A special issue of the Philosophical Transactions of the Royal Society B (Biological Science) — “Biological diversity in a changing world” — paints a bleak picture of what Homo ‘sapiens’ sapiens is doing to the other species on the planet.
Prior to this year, I wrote about extinction only occasionally — since the direct impact of unrestricted greenhouse gas emissions on humanity seemed to me more than reason enough to act. But the mass extinctions we are causing will directly harm our children and grandchildren as much as sea level rise. In particular, I believe scientists have not been talking enough about the devastation we are causing to marine life (see “Geological Society: Acidifying oceans spell marine biological meltdown “by end of century”).
In 2007, the IPCC warned that “as global average temperature increase exceeds about 3.5°C [relative to 1980 to 1999], model projections suggest significant extinctions (40–70% of species assessed) around the globe.” That is a temperature rise over pre-industrial levels of a bit more than 4.0°C. So the 5°C rise we are facing on our current emissions path would likely put extinctions beyond the high end of that range.
Given the irreversibility of mass extinction, and the multiple unintended consequences it engenders, it must be considered one of the most serious of the many catastrophic impacts we face if we don’t act soon.
The special issue contains 16 articles by leading scientists. The abstracts are all online as is the lead piece, also titled, “Biological diversity in a changing world,” by the two biologists who organized the Royal Society’s scientific “Discussion Meeting” and edited the issue.
The authors, Magurran and Dornelas, note that “there are very strong indications that the current rate of species extinctions far exceeds anything in the fossil record,” and conclude that while extinctions are inevitable:
It is the mass extinction currently underway, caused by overexploitation of natural resources, that needs to worry us. Similarly, environmental change has always been prevalent, and has helped shape biodiversity patterns of today. In contrast, never before has a single species driven such profound changes to the habitats, composition and climate of the planet….
As for the oceans, famed oceanographer and ecologist Jeremy Jackson, concludes in his article, “The future of the oceans past”:
Major macroevolutionary events in the history of t he oceans are linked to changes in oceanographic conditions and environments on regional to global scales. Even small changes in climate and productivity, such as those that occurred after the rise of the Isthmus of Panama, caused major changes in Caribbean coastal ecosystems and mass extinctions of major taxa. In contrast, massive influxes of carbon at the end of the Palaeocene caused intense global warming, ocean acidification, mass extinction throughout the deep sea and the worldwide disappearance of coral reefs. Today, overfishing, pollution and increases in greenhouse gases are causing comparably great changes to ocean environments and ecosystems. Some of these changes are potentially reversible on very short time scales, but warming and ocean acidification will intensify before they decline even with immediate reduction in emissions. There is an urgent need for immediate and decisive conservation action. Otherwise, another great mass extinctio1n affecting all ocean ecosystems and comparable to the upheavals of the geological past appears inevitable.
Jackson is the director of the Center for Marine Biodiversity and Conservation at the Scripps Institution of Oceanography. Our ongoing efforts to wipe out sea life may lack the media-grabbing pizzazz of a Titanic oil spill, but it does not lack the punch (see Nature Geoscience study concludes ocean dead zones “devoid of fish and seafood” are poised to expand and “remain for thousands of years”).
As Jackson explains in his 18-minute TED talk,”How we wrecked the ocean”:
If you have the stomach for it, the hour long version is here (but the slides are blurred).
The recent scientific literature on what we’ve done and are poised to do to the oceans is beyond staggering:
- Nature Geoscience study: Oceans are acidifying 10 times faster today than 55 million years ago when a mass extinction of marine species occurred
- Imagine a World without Fish: Deadly ocean acidification “” hard to deny, harder to geo-engineer, but not hard to stop
- Nature Stunner: “Global warming blamed for 40% decline in the ocean’s phytoplankton”: “Microscopic life crucial to the marine food chain is dying out. The consequences could be catastrophic.”
On that last study, Seth Borenstein of the AP explains, “plant plankton found in the world’s oceans are crucial to much of life on Earth. They are the foundation of the bountiful marine food web, produce half the world’s oxygen and suck up harmful carbon dioxide.”
Business as usual — staying on our current emissions path — makes multiple catastrophes likely. The plausible worst-case scenario is beyond imagining.
The Magurran and Dornelas piece ends with this radical conservative quote by Tomasi di Lampedusa from his novel Il Gattopardo:
Se vogliamo che tutto rimanga come ¨, bisogna che tutto cambi!
If we want things to stay as they are, everything must change!