Fact check: Rupert Murdoch misleading on North and South Poles

Updated

Australia should approach climate change with great scepticism, News Corp executive chairman Rupert Murdoch says.

In a recent interview with Paul Kelly from The Australian newspaper, Mr Murdoch said climate change has been happening for as long as the planet has been here, and "there will always be a little bit of it".

To illustrate his point, he said: "At the moment the North Pole is melting a bit, but the South Pole is getting bigger".

ABC Fact Check investigates what is happening in the two polar regions.

The claim: Rupert Murdoch says the North Pole is melting "a bit" but the South Pole is getting bigger.

Rupert Murdoch says the North Pole is melting "a bit" but the South Pole is getting bigger. The verdict: Antarctic sea ice is increasing, but the Antarctic ice sheet is decreasing. In the Arctic, both sea ice and the Greenland ice sheet are decreasing significantly.

Ice in the Arctic and Antarctica

Fact Check assumes when Mr Murdoch says the North and South Pole he is referring to ice in the Arctic and Antarctica.

An expert in Antarctica, Dr Guy Williams from the University of Tasmania, says when making comparisons between the North and South Poles the single most important thing to consider is that the Arctic is an ocean, while Antarctica is a continent. The nearest land mass to the Arctic Ocean is Greenland.

Both polar regions contain two types of ice - ice sheets and sea ice.

An ice sheet is a mass of glacial land ice. It forms in areas where winter snow does not melt entirely over summer.

A March 2014 report by the Antarctic Climate & Ecosystems Cooperative Research Centre, supported by the Australian Government, says sea ice is frozen sea water that forms when the surface of the ocean cools to the point of freezing. As its density is less than that of seawater, sea ice floats on the ocean surface.

Greenland and Antarctic ice sheets

There are two major ice sheets at either end of the globe, with the Antarctic ice sheet dwarfing the Greenland ice sheet found in the Arctic circle. Formed by the gradual build-up of unmelted snow over thousands of years, the sheets are hundreds to thousands of metres thick.

Dr Paul Holland, an ocean modeller with the British Antarctic Survey, a Cambridge environmental research centre supported by public money, told Fact Check that Antarctic ice sheet volume is decreasing. Observational studies show decreases of about about 70 cubic kilometres per year, he says. Observational results show the Greenland ice sheet is also decreasing, losing about 140 cubic kilometres per year, he says.

Dr Williams agrees that the Greenland ice sheet is losing mass and is expected to melt faster and earlier than the Antarctic ice sheet.

Why are the ice sheets melting?

A report by the Intergovernmental Panel on Climate Change, Climate Change 2013: The physical science basis, says the reasons for the changes to the ice sheets are not clear, particularly in Antarctica.

"Attribution of change is difficult as ice sheet and glacier changes are local and ice sheet processes are not generally well represented in climate models," the report says.

It cites research that attributes increased runoff and melt of the Greenland ice sheet since 1990 to global warming and concludes that it is likely that human activity has contributed to the surface melting of Greenland since 1993.

On Antarctica it says: "An analysis of observations underneath a floating ice shelf off West Antarctica shows that ocean warming and more transport of heat by ocean circulation are largely responsible for increasing melt rates."

But it concludes that "owing to a low level of scientific understanding there is low confidence in attributing the causes of the observed loss of mass from the Antarctic ice sheet since 1993".

Both ice sheets are a source of fresh water to the ocean and are important contributors to sea level rise, it says.

Sea ice in the Arctic Sea and around Antarctica

If both the Greenland and Antarctic ice sheets are decreasing, where does that leave Mr Murdoch's claim that the South Pole is getting bigger?

Professor Ted Scambos from the National Snow & Ice Data Centre at the University of Colorado told Fact Check that the only way Mr Murdoch's statement makes sense is to focus solely on seasonal sea ice in the Southern Ocean.

"The data is quite clear that Antarctica's sea ice has grown, and the trend is now greater than the variation from year to year for the past few decades," Professor Scambos said. "There is some data, however, that suggests that prior to the 1970s Antarctica's sea ice was more erratic, and that we may not fully understand how it varies yet."

The data comes from a number of satellite sensors monitoring the sea ice extent, and is well verified by ship reports and aerial photographs, he said. "However, evidence is also strong that the Antarctic ice sheet is shrinking, due primarily to ocean and air current shifts."

The Antarctic Climate & Ecosystems CRC report says changes in Antarctica's sea ice coverage over the course of the seasons is "one of the biggest natural changes on Earth". In winter, sea ice covers about 19 million square kilometres of the ocean around Antarctica, while in summer the sea ice shrinks to around 3 million square kilometres.

Professor Scambos's comments are supported by a report by NASA which says in September 2013 the ice in the sea surrounding Antarctica reached its annual winter maximum and set a new record.

At the other end of the globe, the picture couldn't be more different, with sea ice dramatically decreasing.

The IPCC report cites a 2011 analysis estimating that three quarters of summer Arctic sea ice volume has been lost since the 1980s. It says other research shows the rate of decline increased "considerably" in the decade to 2011.

Dr Holland told Fact Check the best "modelled" estimate is that Arctic sea ice volume is losing about 500-1,000 cubic kilometres per year, while Antarctic sea ice volume is increasing by about 30 cubic kilometres per year.

A September 2013 report from The University of Washington says: "The sea ice uptick in Antarctica is small compared with the amount being lost in the Arctic, meaning there is an overall decrease in sea ice worldwide."

What is causing growth in the Antarctic sea ice?

There are a number of competing theories for why Antarctic sea ice is growing. Dr Williams says the lead "suspect" is the winds.

The Antarctic Climate and Ecosystems CRC's report cites a recent satellite-based study that similarly concludes that winds are "a dominant driver" of change. It also says: "A number of hypotheses have been proposed; all suggest that the response of Antarctic sea ice to climate change (and variability) is far from simple."

It says other studies have proposed that changes in atmospheric temperature, wind stress or precipitation are responsible, or that the melting ice sheet has been leading to the formation of a fresh layer of cool water on the surface of the ocean that freezes easily.

The hypothesis of a link between the melting ice sheet and the increase in sea ice is also raised in the IPCC report.

But it concludes "there is low confidence in the scientific understanding of the observed increase in Antarctic sea ice extent since 1979", partly due to competing scientific explanations for the causes of change.

Dr Holland agrees that the ultimate cause of these sea ice changes is still the subject of active research, with many competing hypotheses.

On the question of whether man-made climate change is the cause, he says: "Human-caused climate change is superimposed upon natural climate variability. It is not known whether either the Antarctic sea ice increase or the Antarctic ice sheet decrease are natural or human-caused."

The verdict

Antarctic sea ice is increasing, but the Antarctic ice sheet is decreasing.

In the Arctic, both sea ice and the Greenland ice sheet are decreasing significantly.

Mr Murdoch's statement is misleading.

Sources

Topics: environment, climate-change, antarctica, australia

First posted