BBC’s Blue Planet II Gets it Wrong on Acidification

Nothing that Hollywood sci-fi screenwriters dream up for outer space begins to rival the beauty and ingenuity of life underwater right here. Blue Planet II captured behaviour that was new to science as well as surprising: giant trevally fish eating sooty terns on the wing; Galapagos sea lions herding yellowfin tuna ashore; an octopus wrapping itself in shells to confuse sharks.

The series also preached. Every episode had a dose of bad news about the ocean and a rebuke to humanity, while the entire last episode was devoted to the environmental cause, featuring overfishing, pollution, climate change and ocean acidification. The team behind the incomparable Sir David Attenborough has acceded to demands that it should push more environmentalism.

Mostly, these sermons were spot on. It is a scandal that eight million tonnes of plastic enter the ocean every year, though 95 per cent of it comes from just ten rivers, all in Asia and Africa, so that’s where the main effort is needed. Plastic kills albatross chicks and even whales.

The series has been accused of cheating in the sequence in which a pilot whale is shown carrying its decomposing calf. The commentary implied, without actually saying, that the calf might have died from ingesting plastic, or from pollutants in its mother’s milk. Yet there was no evidence of how it died. I think that’s unfair on the BBC. The commentary was careful and raised a valid worry.

Why are there still so few killer whales, bottlenose dolphins and great white sharks in European waters, now that seal numbers have hugely increased? There is only one resident pod of killer whales in British waters, and it is dwindling, with no calves born for years.

…snip…

Being at the top of the food chain, these mammals concentrate PCBs in their fat and it renders them sterile (killer whales that eat fish, rather than seals, are doing better). PCBs were used mainly in electrical equipment until they were banned in the 1980s. Off America, this problem is fading: PCB levels have fallen and animals have “offloaded” the pollutants in milk, such that after several births they can bear and feed healthy calves. PCB levels in European waters fell but have now stabilised, implying that they are still getting into the sea somehow.

I was glad to see these issues given more attention, at last, than global warming, having long argued that the obsession with climate change (increasingly recognised as gradual) is diverting attention and money from more urgent environmental issues such as overfishing, pollution, and invasive species.

It was good, too, to hear Attenborough’s recognition, rare on the BBC, that we are living through an unexpectedly bountiful renaissance in some marine ecosystems. Too often we are told only the bad news. The last episode featured the recovery of turtles, as well as the resurgent herring, killer whales and humpback whales of Norway, and the vast concentrations of sperm whales now being seen for the first time since the era of Moby Dick. Many populations of sperm, right, grey, bowhead, fin, blue and humpback whales are now high again and rising at 5 to 10 percent a year, something I never dreamt would happen in my lifetime.

The series could have made the same point about the penguins, fur seals and elephant seals of South Georgia, an island denuded of almost all wildlife about 75 years ago, but now once again teeming. Or about walruses, an Arctic species that has rebounded after centuries of exploitation. When I first visited Spitsbergen in the 1970s there were about 100 walruses there. Today there are about 4,000 and the population is still increasing rapidly.

So it was naughty of Blue Planet II, in showing a sequence in which a mother and calf walrus desperately try to find a bit of ice big enough to bear their weight but not already occupied by other walruses, to imply that this was evidence of climate change threatening a species with extinction. Most of the ice in the Arctic Ocean disappears each summer and reappears each winter. Walruses have hauled out on shore, or on what’s left of the ice at that season, forever. The main thing that has changed is that there are now more walruses, and more polar bears feasting on them, throughout the Arctic.

So the climate change obsession is still sometimes getting in the way of telling the truth. The most dishonest sequence in the series was when Attenborough watched shells dissolving in a tank of acid, to a soundtrack of fizzing noises, and was told by Professor Chris Langdon that although this was “more dramatic than what’s happening in the oceans”, nonetheless “the shells and the reefs are really truly dissolving”.

This is highly misleading in several different ways. Was it carbonic acid, or another acid? The reduction in alkalinity will get nowhere near neutral, let alone actual acidity, even by the end of the 22nd century, so “dissolving” is false, let alone happening now. The changes in ocean pH expected even by the end of this century are minuscule compared with what was shown in that tank, and by comparison with the daily and seasonal changes that an average reef experiences. (Coral bleaching, a different issue, is more serious, but more temporary.)

A 2010 analysis of 372 studies of 44 different marine species found that the world’s marine fauna is “more resistant to ocean acidification than suggested by pessimistic predictions” and that it “may not be the widespread problem conjured into the 21st century”:

Ocean acidification has been proposed to pose a major threat to marine organisms, particularly shell-forming and calcifying organisms. Here we show, on the basis of a meta-analysis of available experimental assessments, differences in organism responses to elevated pCO2 and propose that marine biota may be more resistant to ocean acidification than expected. Calcification is most sensitive to ocean acidification while it is questionable if marine functional diversity is impacted significantly along the ranges of acidification predicted for the 21st century. Active biological processes and small-scale temporal and spatial variability in ocean pH may render marine biota far more resistant to ocean acidification than hitherto believed.

And recent work has established that corals’ ability to make skeletons is “largely independent of changes in seawater carbonate chemistry, and hence ocean acidification…the relevance of their commonly reported finding of reduced coral calcification with reduced seawater pH must now be questioned”. Indeed, one study found that calcifying plankton “respond positively to acidification with CO₂enrichment”,

As a result, cell growth and cellular calcification of E. huxleyi were strongly damaged by acidification by HCl, but not by acidification by CO2 enrichment…The present study clearly showed that the coccolithophore, E. huxleyi, has an ability to respond positively to acidification with CO2 enrichment, but not just acidification.

another that the growth rate of corals also increases with higher carbon dioxide up to 600 parts per million and concluded:

Furthermore, the warming projected by the Intergovernmental Panel on Climate Change for the end of the twenty-first century caused a fivefold decrease in the rate of coral calcification, while the acidification projected for the same interval had no statistically significant impact on the calcification rate—suggesting that ocean warming poses a more immediate threat than acidification of this important coral species.

The producers of Blue Planet II claim every word of the commentary was based on solid scientific evidence. Not in this case. In a magnificent series, they got that one wrong.

Read in full at Matt Ridley Online