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Data collated by the University of Illinois shows that the anomaly in the extent of Antarctic sea ice hit a new record high on 29 June 2014.

Click to enlarge. Here is the Antarctic sea ice anomaly graph released by the University of Illinois on 29 June 2014. The latest version of this graph can be found on our Polar page. Courtesy: University of Illinois.

Click to enlarge. here is the 28 June 2014 sea ice extent graph from the US National Snow and Ice Data Center. This shows the extent of Antarctic sea ice is more than two standard deviations above the long term average – that is, it is statistically significant. You can see the most up to date version on our Polar page. Courtesy: NSIDC.

Sea ice extent in the Antarctic reached a record level in June with an anomaly of some 2.074 million square kilometers above the long term average, according to data published by the University of Illinois Polar Research Group (see top right).

This is statistically significant as the latest data published by the US National Snow and Ice Data Center (NSIDC) shows that sea ice extent in June is more than two standard deviations above the long term average for the period from 1981 to 2010, and has been since April (see bottom right).

The extent of sea ice around the Antarctic has been growing steadily at a rate of around 2.6 per cent per decade, according to NSIDC data. This contrasts with the long term decline in Arctic sea ice. The mystery of increasing Antarctic sea ice during an era of record high global surface temperatures has puzzled climate scientists.

There are some suggestions from computer model research and evidence from satellite tracking of ice that Antarctic sea ice growth in recent years may be due to wind intensification and ocean circulation changes.

A paper published in Nature Geoscience by Paul Holland of the British Antarctic Survey and Ron Kwok of the Jet Propulsion Laboratory of the California Institute of Technology presented satellite tracking evidence that “reveals large and statistically significant trends in Antarctic ice drift, which, in most sectors, can be linked to local winds”. Jinlun Zhang of the University of Washington has used computer models to study the interaction between wind and ice and in a recent paper he concludes that changes in winds are resulting in both more compaction within the ice pack and more ridging, causing a thickening of the pack and making it more resistant to summer melt. In simple terms, wind drives ice out to sea, creating open water near the ice-edge that is more likely to freeze.

But this explanation is far from proven and it is clear that climate scientists can not completely explain what is happening in the Antarctic as the IPCC admitted recently in its latest scientific report published in September when it stated that there is “low confidence in the scientific understanding of the observed increase in Antarctic sea ice extent since 1979”. The IPCC explained that “the shortness of the observed record and differences in simulated and observed variability preclude an assessment of whether or not the observed increase since 1979 is inconsistent with internal variability”.

Source

University of Illinois here.  NSIDC here.

See Zhang’s paper here and Holland and Kwok’s paper here.

See

Our Polar page here and our stories here and here.

The solar desalination demonstration site at Mildura’s Eco Village is using the sun’s power to purify storm water for a community garden. (Russell Murphy, Mildura Council – Mildura Council )

Water is a scarce commodity throughout the world, but for those living in a semi-arid region like Mildura, its accessibility is all the more of an issue.

“It’s really important for industry to realise that there are other ways to come up with fresh water,” says Colin Straub, the president of the Sunraysia Sustainability Network.

Mr Straub is behind Mildura’s Eco Village, a demonstration site for sustainable living.

“Industry, and even householders generate water that is wasted after use, but with this system we can demonstrate that it can be recycled quite simply with a solar system, without a huge amount of cost,” he says.

The system he’s talking about uses solar panels to purify storm water captured at the Mildura landfill, water which is then purified through a desalination unit.

“It’s actually above drinking water quality,” he says.

Let it rain, let it rain

Stuart Eastaugh is the marketing manager for the company who built the system.

“It’s exactly how rain is made,” says Mr Eastaugh.

“The feed water runs through the top of the system; as it runs down over the solar element a percentage of it evaporates and condenses.

“So when it goes from liquid, to gas, back to liquid, you end up with pure water.”

The technology uses multiple modular solar panels, which are connected together to produce large quantities of distilled water from a single source, whether it be seawater, groundwater or contaminated dam water.

There is no power source, other than solar radiation, meaning water is supplied to the system through a pump when the sun comes out.

“It has no running costs, it has minimal maintenance costs and it’s sustainable.” he says.

Decentralising the water supply

This solar purification system will be used to irrigate the community garden in Mildura’s Eco Village, but the Australian company behind it is rolling out projects around the world in places where water is scarce, from Botswana to Bangladesh.

Other projects have been rolled out in Aboriginal communities around the Top End, and Ceduna Council in South Australia has just contracted the company to provide half the town’s drinking water from the sea.

Mr Eastaugh says the system allows for water supplies to be decentralised throughout the world.

“You can have one unit per household, or smaller water farms in a decentralised system to produce water for villages or for small towns.”

The technology to do this has been around for hundreds, if not thousands of years, when a glasshouse would use the power of the sun to distill water in a deep basin underneath.

But it’s only recent technological advances that have made it cost effective for households and businesses.

“In those days there was a huge capital cost, low production and high maintenance,” says Mr Eastaugh.

“We’ve now got a modular panel, which is a flow-through system, so we’re going back to low capital costs and high efficiency.”

The hottest regions of the tropical oceans were one to two degrees Celsius warmer than today during a period of warmth in the Pliocene epoch, three to five million years ago even though CO2 levels were similar, reports a paper published online in Nature Geoscience. This finding opposes previous suggestions that Pliocene tropical ocean temperatures were similar to today even though average global temperatures were three to four degrees higher. Researchers reconstructed the sea surface temperature history of parts of the tropical Indo-Pacific and Atlantic warm pools, using three indicators of past temperature recovered from marine sediments. They found that in the Pliocene, sea surface temperatures in these regions were warmer than today as would be expected in the warmer atmosphere.

Click to enlarge. Scanning electron microscopy (SEM) image of the fossilised shell of planktic foraminifer Globigerinoides ruber. Planktic foraminifera are a highly abundant group of unicellular calcifiers that live in surface or near-surface waters of the open ocean. Courtesy: Richard Abell

Higher concentrations of carbon dioxide (CO2) in the atmosphere cause warming not only at high latitudes but also across tropical regions, according to new research by scientists at the University of Bristol’s Cabot Institute and their collaborators.

The impact of the greenhouse gas CO2 on the Earth’s temperature is well established by climate models and temperature records over the past 100 years, as well as coupled records of carbon dioxide concentration and temperature throughout Earth history.  However, past temperature records have suggested that warming is largely confined to mid-to-high latitudes, especially the poles, whereas tropical temperatures appear to be relatively stable: the tropical thermostat model.

The new results, published in Nature Geoscience, contradict those previous studies and indicate that tropical sea surface temperatures were warmer during the early-to-mid Pliocene, an interval spanning about 5 to 3 million years ago. In an accompanying News and Views article in the journal, Mark Pagani,director of the Yale Climate & Energy Institute, writes that “we are now left to explain an even warmer Pliocene world than previously assumed, even though that world was bathed in atmospheric CO2 concentrations very similar to today.”

The Pliocene is of particular interest because CO2 concentrations then were thought to have been about 400 parts per million, the highest level of the past 5 million years but a level that was reached for the first time last summer due to human activity.  The higher CO2 levels of the Pliocene have long been associated with a warmer world, but evidence from tropical regions suggested relatively stable temperatures.

Project leader and Director of the Cabot Institute, Professor Richard Pancost said: “These results confirm what climate models have long predicted – that although greenhouse gases cause greater warming at the poles they also cause warming in the tropics.  Such findings indicate that few places on Earth will be immune to global warming and that the tropics will likely experience associated climate impacts, such as increased tropical storm intensity.”

The scientists focussed their attention on the South China Sea which is at the fringe of a vast warm body of water, the West Pacific Warm Pool (WPWP).  Some of the most useful temperature proxies are insensitive to temperature change in the heart of the WPWP, which is already at the maximum temperature they can record.  By focussing on the South China Sea, the researchers were able to use a combination of geochemical records to reconstruct sea surface temperature in the past.  Not all of the records agree, however, and the researchers argue that certain tools used for reconstructing past ocean temperatures should be re-evaluated.

The paper’s first author, Charlotte O’Brien added: “It’s challenging to reconstruct the temperatures of the ocean many millions of years ago, and each of the tools we use has its own set of limitations.  That is why we have used a combination of approaches in this investigation.  We have shown that two different approaches agree – but a third approach agrees only if we make some assumptions about how the magnesium and calcium content of seawater has changed over the past 5 million years.  That is an assumption that now needs to be tested.”

The work was funded by the UK’s Natural Environment Research Council and is ongoing.

Dr Gavin Foster at the University of Southampton is particularly interested in coupling the temperature records with improved estimates of Pliocene carbon dioxide levels.  He said: “Just as we continue to challenge our temperature reconstructions we must challenge the corresponding carbon dioxide estimates.  Together, they will help us truly understand the natural sensitivity of the Earth system and provide a better framework for predicting future climate change.”

Abstract

The western warm pools of the Atlantic and Pacific oceans are a critical source of heat and moisture for the tropical climate system. Over the past five million years, global mean temperatures have cooled by 3–4 °C. Yet, present reconstructions of sea surface temperatures indicate that temperature in the warm pools has remained stable during this time. This stability has been used to suggest that tropical sea surface temperatures are controlled by a thermostat-like mechanism that maintained consistent temperatures. Here we reconstruct sea surface temperatures in the South China Sea, Caribbean Sea and western equatorial Pacific Ocean for the past five million years, using a combination of the Mg/Ca-, TEX₈₆^H and U₃₇^k’ surface-temperature proxies. Our data indicate that during the period of Pliocene warmth from about 5 to 2.6 million years ago, the western Pacific and western Atlantic warm pools were about 2 °C warmer than today. We suggest that the apparent lack of warmth seen in the previous reconstructions was an artefact of low seawater Mg/Ca ratios in the Pliocene oceans. Taking this bias into account, our data indicate that tropical sea surface temperatures did change in conjunction with global mean temperatures. We therefore conclude that the temperature of the warm pools of the equatorial oceans during the Pliocene was not limited by a thermostat-like mechanism.

Citation

‘High sea surface temperatures in tropical warm pools during the Pliocene’ by Charlotte L. O’Brien, Gavin L. Foster, Miguel A. Martínez-Botí, Richard Abell, James W. B. Rae and Richard D. Pancost in Nature Geoscience

Read the abstract and get the paper here.

Source

News release issued by the university of Bristol here.

• Oliver Milman
• theguardian.com, Friday 2 August 2013 18.24 AEST

Australia faces significant challenges in responding to the effects of climate change, a number of reports have found. Photograph: Christopher Furlong/Getty Images