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| Evidence | • | Changing Behaviour | • | Kyoto Protocol |
The climate of the Earth is always changing. In the past it has altered as a result of natural causes. Nowadays, however, the term climate change is generally used when referring to changes in our climate which have been identified since the early part of the 1900s.
Scientists have argued whether temperature rises are due to human activities or due to natural changes in our environment. In 2001, the Intergovernmental Panel on Climate Change (IPCC) announced that:
"most of the warming observed over the last 50 years is likely to be attributable to human activities".
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| Variations
in the Earth’s surface temperature, with respect to the average
between 1960 and 1990, is shown year by year since 1860 (red bars)
and approximately decade by decade (black line, a filtered annual
curve suppressing fluctuations below near decadal time-scales).
Over both the last 140 years and 100 years, the best estimate is
that the global average surface temperature has increased by 0.6
± 0.2°C (source: IPCC, 2001). |
The greenhouse effect is very important when we talk about climate change as it relates to the gases which keep the Earth warm. It is the extra greenhouse gases which humans have released which are thought to pose the strongest threat.
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 average sea level.
The IPCC's third assessment report (IPCC, 2001) predicts global temperature
rises by the end of the 21st century of between 1.4° C and 5.8° C The IPCC's
fourth assessment report (IPCC, 2007), eleven of the last twelve years
1995-2006) rank among the twelve warmest years in the instrumental record
of global surface temperature (since 1850). Although the issue of the
changing climate is very complex and some changes are uncertain,
temperature rises are expected to affect countries throughout the
World and have a knock-on effect with precipitation and sea level rises.
Many experts believe the faster the climate changes, the greater the
impacts will be.  |
Click here to view a map of weather stations. |
Key points - projections for climate change globally
- By the second half of the 21st century, wintertime precipitation in the northern mid to high latitudes and Antarctica will rise.
- By the same time, Australasia, Central America and southern Africa are likely to see decreases in winter precipitation.
- In the tropics, it's thought some land areas will see more rainfall and others will see less.
- It is thought that the West Antarctic ice sheet is unlikely to collapse this century. If it were to collapse, sea level rises would be enormous.
- Global average temperatures are predicted to rise by between 1.4° C and 5.8° C by 2100.
- Maximum and minimum temperatures are expected to rise.
- More hot days over land areas and fewer cold days and frost are expected.
- More intense precipitation events are forecast.
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Some of
the Sun’s energy, which reaches the Earth’s surface
heats it up. This heat energy is subsequently emitted from the surface,
as infrared radiation. When this encounters molecules like carbon
dioxide (CO2) and methane (CH4 ), which naturally
exist in the atmosphere, it is absorbed and re-emitted in all directions
and therefore most of it does not escape from the atmosphere. The
effect of this is to keep the Earth warmer than it would be if the
radiation escaped. This is similar to a greenhouse where the heat
cannot escape therefore keeping the environment warmer than outside.
However, as the amounts of CO2 and other greenhouse gases
in the atmosphere increases, more heat is trapped with the consequence
that the Earth’s average temperature is increasing.
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Climate Change in Ireland
The Environment Protection Agency's report (Sweeney et al., 2002) on climate change states that global trends have been largely replicated in Ireland, in which a warming episode from the first decade of the 20th century to the mid-1940s was followed by a cooling trend to the end of the 1970s. The 1990s have been the warmest decade in the Irish instrumental record. At present, Ireland appears to be warming by slightly over 0.25° C per decade. Globally, precipitation has been increasing by 0.5% per decade over the course of the 20th century and most global climate models predict winter increases and summer decreases for Britain and Ireland.
Much of the changes in temperature and precipitation appear related to the North Atlantic Oscillation (NAO), an index of the pressure difference between Iceland and Portugal. The close relationship between climate variables and the NAO suggests that quasi-cyclical changes in "westerliness" still exert a dominant control on year-to-year variations in many climatic parameters in Ireland and these may be masking some of the forcing due to human influences (Sweeney et al., 2002).
Scientists in Ireland and across the World are looking at the evidence of climate change and are also using computer models to come up with predictions for our future environment and weather.
More recent reports state that temperature and precipitation remain the two key climatic parameters showing indication of climate change in Ireland (EPA, 2009). The main findings are:
1. The mean annual temperature in Ireland has increased by 0.7°C between 1890 and 2004.
2. The average rate of increase is 0.06°C per decade. However, as Ireland experiences considerable climate variability, the trend is not linear. The highest decadal rate of increase has occurred since 1980, with a warming rate of 0.42°C per decade.
3. The warmest year on record was 1945, although 6 of the 10 warmest years have occurred since 1990.
4. An alteration of the temperature distribution has occurred, with a differential warming rate between maximum and minimum tempera- tures. Minimum temperatures are increasing more than maximum temperatures in spring, summer and autumn, while maximum tempera-tures are increasing more than minimum temperatures in winter.
5. There has been a reduction in the number of frost days and a shortening of the frost season length.
6. The annual precipitation has increased on the north and west coasts, with decreases or small increases in the south and east.
7. The wetter conditions on the west and north coastal regions appear due to increases in rainfall intensity and persistence.
8. There is an increase in precipitation events over 10 mm on the west coast with decreases on the east coast, there is an increase in the amount of rain per rain day on the west coast, and a greater increase in number of events greater than the 90th percentile also on the west coast.
We are likely to see a further increase in precipitation and sea level rises, possibly leading to more frequent flooding. As temperatures rise, the sea will absorb heat from the atmosphere, causing it to expand and therefore creating sea level rises. Glaciers may melt, producing enough water to raise sea levels by 5-6 metres. Major floods may now occur more frequently, the flood season may become longer and there will be flooding in places where there has never been any before.
Climate change may also affect our health (e.g. due to higher ultraviolet levels), and will require adaptations in ecological patterns and agricultural practices. On the other hand, there will also be some positives of climate change. For instance, our lifestyles could change dramatically as we could spend more time taking part in activities outdoors, leading to a more vibrant (with more employment) tourist industry in Ireland!
Changing our behaviour
In order to cope with the projected changes to the climate we need to change the way we live. Renewable energy is becoming increasingly popular as it is able to harness natural forces and does not emit greenhouse gases. Options include solar power, wind power, geothermal and water power. Nuclear power is also being considered again although the safe disposal of radioactive waste materials and the risks of potential accidents need to be addressed.
In our everyday lives we can make a difference by saving energy, for example, turning off the light when you leave the room, or only boiling the water you need when making a cuppa!
Policies - the Kyoto Protocol
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| Storms are expected to become stronger and more frequent (photo courtesy Irish Examiner). |
Climate change is a global problem that requires a global response. The most influential initiative to reduce greenhouse emissions is the Kyoto Protocol which became international law on 16th February 2005. The protocol iwhich is an addition to the United Nations Framework Convention for Climate Change legally binds those industrialised nations who sign up to the treaty to reduce worldwide emissions of greenhouse gases by an average of 5.2% below their 1990 levels by 2008-2012.
As of July 2006, 164 states and regional economic integration organizations accounting for approximately 62% of carbon dioxide emissions have ratified or are in the process of ratifying the agreement. However, countries like Australia and the U.S.A. have chosen not to ratify the protocol and developing countries have been exempted from it. The protocol is the first global legally binding contract to reduce greenhouse gases.
Individual countries have developed their own methods to meet their targets. The EU has recently created a market in carbon dioxide in which 12,000 factories and power stations have been given a carbon dioxide quota. If they exceed this amount they can purchase further extra allowances. If they fall below the amount they can sell the extra quota for financial gain. This emissions trading scheme is administered by the EPA in Ireland and by DEFRA in the United Kingdom.
In 2000 Ireland published its Climate Change Strategy (Dept. of Environment, 2000). As a response to the Kyoto Protocol the country aimed to limit growth in greenhouse gas emissions to 13% above the 1990 level. However, in a review of the strategy published in 2006 (Dept. of Environment, 2006), it was noted that emissions in 2004 had grown by 23% above the 1990 level. Many other Kyoto signatories are also falling behind their targets, and all are facing a difficult task to achieve their legal obligations.