The Earth’s Climate Change Presented by Musketeer Fionnuala Fox.

The Earth’s climate has always been changing.

 

However, for at least 100 years we have been aware of a serious problem with the way our activities on earth may be affecting the climate. Swedish scientist Svente Arrhenius first raised the issue in 1895, and since then Climate change has now become accepted as possibly the most serious threat mankind has to face.

Tackling climate change is urgent – not only the causes of climate change, but also the effects it will have on our society.

So that we can understand the nature of climate change fully, we will look at three terms which are used when discussing the subject: Climate Change, Global Warming and the Greenhouse Effect.

 

CLIMATE CHANGE

Weather

The weather is the changing conditions we see from day to day – in any given week (especially here in Northern Ireland!) we may see nearly all types of weather – sun, rain, wind, dry spells, warmth and cold.

Climate

Climate, on the other hand, is like a ‘weather average’. Climate is usually based on long term weather records, over 30 years, for example. Climate records could tell us that the average temperature in 2002 in Northern Ireland was 10.2°C, although there would have been many days above or below this temperature.

Climate tells us the average weather conditions we can expect in a particular place at a certain time of the year. You will even have some knowledge of climate – why do temperatures differ between Summer and Winter in Northern Ireland?

Climate Change

Climate is associated with ‘averages’. We know what the climate is like in Northern Ireland, so we know what weather to expect each year.

Question: Do banana trees grow outdoors in Northern Ireland?

Of course, the answer is no – it is not hot and sunny enough here to grow banana trees. In other words, the climate is not suitable. Everything we know about the climate is based on how weather has been in the past.

But weather records, particularly from the 1970s until the present, have been showing something unexpected. The average weather conditions seem to be steadily changing. This is Climate Change.

Weather records have been kept at Armagh Observatory since 1840. In 164 years of weather records, five of the warmest years have occurred since 1990!

‘Climate Change’ refers to the rapid change in local weather patterns which are taking place around the whole world. Right at the beginning of this post I said that Earth’s climate has always been changing – but it is now changing at a faster rate than it has ever done in the past. What is causing this change?

Global Warming

This is a term which describes how the earth’s atmosphere is warming. It suggests that we will have higher temperatures. However, we now prefer to talk in terms of ‘climate change’ – because warmer temperatures are only one type of weather change we will see. There are other ways in which the climate will change – summers will be drier, and winters more stormy and wet.

Greenhouse Effect

In a greenhouse, sunlight comes in through the glass and heats the contents, which then radiate infra-red energy back. Some of this infra-red energy cannot escape through the glass and stays trapped inside the greenhouse, so the temperature climbs – even on a dull day, you’d be surprised how warm it can be!

This is the so-called ‘Greenhouse Effect’. It describes how a closed system heats up by allowing more of the sun’s energy to enter than it lets escape.

Most of our atmosphere is nitrogen and oxygen, but a small amount of greenhouse gases (GHGs) is also present. The most important of these is carbon dioxide. GHGs ‘trap’ some of the infra-red radiation, so they act as a blanket, and keep the earth about 20°C warmer than it would be without them.

Since the Industrial Revolution, man has been burning increasing amounts of fossil fuels like coal, oil and gas. This burning is needed to power our cars, produce our electricity, keep our homes warm and manufacture our goods. A main product of burning fossil fuels is carbon dioxide, which we know is a greenhouse gas. We are increasing the amount of this gas in the atmosphere, so we are making the ‘blanket’ in our atmosphere thicker.

As we produce more carbon dioxide, less heat is able to escape and the Earth becomes warmer. This is man-made global warming, and it is causing climate change.

Other greenhouse gases

Carbon dioxide is only one of the greenhouse gases (GHGs) which humans are responsible for in the atmosphere.

Some GHGs are extremely powerful at trapping heat (for example sulphur hexafluoride is 23,900 times better than carbon dioxide). Also, some GHGs persist in the atmosphere for much longer (some perfluorocarbons can last 50,000 years in the atmosphere). However, carbon dioxide is the main contributor to climate change, due to the sheer volume which is emitted by burning fossil fuels. The next most important GHGs are methane and nitrous oxide.

Carbon dioxide levels appear to have varied by less than 10% during the 10,000 years before industrialization. Since 1800 all 3 main greenhouse gases have risen by at least 30%. However, scientists agree that even if emissions of greenhouse gases are stabilised or reduced now, we will still see the effects of climate change due to past emissions. Scientists believe that these increasing levels of greenhouse gases in our atmosphere have led to the global temperature increases seen in the late 20th century, particularly since 1970.

Scientific knowledge of climate change and the greenhouse effect has helped to inform governments across the world. Industrialized countries signed up to an international agreement – The Kyoto Protocol – which says they will try to limit the amount of greenhouse gases they emit into the atmosphere.

How can countries limit the amount of greenhouse gas they produce? Carbon dioxide is the largest contributor to global warming. Some ways in which governments are trying to reduce emissions involve:

– Energy efficiency – if less energy is used, less fossil fuels have to be burnt, and less CO2 is produced.

– Renewable energy – energy sources like wind and wave power do not produce any emissions.

– Emissions trading – a scheme which encourages large power generators to cut emissions.

Till Next Time

Fionnuala

Musketeer Fionnuala Fox

1 Comment

  1. April 5, 2010 at 9:43 pm

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