Planetary Atmospheres, the Environment and Life (ExCos2Y)

Topic 9: Climate Change

Chris Parkes

Rm 455 Kelvin Building

8. Storm systems

• Storm Systems– Hurricanes

• Formation• Structure

– Tornados• Formation

– Dust Devils, Water Spouts

Revision

Climate Change

• Many forms discussed in lectures:

Earth’s Long-Term Future Climate   • Remained suitable for life for 4 billion years

– Feedback mechanisms

• Sun will continue to warm– Life on Earth ultimately doomed– Loose water > 1 billion years from now– CO2 cycle may provide regulation for longer– Life < 4 billion years

• Earth will become like venus– 1to 4 billion years

– More pressing worries….

Climate Conditions for Human Life

Planets geology and biology:

• Pressure, Temperature – liquid water

• Oxygen – right amount in atmosphere

• Ozone Layer – absorbs UV

• Magnetospheres – deflects solar wind

Human Effects:

• Ozone depletion – now correcting

• Extinction of species

• Global warming

Global warming

• Temperature increased by 0.5o in last 50 years

• Burning fossil fuels adds CO2 to atmosphere

– Concentration significantly higher than in 600,000 years

• Greenhouse mechanism well understood

Global Warming• Effects on climate dependent on feedback

mechanisms– Temperature rise leads to more water evaporation– Water vapour acts as greenhouse gas

• increases temperature

– Water vapour forms clouds, reflect more• decreases temperature

– Temperature rise melts ice– Ice highly reflective, water highly absorbsant

• Increases temperature• And raises sea levels – flooding

• Effects on Forests, Eco-systems:– food production, fresh water

Potential Effects of Global temperature rise

• Glacial Retreat

• Arctic Shrinkage

• Sea Level rise

• Change in ocean currents

• More Intense Hurricanes /extreme weather events

• Changes in eco-systems

Glacier melting / ice caps / lakes

• Retreats of glaciers

World Glacier Monitoring Service

1973 2006

Sea level

• Melting glacier ice gives sea rise– Melting sea ice

does not (as floating)

Contributes further to global warming through albedo

Potential for flooding major areas of population

Predictions IPCC

Fossil CO2 emissions

Global yearly consumption (BP 2008)

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

1965 1970 1975 1980 1985 1990 1995 2000 2005

CO

2 em

issi

ons

(mill

ion

tonn

es)

Oil: emissions

Natural gas: emissions

Coal: emissions

Total emissions

CDIAC total fossil emissions

Climate change in the past

Source T. Stocker 2005

2009 385 ppm(380 ppm in 2007, 330 ppm in 1974)

(Can extend graph to 850'000, T. Stocker 2006)

Homo Sapiens appears

Agriculture begins

Ice Core Data – gives temperature from heavy water (deuterium D)CO2 levels – high correlation

Deuterium=Temperature

CO2

Climate change in the present

Quality of climate models

• Reasonable agreement of models and measured temperatures over past data

Projections

• Range of climate models• Assuming no special action taken

Example exam questions

Q1. What are the potential Effects of Global Warming ?

Q2. How do we obtain long time scale data on previous CO2 levels and temperatures ?

Q3. How does global warming and changes in the Earth’s albedo interact ?