Friday, 26 May 2017

The Past Global Changes Open Science Meeting, Zaragoza…by PhD student Savannah Worne

Savannah presenting preliminary PhD research

“The PAGES (Past Global Changes) project is an international effort to coordinate and promote past global change research. The primary objective is to improve our understanding of past changes in the Earth system in order to improve projections of future climate and environment, and inform strategies for sustainability.” (www.pages-osm.org, Accessed May 2017).

In May 2017, several members from the Centre for Environmental Geochemistry (BGS/University of Nottingham) travelled to Zaragoza, Spain, to give talks and present posters at the PAGES 5th Open Science Meeting (OSM), including myself, Professor Sarah Metcalfe, Dr George Swann, Dr Matt Jones, fellow PhD student Nick Primmer and Dr Stefan Engels. Over 800 scientists from 51 countries also participated, where over the course of the four-day conference there were 9 plenary talks, 344 additional talks and 649 poster presentations across 30 different themes covering  a broad range of topics including Quaternary climate change, Ancient DNA, Volcanic eruptions and Data Stewardship, to name a few.

My personal motivation for attending the PAGES OSM was to share new results from my PhD research, which I have been producing over the last year with my supervisors Dr Sev Kender and Dr George Swann, as well as Prof Melanie Leng from the British Geological Survey and Prof Christina Ravelo from the University of California Santa Cruz. This was the perfect opportunity to present my new results as part of the Mid Pleistocene Transition session. For further information about the Mid Pleistocene transition and my PhD research, please see: http://britgeopeople.blogspot.co.uk/2016/01/a-new-phd-researching-effects-of.html .

We know that in the modern day the Bering Sea is a source region of CO2 the atmosphere, as warm, nutrient rich water from the deep Pacific meets the continental shelf and upwells to the surface, releasing CO2 the atmosphere. However it is hypothesised, that during cold glacial periods since the MPT, upwelling of Pacific Deep Water (PDW) was prevented by stratification of the water column from either increased sea ice or formation of cold intermediate waters, or a combination of the two. Reduction of upwelling PDW may mean that the Bering Sea was a net sink of CO2 to the atmosphere in these severe glacial periods.
 
The PAGES OSM was held at the Auditorio de Zaragoza
To investigate this I used the nitrogen isotope (δ15N) record, which can be used as a record of nutrient utilisation. This is because the light isotope 14N is preferentially taken up by phytoplankton as they grow. So as more of the nutrient supply is used, phytoplankton begin to utilise the 15N as well. Therefore when we look at our sediment record, the ratio of 14N to 15N (δ15N) can tell us how much of the nutrient supply was used at the time the phytoplankton were deposited on the ocean floor.

The preliminary results which I presented at PAGES suggested that during severe post-MPT glacials, a more stratified water column caused high nutrient utilisation despite low phytoplankton productivity. A simultaneous increases in North Pacific Intermediate Water (NPIW) was also found at another nearby site in the Bering Sea (Knudson and Ravelo, 2015). We also found that there were larger variations in post-MPT stratification (0 – 590,000 years ago) than before, concurrent with glacial lengthening. The conclusion was therefore that there was an increase in water column stratification during post-MPT glacials, probably linked to the closure of the shallow Bering Strait (~50m) following sea level drop, and due to the formation of North Pacific Intermediate Water in the Bering Sea. I will now look to continue my research in reconstructing how sea ice evolved during this time, to assess its role in changing productivity, nutrient utilisation and PDW upwelling.
 
Overall, attending the PAGES OSM was highly rewarding, as I got to discuss my first sets of results with a large range of scientists both in my specific field and those with a wider appreciation for palaeoceanography. I am now more enthused than ever to continue my PhD research continue and answer unsolved questions about MPT palaeoceanographic change.

First meeting of the UK consortium of the DeepCHALLA project... by Heather Moorhouse

The DeepCHALLA UK party at the BGS plus International lead
investigator Dirk Verschuren (Ghent University)
We held the first meeting of UK scientists working on the International Continental scientific Drilling Programme’s DeepCHALLA project at a very rainy BGS Keyworth. This NERC funded consortium of scientists is part of a large, international team that will investigate over 214 metres of lake sediment cores dating back to ~250,000 years, to understand climate change in equatorial east Africa.

The sediment cores were retrieved from Lake Challa, a crater lake found 3 degrees south of the equator, on the eastern flank of mount Kilamanjaro, and which lies directly on the border of Tanzania and Kenya. The region is subject to two rainy seasons a year, but the length in between these seasons is changed over thousands of years as the Earth changes it orbit of the Sun, and has led to periods of aridity and drought. In particular, around 110-160 thousand years ago, it is believed that mega-droughts which lasted thousands of years at a time, led to the dispersal of our hominin ancestors out of Africa and caused vegetation changes leading to the high biodiversity of the region today.

The DeepCHALLA drilling rig on the lake
Ice cores from the north and south poles have provided incredible climate reconstructions which have been used to predict future changes to our global climate. However, past climate change in equatorial regions is still relatively unknown. This project will help broaden our perspective of climate change in a region which has suffered droughts and severe food shortages in recent years, and will help modellers to predict future weather patterns here. Furthermore, this lake sediment record is unique because it extends to a period so far back in time that we can test our theories about why our ancestors migrated out of the continent.

A diatom from Lake Challa that will be analysed to reconstruct
250,000 years of climate history in equatorial east Africa
The UK scientists will be involved in providing novel dating techniques and isotopes from the lake Challa sediment record to help determine the timings and nature of climatic change. Colleagues from the University of Cambridge (headed by Christine Lane) will use visible tephra and cryptotephra (not visible to the naked eye) emitted from volcanic eruptions alongside radioisotopes and palaeomagnetic signals (undertaken by colleagues in Belfast (Maarten Blaauw), Glasgow (Darren Mark) and Lancaster (Barbara Maher) to help provide one of the most accurate chronologies of lake sediment cores spanning such millenial timescales in the region. BGS and Lancaster University will undertake analyses of oxygen, carbon and silicon isotopes (Melanie Leng , Philip Barker and me) from diatoms found in the lake sediments to determine changes to the hydrological climate and nutrient cycling. Diatoms are phytoplankton whose cell walls are made up of silica or glass and so, are often well preserved in sediments making them an ideal proxy to investigate. Other work will involve looking at carbon isotopes from organic matter in the sediment which will help to understand changes in the terrestrial vegetation around the lake.

This exciting project will begin with a sampling party in Ghent in June, where we will collect all the mud we need to undertake our analyses. Watch this space for how our project progresses and what interesting stories our data may tell us. We would like to thank ICDP, NERC and Dirk Verschuren and colleagues from Ghent University for their hard work in retrieving a successful sediment record to work on and organising the sampling party.

Heather is a post doctoral research assistant on the NERC funded grant based at Lancaster University.
 




Monday, 22 May 2017

The European Geosciences Union General Assembly, Vienna...by Jack Lacey, Melanie Leng, & Andi Smith

Welcome to EGU! Hosted at the Vienna International Centre, Austria
In April, 14,496 scientists from 107 countries participated in the European Geosciences Union (EGU) General Assembly in Vienna, Austria. Over the course of the five-day conference there were an astounding 4,849 oral and 11,312 poster presentations, with several authored by staff from the British Geological Survey. The BGS Stable Isotope Facility was represented by Jack Lacey, Melanie Leng, and Andi Smith. In this blog they report on their week at EGU and tell us about the work they presented on lake and speleothem records... 
 
This year we travelled to EGU to share new results from work carried out as part of two large international research projects, the Hominin Sites and Paleolakes Drilling Project (HSPDP) and the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) project, and from a detailed speleothem record from Northern Spain.

The HSPDP looks to understand how environmental change influenced human migration out of Africa using long sediment cores recovered from five lakes in the East African Rift Valley. Our main research at the BGS Stable Isotope Facility focuses on one of these sites in particular; Chew Bahir in Ethiopia. Isotope data were used along with other measurements from international colleagues to tell us more about what has driven climate change in eastern Africa over the past 500,000 years, and what conditions were like at the origin of modern humans and their dispersal out of Africa. We are still at a relatively early stage in the project, but it looks like climate had a massive influence on the adaptability of early Homo Sapiens which may have driven them to move out of Africa.

Andi presenting his work on speleothem from Northern Spain
Moving from East Africa to the Mediterranean, Lake Ohrid on the Balkan Peninsula is one of the largest and oldest lakes in Europe, and contains many hundreds of unique species. In 2013, an ICDP drilling campaign recovered cores reaching 570 meters below the lake floor. This exceptional sediment sequence contains a continuous record of environmental change over the past 1.4 million years, and will allow us to study the influence of climate and geological events on evolution of the unique organisms in the lake. It appears that species in Ohrid are able to cope with both long-term and rapid environmental change, and unlike other old lake systems, there have been no major extinction events since the lake formed. The upper half of the core was recently the focus of an open-access special issue in the journal Biogeosciences.

Still further northward, Andi gave a talk on speleothem climate records from Cueva de Asiul in Northern Spain. This small but beautiful cave system has already provided insight into rainfall dynamics in southern Europe throughout the Holocene, in work published in Scientific Reports in 2016. However, this year’s talk focussed on the last 2000 years of the Holocene, showing a strong relationship between rainfall in northern Spain and changes in the North Atlantic Oscillation (NAO). It is hoped that a more detailed investigation of this speleothem will help us to understand in more detail how the NAO has changed in the past and the impact that change had on different areas of Europe. Interestingly the speleothem also reveals a period of major environmental change around AD 1557, possibly recording major deforestation linked to industrialisation on the northern Spanish coast from which the Spanish Armada was launched only a few decades later.

Catch up with #EGU2017 on Twitter
EGU is a very engaging conference and a great place for geoscientists to meet, and share and discuss their research. If you would like to find out more about any of the research above, contact information and links to our EGU abstracts are included below.

Jack Lacey @JackHLacey
Melanie Leng @MelJLeng
Andi Smith @AndiSmith10