Grist - You’re the product of stability on a planetary scale. Around 12,000 years ago, Earth warmed from an ice age into the relatively consistent climate that allowed humans to adopt agriculture, literally putting down roots. That stability, though, is now shattered, as more than 8 billion people rapidly heat the planet, ravage its ecosystems, and plunder its resources.
In a new report, scientists warn that we’ve crossed yet another “planetary boundary,” a threshold that keeps Earth’s systems hospitable to life — a sort of global resilience that allows the planet to absorb shocks. This time, it’s the relentless acidification of the seas that’s crossed into dangerous territory, threatening all manner of marine life, including the organisms at the base of the food web. Of the nine total planetary boundaries, this is the seventh that’s been breached.
“What this health check again and again shows is that we have one interlinked, interconnected Earth system,” said Levke Caesar, co-lead of the Planetary Boundaries Science Lab at the Potsdam Institute for Climate Impact Research and a co-author of the report. “It actually would be fatal if we just concentrate on climate change, because, as we see, there are six other boundaries that have been transgressed. And we’re actually also increasing the pressure on all of these seven boundaries.”
Think of a planetary boundary as a warning sign on a road. At the end of the road is a cliff, representing a tipping point, in which an Earth system dramatically changes, often irreversibly. Researchers are worried, for instance, that parts of the Amazon may be nearing a transformation from rainforests to savannas due to the compounding crises of climate change and deforestation. If that’s the cliff, the concept of a planetary boundary is a big yellow “CLIFF AHEAD” sign, a warning from scientists that we could be approaching a catastrophic shift.
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