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The global mean temperature is not constant – it varies over many timescales. Over the last 150 years the temperature of our planet has been increasing. The graph below shows (in red) the mean sea surface temperature over the North Atlantic since 1870. The data comes from the HadISST data set, produced by the Met Office Hadley Centre. A timeline of the kings and queens of Britain is shown along the top – leaving out Edward VIII who was king for less than a year between George V and George VI.

kings_and_queens

So Edward VII had the coldest reign, George V led to warming, George VI managed to maintain these temperatures then Elizabeth II has turned up the heating in the second half of her reign.

The causes of these changes are not fully understood. Edward VII’s cooling is thought to be due to volcanic eruptions – such as the eruption of Santa Maria in 1902. Elizabeth II’s warming is though to be due to anthropogenic causes, although some contribution from internal variability has also been suggested. George V’s warming is least understood – the Intergovernmental Panel on Climate Change (IPCC) state it is very likely due to natural causes, likely some contribution from manmade causes and possible that internal variability is also involved.

 

 

Island Cloud

This image was taken by a European Space Agency satellite last month, it shows the Juan Fernandez islands, 800 km off the Chilean coast in the Pacific Ocean. The two largest of these islands are 1650 and 922 m high, this is high enough to affect the cloud patterns making pretty patterns in the sky!

As the wind flows past the island the mountains cause drag – wind speed increases further above land as the land causes friction (shown in the picture below). The change in speed causes regions of the atmosphere to have sharp velocity gradients. Where there are large changes in the wind speed vorticity occurs, leading to the observed vortices as the wind passes the mountainous islands.

Wind_Speed_Increase_Height

This process, known as Karman vortices, depends upon the wind speed and island size, for smaller islands a larger wind speed is needed for the patterns to appear. It isn’t only on this large scale that Karman vortices are found though. They can also affect building so engineers need to be aware of the atmospheric turbulence they can cause when building skyscrapers and Karman vortices can also cause car aerials to vibrate at certain speeds.

experimentalvortex

Global average temperature has increased over the last 150 years, leading to widespread ice melt and rising global average sea level. The increase has not been at a constant rate – the Intergovernmental Panel on Climate Change identified two periods of accelerated warming, 1910 to 1945 and 1976 to 2000.

The earlier warming is poorly understood. Climate scientists disagree over causes suggesting solar activity, volcanic eruptions, and manmade emissions. The later warming has been attributed to anthropogenic causes, though scientists disagree over the proportion contributed by internal variability.

I am studying the earlier warming in the North Atlantic. Analysing historical observations I have found atmospheric circulation changes may be a key mechanism behind the warming. Using climate models I can test which processes could have been involved. Climate models are numerical representations of the climate system. They allow specific processes to be studied and can provide data where observations are not available, such as 3D ocean properties. Initial investigations have found large changes in ocean heat transport at the time of the warming.

Understanding the roles of atmospheric circulation and ocean heat transport will help us separate mankind’s influence on climate from natural processes, allowing better estimations of future climate change.

The cruise report from JR265 (my trip down south) has now been published. If you want to read about the science, not just the bits I did, here is a link: http://eprints.soton.ac.uk/208991/

I have been back in the UK almost a month now, so my PhD is back in full swing – or would be if I hadn’t caught fresher’s flu. You’d have thought that by my fifth year of being a student I’d have become immune. Apparently not!

I am studying detection and attribution of climate change. By looking at observations of climate variables, such as mean global temperature, climate change can be detected. By using models and statistical methods these changes can be attributed to a variety of factors, some natural and others caused by human influences.

You can read about attribution methods in more details in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report: http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9.html

The JCR made it into Stanley just after lunch on Christmas Eve. It was strange coming back into where we had been only a few weeks earlier. It had seemed hilly and remote the first time, but after the ice cliffs and empty islands further South it looked a bit more hospitable now!

As soon as the ship had passed custom’s we made a dash to Peacocks, the only clothes shop in Stanley. Having not expected to still be with the ship come Christmas party frocks had not been packed. Luckily there was enough of a selection that we didn’t all match!

Christmas Day started with a phone call from home and a run along the sea front. We had organised a scientists secret santa and, after complaints from some of those not included, a ship-wide secret santa too. During Christmas morning parcels started appearing under the tree. Official celebrations began with pre-lunch drinks and present swapping. Some of the gifts were amazing, especially considering the limited resources available on a ship. I gave fridge magnets and a tutu, and got an engraved glass and ropework keyring.

After the drinks we enjoyed a turkey curry Christmas dinner complete with stuffing samosas. There was no way I could manage Christmas so close to the sea without going in it -in the afternoon a group of us walked to the closest beach, Surf Bay, for a quick dip. The water was surprisingly warm (or at least not cold), whether this was due to the multiple G & T’s or Falklands summer time I’m not sure. As we were enjoying post-swim beer and jaffa cakes we spotted a seal where we had been moments before.

At 6 am on Boxing Day we set off to the airport for 16 hours of flights back to the UK. 24 hours after leaving the ship I made it back home to start the family Christmas celebrations!

I had a brilliant few weeks on the JCR – the crew and officiers were amazing, the scientists made me feel at home, the penguins were amusing. I hadn’t been looking forward to spending Christmas away from home, but it ended up much better than I could have imagined. I now need to find a way to make my modelling PhD involve some ship time…

Finally, here is what has been going on in my office whilst I’ve been away:

http://www.youtube.com/watch?v=n0RWDS6uvV0

For the last few days we have been in the South Orkney Islands dropping off people and supplies. We dropped off a scientist and field assistant at Cape Geddes on Laurie Island, with only a rarely used dilapidated hut for shelter. The two of them are spending six weeks camping with penguins, then moving on to Powell Island.
 Sea ice around the shoreline made dropping them and their supplies off challenging, with growlers closing in around the humbers.
Then we had a day to wait in Signy as some of the ships engineers were sent ashore to fix a generator. We went on a walk over a glacier to see some Chinstrap and Adelie Penguin colonies, complete with chicks!


Now we are heading for South Georgia where we will drop a few bird botherers off at Bird Island, before heading back to Stanley in the Falklands.
Our next port call was Jubany, an Argentine base  on King George Island. Deception Island, an active volcanic caldera, was on the way. It is one of the safest harbours in Antarctica, so the ideal place to test the starboard liifeboat. The island forms a ring with an entrance 230 m wide called Neptune Bellows. Once inside we headed to Whaler’s Bay, a large black sand beach. Due to wind conditions the lifeboat wasn’t put in the water, just lowered and raised a few times. Then the Humbers were put out to do a few runs to shore.

Due to the volcanic activity warm water bubbles through the sand at the edge of the beach, perfect for wallowing in. Once the water is more than a millimetre deep it is Antarctic cold again, but digging a hole in the sand a hot shallow bath could be formed. To good a chance to miss we stripped down to swimsuits (or underwear for those who didn’t think swimming costumes are essential packing for the Antarctic!). I dived straight in, momentarily panicking when I realised I couldn’t touch the bottom, then recovered in the warm bits and repeated for a while.


All along the beach were remnents of whaling stations: large iron boilers to extract whale oil, rusting tanks, derilict buildings, piles of whale bones and an old hangar. It smelt of rotten eggs and steam came off the edge of the water. It was a weirdly atmospheric, but felt like the perfect setting for a Doctor Who episode.
We stopped for some science overnight arriving at Jubany early this morning. The base comprised of orange buildings, with very little snow around, giving it a very desolate appearance.