Analysis: Climate archives allow scientists to visualise the worst and best case scenarios for Ireland's future in seven generations' time
By Jennifer McElwain, Gordon Bromley, Patrick Orr and Sean Jordan, iCRAG
What will Ireland look and feel like 150 years from now? In the year 2174 there will be about seven generations linking you to your future relatives. Maybe getting your head around the future would be easier if we could find a good analogy for time. Consider your family tree – if you trace it back about seven generations into the past, you will end up with your great-great-great-grandparents somewhere in the mid-1800s.
As scientists we seek evidence to answer the question: What will Ireland’s climate look like in 150 years? We gain insight into what the future may bring by looking at what has happened in Ireland’s past. In a way, we reconstruct the family tree of Ireland’s past landscapes and climate - how we got to today from what happened before.
Ireland contains extraordinary archives of past climate locked up in our rocks, peatlands, and lake and ocean sediments. They allow scientists to reconstruct how the seasons changed in the past. But much of this trove of climate information remains underused. We need to double our efforts to extract this paleo-climate information to make it useful for climate policy today.
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The Island of Ireland has well over 400 million years of past climate information stored up under our feet and at the bottom of our seas. Around 55 million years ago if you were to stand on the headlands of the Antrim coast, where the Giant's Causeway is today, you would find yourself surrounded by giant palm trees and water storing Baobabs (those funny upside down looking trees in the Madagascar film), in a much hotter climate than today. Forests extended right up to within the Arctic circle, in an atmosphere that had nearly double the amount of heat trapping carbon dioxide than today. It was simply too warm in the Arctic and Antarctic for snow to freeze.
Around 25 million years ago swamps were extensive in Ireland, particularly around Lough Neagh. These swamps were unlike anything we have today in Ireland – they were not bogs or peatlands, but oozy wet bayous like those of the Mississippi delta around New Orleans, with 30-meter-tall swamp cypress trees living in deep floodwaters. You would need a boat to travel through the swamps.
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At this time, ice sheets had formed across the Antarctic, but not the Arctic, and sea levels had dropped and were beginning to reveal more familiar shorelines of the Irish coast. These Irish swamp forests existed until sometime between five and 2.5 million years ago, when they are last recorded from Galway.
More recent climate archives – those of the past 2.6 million years – provide us with much more prescient information on Ireland's climate and, importantly, on the factors which cause climate change and its cascading impacts. Studies of peatland, cave, and ocean sediments tell just how unprecedentedly fast the rate of current climate change is. They provide evidence for the role of ocean currents and prevailing wind direction in Irish climate change and demonstrate how ice sheet melting influenced the rate of sea level rise and coastal erosion.
Read more: What historical records tell us about changing climate in Ireland
The most detailed and well-studied climate archives allow us as scientists to visualise the worst and best case scenarios for Ireland’s climate future in seven generations' time. These are the data used in the computer models used to predict our future climate. As geoscientists we are used to thinking in the long-term. We know that carbon dioxide levels are currently higher than at any other time over the past 14 million years. We understand that we are hurtling towards ever higher greenhouse gas levels and ever higher ocean temperatures, like those that existed when swamp forests fringed the Irish coast and sea temperatures off Cork were 11°C warmer than today.
Most future climate model projections are for a substantially hotter Irish climate, but they cannot predict all the details. Will it be warmer all year round or will we be subjected to a climate of seasonal extremes with much hotter summers and frigid winters that will require us to drastically adapt infrastructure, agriculture and everyday life? And how rapidly will these climate shifts happen? These are vital considerations for climate adaptation policy and the livelihoods of future generations.
Ireland’s palaeoclimate archives and the scientists who study them can help us answer these questions and allow us to better visualise that future. Forewarned is forearmed.
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Professor Jennifer McElwain is a paleobotanist and PI in iCRAG, the Science Foundation Ireland Research Centre in Applied Geosciences. She holds the 1711 Chair of Botany at Trinity College Dublin where she is also the Director of Trinity College Botanic Garden. Dr Gordon Bromley is a geomorphologist based at the University of Galway, where he leads geologic research on abrupt climate change. He is a FI in iCRAG.
Dr Patrick Orr is a geologist interested in the geological record of past ecosystems. He is an FI in iCRAG and a faculty member of the School of Earth Sciences at University College Dublin. Dr Seán Jordan is a biogeochemist and astrobiologist focused on the origin and evolution of life on Earth. He is an FI in iCRAG, PI of the ProtoSigns Lab in Dublin City University, a faculty member of the School of Chemical Sciences in DCU, and a member of the Life Sciences Institute in DCU.
The views expressed here are those of the author and do not represent or reflect the views of RTÉ
