Lecture 17

• Each year, the ocean naturally exchanges with the atmosphere almost a hundred billion tonnes of carbon as CO2
• Land plants (autotrophs) are terrestrial primary producers: organisms that manufacture, through photosynthesis, new organic molecules such as carbohydrates and lipids from raw inorganic materials (CO2, water, mineral nutrients)
• [Total CO2 in] - [Total CO2 out] = ‘carbon balance’ Terrestrial carbon sinks
• The largest 1% of trees in mature and older forests comprised 50% of forest biomass
• The area of woodland in the UK on 31 March 2019 is estimated to be 3.19 million hectares. This represents 13% of the total land area in the UK, 10% in England, 15%in Wales, 19% in Scotland and 8% in Northern Ireland
• Only 3,090 square kilometres (760,000 acres) of ancient semi-natural woodland survive in Britain – less than 20% of the total wooded area
• • about half of England had ceased to be wildwood by 500 BC (Rackham 1990)
  • The Domesday Book (1086) is evidence that every wood in England belonged to some person or some community
  • Much of the remaining woods were managed by coppicing
• The global carbon budget is imbalanced
• Humans have unbalanced the carbon cycle; Could they fix it?

  • enhanced weathering
  • reforestation
  • soil improvement
  • bioenergy with carbon capture and storage
  • direct air capture