• Dr. Graham Elford

Changes in the arctic sea ice, commencing mid-June 2016

Contributed by Dr Graham Elford. Graham was a lecturer and researcher in the Adelaide University Physics Department from 1949 until his retirement in 1988. He was for a time President of the International Astronomical Union Commission on Interplanetary Dust and has an asteroid named after him [Elford 4974]. Since his retirement he has continued his upper atmosphere research but has in recent years focussed much of his attention on Climate Change - its causes, impacts and how the church needs to respond. Graham has been a corresponding member of the Environmental Action Group since its inception in 2014.

On July 8, 2016 the US Navy showed that the sea ice close to the North Pole looks slushy and fractured into small pieces due to virtually continuous storms centred on the North Pole for some weeks.

The more pulverized sea ice becomes, the larger is the area of the ocean exposed to solar heating. As a result the sea surface temperature rises sufficiently to cause melting of the sea ice. Despite the melting of the sea ice, sea surface temperatures remain close to zero degrees C, since the extra energy will first go into melting the ice. Melting of the ice absorbs 8 times as much heat as it takes to warm up the same mass of water from zero to 10°C. Only after the ice has melted will the extra energy start raising the temperature of the deeper ocean.

Further, sea ice can reflect as much as 90% of the sunlight back into space. Once the ice has melted away, the water of the ocean reflects only 6% of the incoming solar radiation and absorbs the rest.

As the sea ice disappears, it is likely that storms will develop and push the remaining sea ice out of the Arctic Ocean. Strong storms can bring water vapour high up into the stratosphere, contributing to the formation of cirrus clouds that trap a lot of heat that would otherwise be radiated away, from Earth into space.

Another consequence of the Arctic Ocean getting warmer, is that heat will reach hydrates at the seafloor, with the possibility that this will trigger release of huge amounts of methane. While methane doesn’t linger as long in the atmosphere as carbon dioxide, it is 80 times more potent than carbon dioxide as a greenhouse gas.

The following graph show the variation of the global and high northern latitude temperature anomaly for the past.

A distinctive feature of the plot is the increase in the annual temperatures during the last 80 years, and also the more rapid temperature increase of high northern latitude since about 2000. Our particular interest is the right-hand edge of the plot which terminates with data for 2015. Below is a plot which includes temperature anomalies for June 2016.

Recent changes in the Arctic sea ice

The graphic below shows a sequential plot of the January and June air temperature in the Arctic. The red arrow indicates that the June 2016 value of the temperature anomaly is 2.5 deg C greater than the January value.

Further, the extent of the ice sheet has been decreasing for the past 40 years as is shown below.

Further, the extent of the ice sheet has been decreasing for the past 40 years as is shown below.

On 19 July 2016 the National Snow and Ice Data Center announced that the June sea ice extent for the Arctic Ocean averaged 10.6 million square km. It was the fifth time in six months that the shrinking sea ice had reached a new record low.

For Quick Facts on Arctic Sea Ice, Click here

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