Introduction from Chris Clark, Principal Investigator
Why all this sudden activity on the British-Irish Ice Sheet?
Ever since the discovery of ice ages there has been a quest to work out the extent, thickness and geometry of the ice sheet that once covered most of the British Isles. Archibald Geikie’s map in 1894 was an inspired start and steady progress since then has added much detail. There is now a concerted effort to finish the job, doing many decades work in just 5 years with over 40 researchers on the BRITICE-CHRONO project currently blitzing the far corners of the ice sheet. It has never been so heavily investigated. Why the sudden rush?
A perfect storm of stimuli came together…
It was realised that, spread over numerous publications (over 1000!), fragments of the jigsaw puzzle that is – ‘ice sheet information’ – had never been assembled. This was put right in BRITICE, a previous project compiling over 20,000 landforms (e.g. moraines, drumlins) into a map and as downloadable data (GIS) layers.
This brought value to over 100 years of fieldwork, but what about the blanks on the map? Using satellite images and elevation models of the land and seafloor, the whole ice sheet bed was mapped afresh. The jigsaw pieces were now in one box and ready.
From this, and for the first time, a detailed map of the pattern of ice margin retreat was assembled based on, and traceable back, to the underlying landform evidence. Once assembled we started to wonder about the timing, what was the rate of retreat, how and why did it vary, did anything catastrophic happen when North Sea ice broke up?
Over the same time that curiosity-driven academic research on our palaeo ice sheet progressed over the last century, and beyond, humans continued with their uncontrolled Earth-warming experiment. We now know this to be melting ice sheets in Antarctica and Greenland at a rate faster than can be replenished by snowfall, with losses exceeding 100 Gigatonnes per year (100 kilometre-sized ice cubes every year) with indications of acceleration.
The melted ice of course, ends up in the sea, contributing to our fast rise of sea level. Forecasting is difficult because our complexly-interacting Earth system has yet to be completely understood and because it is hard to know when idiot-humans will finally get round to properly reacting to the now-obvious signals. Both uncertainties make forecasting difficult, but the best current estimates place sea level rise by year 2100 as between half a metre and one metre.
The effect that such a rapid rise in sea level would have on people globally, and who have built their existence in a world of slow change, has dramatically focussed the minds of scientists who now need to improve understanding to make more precise forecasts. Just as our weather forecasters use a mix of data and computer models, our glaciologists do likewise with their ice sheet models, which track fallen snowflakes, on their journey of flow as ice, until they reach the sea, as water.
So, the reason that our team is so frantically busy, setting out to do 50 years work in 5, is because glaciologists urgently need a data-rich playground of information on the timing of a retreating ice sheet with which to improve and test their forecasting models – this is the focus of BRITICE-CHRONO . Remember that the weather forecasters get to know whether they were correct or not in a few days’ time, which allows them to keep improving their models. We will do similar for ice sheet forecasters but who need data on timesteps of 1000s of years rather than daily, and we will do so by collecting samples of rock, sand and organics, analysed in our labs (e.g. radiocarbon) to provide dates on the pattern of retreat. So how fast did the British-Irish ice sheet retreat?
Professor Chris Clark, Project leader of BRITICE-CHRONO.Funded and supported by the UK’s Natural Environment Research Council as a consortium project.