What's the fuss about climate change? Your questions answered
World leaders from 195 countries are in Paris to try to find a way to tackle climate change.
The meeting is hoping to agree a fixed target on reducing man-made gasses that scientists say cause extreme weather.
Paris is described as a "turning point" but it's leaving many people with a lot of questions.
We've spoken to Ellie Highwood, professor of climate physics at the University of Reading, for some climate change straight talking.
What problems can climate change cause?
Generally a warmer world. We have got changes to weather patterns, some places that are already dry get less rainfall and other places get wetter.
Is it definitely caused by humans?
The facts are very clear. Humans are changing the climate by burning fossil fuels.
Carbon dioxide levels are higher now than they have been for three million years.
The human race has never had to deal with this before.
Global warming is a compete hoax! Ice caps have got bigger. When are we going to hear the truth?
It might be easier to say the scientists have got their sums wrong but we just haven't.
Ice caps do change from year to year but if you look at the long-term trends then they are going down.
All the facts show the world is heating and most of the warming has been caused by humans. The science also shows us that we can still do something about it by reducing greenhouse gas emissions.
What do leaders need to change?
They need to agree a legally binding set of reductions in greenhouse gas emissions.
If it is not legally binding and doesn't include the whole world then it is going to be a struggle to get it right.
Is this trivial compared to the threat of terrorism?
Terrorism does seem like a bigger problem right now.
However, a big change to the climate could mean there is less food and water.
Then people will fight over that and there will be more wars over food, water and land.
Could we cut emissions by not flying leaders from all round the world and use the internet instead?
People still have to travel and for these kind of detailed negotiations face to face is really important.
We shouldn't feel guilty for going on a plane or going on holiday but all of us can make better use of technology like Skype.
Should we eat less meat?
Eating meat does have an impact on the environment and if everyone around the world ate as much as we do in Britain, it would be even worse.
As individuals we can make greener choices, for example eating locally produced food.
A big part of the problem is transporting the food around the world.
What can we do on a practical level?
Not use you car so much. You could walk or cycle more.
You can make sure you use less energy by doing simple things like switching lights off.
They do make a difference. They seem like small everyday things but they make a big difference.