Global warming is now slowing down the circulation of the oceans — with potentially dire consequences

The Atlantic circulation (AMOC) as part of the global overturning circulation of the oceans

in an animation from NASA, showing what happens globally to create the large, slow current called the thermohaline circulation.

From Washington Post by Chris Mooney 

Welcome to this week’s installment of “Don’t Mess with Geophysics.”
Last week, we learned about the possible destabilization of the Totten Glacier of East Antarctica, which could unleash over 11 feet of sea level rise in coming centuries.

And now this week brings news of another potential mega-scale perturbation.
According to a new study just out in Nature Climate Change by Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research and a group of co-authors, we’re now seeing a slowdown of the great ocean circulation that, among other planetary roles, helps to partly drive the Gulf Stream off the U.S. east coast.
The consequences could be dire – including significant extra sea level rise for coastal cities like New York and Boston.

 The Gulf Stream system is one of Earth's most important heat transport systems.

Now, though, scientists have found evidence for a slowdown of this system, which could have major implications for climate.

(Photo : Gulf of Mexico, NASA/GSFC/Aqua MODIS)

A vast, powerful, and warm current, the Gulf Stream transports more water than “all the world’s rivers combined,” according to the National Oceanic and Atmospheric Administration.
But it’s just one part of a larger regional ocean conveyor system – scientists technically call it the “Atlantic meridional overturning circulation” — which, in turn, is just one part of the larger global “thermohaline” circulation (“thermohaline” conjoins terms meaning “temperature” and “salty”).
For the whole system, a key driver occurs in the North Atlantic ocean.
Here, the warm Gulf Stream flows northward into cooler waters and splits into what is called the North Atlantic Current.
This stream flows still further toward northern latitudes — until it reaches points where colder, salty water sinks due to its greater density, and then travels back southward at depth.

This “overturning circulation” plays a major role in the climate because it brings warm water northward, thereby helping to warm Europe’s climate, and also sends cold water back towards the tropics.
Here’s a helpful visualization, from Rahmstorf and the Potsdam Institute, of how it works:

 Graph of the Atlantic Meridional Overturning Circulation by Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research.

Red colors are surface currents, blue colors are below the surface. “NADW” stands for North Atlantic Deep Water.

And here’s a wonderful video from NASA that visualizes the thermohaline circulation for the entire globe. Rahmstorf also has a blog post up at RealClimate.org explaining his research.

The day after fiction

The system above has a key vulnerability.
What keeps everything churning in the North Atlantic is the fact that cold salt water is more dense than warm water — so it sinks.
However, if too much ice melts in the region — from, say Greenland — a freshening of the cold salt water could occur.
If the water is less salty it will also be less dense, reducing its tendency to sink below the surface.

This could slow or even eventually shut down the circulation.
In the scientifically panned 2004 blockbuster film “The Day After Tomorrow,” it is precisely such a shutdown that triggers a New Ice Age, and utter global disaster and chaos.
That’s not going to happen, say scientists.
Not remotely.
Nonetheless, the new research finds that global warming does indeed seem to be slowing down the circulation. And while hardly catastrophic, that can’t be good news.
Among the very real effects, notes the Potsdam Institute’s Rahmstorf, could be a possible increase in U.S. sea level if the whole circulation were to break down — which would be seriously bad news for cities like New York and Boston.

 As more and more fresh water is released into the ocean by melting glaciers, the Atlantic's most powerful current, the Gulf Stream, is likely to slow down even more

The study uses a reconstruction of sea surface temperatures in the North Atlantic to find that starting in around 1970 or 1975, the overturning circulation started to weaken — an event likely triggered by an unusual amount of sea ice traveling out of the Arctic ocean, melting, and causing freshening.
The circulation then started to recover in the 1990s, but  “it seems this was only a temporary recovery, and now it’s actually further weakened,” says Rahmstorf.

 Despite all the warming that’s taken place since 1970, one little blip of the North Atlantic (shown here in green) has begun to actually cool.

The hypothesized reason for further declines presented by the paper is that the massive Greenland ice sheet may now be losing enough freshwater due to melting to weaken the circulation.
And indeed, it appears that a particular ocean region of the North Atlantic south of Greenland and between Canada and Britain is becoming colder — an indicator of less northward heat transport.

Rahmstorf points to a recent release by the National Climatic Data Center of the National Oceanic and Atmospheric Administration, finding that the winter of December 2014 through February 2015 was the warmest on record for the globe as a whole.
However, there were several anomalies — not just a cold winter for the eastern U.S., but also record cold temperatures in the middle of the North Atlantic:

 According to the National Climatic Data Center, the world just saw its warmest winter ever…except for in one spot in the north Atlantic ocean (the deepest blue color above), which set a record for cold. Which is not good. (NCDC)

“These new NOAA data got me quite worried because they indicate that this partial recovery that we describe in the paper was only temporary, and the circulation is on the way down again,” says Rahmstorf.

So far, the study finds, we’re looking at a circulation that’s about 15 to 20 percent weaker.
That may not sound like much, but the paper suggests a weakening this strong has not happened at any time since the year 900. Moreover, this is already more weakening than scientifically expected — and could be the beginning of a further slowdown that could have great consequences.
The U.N.’s Intergovernmental Panel on Climate Change, in 2013, said it was “very likely” that the Atlantic overturning circulation would weaken over the course of this century, but gave a gigantic range of from 1 to 54 percent, with best estimates at 11 and 34 percent.
We’re already in that window, suggests the new study, and it’s only 2015.
So what would happen if the circulation weakens even more substantially or even shuts down?

Why the U.S. suffers from a Gulf Stream system slowdown

One thing that will not happen from a shutdown of the circulation is a sudden, dramatic freezing of Europe.
It will certainly cool, relative to a world in which the circulation remains robust — but that will be offset by rising average temperatures due to global warming, says Rahmstorf.
The “Day After Tomorrow” scenario will not come to pass.

However, there are many other effects, ranging from dramatic impacts on fisheries to, perhaps most troubling of all, the potential for extra sea level rise in the North Atlantic region.
That may sound surprising, but here’s how it works.
We’re starting out from a situation in which sea level is “anomalously low” off the U.S. east coast due to the motion of the Gulf Stream.
This is for at least two reasons.
First, explains Rahmstorf’s co-author Michael Mann of Penn State University, there’s the matter of temperature contrast: Waters to the right or east of the Gulf Stream, in the direction of Europe, are warmer than those on its left or west.
Warm water expands and takes up more area than denser cold water, so sea level is also higher to the right side of the current, and lower off our coast.
“So if you weaken the ‘Gulf Stream’ and weaken that temperature contrast…sea level off the U.S. east coast will actually rise!” explains Mann by e-mail.

But there’s another factor, too, involving what is called the “geostrophic balance of forces” in the ocean.
This gets wonky, but the bottom line result is that “sea surface slope perpendicular to any current flow, like the Gulf Stream, has a higher sea level on its right hand side, and the lower sea level on the left hand slide,” says Rahmstorf.
(This would only be true in the northern hemisphere; in the southern it would be the opposite.)

 Sea surface temperature anomaly on 20 March 2015.

Note that this is relative to a baseline 1979-2000, which is already a cold period in the subpolar Atlantic.

Source: Climate Reanalyzer.

We’re on the left hand side of the Gulf Stream.
So weaken the flow, and you also raise the sea level.
(For further explanation, see here and here.)
Indeed, researchers recently found a sudden, 4-inch sea level rise of the U.S. East Coast in 2009 and 2010, which they attributed to a slowdown of the Atlantic overturning circulation.
Rahmstorf says that “for a big breakdown of the circulation, [sea level rise] could amount to one meter, in addition to the global sea level rise that we’re expecting from global warming.”
Shutting down the circulation would also almost certainly have effects on global weather — changing around major planetary heat transport processes tends to do that — though scientists don’t know yet what those would look like.

So in sum: It appears that we’ve just seen yet another surprise from the climate system — and yet another process, like the melting of Antarctica, that seems to be happening faster than previously expected.
And indeed, much like with that  melting, the upshot if the trend continues is an especially bad sea level rise for the United States — the country more responsible than any other on Earth for the global warming that we’re currently experiencing.

Links :

• Climate Central : Atlantic Circulation Weaker Than In Last Thousand Years

Sophisticated unmanned submarines investigate two seafloor volcanoes

From GNS Science

New Zealand and American scientists will use one of the world’s most sophisticated unmanned submarine vehicles during the next three weeks to investigate two seafloor volcanoes in the Kermadec Arc, northeast of Bay of Plenty.

 Kermadec Ridge with the Marine GeoGarage

The project is a collaboration involving GNS Science, the Royal New Zealand Navy, and US-based Woods Hole Oceanographic Institution, which owns and operates the autonomous underwater vehicle Sentry.
The multi-purpose 18-day voyage, scheduled to leave Auckland on March 3, is built around a regular Navy supply trip to Raoul Island on HMNZS Wellington.
 This particular voyage will support GNS Science, the Department of Conservation, and the Meteorological Service.
Sentry - the autonomous underwater vehicle - will be deployed from the Royal New Zealand Navy patrol vessel for its day-long missions to skim over the seafloor and gather data.
The target seafloor volcanoes – Macauley Caldera and Giggenbach - are actively venting hot water and gases on the seafloor and are within 100km of Raoul Island.

Both volcanoes have been investigated by surface ships on previous voyages, but this will be the first time they have been explored extensively at close range.
Sentry will travel over the volcanic structures at walking speed and at a pre-determined height above the seafloor.
It will build detailed three-dimensional maps and measure up to 12 different chemical and physical parameters of the ocean and seabed.
It will return to the ship after each mission to download terabytes of data, have its batteries recharged, and to be programmed for its next deployment.
It is scheduled to make eight dives during the voyage, covering about 10 square kilometres of seafloor per dive.

Macauley Caldera and Giggenbach with the Marine GeoGarage

Project leader Cornel de Ronde said the voyage was part of a long-term GNS Science programme to build detailed maps and collect geological data, including hydrothermal venting, at about 30 major submarine volcanoes in the Kermadec Arc, which runs between Bay of Plenty and Tonga.
This will be Sentry’s second visit to New Zealand.
During a GNS Science-led voyage in 2011, it gathered detailed information on four submarine volcanoes northeast of White Island.
“Sentry is the ideal vehicle for obtaining comprehensive information and understanding on the seafloor and the environment around these submarine volcanoes,” said Dr de Ronde, a marine geologist at GNS Science.
“It provides the appropriate level of detail on the geology of the seafloor, the hydrothermal systems, deep-sea habitats, and the occurrence of mineral deposits.”

The project is part of a multi-year research programme by GNS Science to map and understand tracts of seafloor in New Zealand’s vast offshore territory.
New Zealand has sovereign rights over an area of seafloor totalling 5.7 million square kilometres.
This is equivalent to 14 times the size of California or 1 percent of the Earth’s surface.
This area is largely unmapped and unexplored.
The New Zealand landmass equates to just 4 percent of this submerged area – sometimes referred to as the continent of Zealandia.
GNS Science, with support from its international colleagues, has been systematically investigating the volcanic features of the Kermadec Arc since the late 1990s.

 Macauley caldera and sand waves, image created by Susan Merle of NOAA

Background: The free-swimming Sentry is arguably the world’s most sophisticated autonomous underwater vehicle for marine geology applications. Battery-powered and weighing 1.25 tonnes, it is capable of diving to 6000m and spending up to 45 hours under water per mission.
It has four pivoting wings with a propeller on each wing.
It can skim over seafloor terrain at any height and is equipped with about a dozen science and engineering sensors to measure physical and chemical parameters of the ocean and seafloor.
All sensor data is stored on the vehicle and retrieved on recovery.
Woods Hole Oceanographic Institution in the United States owns and operates Sentry.

 The free-swimming Sentry autonomous underwater vehicle will spend the next two weeks exploring submarine volcanoes near Raoul Island in the Kermadec Arc.

Sentry is a part of the National Deep Submergence Facility (NDSF) which is a joint venture involving the US National Science Foundation, the National Oceanic and Atmospheric Administration, and the Office of Naval Research. NDSF, which comprises manned, remote, and autonomous vehicles, is operated by Woods Hole Oceanographic Institution on behalf of the international scientific community.
There are dozens of submarine volcanoes between White Island and Tonga, and many have active hydrothermal vent systems which give rise to extensive seafloor mineral deposits.
The mission with Sentry will help to improve the understanding of the relationships between the hydrothermal venting, the mineral deposits, and the specially adapted marine life that thrives in the hot and chemically-rich environments around the volcanoes.

Macauley Caldera
Macauley Caldera is an oval-shaped submarine crater about 10km by 5km, or about the size of Wellington Harbour. It produced a major eruption about 2000 years ago.
The crater has steep walls and numerous sites are venting hydrothermal fluids.
Venting at one site in particular, a young cone that has grown up inside the crater, is extremely vigorous.
An unusual feature of Macauley are giant sand waves or seafloor undulations that extend outwards for many kilometres on the flanks of the caldera.
These features have been observed at only a handful of submarine volcanoes worldwide.
Sentry will dive inside the caldera to map it in detail and analyse the hydrothermal vents.
It will also study the giant sand wave formations with sonar to see if they are related to the eruption of 2000 years ago.
This will reveal their thickness and whether their structure is chaotic or layered.
A chaotic structure would suggest they were formed by a single large eruption and a layered structure would point to a much less violent formation process.

Giggenbach volcano
Giggenbach is a simple cone volcano similar in size and style to Mount Ngauruhoe.
It is located 800km northeast of the North Island and about 30km from Macauley Caldera.
It is shallower than most submarine volcanoes with its summit about 120m below the sea surface. During a 2005 expedition, scientists found diffuse hydrothermal venting around its summit.
However, the feature that sets Giggenbach apart is the huge volume of carbon dioxide discharging into the sea from one particular vent area.
Scientists know of only one other submarine volcano in the world – NW Eifuku volcano in the Mariana Arc – that is venting more carbon dioxide than Giggenbach.
On this voyage, scientists plan to further investigate the nature of its venting.

Links :

• Blog : http://submarinevolcanoes.blogspot.co.nz/
• YouTube : Exploring Kermadec Arc undersea volcanoes / Life on undersea volcanoes

North Sea Tigers Borgholm Dolphin big seas

Offshore worker, James Eaton, recorded video from the Lomond Platform
The Borgholm Dolphin installation is located 145 miles east of Aberdeen
Waves were the result of a severe storm over the North Sea on January 10

 

From DailyMail

It's enough to make you seasick.
As huge waves crashed against a swaying oil rig, one nearby worker managed to catch the entire harrowing ordeal on camera.
The Borgholm Dolphin installation was filmed amidst the massive swells that were a result of this severe storm.
The oil rig is stationed in the North Sea, about 145 miles east of Aberdeen.

Lomond platform with the Marine GeoGarage

Filmed by James Eaton, an offshore worker on the nearby Lomond Platform, the storm began on January 10, but had been known about for some time.
'The barge pulled off of the [The Borgholm Dolphin] due to upcoming weather on January 9,' James told MailOnline in an email.
'But one of our colleagues had to move over there.
'He is usually a bit delicate so we paid extra attention to the storm and how it would affect him.'

The Borgholm Dolphin (left) closed to the Lomond platform (right) in the Everest gasfield

The weather system was so strong that power was cut to approximately 140,000 properties in Northern Scotland at its worst.
'The storm lasted about two days with big seas,' the 48-year-old Control Room Technician, who has worked offshore for nine years, explained.
'It hasn't really left yet, but there were no injuries.
'We get a lot of storms this time of year, but never really have a vessel or a flotel near us to see how bad it is, so it's a bit unusual.'

Built in 1975, the Borgholm Dolphin is a platform that measures 108m × 61m.
A massive structure, it weighs almost 15,000 gross tonnes and is part of the larger Dolphin Drilling fleet, which also includes rigs off the coast of Norway.

'Tides of the century' in France

Storms and high tides in Saint-Malo (Brittany, France) from Easy Ride.
During Ulla, Dirk, Christine storms in Saint-Malo, February 2014

The bay of St Malo knows among the highest tides in the world.

The so-called "tide of the century" in fact happens every 18 years.
The moon alignment with the sun adds to the gravitational pull on the seas,

creating a high point in the 18-year lunar cycle.

From The Telegraph

Thousands of people gathered at Mont Saint-Michel in northern France on Saturday to watch what is being called "the high tide of the century".

The exceptionally high spring tide, swollen by a "supermoon" effect linked to the solar eclipse on Friday, was predicted to cut off the picturesque island from the mainland with a wall of water as high as a four-storey building.
Friday’s tidal surge was not as high as the 46 feet predicted, and a tiny sliver of causeway no more than a few metres wide resisted the surge of water pushed by the moon's huge gravitational pull on the sea.
However, Saturday's tide on the long, sloping estuary of the River Couesnon could yet go higher, although scientists said low air pressure may have lessened the phenomenon.
As the surge began to make its way along the coast and tidal estuaries surfers took to the water in Pontaubault and waves crashed onto seawalls.

MareeInfo : Tide in Saint Malo today
Exceptional High Spring Tide at Saint Malo (height:13.35m 43.8ft),
the highest spring tides in Europe
The moon acts as a magnet on the oceans.
Its force of attractions is twice as strong as that of the sun.
The sea advances and retreats twice a day with a time shift of 50 minutes each day.
When the moon is above the sea, it attracts the water towards it and so the sea level rises and the tide comes in.
Six hours later, the moon is no longer above the sea and the force of attraction disappears.
The tide then goes out.
The power of the force varies depending on the positions of the sun and moon respectively in relation to the earth.
When the three are aligned the attraction is at its peak.
This is the time of the high tide : during this period the sea advances and retreats the farthest.

Police had difficulty holding back the 10,000-strong crowd eager to get pictures of the scene in the final minutes before the surge on Friday evening, with the tourist hotspot lit up as night fell with 60 spotlights for the occasion.

Mont Saint-Michel, which was named a UNESCO World Heritage site in 1979, is situated one kilometre off the coast of Normandy.

The rocky outcrop is home to the famous Norman Benedictine Abbey of St-Michel.
Michael Dodds, the director of the regional tourism committee, said: "This natural phenomenon is an incredible opportunity for tourism in Brittany at this time of year."

Highest tides at Mont Saint-Michel seen by drone from FLY HD.
On February 21 the tidal coefficient reached 117.
The Mont Saint-Michel 11th century abbey is expected to be entirely surrounded by the English Channel with waters rising by a staggering 14 metres. 
"The eclipse and the tide are linked" said Kevin Horsburgh, head of the Marine Physics and Ocean Climate research group at Britain's National Oceanography Centre (NOC).
"For an eclipse to take place, the sun, the Earth and the moon need to be in a straight line, which is also an essential condition for high tides," he added.

The bay on the coast of Normandy has some of the strongest tides in the world.
Eleven departements along the coast of northern France are on alert for fear of flooding and residents have been told to stay away from beaches and coastal areas.
Similar surges are predicted along the coast of Britain and the Netherlands over the weekend.
The last ‘tide of the century’ was on March 10, 1997 and the next will be on March 3, 2033, making the description something of a misnomer.
The predictions are based on the tide coefficients used by scientists to forecast wave size.

With 120 being the highest, they project a 119 on Saturday.

Until 1879 Mont Saint-Michel was cut off from the mainland during each high tide.

That year a permanent causeway was built to prevent the tide from scouring the silt around the island.
The coastal flats were reclaimed for pastureland, reducing the distance between the shore and the island.

The effect was to encourage the silting-up of the bay.
In 2009 work began on building a hydraulic dam using the waters of the river Couesnon and the tides to help remove the accumulated silt, and make Mont Saint-Michel an island again.
Last year a new 2,500ft bridge was opened to the public.

The bridge allows the waters to flow freely below and around the island at high tide.

 Saint Malo & Le Mont Saint Michel Bay with the Marine GeoGarage

Links :

• GeoGarage blog :  Big spring tide extremes in time-lapse / The science of tides
  

Solar eclipse 2015: what you need to know

Solar eclipse

From The Guardian by Nadia Khomami

Parts of the world will witness a solar eclipse on Friday – a rare phenomenon in which the sun is completely obscured by the moon.
Here’s everything you need to know about the background of the solar eclipse, where to view it and how.

A history of eclipses

Records show that the Babylonians and the ancient Chinese were able to predict solar eclipses as early as 2500 BC, but it was a phenomenon that confounded ancient civilisations for centuries.

The Greeks believed that the solar eclipse was a sign that the gods were angry and death and destruction were on their way.
In fact, eclipse comes from ekleipsis, an ancient Greek word that means obscured, or abandoned.
A fragment of a lost poem by Archilochus (c680–645 BCE) depicted a solar eclipse as such:
“Nothing there is beyond hope, nothing that can be sworn impossible, nothing wonderful, since Zeus, father of the Olympians, made night from midday, hiding the light of the shining sun, and sore fear came upon men.”

In ancient China, the eclipse was seen to foretell the future of the emperor.
More than 4,000 years ago, two Chinese astrologers were executed for failing to predict a solar eclipse.
The Chinese people would get together during an eclipse to bang pots and pans to scare away any demons.
A variety of cultures thought the eclipse was a result of entities devouring the sun.
In Vietnam, it was thought that a giant frog was eating it, while the Vikings thought it was the fault of wolves.
Meanwhile, according to ancient Hindu mythology, the eclipse happened when the deity Rahu was beheaded by the gods for drinking ambrosia.
Rahu’s head was said to have flown into the sky, where it swallowed the sun.

Prevailing superstitions

Superstitions surrounding solar eclipses still exist today.
Many believe that solar eclipses can be a dangerous to pregnant women and their unborn child – a claim that scientists have debunked.
In parts of India, people fast during a solar eclipse because they believe that any food cooked during the time will be poisonous, and in Italy it is believed that flowers planted during a solar eclipse are more colourful than those planted at other times of the year.

How often does a solar eclipse take place?

A solar eclipse can only happen at new moon, when the moon directly blocks sight of the sun from certain places in the world.
It can take place up to five times a year, though according to Nasa, only 25 years in the past 5,000 have had five solar eclipses.
In the last 500 years there have only been eight total solar eclipses that could be seen from the UK.
The last one was in 1999, when thousands of people travelled to Devon and Cornwall to see it.
The UK will not see another eclipse until 2090.

This animation (DailyMail) is designed to appear from the 'point of view' of the eclipse as it will occur on March 20.

It shows the shadow being cast over the UK, Greenland, Europe and into Russia

Where can you see it?

The solar eclipse will take place at around 8.45am GMT and is due to last for a few hours.
Most of it will go unnoticed because its path falls over the North Atlantic and Arctic Oceans.
It will start in Greenland and move counterclockwise towards the northeast, passing over Iceland and the UK.
Phases of the eclipse will be visible from everywhere in Europe, most of northern Africa, western Asia and parts of the Middle East.
Saint John’s in Newfoundland, Canada, will also see a small bit of the eclipse at sunrise, but the rest of North America will not be able to view it.
The sun will be completely blocked out on the Norwegian islands of Svalbard, where some hotels have been booked out for the event since 2008.

One of the best places to view the eclipse will be the Faroe Isles, 200 miles (321km) off the north coast of Scotland, where the moon will cover about 98% of the sun.
In the UK, the sun will be about 98% covered on the Isle of Lewis and about 97% on Shetland.
In London, the eclipse will be at its deepest at about 9.30am, in Manchester at 9.32am and in Edinburgh at 9.35am, though this is subject to weather conditions.
The eclipse time for cities in Europe is available on eclipsewise.com, complete with a map of times and locations.

Stay safe when viewing the eclipse

Observers must take care when taking photos of the eclipse on digital devices, as eye experts have warned that doing so could cause blindness.
Skygazers have been told to not look directly at the sun when they take selfies and other photographs, as doing so can lead to burns at the back of the eye, even with the use of dark sunglasses.
Though looking at the eclipse on a screen is not dangerous in itself, it might lead to inadvertently looking at it in the process of trying to capture the perfect shot.
When viewing the eclipse, you can use a homemade pinhole camera and face away from the sun.
Londoners can also go to the Royal observatory in Greenwich from 8am, where they can join expert astronomers.
Other places setting up special equipment for viewing include the Flamsteed Astronomy Society, the Royal Astronomical Society, Baker Street Irregular Astronomers, the Hampstead Scientific Society and Northolt Branch Astro.
Alternatively, the eclipse can be witnessed from your home, as it will be broadcast live online through the Slooh Community Observatory’s website, slooh.com, from 8.30am.

Scientific implications In 1851, the first photograph of the sun’s corona was taken by the Prussian photographer Berkowski during a solar eclipse.
An eclipse also led to the discovery of helium in 1868 by the French astronomer Pierre Janssen and the British scientist Norman Lockyer, which is why it is named after the Greek word for the sun – helios.
And in 1919, a solar eclipse was used by the British astronomer and mathematician Sir Arthur Eddington to prove Einstein’s theory of general relativity.
For the latest eclipse, hundreds of astronomers are already stationed on Svalbard.
Solar eclipses provide a unique opportunity to study the sun’s atmosphere – the corona – which is much easier to observe with most of the sun’s light blotted out.

One of the biggest mysteries in astronomy is why the corona is so hot.
While the surface of the sun is only about 6,000C (a few times hotter than a blast furnace), the corona reaches 1-2mC.
The heat is not coming from the surface and scientists are working on a plausible explanation for what causes its astonishing heat.
One explanation is that twisting magnetic field lines could cause heating, but more observational evidence is needed.

 The Solar Eclipse In Varanasi - Wonders of the Solar System -

Risk of power failure

The UK has 5GW of installed solar capacity, the equivalent of eight to 10 very large coal power plants.
If skies are clear on Friday morning, the European grid will suddenly lose all this power.
However, since the event is known about in advance, electricity grids are expected to cope well and no power blackouts are expected.

Other celestial events on Friday

In addition to the solar eclipse, Friday is set to see a supermoon and a spring equinox.
A supermoon refers to the moment the moon orbits at its closest to the Earth, making it look bigger than it normally does.
The spring equinox is the time of the year when night and day are of equal length, mid-way between the longest and shortest days of the year.
It is a sign that the Earth’s axis is perpendicular to the sun’s rays.
Some Christian ministers have viewed the rare collision of three celestial events as the beginning of the end of the world.

Links :

• WSJ : Solar eclipse coincides with other rare celestial events
• NASA : Solar eclipse