Galway’s drowned forest shows climate change is nothing new

Prof Michael Williams of NUI Galway believes planning for an uncertain future is better than spending billions to ‘temporarily defer the inevitable’

Prof Michael Williams with some of the 7,500-year-old tree remains at a drowned forest site exposed by storms in Co Galway. Photograph: Joe O’Shaughnessy

Prof Michael Williams with some of the 7,500-year-old tree remains at a drowned forest site exposed by storms in Co Galway. Photograph: Joe O’Shaughnessy

Thu, Apr 17, 2014, 01:00

When Michael Williams, geology professor at NUI Galway, discovered evidence of a 7,500-year-old drowned forest on the northern shores of Galway Bay, he couldn’t have anticipated the huge public response.

Over the last few weeks, low tide has lured hundreds of people out to view, photograph and play around the prehistoric tree stumps with their extensive root systems, which Prof Williams knew to be there and which were exposed in dramatic fashion by this year’s storms on the west coast. A track revealed below the peatline suggests human habitation and adaptation to sea level rise up to 4,500 years ago.

Even as the debate continues as to whether the recent extreme weather is direct evidence of climate change, the transformation of such forests and lagoons into what we now recognise as Galway Bay many thousands of years ago is evidence that such change is nothing new, contends Prof Williams.

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The most recent UN Intergovernmental Panel on Climate Change (IPCC) study, released in late March, found that the effects are already being felt on global food supplies, and contributing to the frequency of natural disasters and conflict. It has also highlighted the ill-preparedness of governments. However, Prof Williams believes we have learned to adapt to such change in the past, and such adaptation has influenced human evolution.

“That forest drowned because of weather,” he says. “It was flourishing 5,000 years ago and then the climate in the north Atlantic changed. It became cooler and wetter, and the sea level began to rise. The forest floor became carpeted in reeds, including phragmites, which we can still see traces of, and which can tolerate semi-saline conditions.”

Prof Williams estimates that sea level would have been at least five metres lower than it is now, and the forest floor eventually succumbed to rain and rising sea. And so, the Neolithic people living off the lagoons and forests, among bears and wolves, had to move. This is because, he says, the Earth behaves in cycles, with climate change an integral part of this.

“What would the Earth be like if the climate never changed, if temperatures remained the same all over the planet, sea levels never rose or fell, carbon-dioxide levels in the atmosphere remained constant?” he asks.

“This is impossible, because of the way the crust of the Earth moves according to the model of plate tectonics. When the plates that make up the crust of the Earth collide, this generates volcanoes, which, if on a large enough scale, can affect the climate.

“For example, the eruption of Krakatoa in 1883 reduced global temperatures by over one degree, and it took another five years for climate to return to normal. This was not a super large volcano by geological standards. All the plates of the crust are in constant motion, so parts drift north or south into warmer or colder climates.”

Some would argue that human evolution “would not have even begun were it not for climate change”, says Prof Williams. “Africa suffered increased aridity at various times over the past couple of hundred thousand years, which led to changes in lifestyle from tree-dwelling apes to grassland-living hominids.

“Not only is climate change inevitable, but if we examine past climates which have existed on Earth, we see that at present the Earth is cooler, sea levels are lower and atmospheric levels of carbon dioxide are less than they have been for most of Earth history, “ he says, reviewing some “snapshots in deep time” (see panel).

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