Climate Change and Oceans

• what does ocean salinity vary between?

  31 and 39 parts per thousand (particles of salt per water molecule)
• why is there a lower salinity when there is more landmass?

  because freshwater washes down from the land into the water
• why is the mediterranean particularly salty?

  because the water is evaporating faster than it can be replenished
• what are the four layers of the ocean?

  epipelagic, mesopelagic, bathypelagic and abyssopelagic
• what are really important for structuring marine ecosystems?

  currents
• what are currents driven by?

  wind and the coriolsis effect
• what direction is water forced in then northern hemisphere?

  clockwise
• what direction is water forced in the southern hemisphere?

  anticlockwise
• what is the largest current on earth?

  the antarctic circumpolar current
• why is the antarctic circumpolar current so important?

  it keeps warm water away from Antarctica, allowing it to maintain its large ice sheet
• what is the most important current for the UK?

  the Gulf Stream
• what do currents create?

  upwelling
• what does the gulf stream do for the UK?

  bring warm Caribbean water that makes the UK climate warmer
• what does upwelling create?

  patchy areas of high productivity
• what causes upwelling?

  areas where two currents are moving away from each other, creating a vacuum which sucks up the deep nutrient rich water from the bottom of the ocean
• what happens when two ocean currents meet?

  we get downwelling
• what do oceans tend to be limited in?

  nitrogen and iron
• what does the ocean being iron limited lead to?

  research into iron fertilisation as a solution for climate change
• what are the five major impacts of climate change on aquatic habitats?

  sea level rise, changes in ocean currents / circulation, acidification, direct impacts of temperature on organisms and precipitation changes which impact hydrology
• what are the three mechanisms driving sea level rise?

  thermal expansion, groundwater extraction and the melting of polar glaciers
• by how much is sea level rising each uear?

  3.4 mm
• at what temperature is water its most dense?

  4 degrees
• how does ground water extraction lead to sea levels rising?

  when we dig up water for human use, we dump it in the oceans once were finished
• if the Greenland ice sheets were to melt, by how much would they raise global sea levels?

  7 metres
• if the antarctic ice sheet was to melt, by how much would it raise global sea level?

  61 metres