Our home in space

some remarks on global heating and ocean acidity

Guy Ottewell

Living things

The global extinction of species now going on is more rapid than any of the great extinctions in the geological record not caused by cosmic collisions.
        That this is so was made clear in a major study, Global Biodiversity Outlookש, in May 2010. It was revised to a lower but still alarming rate by another study reported in the journal Nature in May 2011.
        The declines in species are caused mainly by loss of habitat; and this is due to human encroachment, also to melting ice, rising sea, and other changes brought by global warming.
        Among the species threatened with extinction are emperor penguins, loggerhead turtles, ringed seals, salmon, clownfish, Arctic foxes, and staghorn coral. A few other examples:
        Whales, as we all know, were being driven toward extinction by hunting, still continued by Iceland, Norway, and Japan. But more whales than ever died from hunting are now dying from other human-caused effects. They are hit by ships, entangled in fishing gear, or disoriented by military sonar (now found to be much louder than had been thought). Changing water temperature, and the acidifying of the ocean, forces them to travel farther in search of food.
        Twenty percent of lizard species are now considered endangered. Many lizards live in climates so hot that they must get out of the sun in the middle of the day before it overheats them. With even higher temperatures, the time when they can forage for food grows shorter.
        Walruses have to migrate annually from the southern coast of Alaska through the Bering Strait to the northern coast of Siberia. They weigh up to two tons and are not built for long-distance swimming, so they swim effortfully with their heads raised, as if breast-stroking. They depend on ice floes on which to take rests and from which to dive for the bottom-dwelling shellfish which are their food. With rising temperature the floes have become fewer and thinner.
        Birds are sensitive indicators of climate change, because their populations move about, so it can be very noticeable when suddenly a region has far more or fewer of them. It was estimated (by a 2010 conference of 200 experts on bird migration) that over the past decades 20 billion birds have changed their migration habits. The overwhelming explanation is climate change. Miguel Ferrer of Spain's Higher Council for Scientific Research said: “That has a knock-on effect on almost everything they do, from breeding habits to feeding habits to their genetic diversity, which in turn affects other organisms in their food chain. It's a huge behavioural change, forced on them by rising temperatures.” The last comparable phenomenon that forced such a wave of adaptation on birds was the Ice Age. But the present change is much faster and the adaptation may be much less successful, because available habitats are now so broken up by human use.
        Sir Geoffrey Chandler, business leader and human-rights activist, who died in 2011, wrote to me in 2009: “It is clear to me, as someone who has observed butterflies from his youth, that the population changes I have witnessed and am witnessing are irreversible indicators of climate change. Not as visible and dramatic as the shrinking of the glaciers and ice-sheets, but nonetheless a canary in the mine . . .  History will not forgive the saboteurs and the business interests which have financed the sceptics and continue to argue against the science.“