Archive for the ‘post expedition work’ Category

It is just a bit more than two years since I made my last post here, and since we had the sampling party to take the material from our fantastic expedition back home.

Today, the first major scientific results of our endeavour were published in the journal Nature.
The team led by Jorg Pross, which included myself and my graduate student Claire Huck, found amazing evidence from spores and pollen in the very old cores we recovered. These cores reached back to the early Eocene, a time which is often described as part of the ‘Greenhouse world’. Atmospheric carbon dioxide concentrations were a lot higher back then, probably similar to what we would get when burning all our fossil fuels. We always knew that it must have been warm around Antarctica back then, but our work for the first time shows direct evidence for near tropical warmth at the Antarctic continental margin.

52 Million years ago, the Wilkes Land coast of Antarctica was covered by near-tropical forests as they today occur in NE Australia. Copyright Sven Brenner – Fotolia.com.

Joerg and his colleagues found pollen grains from palm trees and relatives of the modern baobab and macadamia. Such plants have very defined temperature ranges they are happy with, which dictate that even winter temperatures have to have been above 10°C. In contrast today, the winters in this area of Antarctica can easily reach temperatures of -10 to -20°C. Mean annuanl temperatures were probably around 17°C – quite a pleasent environment to live it and different to the ice-dominated world we witnessed two years ago!

The scientific significance of this study is far reaching. We think that during the so-called Greenhouse world atmospheric CO2 concentrations were at least double as high as they are today, and that the temperature gradient between the poles and the equator was much less pronounced than today. However, if we try to simulate the response of the climate system in models, it is very hard to achieve such a low ‘meridional temperature gradient’. Our new data deliver some key benchmark values that now have to be reconciled by models. Being successful at reconstructing Greenhouse climates may be very relevant for looking into our own future.

Before I finish I should of course give a big cheer to Claire Huck who contributed to this study by analysing some of the mud from the Eocene and figuring out where it was coming from based on its geochemical provenance. Watch this space, for more exciting data and results to come from her and from Carys Cook, who works on reconstructing the paleoclimate at the Antarctic margin in the Pliocene, just a few milion years back in time.

Also check the coverage by the BBC, which was among the first to pick up on the story.

Finally the long time without my ship mates was over …

From 15 June to 25 June many of the shipboard participants from IODP expedition 318 met again in College Station, Texas, to bring the first stage of our science mission to conclusion, and make a start to the second stage. The first stage of course was the seagoing part, which you all could follow through the blogs. As I mentioned in my blogs, part of the job when sailing as a scientist in the Integrated Ocean Drilling Programme is to write a lot of reports. Every time we finished drilling at a new site in the ocean, a full report had to be written up, describing the operational side of things, but also the sediments we found, what ages they had, and what their physical properties and geochemical composition was. As you may imagine, doing scientific writing after 9 weeks of 12 hours shifts every day can be quite tough, and hence it was very good that we revisited all our writings and gave it final touches. The big report containing all the information will be published next summer. Why do we wait this long? A lot of the information that is contained in the reports from our Expedition is unique findings that can lead straight into a scientific publication. In order to allow the scientist, who collected the material, to get first dips on publication, a so-called moratorium is in place. This means that for 1 year nobody else but the people who were part of Expedition 318 will see the reports or get any samples.

Imperial PhD student Carys Cook in front of the IODP sign in College Station/Texas.

But don’t worry – we surely will flood upcoming meetings with results much earlier than next summer. To make sure that this will happen, we entered step two, which is the actual shore-based science work. During five days in College Station, we all worked in shifts again to sample all the cores. This time, however, we did take samples for all of our individual science projects. In my case, this is to look at the history of the East Antarctic ice sheet as reconstructed from ice-rafted debris ,and to understand the interplay of continental weathering, ocean circulation and CO2 drawdown during the onset of Antarctic glaciation some 34 million years ago. Two very exciting projects, which I am lucky to have two motivated PhD students for! But also this stage of the expedition will involve a lot of team work -no single group or researcher can do all the analyses required, to answer the big picture questions in Earth and Climate sciences alone. Hence already back on the ship we formed topical teams, which will join forces to tackle the big science questions out there. Happy data production everybody and more soon!

Below a picture from the ‘sampling party’ – looks almost like back on the ship, doesn’t it?

PhD student Elizabeth Pierce (Columbia University), sampling one of the ~15 million year old cores from Expedition 318. Elizabeth is part of the team of research from the Lamont-Doherty Earth Observatory, I collaborate with to understand the provenance of ice-rafted debris around Antarctica.