Models of climate change and their limitations

what is used to make models

• The Intergovernmental Panel on Climate Change, or IPCC, is a group of climate scientists around the world that has used existing data to extrapolate how global temperatures might change in the future under different human activity scenarios

• The IPCC data can be added to other computer models on climate change to see how different parts of the world might be affected under the different scenarios

• Computer models are used to investigate the relationship between carbon dioxide and climate change. Especially looking at the relationship between carbon dioxide concentrations and the earth’s temperature

What can global warming predictions be used to do?

• Plan for the future e.g.

  • Building flood defences

  • Funding scientific research into climate change technologies

• Encourage people to change their activities e.g.

  • Reduce the burning of fossil fuels

  • Increase the use of renewable energy sources such as solar and wind energy

  • Reduce meat consumption

Limitations of models?

• Models taken years to develop and are currently being refined as new research shows how different factors interact.

• Many factors will contribute including the rate of photosynthesis across the world, exchange of carbon dioxide between atmosphere and ocean and effect of changing temperatures on rate of photosynthesis and exchange of carbon dioxide. We don't know exactly how factors other than human activities may affect climate in the future

• The IPCC has produced models based on several emissions scenarios, and we do not know which of these scenarios is most likely

  • I.e. we don't know how successful humans will be at cutting greenhouse gas emissionS

• We do not know whether future technologies will be successful at removing greenhouse gases from the atmosphere e.g. carbon capture technologies may or may not be effective 

• It is unknown exactly how atmospheric gas concentrations might affect global temperatures

• Global climate patterns are complex and therefore predictions are difficult

  • It is possible that a certain tipping point in global temperatures could lead to a sudden acceleration in global warming e.g. permafrost melting may cause a sudden increase in atmospheric methane

    • Permafrost is ground that is frozen all year round

What is weather

Weather describes the state of the atmosphere at a particular time and place with regards to temperature, rainfall, humidity and level of wind.

What is climate

Climate is the average weather conditions in an area over many years. Temperature changes on earths atmosphere can cause changes to weather patterns and long term changes to Climate

Rainfall patterns also changing

effect of lower then expected rainfall in Africa

It is predicted that the low rainfall patterns will continue and

this will mean by 2050 there will be 350 – 600 million people

in Africa who are short of water for crops and drinking

Effect of higher then usual rainfall?

Some areas rainfall is higher than usual and extremely heavy- this causes flooding and will carry away topsoil. Pakistan, India and China have all experienced severe flooding in the last several years

What is extrapolation?

• Extrapolation is when the data is used to make predictions about what will happen next. This looks at the future of the global climate.

• These extrapolations are models and they can be useful however need to be backed by evidence so that the predictions made are valid

How models of monthly rainfall used to prove global warming

• International group of scientists collected monthly rainfall data around the world from 1925-1990 and compared what happened to what the computer models predicted would happen as a result of global warming. They found that many of the changes observed were the same as the changes predicted if global warming was a factor affecting climate change

• IPCC is using some of the predictions shown in diagram to plan international responses to the problems associated with increasing carbon dioxide levels and global warming

Limitations of the models

• It is impossible to tell the exact impact of carbon dioxide on global warming and it is impossible to predict the impact of global warming on specific aspects of the climate.

• Extrapolations from past data do not account for unknown factors of the future. This includes how current trends in resource uses and technologies may change

Effect of global warming of Antarctic

• 2002, 500 billion tonnes of ice broke away from Antarctic peninsula and melted into the sea.

• Antarctic temperatures have increased by 2.5 degrees over the past 50 years and this is a greater increase in temperature than anywhere on earth.

• Ice becomes thinner is a clear indication that global warming is occurring. The Antarctic ice contains 70% of the worlds fresh water

Recent changes in arctic

• The Arctic is changing too. The Arctic sea ice reducing 2.7% each decade since 1978 and many glaciers becoming smaller at rate of about 50m per year.

• Volume of sea water in the seas and oceans also increasing as the Antarctic ice melts. Sea levels are rising.

• Water becomes warmer, o uncreased and this further causes increase in sea levels. There are around 100 million people who live less than 1 metre above sea level

Effect of rising sea levels

• Risk of global warming to countries like Maldives is very obvious. Maldives is flattest country on earth and only 2.4m above sea level at its highest point.

• 2100, 77% of Island mass will be underwater due to rising sea levels. Destroying human, plant and animal populations. Rising sea temperature also killing coral reefs that surroundthe island and reducing world biodiversity