Lecture 6: Ocean circulation and the carbon cycle Flashcards
EARTH’S HEAT BUDGET
• Average annual incoming solar radiation exceeds the average annual outgoing infrared radiation, emitted by the Earth, between 40oN and 35oS
• This results in an energy surplus at low latitudes and an energy deficit at high latitudes
• The areas of heat gain (orange) and heat loss (blue) are equal and as such Earth’s total heat budget is
balanced
• The oceans do not boil away near the Equator or freeze solid near the Poles because heat is transferred by winds and ocean currents from equatorial to polar regions
Earth’s heat budget
- my notes
- Tropics the temps are stable
- Poles- more energy going out than in- energy is redistributed by oceans
- Ocean redistributes energy
- Newfoundland- doesn’t have the delivery of warm water even though same latitude as UK- eastern Canada- cold
Ocean circulation- my notes
- The Atlantic – circulation Antarctica to artic
- Where ever you are- deep surface same temp- not affected by land- insulated by sea
Meridional overturning circulation- my notes
- Air is a fluid
- Differences in water density- cool salty water most dense
- Only pure water is evaporated- h20- more saline the water goes- for instance Mediterranean- most saline area
Gulf stream shut down?- my notes
- Fresh water to north- shutdown circulation
- Gulf stream- responsible for an area being warmer
- UK lot of cooling- regional cooling for western Europe if gulf stream shut down
Meridonial overturning circulation: Atlantic
- my notes
- Cold water new flow- deep at the bed of the Atlantic Ocean (bottom water)- so cold and so saline
- Deep water formation- both at the poles- loads of fresh water- disrupts the circulation
Importance of the pacific- my notes
- Changes to heat delivered to the pacific- changes global atmospheric conditions
- El Niño- pacific phenomenon
- Tropics- sun above the tropics- tropical pacific- trade winds- from the east to the west
- Surface winds- blow east to the west- hot waters in Australia in comparison to south America
- South east Asia- hot rises- monsoon- Singapore experiences 2 monsoons
- Warm water gathers up at south east Asia
- Deep ocean water has a lot of fishes- south America therefore huge fishing industry
- Higher sea level in south east Asia/ Australia than south America
- Now not happening- no monsoon- therefore dry season longer- drought
- Warm water spread along the pacific- therefore fishing industry rapidly decrease south America
- Some flooding in SA
La Nina condition- my notes
- Opposite
- Extreme piling up of warm water in south east Asia
Helps with fishing industry in SA
Enso cycle- el Niño/ la Nina - my notes
- Trade winds strong in normal conditions
- Therefore, driving storm clouds= monsoon
- Dry SA- air cannot rise- therefore dry- desert
- Enso index- help measure el Niño- the one right now is possibly the strongest on record at the moment
Impacts of el Niño event
- my notes
- Wetter SA
- East Africa- wetter then usual
- Southern Africa- drier than usual
The global carbon cycle
- my notes
- Diagram on PowerPoint important
- Flows of carbon
- Industrial revolution- now more carbon in atmosphere than 200 years ago
- Land use change- deforestation- now more carbon in atmosphere
- 6.4 gig tones added every year- burning
- fertilizing the planet- more carbon
- Oceans- water has solid gases- add more c02 into planet- more in the ocean
- Vegetation- deforestation outweighing fertilization
- Humans emit 150 x more than volcanoes- we dominate atmospheric carbon budget
- Wildfires- also important to carbon in atmosphere – carbon neutral- very next season grass grows-however deforestation fires- then replace it with agriculture- bad for environment- the change more important than the release of vegetation
- Humans don’t photosynthesize- we just release
- Humans are not carbon neutral
Carbon uptake on land- weathering and photosynthesis
- Over time carbon dioxide- can be dissolved in rainwater- therefore acid rain
- Calcium carbonate- in rain- then washed in ocean
Role of Oceans in the carbon balance
- Store of carbon
- Contain photosynethising organisms- some type of plankton- phytoplankton- stay in ocean for thousands of years- when die- they buried carbon
- Colder waters- more storage of carbon – more diversity of life
- Oceans now are a sink of co2- ‘carbon sink’
- However, one consequence- is ocean acidification- ph is dropping- shellfish and corals affected- hard for them to grow and reproduce
- Low ph hasn’t reached deep waters yet- just surface
Carbon reservoirs in order of rank
- 1) Rocks/ sediments
- 2) Deep ocean
- 3) Top soil
- 4) Shallow ocean
- 5) Atmosphere
- 6) Land biosphere – carbon neutral
