Wednesday, September 13, 2023

Humanity deep in the danger zone of planetary boundaries: study

Paris (AFP) – Human activity and appetites have weakened Earth's resilience, pushing it far beyond the "safe operating space" that keeps the world liveable for most species, including our own, a landmark study said Wednesday.

Water falling from a melting iceberg drifting along the Scoresby Sound Fjord, in Eastern Greenland 
© Olivier MORIN / AFP/File
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Six of nine planetary boundaries -- climate change, deforestation, biodiversity loss, synthetic chemicals including plastics, freshwater depletion, and nitrogen use -- are already deep in the red zone, an international team of 29 scientists reported.

Two of the remaining three -- ocean acidification along with the concentration of particle pollution and dust in the atmosphere -- are borderline, with only ozone depletion comfortably within safe bounds.

The planetary boundaries identify "the important processes that keep the Earth within the kind of the living conditions that prevailed over the last 10,000 years, the period when humanity and modern civilisation developed", said lead author Katherine Richardson, a professor at the University of Copenhagen's Globe Institute.

The study is the second major update of the concept, first unveiled in 2009 when only global warming, extinction rates, and nitrogen had transgressed their limits.

"We are still moving in the wrong direction," said co-author Johan Rockstrom, director of the Potsdam Institute for Climate Impact Research (PIK) and a co-creator of the schema.

"And there's no indications that any of the boundaries" -- except the ozone layer, slowly on the mend since the chemicals destroying it were banned -- "have started to bend in the right direction", he told journalists in a briefing.

"This means we are losing resilience, that we are putting the stability of the Earth system at risk."

The study quantifies boundaries for all nine interlocking facets of the Earth system.
Headed for disaster

For biodiversity, for example, if the rate at which species disappear is less than 10 times the average extinction rate over the last 10 million years, that is deemed acceptable.

In reality, however, extinctions are occurring at least 100 times faster than this so-called background rate, and 10 times faster than the planetary boundary limit.

For climate change, that threshold is keyed to the concentration of atmospheric CO2, which remained very close to 280 parts per million (ppm) for at least 10,000 years prior to the industrial revolution.

That concentration is today 417 ppm, far above the safe boundary of 350 ppm.

Humans breaching planet's ecological boundaries 
© Valentina BRESCHI / AFP

"On climate, we're still following a pathway that takes us unequivocally to disaster," said Rockstrom. "We're headed for 2.5C, 2.6C or 2.7C -- a place we haven't seen for the past four million years."

"There's no evidence whatsoever that humans can survive in that environment," he added.

Thousands upon thousands of chemical compounds created by humans -- from micro-plastics and pesticides to nuclear waste and drugs that have leached into the environment -- were quantified for the first time in the new research, and found to exceed safe limits.

Likewise for the depletion of "green" and "blue" water, freshwater coming from soil and plants on the one hand, and from rivers and lakes on the other.
Setting limits

An important finding of the new update is that different boundaries feed off and amplify each other.

The study examines in particular the interaction between increasing CO2 concentration and damage to the biosphere, especially forest loss, and projects temperature increases when one or both increase.

It shows that even if humanity rapidly draws down greenhouse gas emissions, unless destruction of carbon-absorbing forests is halted at the same time rising global temperatures could tip the planet onto a trajectory of additional warming that would be hard to stop.

"Next to climate change, integrity of the biosphere is the second pillar for our planet," said co-author Wolfgang Lucht, head of Earth System Analysis at PIK.

Five scenarios of the evolution of the Earth's surface temperature
 © Sabrina BLANCHARD / AFP

"We are currently destabilising this pillar by taking out too much biomass, destroying too much habitat, deforesting too much land."

All the boundaries can be brought back into the safe operating space, the study concluded.

"It's just a question of setting limits for the amount of waste we put into the open environment and the amount of living and non-living raw materials we take out," said Richardson.

Hotly debated at first, the planetary boundaries framework quickly became a pillar of Earth system science, with its influence extending today into the realm of policy and even business.

© 2023 AFP


Earth is outside its ‘safe operating space for humanity’ on most key measurements, study says


 A woman is silhouetted against the setting sun as triple-digit heat indexes continue in the Midwest, Aug. 20, 2023, in Kansas City, Mo. Earth is exceeding its “safe operating space for humanity” in six of nine key measurements of its health, and two of the remaining three are headed in the wrong direction, a new study said. 
(AP Photo/Charlie Riedel, File)

BY SETH BORENSTEIN
 September 13, 2023

Earth is exceeding its “safe operating space for humanity” in six of nine key measurements of its health, and two of the remaining three are headed in the wrong direction, a new study said.

Earth’s climate, biodiversity, land, freshwater, nutrient pollution and “novel” chemicals (human-made compounds like microplastics and nuclear waste) are all out of whack, a group of international scientists said in Wednesday’s journal Science Advances. Only the acidity of the oceans, the health of the air and the ozone layer are within the boundaries considered safe, and both ocean and air pollution are heading in the wrong direction, the study said.

“We are in very bad shape,” said study co-author Johan Rockstrom, director of the Potsdam Institute for Climate Impact Research in Germany. “We show in this analysis that the planet is losing resilience and the patient is sick.”


Haze  SMOG blankets the main business district in Jakarta, Indonesia, Aug. 11, 2023.
 (AP Photo/Dita Alangkara)

In 2009, Rockstrom and other researchers created nine different broad boundary areas and used scientific measurements to judge Earth’s health as a whole. Wednesday’s paper was an update from 2015 and it added a sixth factor to the unsafe category. Water went from barely safe to the out-of-bounds category because of worsening river run-off and better measurements and understanding of the problem, Rockstrom said.

These boundaries “determine the fate of the planet,” said Rockstrom, a climate scientist. The nine factors have been “scientifically well established” by numerous outside studies, he said.

If Earth can manage these nine factors, Earth could be relatively safe. But it’s not, he said.

In most of the cases, the team uses other peer-reviewed science to create measurable thresholds for a safety boundary. For example, they use 350 parts per million of carbon dioxide in the air, instead of the Paris climate agreement’s 1.5 degrees (2.7 degrees Fahrenheit) of warming since pre-industrial times. This year carbon in the air peaked at 424 parts per million.

The nine factors are intermingled. When the team used computer simulations, they found that making one factor worse, like the climate or biodiversity, made other Earth environmental issues degrade, while fixing one helped others. Rockstrom said this was like a simulated stress test for the planet.

The simulations showed “that one of the most powerful means that humanity has at its disposal to combat climate change” is cleaning up its land and saving forests, the study said. Returning forests to late 20th century levels would provide substantial natural sinks to store carbon dioxide instead of the air, where it traps heat, the study said.

Biodiversity – the amount and different types of species of life – is in some of the most troubling shape and it doesn’t get as much attention as other issues, like climate change, Rockstrom said.

“Biodiversity is fundamental to keeping the carbon cycle and the water cycle intact,” Rockstrom said. “The biggest headache we have today is the climate crisis and biodiversity crisis.”


Surfers float in the water while waiting for a wave in Malibu, Calif., Aug. 31, 2023. 
(AP Photo/Jae C. Hong)


University of Michigan environmental studies dean Jonathan Overpeck, who wasn’t part of the study, called the study “deeply troubling in its implications for the planet and people should be worried.”

“The analysis is balanced in that it clearly sounds a flashing red alarm, but it is not overly alarmist,” Overpeck said. “Importantly, there is hope.”

The fact that ozone layer is the sole improving factor shows that when the world and its leaders decide to recognize and act on a problem, it can be fixed and “for the most part there are things that we know how to do” to improve the remaining problems, said Carnegie Mellon chemistry and environment professor Neil Donahue.

Some biodiversity scientists, such as Duke’s Stuart Pimm, have long disputed Rockstrom’s methods and measurements, saying it makes the results not worth much.

But Carnegie Mellon environmental engineering professor Granger Morgan, who wasn’t part of the study, said, “Experts don’t agree on exactly where the limits are, or how much the planet’s different systems may interact, but we are getting dangerously close.”


“I’ve often said if we don’t quickly cut back on how we are stressing the Earth, we’re toast,” Morgan said in an email. “This paper says it’s more likely that we’re burnt toast.”

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