Читать книгу High Tide: How Climate Crisis is Engulfing Our Planet - Mark Lynas - Страница 14

Evidence of dramatic climate change is piling in from right around the Earth’s polar regions. Greenland’s ice sheet is thawing so fast that meltwater is running off at a rate equivalent to the annual flow of the Nile.⁸,⁹ Throughout the Northern Hemisphere winter snowcover has declined by a tenth since 1979,¹⁰ whilst rivers and lakes are freezing a week later and thawing a week earlier than a century ago.¹¹ Alaskan mountain glaciers are losing ice at a rate fast enough to have a measurable impact on global sea levels,¹² whilst other glaciers and snowfields are disappearing throughout the region.¹³

This warming is mirrored in the Southern Hemisphere, where the Antarctic Peninsula is warming at a rate similar to that in Alaska. (The Antarctic continental interior, which is surrounded by cold circumpolar winds and sea currents which isolate it from wider global temperature changes, has warmed much more slowly, if at all.) As a result, snowcover and glaciers on the Peninsula are shrinking, ice-dependent Adelie penguin populations shrinking and new plants are beginning to colonise the landscape.¹⁴

About 10,000 square kilometres of ice shelf have been lost from both sides of the Antarctic Peninsula, culminating in March 2002 with the spectacular collapse of the Larsen B ice shelf, an event which made headlines around the world. Before its sudden demise, Larsen B was a floating wedge of ice 200 metres thick and larger than the entire country of Luxembourg. ‘The speed of it is staggering,’ said a British Antarctic Survey glaciologist at the time, as his ship navigated through the armada of new icebergs. ‘Hard to believe that 500 billion tonnes of ice sheet has disintegrated in less than a month.’¹⁵

Much of what I had heard from Alaskan residents is backed up by hard scientific evidence. As Clifford Weyiouanna told me, sea ice is thinning rapidly. This observation is confirmed by submarine cruises under the Arctic ice, which reveal a thinning trend of over 40% over the last thirty years.¹⁶ The total area of Arctic sea ice is also diminishing rapidly: satellite data shows an area one and a half times the size of Wales is lost every year.¹⁷ In September 1998 ice cover in the Beaufort and Chukchi seas around Alaska (Shishmaref is on the Chukchi Sea) reached a record low, a quarter less than the previous minimum extent over half a century of observations.¹⁸

As Clifford and other Shishmaref Eskimo residents told me, this reduction in sea ice is bad news for marine life, much of which congregates around the edges of the ice, where multitudes of plankton and fish form a food bonanza. Walruses, for example, need sea ice thick enough to hold their weight but in shallow enough water to allow them to dive and feed on the sea bottom. Similarly, ringed seals depend on sea ice as a habitat for pupping, moulting, foraging and resting. The same is true for many Arctic species: the health of populations of walruses, ringed and bearded seals, polar bears, belugas and bowhead whales are all strongly correlated with sea ice cover.

The reported changes on land are also well supported by scientific research. Satellite pictures of the Alaskan interior confirm that lakes and ponds have been drying up during the last decade.¹⁹ The IPCC suggests that this phenomenon is linked with melting permafrost: frozen ground forms an impermeable layer, but once it thaws, surface lakes can drain away.²⁰ As I had discovered in Fairbanks, widespread permafrost melting is well underway across large areas of Alaskan territory, affecting not just buildings and roads, but also wild forests.

Huge areas of woodland have also been destroyed by another side-effect of warming – spruce-bark beetle infestations, which have killed 2.3 million acres of trees since 1992 across a broad swathe of southern Alaska. The devastated area reaches right to Anchorage itself, and visitors flying into the city’s airport cross islands covered with the bristling, white skeletons of dead trees which are easily visible through the plane windows. It’s the worst insect outbreak ever to hit North American forests, and is directly related to higher temperatures: in colder winters, the beetle eggs had been killed off and the population had been unable to explode.²¹

On the southern Kenai Peninsula, an area famed for its undisturbed natural forests, the beetles attacked like a plague of locusts. One local wildlife specialist compared it to ‘an Alfred Hitchcock movie’. As he told Alaska Magazine: ‘They would be in your hair and eyes, you’d have to brush them off. I’ve heard people saying they could see them in clouds, miles off, coming down the valley.’²² And the only thing that stopped the plague was when there were no more trees left alive to attack.