Earth Is Hurtling Towards a Catastrophe Worse Than the Dinosaur Extinction
At several points in the history of our planet, increasing amounts of carbon dioxide in the atmosphere have caused extreme global warming, prompting the majority of species on Earth to die out.
In the past, these events were triggered by a huge volcanic eruption or asteroid impact. Now, Earth is heading for another mass extinction — and human activity is to blame.
I am an Earth and Paleo-climate scientist and have researched the relationships between asteroid impacts, volcanism, climate changes and mass extinctions of species.
My research suggests the current growth rate of carbon dioxide emissions is faster than those which triggered two previous mass extinctions, including the event that wiped out the dinosaurs.
The world's gaze may be focused on COVID-19 right now. But the risks to nature from human-made global warming — and the imperative to act — remain clear.
Past Mass Extinctions
Many species can adapt to slow, or even moderate, environmental changes. But Earth's history shows that extreme shifts in the climate can cause many species to become extinct.
For example, about 66 million years ago an asteroid hit Earth. The subsequent smashed rocks and widespread fires released massive amounts of carbon dioxide over about 10,000 years. Global temperatures soared, sea levels rose and oceans became acidic. About 80% of species, including the dinosaurs, were wiped out.
And about 55 million years ago, global temperatures spiked again, over 100,000 years or so. The cause of this event, known as the Paleocene-Eocene Thermal Maximum, is not entirely clear. One theory, known as the "methane burp" hypothesis, posits that a massive volcanic eruption triggered the sudden release of methane from ocean sediments, making oceans more acidic and killing off many species.
So is life on Earth now headed for the same fate?
Comparing Greenhouse Gas Levels
Before industrial times began at the end of the 18th century, carbon dioxide in the atmosphere sat at around 300 parts per million. This means that for every one million molecules of gas in the atmosphere, 300 were carbon dioxide.
In February this year, atmospheric carbon dioxide reached 414.1 parts per million. Total greenhouse gas level — carbon dioxide, methane and nitrous oxide combined — reached almost 500 parts per million of carbon dioxide-equivalent
Author provided / The Conversation /CC BY-ND
Carbon dioxide is now pouring into the atmosphere at a rate of two to three parts per million each year.
Using carbon records stored in fossils and organic matter, I have determined that current carbon emissions constitute an extreme event in the recorded history of Earth.
My research has demonstrated that annual carbon dioxide emissions are now faster than after both the asteroid impact that eradicated the dinosaurs (about 0.18 parts per million CO2 per year), and the thermal maximum 55 million years ago (about 0.11 parts per million CO2 per year).
An asteroid wiped out the dinosaurs 66 million years ago. Shutterstock
The Next Mass Extinction Has Begun
Current atmospheric concentrations of carbon dioxide are not yet at the levels seen 55 million and 65 million years ago. But the massive influx of carbon dioxide means the climate is changing faster than many plant and animal species can adapt.
A major United Nations report released last year warned around one million animal and plant species were threatened with extinction. Climate change was listed as one of five key drivers.
The report said the distributions of 47% of land-based flightless mammals, and almost 25% of threatened birds, may already have been negatively affected by climate change.
A diagram showing the weakening Arctic jet stream, and subsequent movements of warm and cold air. NASA
This allows north-moving warm air to cross the polar boundary, and cold fronts emanating from the poles to intrude south into Siberia, Europe and Canada.
A shift in climate zones is also causing the tropics to expand and migrate toward the poles, at a rate of about 56 to 111 kilometres per decade. The tracks of tropical and extra-tropical cyclones are likewise shifting toward the poles. Australia is highly vulnerable to this shift.
Uncharted Future Climate Territory
Research released in 2016 showed just what a massive impact humans are having on the planet. It said while the Earth might naturally have entered the next ice age in about 20,000 years' time, the heating produced by carbon dioxide would result in a period of super-tropical conditions, delaying the next ice age to about 50,000 years from now.
During this period, chaotic high-energy stormy conditions would prevail over much of the Earth. My research suggests humans are likely to survive best in sub-polar regions and sheltered mountain valleys, where cooler conditions would allow flora and fauna to persist.
Earth's next mass extinction is avoidable — if carbon dioxide emissions are dramatically curbed and we develop and deploy technologies to remove carbon dioxide from the atmosphere. But on the current trajectory, human activity threatens to make large parts of the Earth uninhabitable - a planetary tragedy of our own making.
Reposted with permission from The Conversation.
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By Naomi Larsson
For centuries, the delicate silver dove has been a symbol of love and fidelity.
Biodiversity and Habitat Loss<p>Their near extinction is a symbol of the <a href="https://www.dw.com/en/global-biodiversity-outlook-targets-extinction-summit-new-york-pledge/a-54932895" target="_blank">biodiversity crisis</a> in the UK, largely driven by habitat destruction. Britain is now one of the countries with the most <a href="https://www.wwf.org.uk/future-of-UK-nature#:~:text=The%20UK%20is%20one%20of,than%20half%20are%20in%20decline" target="_blank">depleted nature</a> in the world according to the World Wildlife Fund. Half its plant and animal species are in decline and more than <a href="https://www.rspb.org.uk/about-the-rspb/about-us/media-centre/press-releases/let-nature-sing-wales/#:~:text=a%20natural%20tragedy.-,Over%2040%20million%20birds%20have%20vanished%20from%20UK%20skies%20in,unaware%20of%20the%20impending%20danger" target="_blank">40 million birds</a> have vanished in just half a century.</p><p>"[Turtle doves] are the canary in the [coal] mine because there are all these other species before it and after it," said Tree. "It's an umbrella for all the other species that are heading that way."</p><p>Turtle doves migrate south through Europe to sub-Saharan Africa between July and September, ending up in dry woodland and farmland areas of countries like Mali and Senegal for winter. </p><p>Droughts in West Africa and the Sahel region are believed to have contributed to the fall in turtle dove species recorded in northern Europe, with low rainfall reducing supplies of the seeds and insects the birds rely on for energy for the long journey home.</p>
Conservation and Farming<p><a href="https://www.operationturtledove.org/" target="_blank" rel="noopener noreferrer">Operation Turtle Dove,</a> a partnership project of charities including the Essex Wildlife trust, works with landowners and farmers to actively build turtle dove habitat.</p><p>Outten works with <a href="https://www.ebws.org.uk/birdsites/blue-house-farm-ewt-north-fambridge" target="_blank">Blue House Farm</a>, a 660-acre nature reserve in the UK county of Essex, where they have replicated weedy fallow plots. </p><p>"We work on it every year to make sure it's in the condition it needs to be with plants such as clovers and black medic," Outten said. "These plants are native to the landscape and produce the seed the birds feed on." </p><p>The birds eat a wide range of seeds from various plants that would have been abundant 50 or 100 years ago, added Guy Anderson, program manager for species recovery with The Royal Society for the Protection of Birds (RSPB). </p><p>"But it's simply true that with the gradual process of <a href="https://www.dw.com/en/farming-without-pesticides-how-can-we-make-agriculture-greener/a-52216796" target="_blank" rel="noopener noreferrer">intensifying our agricultural production</a>, the availability of those seeds has dropped and dropped," said Anderson.</p><p>Part of the project includes supplementary feeding — providing sources of food in the form of seed or grain. Under the Countryside Stewardship Scheme in England, farmers can receive financial support to create a turtle dove habitat. </p><p>Though they haven't recorded an increase in doves across the sites in the four years of working on the project, Outten said they are seeing improvements in how landowners and farmers manage habitat for the birds. </p>
A Turtle Dove Haven<p>The 3,500-acre Knepp Estate in West Sussex is another project taking a different approach and one of the few places where turtle dove numbers are increasing.</p><p>Isabella Tree and her husband Charlie Burrell converted their intensively farmed land into a rewilding project almost 20 years ago. They have let the land return to nature.</p><p>Just one year after they'd finished <a href="https://www.dw.com/en/uks-most-talented-architects-are-not-human/a-35952128" target="_blank">rewilding</a> the southern part of their property, they heard turtle doves for the first time. It's now a breeding hotspot for the birds with an estimated 19 pairs. Knepp is also home to <a href="https://www.rewildingbritain.org.uk/rewilding/rewilding-projects/knepp-estate" target="_blank" rel="noopener noreferrer">2% of the UK's population</a> of nightingales. </p><p>Tree is critical of supplementary feeding schemes that, in her view, are short term. She questions the chances of turtle doves getting to feed on scattered seeds before other mammals eat them first.</p>
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