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Tuesday 23 September 2014

The main impacts

Published 21/04/2014 | 02:30

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Mean annual temperatures have risen by 0.7C over the past century. They could rise by 1.4C to 1.8C by the 2050s, and to in excess of 2C by the end of the century – or even between 3C and 4C under a worst-case scenario.

Summer and autumn will warm faster than winter and spring. The midlands and east will warm more than coastal areas.

There is less certainty about rainfall, but during the winter volumes are projected to increase by 10pc by the 2050s. Corresponding reductions of 12pc – 17pc are also expected during the summer.

By 2080, winter rainfall will have increased by 11pc – 17pc, with summer reductions between 14pc and 25pc.

Lengthier heatwaves, a significant reduction in the number of frost days, longer rainfall events in winter and more intense downpours in the summer are projected.

Storm surges, coupled with sea-level rises, are likely to result in coastal flooding.

Ocean acidification

Increased levels of CO2 in the atmosphere means our oceans are becoming more acidic, with levels of the compound rising 30pc since the industrial revolution.

The impact is uncertain, but key species and habitats may be threatened with an impact felt in fisheries and aquaculture.

Among the species at risk include sea urchins, star fish, mussels, oysters and clams. In addition, juvenile fish could also be affected.

The Marine Institute puts the value of Irish aquaculture at some €105m a year. Losses could be as high as €9m.

Agriculture

Climate change could cost farmers as much as €2bn a year by the middle of the century due to pests, droughts and reduction in crop yields.

The role of regional rainfall and climate change was evident last year, when a poor growing season in 2012, combined with a long winter, resulted in a severe fodder shortage, a report for Stop Climate Chaos said.

Economic costs were estimated at €900m by the Irish Creamery Milk Suppliers Association.

The range of many insects will expand or change, fuelling concerns about the spread of Blue Tongue Virus in cattle and sheep.

Declining crop yields, flooding, and plant and animal stresses during extreme weather events also present problems.

Summer water shortages, especially in the east, may require crops to be irrigated.

In all, economic costs between €1bn and €2bn may arise although preventative adaptation measures will help reduce this bill substantially.

Humans/Animals

While milder winters will reduce cold-related mortality rates among the elderly and frail, this may be offset by increases due to heat stress during the summer.

Economic costs are likely to arise from more frequent flooding and storm events.

The early onset of spring may also affect birds and insect species, with leaf unfolding happening up to three weeks earlier today than 40 years ago.

Met Eireann says that butterflies are an ideal group for studying the effects of climate change because their life-cycle, activity, distribution and abundance are all affected by temperature. The earlier onset of spring poses problems for both butterflies and birds.

"If spring temperatures cause caterpillars to emerge before leaves have unfolded, many caterpillars will perish," Met Eireann said. "In addition, if birds arrive after the peak timing in availability of caterpillars, fewer chicks will survive and more leaves will be consumed by the herbivores."

European butterfly communities have shifted northwards during the period 1990-2008 by 114km. In Ireland, species including the Speckled Wood butterfly have expanded their range.

Migrant birds are arriving earlier, including the Whooper Swan. Changes will also affect fish species including cod, and could lead to the possible extinction of vulnerable species requiring cooler conditions – such as the Arctic char.

Irish Independent

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