ES102 Lecture Notes - Lecture 4: West Antarctic Ice Sheet, Sea Level Rise, Sahel
Lecture 1: Impacts of Climate Change and What to do
→ underlying science in last week - human activity has reduced a key carbon sink (forests),
other sinks are not likely to make up for the loss
Implications of elevated atmospheric concentrations of GHGs
● Increase earth’s average temperature
● Patterns and amounts of precipitation likely to change
● Ice and snow cover, permafrost, in decline
● Sea level rises
● Acidity of the oceans increases (oceans are carbon sink, more CO2 in oceans drives up
acidity killing marine life)
How much will global temperatures change?
● Depends on how high our future GHGs will be on a global scale
● Scenarios
○ Do nothing, and emissions continue to accelerate (by end of century about
1000ppm - currently just under 400ppm)
○ Immediate cap and rapid reduction of global emissions
● Future global temps
○ In do nothing scenario - rise of about 8 degrees F by end of century
○ Best case scenario - rise of about 4 degrees F by end of century
○ Future temp changes will not be evenly distributed across the Earth
○ Higher latitudes, altitudes will warm more rapidly (COULD CITE THIS FOR LAB)
Other future impacts…
More extreme storm events
● Areas exposed to cyclones (south indian ocean, north west pacific, south pacific,
northeast pacific, north atlantic - where storm increase would happen)
● Increase in hurricanes and severity of these hurricanes
● Why would storms be more extreme?
○ Tropical storms/cyclones occur over oceans - severity depends on how high sea
surface temp is… increasing, currently about half a degree higher than avg
More severe droughts over continental areas
● Seasonal precip shortfalls linked to sea surface temp
● Higher avg temps increase evapotranspiration rates
● Areas in africa (most prone), asia, australia
● Drought in areas in africa already experiencing conflict - less food = more conflict (sahel
belt)
Arctic sea ice is in retreat
● Greenland’s ice sheet is melting - more water going into oceans
find more resources at oneclass.com
find more resources at oneclass.com
● West antarctic ice sheet is also melting
● Changing sea levels
● Why does sea level rise come with global warming?
○ Water volume increases
○ Land based ice melting
● Regions most exposed to sea level rise - around major rivers etc
A great unknown
● Release of methane trapped in northern land
Who should worry about climate change?
● Requires an understanding of vulnerability
○ Vulnerability = potential for harm or loss
○ V = f(E,S,A) where E = exposure, S = sensitivity, A = adaptive capacity
○ Exposure (eg live on a hill vs not)
○ Sensitivity (eg thailand depends on fishing)
○ Exposure and sensitivity are similar for Holland and Bangladesh, but adaptive
capacity of Holland is very diff than Bangladesh
So what should we do about climate change?
● Scientists recommend two priorities:
○ Mitigation
○ Build adaptive capacity
● Mitigation
○ Refers to making efforts to reduce greenhouse gas emissions
○ Key instruments for achieving:
■ UN framework convention on climate change - UNFCCC
■ Kyoto protocol
○ UNFCCC
■ Came into force in 1994
■ 189 countries have signed including USA, Canada, Australia, EU, India,
China, Brazil
■ Signatories agree to:
● Track and reduce GHGs
● Help poorer countries
● Meet yearly to monitor/modify implementation strategies
(conference of the parties COPs)
○ Kyoto Protocol
■ Agreement reached in kyoto 1997
■ Specific emissions reduction targets
■ Had to reduce emissions to 5% below 1990 levels by 2008-2012
■ Unsuccessful
■ Rationale for kyoto
■ Countries that created the problem should take the lead in fixing it
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Lecture 1: impacts of climate change and what to do. Underlying science in last week - human activity has reduced a key carbon sink (forests), other sinks are not likely to make up for the loss. Patterns and amounts of precipitation likely to change. Acidity of the oceans increases (oceans are carbon sink, more co2 in oceans drives up. Ice and snow cover, permafrost, in decline acidity killing marine life) Depends on how high our future ghgs will be on a global scale. Do nothing, and emissions continue to accelerate (by end of century about. Immediate cap and rapid reduction of global emissions. In do nothing scenario - rise of about 8 degrees f by end of century. Best case scenario - rise of about 4 degrees f by end of century. Future temp changes will not be evenly distributed across the earth. Higher latitudes, altitudes will warm more rapidly (could cite this for lab)
