Mass Extinction Event 2 Billion Years Ago Killed 99% of Life on Earth, Study Finds
Some two billion years ago, a significant decline of once-abundant oxygen killed as much as 99 percent of all life on Earth in a mass extinction event larger than the one responsible for the dinosaur die-off.
Publishing their work in Proceedings of the National Academy of Sciences, a team of researchers describe the catalyst of the Great Oxidation Event (GOE) that occurred between 2.05 and 2.4 billion years ago. In the years leading up to the GOE, oxygen levels in the Earth's atmosphere had increased significantly, resulting in the multiplication of ancient minuscule microorganisms. Suddenly, oxygen levels plummeted in what soon became one of the "most transformative events in all of Earth's history," shifting from "feast" to "famine" conditions that followed in the next 1 billion years, paving the way for complex life as we know it today.
"We were very surprised," co-author Peter Crockford, a postdoctoral researcher at the Weizmann Institute of Science and Princeton University told Newsweek. "We didn't expect to see such a large signal, nor did we expect to find it in this specific type of sample.
"Over the 100 to 200 million years before this die-off event there was a large amount of life on the planet, but after this event a huge portion died off," said Crockford. "However, instead of recovering like more recent mass extinctions, the amount of life on the planet or size of the biosphere stayed small for the following billion years of Earth's history—about two billion to one billion years ago."
But how or why that shift occurred has long been contested — until now.
Barite crystals in the Costello Formation in Canada. Malcolm Hodgskiss
Scientists turned to barite, a sulfate mineral found in the Belcher Islands in Canada's Hudson Bay that shows the geological record of oxygen in the atmosphere. An analysis of isotope geochemistry found negative values that occurred shortly after the GEO, implying a collapse in primary productivity that triggered a shift in the availability of nutrients like phosphorus. Altogether, this caused an enormous drop in life perhaps due to a decrease in oxygen levels.
"The fact that this geochemical signature was preserved was very surprising," said study co-author Malcolm Hodgskiss. "What was especially unusual about these barites is that they clearly had a complex history."
The increase of life in correlation with atmospheric oxygen confirms a theory known as "oxygen overshoot" whereby photosynthesis from ancient microorganisms and the natural weathering processes of rocks resulted in an increase of oxygen in the atmosphere. Oxygen-emitting organisms eventually exhausted their nutrient supply in the ocean, resulting in declining populations in a world much different than how we know it today, where a stable atmosphere balances oxygen production with consumption.
The findings shed light into ancient processes that eventually resulted in Earth as we know it today. By further studying how Earth behaves throughout time, scientists say they can better understand how atmospheres operate on planets outside of our solar system, specifically the interlink between the biosphere (where organisms live) and how that relates to levels of oxygen and carbon dioxide in the atmosphere.
"Some of these oxygen estimates likely require too many microorganisms living in the ocean in Earth's past," said Crockford. "So, we can now start to narrow in on what the composition of the atmosphere could have been through this biological angle."
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By Governor Jay Inslee
Climate Week this year coincides with clear skies in Washington state for the first time in almost two weeks.
In just a few days in early September, Washington state saw enough acres burned – more than 600,000 – to reach our second-worst fire season on record. Our worst fire season came only five years ago. Wildfires aren't new to the west, but their scope and danger today is unlike anything firefighters have seen. People up and down the West Coast – young and old, in rural areas and in cities – were choking on smoke for days on end, trapped in their homes.
Fires like these are becoming the norm, not the exception.
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By Bill McKibben
To understand the planetary importance of this autumn's presidential election, check the calendar. Voting ends on November 3—and by a fluke of timing, on the morning of November 4 the United States is scheduled to pull out of the Paris Agreement.
President Trump announced that we would abrogate our Paris commitments during a Rose Garden speech in 2017. But under the terms of the accords, it takes three years to formalize the withdrawal. So on Election Day it won't be just Americans watching: The people of the world will see whether the country that has poured more carbon into the atmosphere than any other over the course of history will become the only country that refuses to cooperate in the one international effort to do something about the climate crisis.
By Oliver Milman
The climate crisis is set to be a significant factor in a U.S. presidential election for the first time, with new polling showing a clear majority of American voters want decisive action to deal with the threats posed by global heating.
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America's largest national forest, Tongass National Forest in Alaska, will be opened up to logging and road construction after the Trump administration finalizes its plans to open up the forest on Friday, according to The New York Times.
Aerial view of the Tongass National Forest. Alan Wu / Flickr / CC BY-SA 2.0
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By Ruby Russell and Ajit Niranjan
Hamstrung by coronavirus lockdowns, frustrated school strikers have spent months staging digital protests against world leaders failing to act urgently on climate change.
Pandemic Stalls Protests<p>Last November, the head of the UN Environment Program was among the public and scientific figures to warn that 2020 offered a last chance to cut emissions. Then, few could have suspected this deadline would coincide with an unprecedented public health emergency.</p><p>The pandemic has <a href="https://www.dw.com/en/tough-times-ahead-for-climate-protesters-during-corona-pandemic/a-52978469" target="_blank">dealt climate activism a blow</a>. Niedeggen says that as a movement demanding that the world act on scientific advice, the school strikers took lockdown restrictions extremely seriously, halted public protests immediately and took their activism online.</p><p>On April 24, Fridays for Future organized a "digital strike," with Niedeggen hosting a that racked up close to a quarter of a million views. "We were not physically standing together, but we were all fighting together," she says.</p><p><a href="https://www.dw.com/en/climate-strikers-get-inventive-during-the-covid-19-crisis-fridays-for-future/a-53229262" target="_blank" rel="noopener noreferrer">Activists also gathered thousands of placards</a> from across Germany to lay out in front of the German Bundestag around the central slogan: "Fight every crisis."</p>
Opportunity for a New Normal<p>Last September's Global Climate Strike drew young and old protestors around the world, with organizers estimating a global turnout of 7.6 million, including an estimated 270,000 people in Berlin. Activists have adjusted this year's event to account for social distancing and different levels of coronavirus restrictions in cities taking part.</p><p>They say COVID-19 also presents opportunities.</p><p>"The pandemic shows that we can change our normal daily life, and we are very able to adjust to a situation of crisis," she says. The key question is how economies get back on their feet: "We have the possibility to build a new normal, to build a renewable world order, and an environmentally just, climate-just normal for everybody."</p><p>In July, Jeng was among 20 female Fridays for Future activists from the Global South to sign an open letter to G20 finance ministers warning that their decisions in "exclusive backrooms" over stimulus packages and corporate bailouts would "lock in development pathways for decades."</p><p>"The system is not broken, it was built to be unjust. We don't need recovery, we need a reboot," the letter reads, stressing that "black people, indigenous peoples and people of color," have been disproportionately hit by the economic, climate and coronavirus crises. </p>
Policy 'Not Quite There Yet'<p>Figures on stimulus spending do not suggest their words had much impact. The ministers were criticized for failing to relieve the debt of poorer countries, and according to <a href="https://www.energypolicytracker.org/region/g20/" target="_blank" rel="noopener noreferrer">Energy Policy Tracker</a>, G20 countries by August had pledged $169 billion (142 billion euros) to fossil fuels since the beginning of the pandemic.</p><p>Katrin Uba, associate professor of political science at Uppsala University in Sweden, is researching Fridays for Future. She says that despite the movement raising awareness and gaining access to policymakers, real policy change "is not there yet."</p><p>Still, she stresses that social movements go through waves of mobilization as public attention on their core issues ebbs and flows. And perhaps one of Fridays for Future's biggest achievements is birthing a politically active generation that will keep the fight up long after corona becomes a memory. </p><p>"We know clearly from our research that many of the people who came to the streets hadn't done any protesting before in their lives," she told DW. "And we also know that if you do one protest, you are likely to do more."</p>
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