Climate change

See the EPA lecture series for presentations and discussions of many of the issues raised in the sections below.

Yes, climate change is real. The scientific evidence is unequivocal. According to the Intergovernmental Panel on Climate Change (IPCC) Report, 2007 most of the observed increase in globally averaged temperatures since the mid-twentieth century is very like due to the observed increase in anthropogenic greenhouse concentrations (very likely equates to 90% probability in this context). If these emissions are not reduced they will have potentially catastrophic, worldwide effects.

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Are future climate projections accurate?

Future global climate projections are based on the best information that is available at the moment. There are some differences in the modelling techniques employed by different climatologists, but their findings are broadly consistent. The reliability of these models is always increasing as technology becomes more and more advanced.

Significant difficulties exist in translating the global findings to the regional and local scale i.e. how climate change will impact on a national or local scale. Much work is ongoing to help provide more accurate information to identify local risks and to allow planning for local adaptation.

For detailed information about different climate models see:

Climate Models and Their Evaluation

Implementation of the Global Climate Observing System in Ireland

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What about natural carbon sinks?

There are two major natural sinks that facilitate the removal of CO₂ from the atmosphere: oceans and forests.

It is interesting to note that experts believe that up to 50% of the CO₂ emitted to the atmosphere by the burning of fossil fuels since the beginning of the Industrial Revolution have been removed from the atmosphere by the oceans. Without this natural sink we would be in a far more serious position now. Unfortunately, in recent years, strong evidence has emerged that the ocean's capacity to remove additional CO₂ from the atmosphere is reducing. If this proves to be the case, then the rate at which CO₂ concentrations is increasing in the atmosphere will accelerate, with more of the emitted CO₂ we put into the atmosphere staying in the atmosphere causing increased or accelerated climate change.

The forests of the world store an enormous amount of carbon. With deforestation, much of this carbon is effectively released to the atmosphere as CO₂, (either through burning or decay); only a small fraction remains for a significant length of time as timber. Reforestation, that is the replanting of old forest, and afforestation, that is the planting of new forest, both offer opportunities at a global and national scale to reverse the trend and remove additional CO₂ from the atmosphere. Protection and sustainable management of existing forests, worldwide, are required to keep this vast store of carbon intact.

The soil acts as a third very important natural store of carbon, both globally and nationally. In Ireland, some 90% of the stored carbon resides in the soil, including peat. The rest is in biomass, especially forest and grass. Soil carbon is threatened when the surface of the soil is disturbed, and air can penetrate deeper into the soil than is normal. Soil management may become an increasing part of the effort to reduce CO₂ in the atmosphere.

However, the balance maintained by this complex cycle of carbon sinks is easily upset. In a warmer world, for example, the oceans are less efficient in absorbing CO₂. Planting more forests may help to offset some of the CO₂ produced by the burning of fossil fuels. But, realistically, this on its own will not solve the problem.

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Is this not a natural progression, climate has varied over the ages?

Although it is true that there are natural processes, which lead to very significant climate change, the evidence indicates that these known processes are not responsible for the rate of climate change we have experienced in recent decades. The new driver for climate change is anthropogenic emissions of GHGs. This has been superimposed on the natural cycle of climate variatility, leading to a rate of climate change which has not occurred at any other time in recent geological history.

For more check out the EPA lecture series.

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What evidence is there?

Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level.

Ice cores, sediment cores, corals, fossil records and other techniques such as palynology are some of the sources of evidence for past climate change.

Palaeoclimate information supports the interpretation that the warmth of the last half-century is unusual in at least the previous 1300 years.

Working Group 1 of the IPCC Fourth Assessment Report analyses the human and natural drivers of climate change.. This report builds on information gathered and researched from the previous six years. It offers a concise review of the evidence and reliability of information related to climate change.

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Are we taking global volcanic activity into account?

Yes. Global volcanic activity is taken into account. Large volcanic eruptions (e.g. the 1991 eruption of Mount Pinatubo in the Philippines) inject a massive amount of aerosol material into the upper atmosphere. Volcanic eruptions of this magnitude can result in significant global cooling for 1 to 2 years until these aerosols are removed from the atmosphere. These events are very sporadic and do not have a long-term impact on climate.

Is the North Atlantic heat conveyor at risk of stopping due to climate change?

The “switching off” of the North Atlantic heat conveyor is a type of phenomenon listed as a low probability, high-risk event. An asteroid striking the Earth is another example. Other climate related examples include the loss of the Greenland and Antarctic Ice Sheets, major disruption of the El Niño, La Niña processes, as well as disruption to other ocean currents. These events are very unlikely, and most modelling groups cannot simulate any realistic scenarios which might lead to such events. However, if such events were to occur (and we do know they have happened in the past) then the consequences would be catastrophic. Therefore, in short, there is a chance of a catastrophic event of this type, but the risk is considered to be very small. They attract the attention of headline writers because a disaster makes better “news”.

See Chapter 5 of the IPCC 4th Assessment Report (page 396 discusses some of these issues).

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What is the Intergovernmental Panel on Climate Change?

The Intergovernmental Panel on Climate Change (IPCC) is the scientific governmental body set up in 1988 by the World Meteorological Organisation ( WMO ) and the United Nations Environmental Programme (UNEP).

The aim of the IPCC is to be an objective source of information about the causes of climate change, its potential environmental and socio-economic consequences and the adaptation and mitigation options to respond to it.

The information provided by the IPCC is based on material that is published in peer-reviewed scientific literature. Its reports are based on scientific analysis and reflect the viewpoints existing within the scientific community. The comprehensiveness of the scientific content is achieved through contributions from experts in all regions of the world and all relevant disciplines. Its reports are subject to a two-stage review process by experts and governments.

Because of its intergovernmental nature, the IPCC is able to provide scientific technical and socio-economic information in a policy-relevant but policy neutral way to decision makers. When governments accept the IPCC reports and approve their 'Summary for Policymakers', they acknowledge the legitimacy of their scientific content. Find out more about the IPCC.

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What is the UNFCCC?

The United Nations Framework Convention on Climate Change (UNFCCC) was established by world governments in 1992. The UNFCCC provides an overall framework for development of international actions to address climate change. The objective of the UNFCCC is to stabilise atmospheric greenhouse gases at a level that would prevent dangerous human interference with the climate system. However, the convention did not identify what constituted dangerous climate change or how it might be prevented. See www.unfccc.de for further details.

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What are the likely impacts for Ireland?

Significant changes are expected in the Irish climate in the coming decades. The impacts will be diverse and vary regionally. Some regions for example, will suffer more than others through exposure to extreme weather events, drought, disease or rising sea levels.

While there may be some benefits (e.g. through warmer winters or increased crop yields) the overall effects are estimated to be highly negative and will have major social, economic and environmental implications. The possible impacts of climate change are unpredictable, diverse and subject to continued scientific study. The links below give more information on the likely impacts for Ireland :

'Ireland in a Warmer World' (Met Éireann)

'Climate Change, Scenarios and Impacts for Ireland' (EPA)

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What are the impacts for Irish agriculture?

There is a close relationship between agricultural systems and climate. For this reason, agriculture in Ireland will be impacted as our climate changes. No catastrophic effects are predicted for Irish agriculture in the shorter term; indeed some initial benefits may even accrue due to the projected increase in temperature and lengthening of the growing season.

Increased winter rainfall will cause increased run-off from agricultural lands and may increase, for example, nitrate impacts on sensitive ecosystems and receiving waters. Drought stress may occur if prolonged dry spells occur during the summer months as is projected in certain climate scenarios. These may impact on yields. The capacity of agricultural systems to adapt to environmental and other changes is recognised e.g. though introduction of new crops. Hence, if the extent of climate change is limited though effective international agreement and actions then the most adverse impacts can be avoided. We can cope with many of these changes by changing the crops we grow and through farm management. See 'Climate Change, Scenarios and Impacts for Ireland', (Sweeney et al, 2003). (Pages 44/45 for the likely impacts on our crops).

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What are the impacts for Ireland 's biodiversity?

In Ireland , climate change is predicted to lead to warmer and drier summers, milder and wetter winters and an increase in the frequency of extreme weather events. Such climatic changes will disrupt Irish wildlife and our natural environment.

· Warmer weather may lead to changes in the life cycles of insects, birds, plants and mammals

· Changes in weather patterns could lead to behavioural change in pests and pollinators and disturb the delicate balance that exists in the wild

· In the Irish marine environment, some species may suffer including kelp, barnacles and starfish, while others such as cuttlefish and purple sea urchin may thrive more in the changed climate

· Climate change may also bring changes in the distribution and abundance of invasive species

Evidence of changing life cycles has already been seen in the international migratory patterns of birds and some insects. For example, the Little Egret, commonly found in Mediterranean Europe, is now a regular visitor in Irish coastal ecosystems

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