Lecture 10

• Criteria for a pollutant being designated a planetary boundary:

  1. Pollution must be irreversible or very difficult to reverse
  2. Disruptive effect is detectable at the global scale
  3. The pollution must disrupt Earth System processes
• Criteria 1 - the pollution must be irreversible or very difficult to reverse

  • estimated 8 million metric tonnes of plastic waste enters world's oceans from coastal regions yearly
  • around 90% of plastics produced have not been recycled
  • "geological marker of the Anthropocene" - plastics are everywhere
• "Floating islands" of Plastic - Great Pacific Garbage Patch: made up of mostly microplastics and discarded fishing gear

  • 1.6 million km/2
• Where does most plastic come from?

  1. Packaging
  2. Textiles
  3. Other sectors
  4. Consumer products
• Where does the plastic come from?

  1. East Asia and Pacific
  2. South Asia
  3. Sub-Saharan Africa
  4. Middle East and North Africa
• Plastic waste trading:

  • 2017 - China introduced a complete ban on imports of non-industrialised plastic waste
  • This plastic waste will have to be handled domestically or exported to another country
• Criteria 2 - the disruptive effect is detectable at a global scale

  • effects are rapidly distributed globally
  • effects of the contaminant are only observable at a global scale
  • there is a time delay between the exposure of the contaminant and the effects
• Criteria 3 - the pollution must disrupt Earth System processes

  • marine plastic pollution - direct effect on organisms, indirectly acts as a vector of other pollutants, systemic effects that cascade across ecosystems
  • mismanagement of discarded plastic implies alteration to food webs, habitats and biogeochemical flows
• Criteria 3 - links of marine pollution to climate change

  • Copepods ingest microplastics - poop doesn't settle as quickly into marine sediments - changes ocean carbon storage
  • Sunlight accelerates disintegration of plastics - releases methane
  • Plastics floating in Arctic waters - interferes with ice formation and melt
• How to address the plastic problem: Larger scale

  • development of effective waste management infrastructure in all countries
  • cease plastic trade from rich to low/middle-income countries that do not have enough waste management infrastructure
  • strict legislation and management of fishing activity and waste
• How to address the plastic problem: Smaller scale

  • reduce/eliminate single-use plastic
  • go to re-fill stores for products
  • checking for microbeads in products
  • participate in clean-ups
• No planetary boundary but it has already been crossed