In its most recent report, the Intergovernmental Panel on Climate Change’s predicted sea levels are likely to rise by between 0.26 m and 0.97 m by 2100 – a range encompassing both its highest and lowest emissions scenarios. But according to a new survey of sea level experts, the results of which have been published recently on line in Quaternary Science Reviews, that range might be an underestimate. In the study 90 researchers from 18 different countries were asked for their expert opinion on future sea level rise.Two thirds of those questioned said they thought sea levels could rise higher than the IPCC’s upper estimate for the end of the century.
Over the coming weeks we will introduce members of each team working on the iGlass consortium project. Today we will introduce the team from the National Oceanography Centre in Liverpool.
Dr Mark Tamisiea
Mark Tamisiea is a geophysicist that studies the motion of the Earth’s crust and variations of water depth in the oceans caused by past and present changes of the ice sheets. This collective response of the crust ond oceans is typically called glacial isostatic adjustment (GIA). His Ph.D. in physics from the University of Colorado at Boulder examined how solid-solid phase transitions in the Earth’s mantle might affect observations of GIA. Starting with his post-doc at the University of Toronto, his work has focused on the regional sea level changes caused by GIA. Understanding the regional differences is vital to interpreting the causes of past and present sea level change. Mark has been at the National Oceanography Centre (formally the Proudman Oceanographic Laboratory) since 2007 and prior to that was at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts.
Dr Svetlana Jevrejeva
Svetlana Jevrejeva is a physical oceanographer who works for NOC Liverpool since 2002. Her main research interests are in the variability of global and regional sea level change and development and application of advanced statistical methods. She had contributed to the development of the wavelet coherence method and is author of the unique sea level reconstruction since 1700. She has major publications in the field of time series analysis and the application of novel statistical methods to earth science problems. During the Fifth Assessment report of Intergovernmental Panel of Climate Change (IPCC) she was a Lead Author of the Working Group 1 chapter on Sea level changes. Recent work has focused on sea level projections by 2100, changes in extreme sea levels in the past and their link to climate change.
Dr André Düsterhus
André Düsterhus is a meteorologist specialised in statistical data analysis. He is part of iGlass since 2013 and is working on the connection between GIA modelling and observations of the sea-level variations in the past interglacials. This is done by using verification and data assimilation techniques with a focus on Bayesian statistics. Prior to his appointment at NOC Liverpool, André had received his diploma and PhD in meteorology at the University of Bonn and worked within the climate dynamics workgroup of Andreas Hense. His PhD thesis covered the development of quality assurance procedures within data publication processes. A focus was set therein on the development of statistical quality assurance tests on general data and data peer review schemes.
Metres of sea-level change. Hundreds of thousands of years. The entire globe. The scale of the iGlass research project is rather large. But some of the research is based on the humblest of creatures: benthic foraminifera.
If you have a really big one it might be an entire millimetre. Benthic foraminifera are unicellular protists who live on top of, or in the top layer of, marine sediment. Every species has its own niche; for instance, some like coarse sediments, some like fresh food, some like warm water, etcetera. Some of the more adventurous species even live in salt marshes. These are, if you will, the scuba divers among foraminifera; all foraminifera need salt water to live, but these brave souls have become accustomed to do without for substantial amounts of time.
The reason why foraminifera, in spite of being such modest creatures, get so much attention from the palaeoclimate community is that they build some sort of skeleton, and aretherefore often very well preserved in sediments. They can be tens of millions of years old and still look like they died last week. They take the information they contain into their graves, and in this case that’s a good thing. If you know which species prefers what environment, you can “read” sediments they are found in.
The York and Durham teams drilled cores through interglacial sediments.
We drilled in the middle of Norfolk, but we know that area has been inundated in previous interglacials, and indeed, we found both freshwater and marine sediments in our cores. And using the foraminifera in them, we are reading them. We are looking for changes reflected in the various species encountered; will we get a gradual change from the shallowest foraminifera, which are the ones that actually live above sea level but still within reach of high tide, through the ones that live in shallow water, to those that prefer deeper waters? Or will we see several of such sequences? Or an instantaneous shift from no foraminifera to relatively deep-water species? Watch this space for results…
We found some 10, 000 foraminifera (and counting). They were picked out of the samples by two different scholars, so we keep them all in order to be able to check we have comparable ideas of which species is which (since you ask; no, identifying the species is not a straightforward task). Keeping them also allows us to always go back to the source material in case of questions arising. And after the questions iGlass asks have been answered, who knows what other questions such a collection can help tackle!