Our planet is surrounded by a blanket of gases which keeps the surface of the earth warm and able to sustain life - this is called the greenhouse effect and it's a natural process.
The difference now, though, is that we, rather than nature, are increasing the level of those greenhouse gases, especially carbon-dioxide. So, the blanket is getting thicker, trapping in heat -
that's global warming. As a result, our climate is starting to change.
A warmer climate? Here in the north, that sounds like a good thing. Global warming though, may lead to a warmer climate, but it would also bring unpredictable and extreme weather.
This, in turn, could affect almost every aspect of our lives from our homes and gardens, to our food and water; from the way we get around, to our work and leisure. And, of course, our countryside, parks, rivers, trees and wildlife will be affected too.
What causes climate change?
There is now such strong evidence that all but a few scientists believe it's humans who are making the climate change, rather than nature.
By burning fossil fuels like coal, oil, gas, petrol and diesel to make electricity, to power our transport and to keep industry running, we release billions of tonnes of carbon-dioxide into the atmosphere every year. And carbon-dioxide is the main greenhouse gas.
We've cut down forests to develop land for agriculture too. With fewer trees to absorb carbon-dioxide, the gas builds up in the atmosphere. The farming that replaces the forests can be a source of greenhouse gas as well.
And other greenhouse gases - including methane, which is produced by landfill sites and rice paddies.
In fact, concentrations of greenhouse gases are now higher than at any point in the past 800,000 years - something entirely new in human history.
How are we, here in Calderdale, adding to those greenhouse gases? Click here to find out more >
What will climate change actually mean? Click here to find out >
