The man in seat 17B calls calls the air hostess.

17B
I'd like to nip outside for a breath of fresh air.

AIR HOSTESS
You can't go out dressed like that, it is minus fifty out there.

17B
Do I need a hat?

The Atmosphere

The atmosphere is the blanket of gas that surrounds our planet.

By observing the temperature of the atmosphere, scientists have identified five seperate layers.

From the ground up, these layers are called the troposphere, stratosphere, mesosphere, thermosphere and exosphere.

The first two layers are important for the story about air travel and climate change.

The Troposphere

The lower level of the atmosphere, the troposphere, extends from ground up to 10 to 13 kilometres.

The troposphere contains over 75% of all the gas in the atmosphere plus water and dust.

Most of the weather is found in the troposphere and this is the part of the atmosphere that is heating up due to global warming.

The Stratosphere

Above the troposphere is the stratosphere a very cold and dry place where the airliners cruise.

About two hundred thousand people can be found in the stratosphere at any one time, sitting on airliners.

The only people above them are astronauts.

Some clouds form in the stratosphere including the cirrus clouds shown here.

Radiative Forcing Index

The stratosphere is very cold, and the hot gases from jet engine exhaust behave differently up here than closer to the ground.

In particular, they have an increased warming effect up to five times greater than equivalent emissions released at ground level.

This increase in warming is referred to as the Radiative Forcing Index (RFI) and My Clean Sky recommends using a RFI value of 1.9.

My Clean Sky Carbon Calculator

My Clean Sky excludes a value for the Radiative Forcing Index from its air travel carbon calculation.

However, users who do wish to include the radiative forcing index in their air travel carbon calculation can easily add it.

This is achieved by multiplying their emissions by 190% in the 'Offset Percentage' box on the calculator.

Check the emissions from your last flight now.