Human activity jeopardising Earth’s life-support systems, study says
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Polar bears have long been a symbol of the consequences of climate change, as rising temperatures melt away the Arctic sea ice upon which they depend for survival.
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BERLIN - Life-support systems on Earth are facing greater risks and uncertainties than ever before, with most major safety limits already crossed as a result of planetwide human interventions, according to a scientific study released on Wednesday.
In a “health check” for the entire planet published in the Science Advances journal, an international team of 29 experts found that Earth is now “well outside of the safe operating space for humanity” due to human activity.
The study, expanding on a 2015 report, said the world had now crossed six of nine “planetary boundaries” – the safe limits for human life in areas such as the integrity of the biosphere, climate change, and the use and availability of fresh water. In all, it said, eight of the nine boundaries are under more pressure than in the 2015 assessment, with only the sky’s ozone layer improving – raising the risk of dramatic changes in living conditions on Earth.
“We don’t know that we can thrive under major, dramatic alterations of our conditions,” lead author Katherine Richardson from the University of Copenhagen told a news conference.
The authors said crossing the boundaries did not represent a tipping point where human civilisation would just crash, but could bring irreversible shifts in Earth’s support systems.
“We can think of Earth as a human body, and the planetary boundaries as blood pressure. Over 120 / 80 does not indicate a certain heart attack, but it does raise the risk,” Professor Richardson said.
The scientists also sounded the alarm on increasing deforestation, the excessive consumption of plants for fuel, and the proliferation of man-made products like plastic, genetically modified organisms and synthetic chemicals.
“There are hundreds of thousands of human-made chemicals that are thrown into the environment now,” Prof Richardson said. “We’re constantly surprised by the effects of these human impacts.”
Scientists sounded the alarm on increasing deforestation, the excessive consumption of plants for fuel, and the proliferation of man-made products such as plastic, genetically modified organisms and synthetic chemicals.
PHOTO: REUTERS
Of the nine boundaries assessed, only ocean acidification, ozone depletion and airborne pollution – mainly soot-like particles – were judged to be within safe limits. But the ocean acidification boundary was close to being breached.
The atmospheric concentration of carbon dioxide, the main greenhouse gas, has risen to around 417 parts per million (ppm), significantly higher than the safe level of 350 ppm.
The current rate of species extinction is also estimated to be at least tens of times faster than the average rate over the past 10 million years, meaning the planet has already crossed the safe boundary for genetic diversity.
Professor Johan Rockstrom, the study’s co-author and director of the Potsdam Institute for Climate Impact Research, hoped the world would see the findings as a wake-up call. “In my career, I’ve never been sitting on so much evidence as today and been so clear in our communication,” he said, adding that he was disappointed with the outcome of last week’s United Nations Global Stocktake report which found that while there has been global progress in climate change mitigation since the landmark Paris Agreement in 2015, more needs to be done to limit temperature rise to 1.5 deg C.
The report will form the basis of the COP28 climate talks in Dubai later in 2023.
“It is a complete failure... and it’s a large risk... We’re still following a pathway that takes us unequivocally to disaster,” he added. REUTERS
