The climate of an area is the average and variations of weather over long periods of time. For example, rainforests are found in tropical climates, where the weather is constantly warm and there are high levels of rainfall. A Mediterranean climate will usually have warm dry summers, and mild and wet winters. Some countries have mostly hot dry weather, experiencing what is called an arid or semi-arid climate.
Northern Ireland has a temperate climate, with mild winters and summers, and rain throughout much of the year. However, even in a small country like ours, there can be distinct local variations in weather, in particular when looking at rainfall. Where do you think the wettest and driest areas in the country are located?
Pupils from schools across Northern Ireland came together to hold an Eco-Schools Climate Change Summit at Parliament Buildings. On 14th February 2013, they shone a spotlight on the effects of climate change in Northern Ireland and across the globe. Young people in Northern Ireland are doing their part to tackle climate change through Eco-Schools projects including energy saving, reducing waste and developing school gardens. The event was a special occasion to address the issue of climate change and included schools presenting their findings on climate change issues in countries around the world through colourful presentations and innovative displays.
There is a blanket of gases surrounding the planet which helps keep the surface of the earth warm enough to sustain life. The gases in the atmosphere, including carbon dioxide, allow sunlight in but trap much of the heat. Were it not for this so-called ‘greenhouse effect', we would live on a much colder planet: the average surface temperature of the Earth would be -18°C. The presence of greenhouse gases in the atmosphere raises the Earth's temperature by 33ºC to its current surface average of 15ºC.
However, it must be remembered that the climate of the Earth has been changing consistently over its 5-billion-year history. Such changes in climate usually occurred very slowly over many thousands of years. They happened primarily as a result of the effects the sun, land, oceans and atmosphere have on each other.
Even in Northern Ireland, we do not have to go too far back in time to find a climate very different from today. The most recent ice-age in Ireland only took place between 30,000 years ago to about 14,000 years ago. Most of the area of this island was covered in ice, had sea levels 50m below today's levels, and was joined to Britain and mainland Europe. As the ice melted across Europe and the world, sea levels rose and we became an island once more. Even as recently as the 14th century, Europeans lived through what is known as the “Little Ice Age."
So why are we so worried about climate change, if it is something that occurs naturally and has happened throughout the history of the Earth? What impacts are we having through our lifestyles, and can we influence the situation?
The vital difference between the current period of global warming compared to previous cycles of climate change is how quickly the rate of change is happening. The planet has warmed by about 1°C over the past 100 years, and most scientists now agree that this is mainly as a result of the increasing amount of greenhouse gases (particularly CO2) released into the Earth's atmosphere from human activity.
As a result of the billions of tonnes of CO2 (and other greenhouse gases) released globally each year the blanket of gases in the atmosphere is trapping more heat inside, resulting in global warming and unpredictable weather patterns. As far back as 1967 the first reliable computer simulation calculated that global average temperature could increase by more than 4°C when the atmospheric CO2 levels reach double that of pre-industrial times. However, it is only relatively recently that the full extent of the dangers and possible effects of climate change have emerged.
Climate change has always occurred as a result of natural processes such as plate tectonics, volcanic activity, interactions between land, oceans and the atmosphere, as well as variations in sunlight intensity. However, it is believed that human activity has played a large part in recent changes in climate, particularly since the industrial revolution. Because of this the Earth has been subjected to increasing temperatures, melting of ice-caps and glaciers, rising sea levels, and unpredictable weather patterns.
Changes in climate resulting from human activity is not just a recent phenomenon. For thousands of years we have been cutting down trees both to use the wood for fuel and construction, and to develop land for agriculture. Fewer trees to absorb carbon dioxide will result in more CO2 building up in the atmosphere. There can even be a more direct effect, as is believed to have occurred in Greece and other Mediterranean countries over the last 2000 years. Widespread deforestation led to fewer trees absorbing the incoming sunlight, as well as greater soil erosion due to exposure. The modern climate is now significantly hotter and drier.
In more recent years, rising levels of greenhouse gases in the atmosphere, such as nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2) in particular, have been identified by scientists as the primary cause of global warming. Although CO2 levels have varied hugely over the last 600 million years, the current atmospheric concentration of CO2 was recently calculated at 379ppm (parts per million), compared to pre-industrial levels of just 280ppm.
Most of our emissions, CO2 in particular, come from the burning of fossil fuels such as coal, gas and oil. Fossil fuels are used primarily for transport, heating and electricity generation. Every time we turn on the radio or television, light a fire, or drive to the shops, we are contributing to the increase of CO2 in our atmosphere. Most of what we purchase will also lead to CO2 emission in some way, either as a result of its manufacture and packaging, or transport of the item, or both. This includes the purchase of tropical fruits and vegetables, or fruit and vegetables bought out of season, which may have been transported large distances to reach your kitchen.
Finally, other factors including livestock and cement manufacture play an important role in emissions of CO2 and other human-induced greenhouse gases such as nitrous oxide and methane.