Natural Environment Blog

Scientists have made a breakthrough in determining what actually causes ice shelves in the Antarctic and Greenland to break apart, resulting in icebergs and contributing to increased sea levels.

The findings, reported in the latest edition of the Science journal, could lead to improved climate change models, as scientists will now be able to predict more accurately where icebergs will “calve off” from their parent ice shelves.

Scientists have discovered the main factor to cause ice to calve away from ice sheets, creating icebergs, and resulting in higher sea levels. Photo: Kim Hansen.

The term “calving” in this context, refers to ice breaking off the ice shelves and landing in the ocean, causing icebergs to form. Typically, a shelf front will extend forward for years or decades between major calving events. 

Until now, the main problem for scientists was determining where an ice shelf was to calve. At what point does an ice shelf have so much ice hanging over the ocean that it starts to break off?

What made this a particularly difficult question was that, there didn’t seem to be a common size between ice shelves. For example, the Ross Ice Shelf in Antarctica hangs over the ocean for as much as 500 miles. Other ice shelves only extend for a mile or two before breaking up.

The Need For A Law For Ice Shelf Calving

To date there hasn’t been a law based on physical principles that explains ice shelf calving.

“To predict the future of the ice sheet and to understand the past, we have to put the information into a computer,” says Richard B. Alley, the Evan Pugh professor of geosciences. “The models we have do not currently have any way to figure out where the big ice sheets end and where the ice calves off to form icebergs.”

Because of this, the scientists searched for the most important variable that determines where an ice shelf will break off into the ocean - not an easy task according to professor Alley. 

“Fracture-mechanics problems are invariably difficult,” he says.

“Earthquake prediction comes to mind, or guessing whether a tea cup pushed off the table will break or bounce upon hitting the floor. With the tea cup, a drop from 1 mm high won’t break it, and a drop from 100 m almost surely will — one term, the height of the drop, explains a whole lot of the behavior.” he added.

“Our hope was to find such a dominant term in calving of bergs from ice shelves.” 

Simple Law for Ice Shelf Calving

The scientists believe they have found a dominant term that can be used to forecast ice shelf calving.

In the tea cup example, the height of the tea cup was the dominant term. With ice shelves, the scientists found that the spreading tendency in the direction of ice and berg motion was the dominant term.

The equation is the rate of spreading times the width of the shelf times thickness multiplied by a constant.

In other words, it is the rate at which ice shelves spread that is the most important variable that determines when an ice shelve is about to calve.

“The spreading rate can be calculated from ice thickness and a few other things that are already solved for in numerical models, so we have provided a practicable calving law,” said Alley. “At present, models rarely if ever calculate physically where the ice ends, instead stopping the model before the ice ends or using some other relation that is not fully physical.” 

Global Warming

Armed with this knowledge, scientists will be in a better position to forecast the impact of global warming on sea levels.

Computer models will be able to use this information to better predict how ice sheets will behave in warmer temperatures.

Scientists recently predicted that sea temperatures would rise by over a meter by the end of this century.

Census researchers from New Zealand hold giant Macroptychaster sea stars that can grow up to 60cm across. Photo: National Institute of Water and Atmospheric Research, New Zealand, 2007.

Scientists are well on their way to releasing the world’s first Census of Marine Life (CoML), with astonishing discoveries continuing to being made and more than 5,300 new species found since 2003.

In fact, new species are being discovered faster than they can be described and named.

Discoveries aren’t just limited to new species though. Many of the surprising discoveries are related to distribution and abundance of known marine species throughout the world. 

Highlights of the discoveries will be officially released at the World Conference on Marine Biodiversity being held in Spain this week. The conference, organized by the Census’s European affiliate program on Marine Biodiversity and Ecosystem Functioning, will take place in Valencia between 11th and 15th of November.

In the meantime, the CoML fourth highlights report outlines some of the major discoveries.

Highlights

There are many highlights outlined in the report. Some of the major ones include:

A male sea spider carries its eggs on specially adapted appendages under its body; it is one of many possible new species from the Antarctic. Census researchers are trying to understand the evolutionary history of these curious animals. Photo: Cédric d’Udekem, Royal Belgium Institute for Natural Sciences 2007.

• “White Shark Café” - Scientists have discovered previously unknown behavior of white sharks travelling long distances to the Pacific each winter. During this time, the sharks will make frequent, repetitive dives to depths of 300 meters. While researchers are unsure of the reason, they suspect that it may have something to do with feeding or reproduction.
• Giant amphipod - During an expedition to the Antarctic, scientists discovered one of Antarctica’s biggest-ever amphipod crustaceans, measuring almost 10 centimeters long. The CAML scientists also found around 1,000 other species, including eighteen potentially new species. The discovery was made possible due to the collapse of the Larsen A and B ice shelves, which allowed the scientists to explore a 10,000 kilometer section of the Antarctic Weddell Sea.
• High percentage of new species - An Australian expedition - COMARGE “Voyages of Discovery” - resulted in a very high discovery rate of new species. Of the 524 Decapoda (crabs, shrimps, prawns, lobsters, etc) species found, 33 percent are thought to be new species. Furthermore, 25 percent are records in the region, and eight percent are records for Australia. 
• Giant oysters - The COMARGE explorers discovered dense communities of gigantic oysters. The oysters, thought to be a new species, are 20 cm long and reside at a depth of 700 meters.
• World’s deepest known active hot vent - ChEss scientists in the Mid-Atlantic Ridge explored the world’s deepest known active hot vent, field named Ashadze. The hot vent is over 4,100 meters deep, dominated by anemones, polychaete worms and shrimp.

Juvenile representatives of the Antarctic and deep-sea genera of octopuses. Clockwise from top left , (1) Pareledone charcoti, a shallow-water species from the Antarctica Peninsula, (2) Thaumeledone gunteri, a deep-water species endemic to South Georgia, (3) Adelieledone polymoprha, a species endemic to the western Antarctic, (4) Megaleledone setebos, a shallow-water circum-Antarctic species endemic to the Southern Ocean. Photo credit: I. Everson (T. gunteri), M. Rauschert (M. setebos), L. Allcock (P. charcoti. A, polymorpha).

Good Progress

A brightly colored comb jelly swims in the high Arctic waters of the Canada Basin. Photo: Kevin Raskoff, Monterey Peninsula College.

Scientists involved in the project appear to be happy with the progress so far.

“Not only do we have a better picture of the distribution of the animals that stay in place, we are approaching a global picture of the movements of animals, whether swirling in eddies the size of Ireland, or commuting 8,000 kilometers across ocean basins,” said Ron O’Dor Canadian squid expert and Census co-senior scientist.

“And understanding how behavior and the environment combine to determine the movement of many animals is within reach.” he continued.

French deep-sea explorer and vice-chair of the Census, Myriam Sibuet (France) said “The impressive number of landmark findings over the past two years reveals the richness of what remains to be discovered.  The vastness of the ocean and our new research tools keep marine biology forever young.”

About Census of Marine Life

The Census of Marine Life (CoML) is a 10-year scientific initiative to assess and explain life in the oceans. Including a global network of more than 2,000 researchers from 82 nations, the purpose of the initiative is to assess and explain the diversity, distribution, and abundance of marine life. The first consensus will be released in 2010.

The project was brought about by the fact that we still have relatively little knowledge about what lives in our oceans. To date, there isn’t a single list or database that contains all known marine species - let alone their distribution, and abundance. 

Scientists estimate that there could be more than a million marine species if all small animals and protists are included. To date, only about 230,000 species have been described and reside in jars in collections in museums of natural history and other repositories.

The 4th CoML highlights report will be officially released at the World Conference on Marine Biodiversity, Valencia, Spain, Nov. 11-15.

Antarctica has finally had it’s first passenger jet.

Last night, an Airbus A319 left Australia and landed in Antarctica at 3am. Passengers included Peter Garrett - Australia’s Environment Minister (also famous for his time as lead singer in Australian rock band Midnight Oil), 7 scientists, and 11 other passengers. The 7 scientists will remain in Antarctica to carry out research.

The flight was made possible because a suitable runway has only recently been completed. Wilkins Runway is 4 kilometers long, 500 meters deep, and took $46 million to complete. Wilkins Runway is approximately 70 kilometers from Casey Station.

Although tourists won’t be boarding any flights soon, the new runway enables quick access for scientists to Antarctica. It eliminates the need to travel for 2 weeks through the southern oceans. Australian Antarctic Division (AAD) hopes to make up to 20 flights to Antarctica per year. This will be a huge win for research in the Antarctica - especially in the area of climate change and global warming.

Peter said the project “It’s a remarkable engineering feat these people have achieved. It’s a logistical triumph and connects the last two continents to be linked by air“.

He also said “This is a very big occasion, it certainly is historic. A new era will unfold for us in terms of looking after our planet.“

There seems to be some conflicting reports on where the wettest place on earth is. Some say the wettest place on earth is in Hawaii. Others reckon it’s wetter somewhere in India. Either way, these places are wet!

What I mean by the “wettest place on earth” is the place that gets the most rain fall per year. So this automatically rules out Antarctica. Although over 90% of Antarctica is ice (i.e. frozen water), it hardly rains there. In fact it’s one of the driest places on earth!

Anyway, here’s a list of some of the wettest places on earth:

• Mount Wai-’ale-’ale, Kauai records an average of up to 13,000 millimeters of rain per year. Rain has been known to fall for up to 360 days per year!
  Mount Tutenendo, Colombia records up to 12,045 millimeters rain per year
• Lloro, Colombia has around 13,299 millimeters rain per year. Note that this rain fall is an estimated amount according to The National Climatic Data Center.
• Cherrapunji,north-eastern India gets an average rain fall of 10,820 millimeters per year. Note that most of this rain falls between June and August (known as the ’south-west monsoon’, or wet season).
• Mawsynram, India has been quoted by the American National Climatic Data Center as having an annual average rainfall of 11,871 millimeters . BBC Weather has quoted 11,877 millimeters . Note that Mawsynram is not far from Cherrapunji.
• Milford Sound in New Zealand gets an average of between 7,000 millimeters and 9,000 millimeters of rain each year. Also, Franz Josef Glacier is not far behind Milford Sound as far as rainfall goes. And I should know - I’ve experienced over 400 millimeters of it over night while sleeping in a tent there!

So, take your pick. If you’re looking for rain, any of these places should be able to deliver

So now that we’ve established where the hottest place on earth is, let’s look for the coldest place on earth.

According to records, the coldest place on earth is Antarctica. Antarctica’s average temperature is 75 degrees Fahrenheit (60 degrees Celsius).

But that’s just the average temperature. What about the coldest temperature? On July 21, 1983, at the Russian base “Vostok”, the temperature was measured at -129 degrees Fahrenheit (-89 degrees Celsius).

As well as being the coldest place on earth, Antarctica is also one of the driest places on earth and is technically a desert. Not to be outdone, it is also the wettest place on earth (if that makes any sense!). It’s the wettest place on earth because over 90 percent is covered in ice (which, as you’re probably aware, is frozen water).

Because Antarctica is so cold, the only humans to go there usually only visit for a short time. Penguins are happy to stay there though!

If you ever wondered where the hottest place on earth is, try this.

• On 13 September 1922, Al ‘Aziziyah in Libya reached an amazing 57.7 degrees Celsius (that’s 135.9 Fahrenheit!). Libya is a country in the northern part of the African continent.
• Death Valley, California, U.S.A is not far behind - with a temperature of 56.7 degrees Celsius (134.0 degrees Fahrenheit) recorded on 10 July, 1913.

Hottest places in other continents include:

• Asia’s hottest place is Tirat Tzvi, Israel (then part of the British Mandate of Palestine) at 53.9 degrees Celsius (129 degrees Fahrenheit) recorded on 21 June 1942.
• Oodnadatta in South Australia is Australia’s hottest place with 50.7 degrees Celsius (123.3 degrees Fahrenheit) recorded on 2 January 1960.
• Hottest place in Europe was Seville, Sevilla (province), Spain with 50.0 degrees Celsius (122 degrees Fahrenheit) on 4 August 1881
• Rivadavia, Argentina recorded 48.9 degrees Celsius (120 degrees Fahrenheit) on 11 December 1905
• Awatere Valley and Rangiora, New Zealand was Oceania’s hottest place with 42.4 degrees Celsius (108.3 degrees Fahrenheit) on 7 February 1973
• And if you ever wondered how hot it gets in antarctica, try 14.6 degrees Celsius (58.3 degrees Fahrenheit) at Vanda Station on 5 January 1974

It’s interesting that with the recent urgency of global warming, that there isn’t a more recent record. In reality, there are probably hotter temperatures around the world occurring on a regular basis, it’s just that we aren’t there to record it.

OK, the term “global warming” refers to the whole world heating up. But, the world isn’t just heating up at the same rate all over. Some parts are heating up at a greater rate than others.

The Arctic is being hit the hardest - it’s heating up at up to 3 times the rate of other parts of the world! The Arctic has increased in temperature by 2.7 degrees fahrenheit (1.5 degrees Celsius) over the last 30 years.

Interestingly, according to this heat chart of 2005, some parts of Africa are heating up at a similar rate to the Arctic. Note that this chart is showing the rate of the change in temperature - not the actual temperature.