One reason for climate change is the increase in carbon dioxide in the air giving us a greenhouse effect called global warming.

Green plants taken in carbon dioxide and give out oxygen when they are in light. The result is a building block containing carbon for growing. Plants are the basis for virtually all the food we eat. Unfortunately, we recycle the carbon in our food very quickly into the air as carbon dioxide when we breathe out.

Trees are plants that make wood so they can be tall and live a long time. Wood has a lot of carbon in it and so trees are a store for the carbon they took from the air. If there were no trees on planet earth global warming would happen much faster.

In the natural way of things trees die and rot and the carbon in them goes back into the air as carbon dioxide, so in the long term they don't affect global warming, but this assumes that we keep the number of trees the same. Things are different, worse, if we prevent them growing again or, better, if we allow trees to grow where they didn't before.

One reason for growing trees is so that we can use the wood in them. If we keep the wood we use a long time it means the carbon in them does not get back into the air so quickly. For more than 200 years Nelson's flagship, HMS Victory, has helped save the planet from global warming by locking up carbon in its timbers. The more we make and keep wood in ships, furniture, books and buildings, the more we delay the time when carbon gets back to the air, and the more we slow down global warming and resist the bad things we expect from climate change.