The nine ecological ceilings are from the planetary boundaries put forward by a group of Earth-system scientists led by Johan Rockström and Will Steffen.[4] These are:

  • Climate change — the human-caused emissions of greenhouse gasses such as carbon dioxide and methane trap heat in the atmosphere, changing the Earth’s climate.
  • Ocean acidification — when human-emitted carbon dioxide is absorbed into the oceans, it makes the water more acidic. For example, this lowers the ability of marine life to grow skeletons and shells.
  • Chemical pollution — releasing toxic materials into nature decreases biodiversity and lowers the fertility of animals (including humans).
  • Nitrogen and phosphorus loading — inefficient or excessive use of fertiliser leads to the fertilizer running off to water bodies, where they cause algae blooms which kills underwater life.
  • Freshwater withdrawals — using too much freshwater dries up the source which may damage the ecosystem and be unusable after.
  • Land conversion — converting land for economic activity (such as creating roads and farmland) damages or removes the habitat for wildlife, removes carbon sinks and disrupts natural cycles.
  • Biodiversity loss — economic activity may cause a reduction in the number and variety of species. This makes ecosystems more vulnerable and may lower their capacity of sustaining life and providing ecosystem services.
  • Air pollution — the emission of aerosols (small particles) has a negative impact on the health of species. It can also affect precipitation and cloud formation.
  • Ozone layer depletion — some economic activity emits gases that damage the Earth's ozone layer. Because the ozone layer shields Earth from harmful radiation, its depletion results for example in skin cancer in animals.

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