The science of global warming is complicated. We’ll try to keep it simple.

Part of the planet’s atmosphere – not much, only about one percent – is made up of gases known as greenhouse gases. Sunlight passes through the atmosphere and then reflects off the earth’s surface in the form of heat. If you want to sound like a scientist, you could call this heat “infrared radiation”. Greenhouse gases keep some of this heat from escaping into space. They act like the glass roof on a – you guessed it! – a greenhouse!

If there were no greenhouse gases, the Earth would be a cold, lifeless place. So come on, everybody, let’s hear it for greenhouse gases!

But hang on a second. Ever heard of having too much of a good thing? Well, that’s the situation we’ve got on our hands now.

For the past 150 years, as industries have grown, greenhouse gases have been pumped into the atmosphere in huge quantities. Now they are trapping a lot more heat than they used to. That’s why temperatures in our big global greenhouse are going up.

What are the major greenhouse gases?

The most important greenhouse gas is water. Yes, that’s right, good old H2O. Industrialization hasn’t added much water to the atmosphere. But as the planet heats up, more water evaporates and enters the atmosphere. This makes things hotter, which means more water evaporates. It’s a vicious circle.

The major greenhouse gas that has been produced by humans is carbon dioxide. Carbon dioxide is created when we burn things, especially fuels like coal, natural gas and oil. Because these fuels were made millions of years ago, they are often called “fossil fuels”. And because it took millions of years to produce them, we can safely say we won’t be able to make more any time soon. That’s why they are known as non-renewable energy sources.

OK, now get this: industry spews about 6.3 billion tonnes of carbon dioxide into the atmosphere every year. That’s the equivalent of 19 thousand Empire State Buildings.

Carbon dioxide is also released when we change the way we use the land. One of the most drastic ways we are changing the world’s landscape is by clearing forests.

Deforestation releases at least a billion tonnes of carbon dioxide into the atmosphere every year. We’ll do the math for you: that’s about 3 thousand Empire State Buildings.

Protecting forests helps reduce the amount of carbon dioxide entering the atmosphere. What’s more, forests absorb carbon dioxide from the air. They act as a giant carbon dioxide sink. This process is called “carbon sequestration”. Drop that term into a conversation and impress your friends.

Find out more about forestry and global warming.

Methane and nitrous oxide are the other main greenhouse gases. Agriculture releases significant amounts of theses gases into the atmosphere. Find out more about agriculture and global warming.

What’s going to happen?

The truth is we don’t know exactly what is going to happen as Planet Earth heats up. But here are some things the scientists are predicting might happen as a result of global warming:

• more severe storms and floods along the world's increasingly crowded coastlines are likely
• in sub-Saharan Africa, agricultural yields will decrease dramatically even with minimal increases in temperature;
• salt water from rising sea levels will reduce the quality and quantity of freshwater supplies
• most of the world's endangered species – some 25 per cent of mammals and 12 per cent of birds – may become extinct
• higher temperatures are expected to expand the geographic range of some dangerous diseases, such as malaria.

It is the poorer nations of the world that will feel impact of climate change the most. This is unfair because it is industrialized countries in North America and Western Europe, along with a few others, that are responsible for most of the greenhouse gas emissions.

And here’s more bad news: global warming’s not going away any time soon. After 150 years of industrialization, global warming has picked up a good head of steam. It’s going to affect the planet for hundreds of years, even if we do manage to reduce greenhouse gas emissions.

That doesn’t mean we should give up hope and do nothing. The exact opposite is true. Global warming has become a fact of life that affects all of us. We must learn more about it, find ways of controlling it and reducing the damage it may cause.