50 years. That’s twice the warming of the entire planet since 1850.

But there is nothing so bad that it cannot get any worse.

The AR6 Report, the great report presented by the Intergovernmental Panel on Climate Change (IPCC), provided for the first time an interactive atlas with regional climate forecasts in the short, medium and long term. The Climate Commission concluded that since it is imperative that around 2030 we will already exceed the 1.5°C risk threshold for global warming, it is best to provide information on what will happen in the coming years, to support government adaptation actions.

There are three regions in Brazil that worry scientists: the northeast, which has already become drier than usual due to human activity; the south, which became more rainy; A large area is called the “South American Monsau Region” or SAM, which includes parts of Brazil, Peru, Bolivia and Argentina. According to AR6, this region will experience one of the world’s largest temperature increases on the hottest day of the year – 1.5 times to twice the average rate of global warming. Much of the Amazon and Midwest, including DF, are located in this region.

In October 2021, the hottest month of the year, the average prediction of the 34 computer climate models used by the Intergovernmental Panel on Climate Change was that the SAM would be 2.2°C warmer than it was during the pre-industrial era. In the worst-case emissions scenario, for October 2031, the average warming would be 2.8°C. In 2091, if we do nothing, the average will be 8.5°C higher. This would mean, essentially, the impossibility of human life in the region – with a temperature increase of 4 degrees Celsius, it would already be impossible to live without staying in permanently cooled environments.

This extreme scenario can be practically ignored: the post-Paris world has left, at least for the time being, the worst-case scenario path for the Intergovernmental Panel on Climate Change. But, even in milder emissions scenarios, the next few years will save hell on earth for Brazilians. And I’m not just talking about politics.

Claudio Angelo is the Communications Coordinator at Climate Observatory and author of Death Spiral – How Humanity Changed the Climate Machine (Companhia das Letras, 2016)