The life and death of an iceberg (and a message to bears)
The iconic symbol of climate change is the polar bear. Often stood, looking somewhat stranded, on a glacier. Being such a reluctant ambassador for global warming woes must take its strain, but over the years we too have become desensitised. The message, even though we know it’s out there and a mighty fine problem, has become a tad jaded.
Which is why programmes like BBC2’s Operation Iceberg are so important. A team of polar explorers and climate scientists heading out into the arctic to investigate the unknown world of the iceberg to investigate the creation, life and death of these frozen behemoths. Environmentalist Chris Packham also hitched a ride, mainly for the wildlife (cue the polar bears).
I’m not an expert in icebergs – who is? – but these basically form when parts of a glacier snap off. What the team wanted to find out was why they snap off in the fashion that they do, and what happens to the iceberg once it becomes separated, alone and adrift.
For me, the most shocking sight was the sudden, unpredictable nature of these snaps and the enormity of ice release, it felt akin to watching an avalanche unfold. Witnessing an actual moment of climate change devastation was sobering to say the least.
As an iceberg is released it gains heat from the environment – this rate of heat loss is key to understanding how fast the ice is melting. The team drilled down into the ice, which looked hard as marble, to measure the core temperature. They estimated at the coldest point it was -13°C – surprisingly chilly and not what they expected.
To investigate further they measured the temperature of the ocean at different depths around the iceberg. They found that at deeper levels, it was sub-zero – this effectively cocooned the ice and prevented heat loss. Not so nearer the surface towards sea level – the higher temperatures here were rapidly eroding the ice.
The team discovered that snaps happen because the top of the glacier, or subsequent icebergs, are chiselled away around the edges by warmer sea temperatures while the deeper submerged core remains relatively intact. This process eventually acts as a destabiliser and results in more chunks of collapse.
But what about the polar bears? Well they were on the iceberg too, curious as to this latest round of human intervention. Packham carried out a straw poll census by helicopter and estimated that on this particular iceberg, which spanned some 40 square kilometers, there were between 15 to 20 bears. A surprising high number.
“Something is keeping them here,” he mused. As his team dived into the ocean and assessed the surrounding eco-system, it quickly became apparent it was rich in ‘bear burgers’ (seals) and amazing sea gooseberries and sea angels which the seals love to feast on in turn.
On a positive note, this was the first time such a large number of bears had been recorded on a tabular iceberg. According to Packham, such icebergs are acting as a valuable refuge for the animals until the sea ice returns in the winter. What is worrying however is how long these icebergs remains a security blanket.
The rate at which glaciers and their iceberg splinters crumble is the real issue. As icebergs float south towards the Atlantic Ocean, their demise deepens – in perhaps as little as a year, they will disappear completely into the water. For 40 square kilometers that’s no mean feat.
That end may come even sooner – the team left a tracking device embedded into the iceberg which will transmit the final hours of its life. Interestingly, the programme made no mention of climate change until 35 minutes in, and kept it brief when it did. When footage is this powerful, it doesn’t need overstating.maxine perella