Facing down the rising rivers

Predicting the future is notoriously difficult, but if the latest climate change projections are accurate, Ireland faces a greatly increased risk of flooding and damaging storms, writes Dick Ahlstrom

THE ANNUAL RATES of flooding along the Suir, Blackwater and other rivers are expected to double in the coming decade, and we can expect more storms similar to the hugely damaging Hurricane Charley, according to climate modelling data.

The predictions of what climate change might bring will form part of a public talk to be given in Dublin tomorrow by Prof Peter Lynch of University College Dublin’s Meteorology and Climate Centre. He will describe how the increasing sophistication of climate models means we can predict the future to see what climate change will mean for us all.

The Centre is within UCD’s school of mathematical sciences, and Prof Lynch’s is one of about 20 lectures taking place between now and June, a series organised by the university’s Earth Systems Institute. Set up over the past year, the institute pulls together expertise available on campus “in all areas of the Earth system”, Prof Lynch says.

It is hugely multidisciplinary, involving meteorologists and computer experts, but also engineers, health experts, economists, social and policy specialists and geoscientists. “It looks at how the changes are going to impact on the island of Ireland.”

Mostly, the information delivered by the models is not encouraging, Prof Lynch will tell his audience. There are also major uncertainties inherent in them which makes it particularly difficult to predict something wholly unexpected that might arise.

What is not in doubt is the reality of climate change, he says. “We know it is warming and will continue to warm, and CO2 is the central cause, the burning of fossil fuels.” It is warmer now than it has been for the past half a million years. “We are outside the range of natural variation.”

The latest modelling systems look at all aspects of the Earth system, from the atmosphere and the oceans to the forests, ice cover, land masses and cloud cover.

“We need to model the entire Earth system because there are interactions between them,” he says. “Cloud feedbacks are the largest uncertainty in the system. This really is a source of serious uncertainty.”

Some results remain alarmingly consistent, however, including a doubling of the flooding incidents seen on some of our river systems including the Suir and the Blackwater, he says. This is predicted with a relatively conservative 1.5 degree increase in average temperatures.

Higher sea water temperatures are also expected to bring more powerful and more frequent storms. “The intensity of storms will increase,” he says.

The 1986 visit of the remnants of Hurricane Charley caused significant damage in Ireland, and this type of event is going to be repeated in the future.

“The old patterns are being broken and there is evidence hurricanes are becoming more destructive,” he states.

The greatest fear relates to what he calls “unanticipated emergent phenomena”, which are “some new things we haven’t been able to predict at all”.

Some of these may arise due to a “positive feedback”, where a change serves to accelerate further change in a runaway reaction.

“The worrying thing about the climate system is there are a number of these feedbacks.”

The loss of reflective polar ice results in more dark earth and sea, which heat faster and thereby speed up further ice loss. Melting permafrost releases the greenhouse gas methane, which causes more atmospheric warming, which causes more melting. “It could be catastrophic,” Prof Lynch suggests.

These changes are akin to an asteroid strike, a low probability event that if it occurs carries enormous consequences.

“There is an unquantifiable risk of a catastrophic climate change,” he believes. “Being prudent is recognising the risk. We have got to reduce CO2 emissions to avoid a tipping point.”

We have also got to prepare policies to help us cope with the changes when – not if – they come.

The data delivered by Prof Lynch comes via the C4I, Community Climate Change Consortium for Ireland (www.c4i.ie). It has been able to make use of the huge computer power available from the Irish Centre for High-End Computing (www.ichec.ie), which supports Irish research activity.

Prof Lynch’s talk, Meteomaths: Calculating Ireland’s Warming Climate, takes place at 12.30pm tomorrow at the Royal College of Physicians of Ireland, 6 Kildare Street, Dublin 2. The lecture is free and open to the public and is designed for a non-specialist audience