Search Results for Tag: thawing
Exploring the North – Looking South: On a bottle of wine and into the ocean
But the Arctic isn’t the only place that’s important for the planet. Just on the other side of the planet, there’s another precious region: Antarctica. Why? Antarctic glaciologist Kenichi Matusuoka from the Norwegian Polar Institute explains this with the help of a bottle of wine.
Imagine holding a bottle of wine. The wine inside the bottle is very precious (and expensive), compared to the rest of the bottle – the glass body and the bottle cork. The wine corresponds to the ice in Antarctica: It is important for the planet as its melting could lead to a rise of 45 meters in sea levels.
Now imagine you turn the bottle upside down – the previously unimportant cork now becomes quite important as otherwise the precious wine would pour out. You can well imagine that the cork is now crucial, whether or not it’s a crumbly old cork that is only plugged loosely in the bottle neck, if you want to find out whether the wine will pour out or not.
That is why scientists focus on investigating the properties and melting behaviour of ice shelves, which is what the cork corresponds to. To be correct: Antarctica does not only have one “cork” like a bottle has, but several – those on top behave differently. But the overall research question is, whether climate change weakens the corks/iceshelves so intensely that they cannot withstand the pressure of the wine/Antarctic ice and finally might let it pass.
During my travels in the Arctic region, I actually met a researcher who worked on the dynamics of Antarctica’s ice shelves. Tore Hattermann investigated the melting of a certain ice shelf underside. To get back to the cork analogy, you can imagine that it is rather crucial what size the cork has. If it’s too slim, the wine behind can easily push it away.
In West Antarctica, for example, a change in ocean circulation leads to warmer water below the ice shelves that starts to melt, contributing to more than two thirds of Antarctica’s mass loss. Now, computer simulations predicting that those circulations also transport warm water below the Fimbul ice shelf suggest additional melting. The Fimbul ice shelf is located not in the West, but in the East and has similar geographic conditions as the melting Western shelves have.
So, together with other scientists, Tore went on an Antarctica expedition to see whether the simulations are correct and if they could really find warmer water underneath the Fimbul ice shelf. Using boiling water, they drilled holes through 400 meters of ice and passed oceanographic instruments into the ocean below. Over two years those instruments measured water properties: its flow velocity, temperature, salinity and oxygen content. After analyzing the data collection, Tore could prove that the computer simulation was wrong: There was not that much warm water circulating under the Fimbul ice shelf, therefore it wasn’t melting at the extent predicted.
For most people this might seem a disappointment, but for scientists this is rather routine: proving models (wrong). In order to improve or adjust the models in the next step, therefore they depict reality better and predict Antarctic ice shelf melting correctly.
Watch out for the next issue to find out, what the expedition to Antarctica was like for Tore.
DateApril 25, 2013
TagsAntarctica, Arctic circle, climate change, global warming, ice dynamics, ice shelves, kenichi matsuoka, norwegian polar institute, npi, sealevel rise, thawing, tore hattermann
Keep to +2 degrees might not prevent permafrost from melting
Large parts of the Northern hemisphere from Alaska to China hold a dangerous treasure. 24 percent of this land’s ground is frozen throughout the year – so called permafrost. It holds more than 1,000 gigatons of the most dangerous greenhouse gases: carbon dioxide and methane. Release of those would accelerate climate change to great extend.
Now, researchers found evidence that permafrost could start melting already at a 1.5 degrees Celsius rise in temperature. Also, the world already warmed up by 0.6 to 0.7 degree Celsius compared to the preindustrial level. So adding another 0.8 could already let permafrost melt.
That’s at least what happened in former times, as the scientists from Britain, Russia, Mongolia and Switzerland found out. They went into Siberian caves located along the ‘permafrost frontier’ studying stalactites and stalagmites as they function as a kind of climate archive – they only grow when liquid rainwater and snow melt drips from the surface into the caves.
“The stalactites and stalagmites from these caves are a way of looking back in time to see how warm periods similar to our modern climate affect how far permafrost extends across Siberia”, said Dr Anton Vaks of Oxford University’s Department of Earth Sciences, who led the work.
The amplifying effect on global warming the release of greenhouse gases held in the permafrost would have, exceeds everything climate models yet suggest. So, though almost 200 nations agreed in 2009 to the 2 degree target for global warming, this may not be enough to keep permafrost from melting and thus to mitigate climate change.
DateFebruary 22, 2013