A new study confirms that, like a comet hitting the dinosaurs—slower but just as deadly—human activity is cutting off entire branches from the tree of life.
“Globally, they are changing the trajectory of evolution and destroying the conditions that make human life possible,” the ecologists said. warn in their new paper.
“It is an irreversible threat to the persistence of civilization and the viability of future environments Homo sapiens.”
Over the past few months, the sixth mass extinction has become devastatingly visible.
All the front pages of the media are talking about tourists fleeing the fires in Rhodes.
But let’s not forget that fauna and flora are also devastated and that this is much more serious than tourists who will have to shorten or cancel their holidays. pic.twitter.com/6HnK5vMex4— Debbie_banks (@Debbie_banks30) July 24, 2023
We were witnesses mass deaths of seabirdsthe shores were littered with shoals of dead fish and sea lions poisoned by the heat caused by the algal bloom. Entire populations of penguins failed to reproduce last year, and researchers have been studying the alarming decline in insect life for years.
So ecologist Gerardo Ceballos of the National Autonomous University of Mexico and conservation biologist Paul Ehrlich of Stanford University reviewed species extinctions since AD 1500 and compared them over the last 500 million years. They found that 73 genera of animals with backbones have become extinct in the last 500 years.
Genus is a taxonomic classification just above species, grouping the most closely related organisms together in a family tree, much like siblings.
This rate is 35 times higher than previous extinctions at the genus level.
Without human influence, it would take 18,000 years for the same number of genera to reach their end. Other studies have also found similarly high extinction rates for plants, fungi and invertebrates.
“(The sixth mass extinction) causes rapid mutilation of the tree of life, where entire branches (collections of species, genera, families, etc.) and the functions they serve are lost,” explain researchers.
Tens of thousands of fish have washed ashore along the Texas Gulf Coast since Friday after being starved in the warm water. “It doesn’t take long before they’re sitting there in 90-degree heat and they’re really smelling bad,” the official said. pic.twitter.com/hkJyoxQz6e
— The New York Times (@nytimes) June 11, 2023
The biosphere we live in is extremely interconnected, so the loss of groups of species that play specific functions in their interconnected living web can have serious cascading consequences.
“We and all other species have evolved together and thrive in a stable tree of life,” Ceballos and Ehrlich sayso the loss of entire ecological functions performed by groups of species directly affects us as well.
For example, loss of mosquitoes eating frogs occurred alongside increasing malaria infections in Central America.
Hundreds of little penguins lie dead, their tiny frames emaciated.
They desperately searched for food, but died of prolonged starvation as the warming ocean drove the fish away.
It’s not the insults from CC deniers that sadden me, it’s the harsh reality of climate change. pic.twitter.com/AGxjhlAxBP
— Tom (@DrTOMontgomery) May 14, 2023
What’s more, this attrition rate will increase, Ceballos and Ehrlich calculate. If we continue on our current trajectory and all currently threatened genera become extinct by 2100, the equivalent 300-year loss since 1800 would take 106,000 years at normal background extinction levels.
The most vulnerable species are usually the most unique but overlooked on the planet. Along with them, we will lose millions of years of evolutionary history that can never be repeated, as well as the loss of critical functions they performed that helped keep all the surrounding biological cycles running like a well-oiled machine.
“Evolution took millions of years to create functional replacements for extinct organisms,” Ceballos and Ehrlich Note.
Climate change alone is creating massive destabilization across these systems, disrupting the critical timing of ecosystem services such as pollination, reducing species species and allowing new ones to invade more easily.
Next new study documented these exact processes in an Arizona dry stream between 1985 and 2019.
“Our study provides evidence of climate change-induced changes in the mechanisms underlying long-term community stability, resulting in an overall destabilizing effect,” Junna Wang and team write.
Hundreds of dead fish found in Quintana Beach County Park pic.twitter.com/F6iWmE93Mh
— FOX26Houston (@FOX26Houston) June 10, 2023
However, the sixth mass extinction is much bigger than the huge cluster disaster of climate change itself.
From plastics to pesticides, habitat loss and poaching, we won’t let life stop around us.
“If we are to prevent these extinctions and their societal impacts, an immediate political, economic and social effort of unprecedented scale is necessary,” say Ceballos and Ehrlich.
Unlike the comet that wiped out the non-avian dinosaurs, we are aware of our actions and have the ability to change course.
“What happens in the next two decades is very likely to determine the future of biodiversity H. sapiens” team concludes.
This research was published in PNAS.
