This page was contributed by Matthew Amesbury from the University of Exeter. All photographs are copyright Matthew Amesbury.
Antarctic science – it’s NOT all about the ice! | A 4000 year record of Antarctic Peninsula climate change | Moss banks on Green Island | Moss banks as a palaeoenvironmental proxy | Further Reading | References | Comments |
Antarctic science – it’s NOT all about the ice!
Regular readers of the AntarcticGlaciers website could be forgiven for thinking that science in Antarctica is all about the ice. You might, for example, reasonably expect a research project studying Antarctica’s past climate to be using ice cores, some over 4 km thick and hundreds of thousands of years old.
But in the northernmost extremes of this undeniably icy continent, on the Antarctic Peninsula, a quite difference source of scientific information is slowly growing away, locking in information as it goes, minding its own business in the mere 0.3% of the Antarctic continent that is ice free. What is it?! Deep banks of moss have been accumulating on islands to the west of the peninsula for thousands of years and research is currently underway that exploits these remarkable formations as an archive for information on past climate change in the region.
Dramatic temperature changes over the last 50 years have resulted in changes in these moss banks, which were unprecedented over the last 150 years.
A 4000 year record of Antarctic Peninsula climate change
Antarctic Peninsula temperatures have risen by 3°C over the past 50 years, making it one of the most rapidly warming parts of the globe. This warming has been associated with a range of impacts including decreased sea-ice extent, ice-shelf collapse and glacier retreat. However, meteorological data has only been recorded on the Peninsula since the 1950s, so our knowledge of the longer term context of this temperature rise is limited. To address this, we are developing records of past climate stretching back some 4000 years from these slowly growing moss banks.
Moss banks on Green Island
As a temperate peatland scientist by training, I still have to pinch myself to think that just over a year ago to the day, I was on a ship crossing Drake’s Passage (the less detail I give you of that journey the better for everyone) bound for the most extraordinary fieldwork I’m ever likely to undertake. We were heading for Green Island, a small rocky bump and Antarctic Specially Protected Area not far from the Ukrainian Vernadsky/Faraday research base about half way along the western side of the Peninsula.
The year before (2012), my colleagues had attempted to take a core from the very same island but were held back by impenetrable pack ice. Last year, despite passing through uncharted waters, seas choked with heaving, grinding icebergs and a whipping cross current, we managed to make our landing along with 500 kilograms of field kit (including the pre-requisite months worth of emergency rations) on a rocky embayment on the sheltered eastern side of the island.
Moss banks as a palaeoenvironmental proxy
Mild summers allow slow moss growth
The days that followed perfectly illustrated why mosses have been able to take a hold and grow in this area. Temperatures hovered well above freezing (warmer than the UK at the time) and the rain lashed down as we worked away on the exposed banks. In the short Austral summer, it gets just about warm and wet enough to permit vegetative growth in this part of the Antarctic Peninsula. The Polytrichum mosses at the surface of the moss banks might have the time and energy to grow by just a few millimetres each year before being frozen solid and covered in snow over the winter. The following year they will wake up and start all over again. By such small increments have enormous moss banks grown – on Elephant Island, a site perhaps more famed for its role in Shackleton’s ill-fated Endurance expedition in 1916, the moss banks are almost three metres deep!
Past climate archives
The moss banks we study are ideal archives for research into past climate. The plant material in them is well preserved through freezing in permafrost, so it can be dated easily using radiocarbon dating. They are dominated by just one or two species making results simpler to interpret and despite the seemingly slow growth rates, low levels of decomposition mean we can develop records with about one sample per decade – pretty high resolution for this type of study.
Cores of moss show rapid and unprecedented change over the past 50 years
By taking cores through the banks of moss, we can reconstruct temperature and precipitation rates through the last few centuries, long before the instrumental record. So far, we’ve been able to show that rapid changes in a moss bank located at the southernmost extent of moss growth on the Peninsula were coincident with the rapid temperature changes recorded over the past 50 years and unprecedented over the past 150 years. We continue to work on extending this context back further in time from our deeper cores.
A welcome splash of green moss
So next time you think about all the science taking place in Antarctica, spare a thought for the tiny proportion of this remarkable continent covered in hardy mosses, providing a welcome splash of green on an otherwise white canvas.
- Visit the project website here to find out more.
- Visit the Bogology website to find out more about peat and bogs and moss and climate change.
- Unlocking the Secrets of Antarctic Moss Banks (Planet Earth)
Turner, J., Bindschadler, R., Convey, P., di Prisco, G., Fahrbach, E., Gutt, J., Hodgson, D., Mayewski, P., and Summerhayes, C. 2009. Antarctic Climate Change and the Environment. Cambridge: Scientific Committee on Antarctic Research.
Royles, J., Amesbury, M. J., Convey, P., Griffiths, H., Hodgson, D. A., Leng, M. J. and Charman, D. J. 2013. Plants and soil microbes respond to recent warming on the Antarctic Peninsula. Current Biology 23, 1702-1706.
About the Author
Matt Amesbury is a Research Fellow at the University of Exeter. He is an expert testate amoebae analyst with broad interests in Holocene climate change and peatland palaeoecology. He is currently working on peat from New Zealand as well as moss banks in Antarctica. He is co-founder of the website Bogology which aims to share the science of peatlands and past climate change in a light-hearted and accessible way. He’d love you to visit him there.