NASA MODIS: The Shrinking of the Aral Sea 2001 - 2014

The Aral Sea in 2001

Although irrigation made the desert bloom, it devastated the Aral Sea.

This series of images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite documents the changes.

At the start of the series in 2000, the lake was already a fraction of its 1960 extent (black line).

The Northern Aral Sea (sometimes called the Small Aral Sea) had separated from the Southern (Large) Aral Sea.

The Southern Aral Sea had split into eastern and western lobes that remained tenuously connected at both ends.

The Aral Sea in 2014

Read the full story and view the full series of images taken by MODIS from 2001 to 2014, here.

Jupiter's Great Red Spot is shrinking

In this comparison image the photo at the top was taken by Hubble's Wide Field Planetary Camera 2 in 1995 and shows the spot at a diameter of just under 21 000km; the second down shows a 2009 WFC3 photo of the spot at a diameter of just under 18 000km; and the lowest shows the newest image from WFC3 taken in 2014 with the spot at its smallest yet, with diameter of just 16 000km. 

Image courtesy NASA, ESA, and A. Simon (Goddard Space Flight Center). 

Jupiter's Great Red Spot is a churning anticyclonic storm. It shows up in images of the giant planet as a conspicuous deep red eye embedded in swirling layers of pale yellow, orange and white. Winds inside this Jovian storm rage at immense speeds, reaching several hundreds of kilometres per hour.

Historic observations as far back as the late 1800s gauged this turbulent spot to span about 41 000 kilometres at its widest point - wide enough to fit three Earths comfortably side by side. In 1979 and 1980 the NASA Voyager fly-bys measured the spot at a shrunken 23 335 kilometres across. Now, Hubble has spied this feature to be smaller than ever before.

"Recent Hubble Space Telescope observations confirm that the spot is now just under 16 500 kilometres across, the smallest diameter we've ever measured," said Amy Simon of NASA's Goddard Space Flight Center in Maryland, USA.

Amateur observations starting in 2012 revealed a noticeable increase in the spot's shrinkage rate. The spot's "waistline" is getting smaller by just under 1000 kilometres per year. The cause of this shrinkage is not yet known.

"In our new observations it is apparent that very small eddies are feeding into the storm," said Simon. "We hypothesised that these may be responsible for the accelerated change by altering the internal dynamics of the Great Red Spot."

Simon's team plan to study the motions of these eddies, and also the internal dynamics of the spot, to determine how the stormy vortex is fed with or sapped of momentum.

New Zealand's Southern Alps glaciers reducing rapidly

Hochstetter Icefall feeding the retreating Tasman Glacier in the Southern Alps of New Zealand's Southern Island.

Credit: Dr. Huw Horgan

Historic records show Franz Josef Glacier retreated three kilometres in the last century and mathematical modeling indicates it is likely to retreat even more this century.

Other glaciers in the region, including Fox Glacier, are declining at similar rates as a result of climatic change says Dr Brian Anderson, a senior research fellow at the Antarctic Research Centre, who is supported by a Marsden Fast Start research grant.

Dr Anderson says mathematical modelling helps him, and other researchers in the team, understand how glaciers have evolved since the last ice age.

It also helps them analyse what is occurring now and predict how many glaciers in the Southern Alps will fare in the future.

Brian Anderson

"It's important to see the long term picture to really understand what's going on. That's because many of our glaciers—Fox and Franz Josef particularly—change so quickly and, apparently, so erratically.

"In the 12 years we've been carrying out this study, we've seen them rapidly retreat and then rapidly advance."

"It's not until we look back over the past century that we see an overall pattern of retreat emerging," says Dr Anderson.

"Looking ahead, we are likely to see warmer and wetter weather, which means Franz Josef and Fox glaciers will retreat a lot—our best estimate is that they will be seven or eight kilometres shorter than present by 2100."

The research findings are being collated and published as part of the Antarctic Research Centre's glacier monitoring project which also involves Dr Ruzica Dadic, Dr Huw Horgan and Associate Professor Andrew Mackintosh.

Together, the researchers are observing and measuring three glaciers—the well-known Franz Josef and Tasman glaciers and the lesser-known Brewster Glacier.

Nicolas Cullen

Other collaborators on the Brewster Glacier project are Dr Nicolas Cullen at the University of Otago and Dr Andrew Lorrey at NIWA.

The data gathered is contributing to the University of Zurich's World Glacier Monitoring Service.

Dr Anderson says: "Already we are seeing issues at Franz Josef Glacier, where walking access has not been possible for more than a year, and tourists are now being flown onto the ice."

"These are the kinds of things being predicted to happen around the world as glaciers decline and temperatures continue to warm," he says.

Earlier this year, Dr Anderson says a 70-metre chunk of ice broke off the terminal face of Tasman glacier, releasing an estimated seven million cubic metres of ice into Tasman Lake.

"Tasman is undergoing rapid decline right now, with large chunks breaking off and falling into Tasman Lake.

We are using time-lapse photography to capture these 'calving' events as they happen and gather valuable information on ice loss and glacier behaviour at the same time."