4.9.2.2 Human activities which contribute to an increase in greenhouse gases in the atmosphere

human activities increase the amounts of greenhouse gases in the atmosphere. These include:

• carbon dioxide (CO2)

• methane. (CH4 )

Examples of human activity include:

o Driving (CO2 )

o Consuming electricity (CO2 )

o Raising livestock (cows – CH4 )

o Decay of organic waste in landfill sites (CH4 )

How do scientists believe human activity will affect the earths temperature

-Based on peer-reviewed evidence,

-many scientists believe that human activities will cause the temperature of the Earth’s atmosphere to increase at the surface

-and that this will result in global climate change

Why is it difficult to model global climate change

it is difficult to model such complex systems as global climate change

How does this affect models and the evidence for global warming

This leads to:

-simplified models,

-speculation

-and opinions presented in the media

that may be based on only parts of the evidence and which may be biased.