World’s Species Numbers Stay Much The Same. But For How Long?
Tim Radford
Read Time: 5 mins
Life is on the move. Everywhere, the mix of creatures is changing for better and worse. The world’s species remain diverse. But for how long?
Biodiversity – that vital mix of the world’s species, insects, worms, birds, mammals, fish, amphibians, microbes, plants and fungi that make up an ecosystem – is being reorganised. Change is happening almost everywhere on land and much faster in the seas that cover seven-tenths of the globe.
But when an international team of researchers looked at 239 studies that catalogued 50,000 changes in the living world over the decades, they arrived at a paradoxical puzzle.
The composition of an ecosystem is being altered, and altered sometimes at speed, by rising temperatures driven by human use of fossil fuels, by human colonisation of the grasslands, forests and wetlands, and by human disturbance of coral reefs, sea meadows, mangrove swamps and other submarine habitats.
But on average, the richness of life – the sheer numbers of species – in the world’s more closely studied ecosystems has remained much the same: that is, as some creatures or growths vanish from a cloud forest or an estuarine mudbank, the space they occupied is colonised by newcomers more comfortable with change.
Mixed picture
“Our study shows that biodiversity is changing everywhere, but we are not losing biodiversity everywhere. Some places are recovering and adapting,” says Maria Dornelas of the University of St Andrews in the UK.
“However there is a lot of recovery taking place silently in the background, and many places where not much is happening. Our study puts these things on the map and shows they are not contradictory.”
The finding seems to question two decades of scientific orthodoxy: that because of human action, species are being extinguished at an accelerated rate. Extinction is a part of evolution, but biologists calculate that it is now happening at least a thousand times faster than the average rate for the past 500 million years.
“A sixth mass extinction could still be happening while local scale richness shows little change”
The latest study, in the journal Science, suggests that the big picture is more complicated: as environments change, so does the mix of local species. Some migrate, some adapt, some invade. Overall, the richness of the local population may not change a lot.
But this finding may not be inconsistent with global alarm about species loss on a massive scale as human numbers go on rising, and levels of greenhouse gas continue to soar. Change is happening faster in the tropics, those regions with the greatest variety of life. The dangers have not evaporated.
It might be that local species with narrow ranges were being replaced by more resilient plants or animals capable of surviving a much wider range of conditions: if so, the numbers of species in any local ecosystem might remain stable but the variety of life overall could still be diminished.
And Andrew Gonzalez of McGill University in Canada says: “The Earth is going through a great geographic reorganisation of its biodiversity in response to human activities and climate change. Given what we know it is likely this will continue for decades to come.” – Climate News Network
About the Author
Tim Radford is a freelance journalist. He worked for The Guardian for 32 years, becoming (among other things) letters editor, arts editor, literary editor and science editor. He won the Association of British Science Writers award for science writer of the year four times. He served on the UK committee for the International Decade for Natural Disaster Reduction. He has lectured about science and the media in dozens of British and foreign cities.
Book by this Author:
Science that Changed the World: The untold story of the other 1960s revolution by Tim Radford.
Life After Carbon: The Next Global Transformation of Cities
by Peter Plastrik , John Cleveland The future of our cities is not what it used to be. The modern-city model that took hold globally in the twentieth century has outlived its usefulness. It cannot solve the problems it helped to create—especially global warming. Fortunately, a new model for urban development is emerging in cities to aggressively tackle the realities of climate change. It transforms the way cities design and use physical space, generate economic wealth, consume and dispose of resources, exploit and sustain the natural ecosystems, and prepare for the future. Available On Amazon
The Sixth Extinction: An Unnatural History
by Elizabeth Kolbert Over the last half-billion years, there have been Five mass extinctions, when the diversity of life on earth suddenly and dramatically contracted. Scientists around the world are currently monitoring the sixth extinction, predicted to be the most devastating extinction event since the asteroid impact that wiped out the dinosaurs. This time around, the cataclysm is us. In prose that is at once frank, entertaining, and deeply informed, New Yorker writer Elizabeth Kolbert tells us why and how human beings have altered life on the planet in a way no species has before. Interweaving research in half a dozen disciplines, descriptions of the fascinating species that have already been lost, and the history of extinction as a concept, Kolbert provides a moving and comprehensive account of the disappearances occurring before our very eyes. She shows that the sixth extinction is likely to be mankind's most lasting legacy, compelling us to rethink the fundamental question of what it means to be human. Available On Amazon
Climate Wars: The Fight for Survival as the World Overheats
by Gwynne Dyer Waves of climate refugees. Dozens of failed states. All-out war. From one of the world’s great geopolitical analysts comes a terrifying glimpse of the strategic realities of the near future, when climate change drives the world’s powers towards the cut-throat politics of survival. Prescient and unflinching, Climate Wars will be one of the most important books of the coming years. Read it and find out what we’re heading for. Available On Amazon
From The Publisher: Purchases on Amazon go to defray the cost of bringing you InnerSelf.comelf.com, MightyNatural.com, and ClimateImpactNews.com at no cost and without advertisers that track your browsing habits. Even if you click on a link but don't buy these selected products, anything else you buy in that same visit on Amazon pays us a small commission. There is no additional cost to you, so please contribute to the effort. You can also use this link to use to Amazon at any time so you can help support our efforts.