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Pi finds a strange and beautiful island where life can’t survive. wildfox76/Flickr

Life of Pi’s acidic island a warning for our warming world

The recently released film Life of Pi directed by Ang Lee and based on Yann Martel’s novel of the same name, is a fable for our climate change times. Much of the plot involves the struggles of a teenage boy named “Pi” Patel, trying to survive a shipwreck in which his family dies. With resonances to the Noah’s Ark biblical story, Pi becomes stranded in the Pacific Ocean on a lifeboat with a tiger named Richard Parker.

Pi is a piphilologist, meaning that he has learnt to memorise the numbers constituting π, the record for which, according to the Guinness World Records, is 67,890 digits. Pi, the ratio of the circumference of a circle to its diameter, is an irrational and transcendent number, meaning it has an infinite number of digits in its decimal representation. All of this may give us insight into the character and mythical import of the film’s protagonist.

Initially in the lifeboat along with Pi are an orangutan who has lost a baby, an aggressive spotted hyena and an injured zebra. The hyena eats part of the zebra, then mortally wounds the orangutan, at which point Richard Parker leaps from under the tarpaulin and kills the hyena.

After many trials, Pi and Richard Parker reach a strange island made of plants that Pi eats. It has a forest, fresh water pools, and a large population of meerkats that sustain Richard Parker. At night, however, the meerkats flee to the trees and Richard Parker to the lifeboat.

Pi watches from a branch as the island’s fresh water turns acidic, digesting fish that have died in the pools. He sees that the water around the island is filled with fluorescent jelly fish. Pi finds a human tooth inside a flower. He decides the island is carnivorous and decides to leave with the tiger in their boat.

The fabulous nature of this part of Pi’s story later suggests to Japanese investigators of the ship’s sinking that Pi is not telling the truth.

Castello Aragonese is almost as strange and hostile as Pi’s acidic island. Gabriele Margapoti

Castello Aragonese is a small island which really exists in the Tyrrhenian Sea near Naples. Bubbles of carbon dioxide rise from volcanic vents on the seafloor and dissolve to form high concentrations of carbonic acid that make seawater corrosive. That real island offers insight into the acidification of the world’s oceans, as they absorb increasing amounts of anthropogenic atmospheric carbon dioxide thanks to our excessive burning of “archived” photosynthesis fuels (oil, coal and natural gas).

Like the floating island Pi and Richard Parker discover, the island of Castello Aragonese creates beds of vivid green sea grass and sustains swarms of translucent jellyfish and algae. Yet no other life survives in its waters. All the world’s oceans are predicted to become this acidified by 2100 with severe impacts on small lifeforms in the ocean.

The pH scale measures acidity in terms of the concentration of hydrogen ions that substances release. It runs from zero (highly acidic) to 14 (highly basic) and is logarithmic (small numerical changes representing large effects). Seawater is usually slightly basic, with a pH around 8.2. CO2 emissions have already reduced the pH of surface sea water by about 0.1, meaning the water has become 30% more acidic. Surface pH is predicted to drop to a further 1% by 2100. At that point (because pH involves a logarithmic scale), seawater will be 150% more acidic than it is now.

Even if our CO2 emissions were stabilised today, it would take tens of thousands of years for ocean pH to return to normal. Coral reefs and the small creatures that sustain the food chain for whales, for example, would perish, the oceans will become so corrosive (like those of the waters around Pi’s island) that the shells of many small sea creatures will simply dissolve.

The acidic island of the Life of Pi film contains a subtle, artistic warning for humanity. The Ark of Pi released a tiger rather than a dove when it reached dry land, and when the tiger reached land it didn’t look back to help its human rescuer. In Richard Parker the tiger we may be seeing the not too pleasant face of Gaia.

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