Paris climate talks: Why all the fuss over 2 measly degrees?

As leaders from about 150countries around the world gather in Paris for the next two weeks, they have already agreedon one point: Global average temperatures must not be allowed to rise more than 2 C over the averages of the pre-industrial era.

• Paris climate summit opens with offers to help developing nations cope, adapt
• How a 2 C temperature increase could change the planet
• What do you expect from the Paris climate change summit?

The questionthat remains for world leaders is: how?

The question for most other people is: why?

Two degrees may not seem like much of a change in a country with places that routinely experiencetemperature swings from 30 C in one seasondown to 30 C just a few months later but we are talking about the average for the entire globe.

And that means it's a change that will be felt in the air, onlandand inthe water.

Watch the video above or hereto see how and why two degrees matters.

Effects of temperature change