Changes wrought by decades of pillaging and poisoning forests, oceans, soil and air threaten society "at least as much as climate change," said Robert Watson, who chaired the 132-nation meeting that validated a Summary for Policymakers forged by 450 experts.
Alarmingly, the accelerating pace at which unique life-forms are disappearing – already tens to hundreds of times faster than during the last ten million years – could tip Earth into the first mass extinction since non-avian dinosaurs died out 66 million years ago.
In the short term, humans are not at risk, said Josef Settele, a professor at the Helmholtz Centre for Environmental Research in Germany and co-chair of the UN Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES).
Halting and reversing these dire trends will require "transformative change" -- a sweeping overhaul of the way we produce and consume almost everything, especially food, the report concluded.
"We are eroding the very foundations of our economies, livelihoods, food security, health and quality-of-life worldwide," said Watson.
"By transformative change, we mean a fundamental, system-wide reorganisation."
The pushback from "vested interests," he added, is likely to be fierce.
Drawing from 15,000 sources and an underlying 1,800-page report, the executive summary details how our species´ growing footprint and appetites have compromised the natural renewal of resources that sustain civilisation, starting with fresh water, breathable air, and productive soil.
An October report from the UN´s climate science panel painted a similarly dire picture for global warming, and likewise highlighted the need for social transformation "on an unprecedented scale" to cap the rise in temperature at 1.5 degrees Celsius (2.7 Fahrenheit).
The global thermometer has already gone up by 1C, and on current trends will rise another 3C by century´s end.
Climate change and biodiversity loss, it turns out, feed off each other in a vicious cycle.
Deforestation and industrial agriculture are major drivers of species and ecosystem decline, but also account for at least a quarter of man-made greenhouse gas emissions.
Global warming, in turn, is pushing thousands of animals and plants out of their comfort zones, and intensifies the kind of heatwaves and droughts that recently fuelled unprecedented fires in Australia, Indonesia, Russia, Portugal, California and Greece.
For the first time, the UN body has ranked the top five causes of species lost and the degradation of Nature.
By a long shot, the first two are diminished or degraded habitat, and hunting for food or trade – often illicit – in body parts.
All but seven percent of major marine fish stocks, for example, are in decline or exploited to the limit of sustainability despite efforts by regional management organisations to fish sustainably.
Global warming is third on the list, but is likely to move up.
Numbers four and five are pollution – 400 million tonnes of heavy metals, toxic sludge and other waste are dumped into oceans and rivers each year – and alien species, such as rats, mosquitoes, snakes and plants that hitch rides on ships or planes.
The heavily negotiated text does not set benchmarks for progress or "last chance" deadlines for action, as does the 2018 climate report. Nor is the panel mandated to make explicit policy recommendations.
But it does point unmistakably to actions needed: reduce meat consumption, halt deforestation in tropical countries, discourage luxury consumption, slash perverse subsidies and embrace the concept of a low-growth economy.
The report will "serve as a basis for redefining our objectives" ahead of a key meeting of the UN Convention on Biological Diversity in China in October 2020.
On the other hand, top diplomats from the United States, Russia and other nations which border the Arctic are meeting today (Monday) in Finland to discuss policies governing the polar region, as tensions grow over how to deal with global warming and access to mineral wealth.
Countries have been scrambling to claim territory or, like China, boost their presence in the region as thawing ice raises the possibility of exploiting much of the world’s remaining undiscovered reserves of oil and gas, plus huge deposits of minerals such as zinc, iron and rare earth metals.
With time-saving Arctic shipping routes also opening up, the Pentagon warned on May 2 of the risk of Chinese submarines in the Arctic.
That followed a sharp statement by US Secretary of State Mike Pompeo — who will give a speech at the Arctic Council meeting in Rovaniemi, Finland today — rejecting a role for China in shaping Arctic policy.
The Arctic Council is made up of the United States, Canada, Russia, Finland, Norway, Denmark and Iceland, with the region’s indigenous populations also represented.