The world is skating on ever thinner ice

“Time to listen to the ice scientists about the Arctic death spiral” (The Guardian, 18 August 2016), quotes Peter Wadhams, currently professor of ocean physics at Cambridge University, who knows a thing or two about global warming.

Wadhams has studied Arctic sea ice for more than 40 years. He says that its September minimum used to cover 8 million sq km and today it hovers around 3.4 million. Declining by 13% every 10 years, by the end of this century there will be no Arctic sea ice in September, and perhaps none at all for four or five months at a time.

An inevitable result will be the release of immense amounts of methane gas, increasing the greenhouse effect and accelerating global warming. The Guardian article goes on to describe this year’s wild temperature fluctuations:

“Britain and northern Europe may have had average temperatures, but 500 million people in the Middle East and North Africa, along with most of south-east Asia, have experienced droughts and searingly hot days and nights, which are only partly to do with the natural El Niño phenomenon. Meanwhile, China, India and the US have seen some of their longest heatwaves and worst floods in decades, and nearly 100 million people will need food aid in the coming months because of disrupted rainfall patterns.

Mitribah in Kuwait has reported a world record 54C, India and Iran have both recorded their highest ever temperatures, and deadly heatwaves have struck China, the US, Indonesia and New Zealand. We are perilously close to the 1.5C limit of warming that all countries signed up to in Paris last year and on track for a 3C-4C increase which would make much of the world uninhabitable.”

Confirming what all but the most obdurate already know, the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (2014) noted that:

“Surface temperature is projected to rise over the 21st century under all assessed emission scenarios. It is very likely that heat waves will occur more often and last longer, and that extreme precipitation events will become more intense and frequent in many regions. The ocean will continue to warm and acidify, and global mean sea level to rise.”

Images of the Earth with two ice caps are common. Antarctica, a landmass covered in ice, holds about 90% of the world’s ice and 70% of its fresh water. If all the Antarctic ice melted, sea levels around the world would rise about 61 meters (200 feet). However, the average temperature in Antarctica is -37°C, so at the moment there is little danger of that happening.

At the North Pole, the ice is not nearly as thick. If it melted, sea levels would not be affected. But it’s a different story on nearby Greenland. If its ice uncongealed, ocean levels would rise seven metres (20 feet). Greenland is closer to the equator than Antarctica, so the temperature is significantly higher and the ice is more likely to melt.

Scientifically speaking, there is a less dramatic reason for higher sea levels than polar ice melting. Water is densest at 4 degrees Celsius. Above and below this temperature, its density decreases (the same weight of water occupies a bigger space). As the overall temperature of the water increases, it expands, making the oceans rise.

Higher temperatures and higher sea levels. We are in for a rough ride.

Sea-ice-2016(2)

Photo credit: NASA Goddard’s Scientific Visualization Studio/C. Starr.

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