4.a Climate Modelling

What is a representative concentration pathway (RCP)

A method for GHG scenarios from 2013 onwards

What is the worst case RCP?

8.5

What is the second worst case RCP?

6

What is the second best case RCP?

2.6

What is the best case RCP?

2.6

What was the claim in 2007 made by the IPCC?

The Himalayan glaciers may dissappear by 2035

Why is the IPCC making a false claim bad?

1. Countries rely on them for information to make climate decisions

2. Fuels the climate change debate

What do the temps range between for the rise in tem in the next 70-80 years?

0.3C to 4.8C

What is the most likely temp rise?

2C

What was the level that oceans rose between 1901 and 1990?

1.5mm/year

What does RPC2.6 say the sea is going to rise by?

0.28m (by end of century)

What does RPC 8.5 say the sea is going to rise by?

0.98m (by end of century)

Pos Declining forest cover

• Global temps rise

• Tropical forests trees become stressed

• So die

• Releasing CO2 - trees are a store

• Resulting in higher temps

• Which puts more stress on trees

Pos Increased evaporation

• Warming increases from ocean and land surfaces

• Atmospheric WV increases

• Raises global temps

• Creating further evaporation

Pos Melting permafrost

• High temps

• Thawing of permafrost

• CH4 and CO2 are released

• Enhanced greenhouse effect

• Results in more thawing

Pos Increased cloudiness

• More water in the atmosphere

• Increases the cover of high altitude cirrus clouds

• Help to radiate heat from the earth

• So contribute to temp rises

• More evaporation

Pos Increased ocean acidity

• Oceans absorb CO2

• They become more acidic

• Increased acidity means that oceans reduce their ability to absorb CO2

• So more CO2 in the atmosphere

Pos Release of methane hydrates

• Oceans warm

• Release of methane hydrates (found in ocean sediments)

• Methane is 20x more potent than CO2

Pos Reduced albedo

• High temps

• Melting of glaciers/ice/snow

• Reduced albedo

• More solar radiation absorbed at the surface

• Temps increase

• More melting

Neg Increased cloudiness

• High rates of evaporation and levels of atmospheric EV

• Incerases cloud cover

• Leads to an increase in reflection of solar radiation back into space

• Lower temps occur

Neg Increased aerosols in the atmosphere

• Burning fossil fuels releases aerosols of smoke/dust/sulphur

• Aerosols reflect solar radiation back into space

• Which lowers global temperatures

• This is known as global dimming

Neg Expansion of forest

• Temps rise

• Tree line advances forwards

• Expansion of forests helps to absorb more CO2

• Decreases CO2 in the atmosphere

• Temps decrease