Impact of climate change

Climate and weather

We are learning how to:

• explain climate change in terms of human activity

• consider the impact of climate change.

Climate and weather are different things and should not be confused. The weather is about what is happening now at a particular place. We might describe the weather in Kingston today as wet or dry, warm or cold, windy or calm.

The climate is concerned with weather conditions over a long period of time in a large area. It is more general and gives a more overall picture. When we say that the climate in Jamaica is generally warm and sunny this doesn’t refer to a particular day but to most days.

Climate change

Although we might say that the climate in an area is warm and dry in the summer and cold and wet in the winter this doesn’t mean that every summer day is equally warm and dry and every winter day is equally cold and wet.

You might have heard people say things like ‘last summer was hotter than usual’ or ‘there wasn’t much rain last winter’. Within any area there are natural fluctuations in the climate. When global warming and climate change was first suggested not all scientists were convinced that the greenhouse effect was to blame. They argued that what countries were experiencing was simply natural variation. The situation has now become clearer and most scientists accept that global warming is responsible for unseasonal weather conditions that have affected large areas of the world over the past decade.

In 2012, a study of the climate in Jamaica found that the frequency of warm days, warm nights and extreme high temperatures had increased while there were fewer cool days, cool nights and extreme low temperatures. In other parts of the world, the climate change has been far more dramatic. Here is an example.

Glaciers are found near the tops of high mountains or at the Earth’s poles where it is very cold. They are sometimes described as rivers of ice. Snow accumulates over time, continually forming huge sheets of ice that flow very slowly down the mountain. The top of the glacier is continually replenished while the bottom will eventually melt as it warms up.

Global warming has accelerated the rate with which glaciers are melting all around the world. At first glance this might seems a good thing since it releases lots of fresh water into the environment. However, this also causes problems.

• Valleys into which glaciers flow have now become lakes and local environments have been lost.

• Where the water flows out to sea, the salinity decreases, which affects marine organisms.

• The level of the sea is rising, which affects low-lying countries like the Maldives in the Indian Ocean.

Activity 8.5.1

How might climate change in Jamaica affect my life? Your teacher will organise the class into small groups for this activity.

Within your group discuss how you think your life might be affected if there are long-term climate changes in the Caribbean. You might consider:

Advantages like: more sunlight = more electricity from solar power plants

Disadvantages like: less rain = more expensive vegetables and fruits

Check your understanding

1. The following pictures show the Muir Glacier in Alaska, USA in two different years.

Fun fact

On the planet Venus, the greenhouse effect traps so much heat energy that the average surface temperature is 462 °C.

a) How many years passed between the two pictures?

b) What is the main change that can be seen in the pictures?

c) Suggest a reason for this change.

Key terms

climate conditions like average temperature, average rainfall over an area over a long period of time weather local conditions on a day like temperature, amount of rainfall, wind direction glacier extremely large mass of ice which moves very slowly, often down a mountain valley