Six of 9 planetary boundaries have been breached because of human activities: Study

Six of 9 planetary boundaries have been breached because of human activities: Study

Subject :Environment

Section: Climate Change

Context:

• The world has breached six of the nine planetary boundaries necessary to maintain Earth’s stability and resilience, according to a new study.

Study findings:

• The findings are an update to the planetary boundaries framework, which was first launched in 2009, to define the environmental limits within which humanity can safely operate.
• The six boundaries include climate change, biosphere integrity (genetic diversity and energy available to ecosystems), land system change, freshwater change (changes across the entire water cycle over land), biogeochemical flows (nutrient cycles), and novel entities (microplastics, endocrine disruptors, and organic pollutants).

Research methodology and analysis:

• The planetary boundary for atmospheric carbon dioxide concentration and radiative forcing (represents the size of the energy imbalance in the atmosphere) should be at 350 parts per million (ppm) and 1 Watts per square meter (Wm−2), respectively. Currently, this has reached 417 ppm and is 2.91 W m−2.
• The global area of forested land has reduced from 75% to 60%.
• Normal rate of extinction should be less than 10 extinctions per million species-years, but it is greater than 100 extinctions per million species-years.
• Over 10 percent of the genetic diversity of plants and animals may have been wiped out over the last 150 years.
• Human impacts on blue and green water were calculated to be 18.2 per cent and 15.8 per cent, respectively, which is higher than the boundary of 10.2 per cent and 11.1 per cent, respectively.
• Flow of nutrients such as nitrogen and phosphorus:
  • Changing nutrient availability has huge consequences for biodiversity and water quality.
  • In addition, reactive nitrogen [includes oxides of nitrogen (NOx), ammonia (NH3), and nitrous oxide (N2O)] can lead to the production of potent greenhouse gasses that worsen climate change.
• Stratospheric ozone depletion, aerosol loading and ocean acidification were found to be within the planetary boundary.
  • Aerosols are minute particles from combustion processes, biomass burning, and plant/microbial materials suspended in the air. They also trap hear and increases the global temperature.

Net primary production (NPP) of an ecosystem:

• This is estimated by the gross productivity minus energy lost in respiration. It the net energy stored in the plants. This energy serves as food for the animals that feed on plants. It is measured as the amount of organic matter produced in a community in a given time.
• It is equal to the difference between the amount of carbon produced through photosynthesis and the amount of energy that is used for respiration.