Blue Arctic Doug Allan will be speaking for RSGS at Perth Concert Hall on 21st December, tickets are available here. By Doug Allan We have already lost one sea from the map. The Aral Sea was a huge inland body of water that fell victim in the 1950s to the agricultural policies of the Soviet Union. Water from its two river sources was intentionally diverted for cotton cultivation. Decreasing water flow into the sea caused a rise in salinity, the abundant freshwater fish species began to die out, the sea itself began to dry out. Now a mere 10% of its previous area, what happened to the Aral is recognised as one of the world’s worst ecological disasters caused by humans. The Arctic Ocean is now being changed. The top of the world is no longer white, but blue. Its ice is disappearing. The Arctic Ocean is the one that’s least visible on a standard map projection of the world. It lies at the top of the double-page spread in the atlas, looking like a sliver of blue along the top above Greenland, the Canadian islands, Alaska and Russia. Or on a spinning globe, the kind on your desk, it’s where the axis rod runs north to south, with always some kind of spreader piece on the rod where it enters the globe. Watch most people pick up a globe, and they automatically line up their eyes with the equator; they often never think to tilt the globe down so they can see the very north of our planet. I’m trying to say that an awful lot of people don’t actually realise that while Antarctica is a huge frozen continent surrounded by water, the Arctic is the opposite. A wide frozen sea bordered by land. We’ve long been interested in the ice covering the Arctic basin. At the height of the Cold War, both protagonists knew full well that the shortest distance between the Soviet Union and the USA wasn’t trans-Atlantic but trans-polar, across the top. And if you could have your missiles launched from submarines that had punched through the ice right next to the northern shoreline of your enemy, the surprise element would be even more lethal. So submarines from both sides with upward facing sonar criss-crossed under the winter Arctic ice, gathering data on ice distribution and thickness. Now, satellites look down from above. Their radar altimeters measure the distance with millimetric accuracy from satellite to the surface of the ice on the Arctic Ocean below. When the signal bounces off water rather than ice, that distance obviously is fractionally greater. There’s been a massive reduction in the amount of lumpy multi-year ice in the last 25 years; most ice covering the Arctic Ocean now is flat, so subtract your satellite-to-ice distance from your satellite-to-water distance and you have the ice thickness above the water. Seven-eights of floating ice is under the water, so it’s simple to calculate the overall thickness of that flat ice. In 1976, the average thickness of winter sea ice (mid-February) was eight metres. It’s now down to 60% of that value. Thinner ice in winter melts earlier in the (warmer) springs. So over summer there’s more black, open water. Black absorbs heat, sea warms more, takes longer to cool down, freezes later in autumn, thinner ice in winter. You get the picture: we’re in a positive feedback loop whereby there’s nothing to stabilise the system, the changes keep on happening, getting greater through the years. Just as thickness has reduced, so has the area of ice present. Over winter, the ice still covers much of the Arctic basin (though a heatwave of +2°C in December 2017 at the North Pole is undermining that statement), but in mid-September (the month of minimum cover) the picture over the years is clear. In the mid-1980s 7.2 million square kilometres of ice was present; in 2012 it was a mere 4.2 million. It hasn’t been linear decline over the years; some summers have seen a little (temporary) recovery. But you can say with certainty that the summer Arctic now is very different from that of 30 years ago. The Arctic ice has been very eloquently but accurately described as being in a Death Spiral. If we combine thickness and area we arrive at a measure of the volume of ice present. Calculate the volume over the years, month by month, and yes of course it goes up and down over the winter and summer seasons. But overall, the trend is clear. The overall total amount of ice is decreasing in both winter and summer. It’s spiralling down to the inevitability of summers that will be effectively ice-free. Pen Hadow and his team tried in 2017 to take a sailboat to the North Pole, Sébastien Roubinet attempted it with his crew last year. Neither was successful but it’s only a matter of time before someone will make it. I predict, very soon. There’s another dangerous consequence of this positive feedback loop in the ice. Under the shallower parts of the Arctic Ocean, above the continental shelf areas, vast amounts of methane gas are frozen solid in a crystalline form. These clathrates exist because of the pressure of the water above, and the cold temperature of that water. But warming of the ocean is breaking down the clathrates, releasing the methane, which is visible bubbling to the surface in certain areas at a much higher rather than previously. Methane as a gas is 20 times more efficient per volume than CO2 at heating the atmosphere. There’s real concern that methane release could be one of the tipping points we’ll cross that puts climate control even further out of our reach. Life in the Arctic has evolved to depend on the ice. Ringed, harp and hooded seals give birth on it, polar bears would live on it all year round if they could. Polar bears are classed as marine mammals, like whales or walrus. Whales live IN the sea, polar bears live ON it. Screw with that crucial environment, degrade it, break it up sooner, cut down the amount of it, and it’s like chopping down the rainforest round the orangs and expecting to find them in your new palm oil plantation. It ain’t gonna happen. The changing Arctic is exacting a toll already: hungrier females who have less time to hunt on the later-forming autumn sea ice are giving birth to fewer cubs. Those cubs are also lighter, less likely to survive the rigours of the first months on the ice when they come out of the den. More cub mortality, areas of where melt over summer just doesn’t leave the bears enough ice where they can make a living… the polar bear is walking into an uncertain future. In the next 30 years we could see a reduction in their current circumpolar range, and a drop in their number. Some estimate from 24,000 at the moment to around 10,000. Fact is, it’s hard to predict. But we’ve already seen nature’s solution. A handful of pizzlies have been confirmed, hybrids from a union between a male polar bear and a female grizzly. And, perhaps even more surprisingly, these hybrids can be fertile themselves. Nature sure is resilient, but that’s a hell of a costly and uncontrolled experiment we’ve been carrying out to make the point. I’ve written here about sea ice in the north disappearing because of warming. Let’s also remember that increased CO2 in the atmosphere also means greater concentrations in the sea. Making the seas more acidic. Posing big threats to coral reefs and any animal (or developing larvae) with a calcium carbonate shell. Like some of the plankton species in the polar zones upon which so many fish (and big whales like the bowhead) depend. My support is with the youngsters who came out of school in February to protest about climate change. They have as much right as we had to go see an icy Arctic; we have to embrace the mighty changes necessary to ensure they keep that right. Climate change – shouldn’t we call it climate breakdown? – is without a doubt the number one issue facing us right now. We’ve already lost one sea, there’s a very real risk of losing an ocean. We must do much more to turn the tide.