Climate Change: Testing the limits of our planet

Context

• Transformative changes must be considered to keep Earth safe for the future

What is the present scenario?

• The population of vertebrate species on Earth in the wild saw a dramatic fall of about 30% between 1970 and 2006, with the worst effects being in the tropics and in freshwater ecosystems.
• The ecological footprint of humanity — the natural habitats, such as water and land, transformed or destroyed as a result of human activity — far exceeds the biological capacity of the earth.

What is Holocene Epoch?

• The Holocene Epoch is the current period of geologic time. .
• This term can be misleading, though; modern humans were already well established long before the epoch began
• This epoch has since given way to the Anthropocene, which has led to over-reliance on fossil fuels, industrial agriculture and pollution in water, soils and air, loss of species
• This has been devastating for many life forms and connected ecosystems throughout the planet.

What are the Biophysical Considerations?

• Ecosystems that are stressed by the exposure to pollutants may not recover once the pollutants are removed.
• When ecological thresholds or tipping points are crossed, significant large-scale changes may occur, such as breakdown of glaciers in Greenland and the Antarctica, the dieback of rainforests in the Amazon, or failure of the Indian monsoons
• greenhouse gas (GHG) emissions increase ocean acidification, land-use change often increases GHG emissions, and increasing nitrogen and phosphorus deplete species biodiversity and freshwater resources and increase warming from climate change.

What are the nine planetary boundaries?

• Planetary boundaries are support systems for life on Earth “carrying capacity” and defining “limits to growth”.
• Stratospheric ozone depletion
  The stratospheric ozone layer in the atmosphere filters out ultraviolet (UV) radiation from the sun. If this layer decreases, increasing amounts of UV radiation will reach ground level.
• Loss of biosphere integrity (biodiversity loss and extinctions)
  The Millennium Ecosystem Assessment of 2005 concluded that changes to ecosystems due to human activities were more rapid in the past 50 years than at any time in human history, increasing the risks of abrupt and irreversible changes
• Chemical pollution and the release of novel entities
  Emissions of toxic and long-lived substances such as synthetic organic pollutants, heavy metal compounds and radioactive materials represent some of the key human-driven changes to the planetary environment.
• Climate Change
  Recent evidence suggests that the Earth, now passing 390 ppm CO2 in the atmosphere, has already transgressed the planetary boundary and is approaching several Earth system thresholds.
• Ocean acidification
  Around a quarter of the CO2 that humanity emits into the atmosphere is ultimately dissolved in the oceans. Here it forms carbonic acid, altering ocean chemistry and decreasing the pH of the surface water.
• Freshwater consumption and the global hydrological cycle
  The freshwater cycle is strongly affected by climate change and its boundary is closely linked to the climate boundary
• Land system change
  Land is converted to human use all over the planet. Forests, grasslands, wetlands and other vegetation types have primarily been converted to agricultural land.
• Nitrogen and phosphorus flows to the biosphere and oceans
  The biogeochemical cycles of nitrogen and phosphorus have been radically changed by humans as a result of many industrial and agricultural processes
• Atmospheric aerosol loading
  Atmospheric aerosol planetary boundary was proposed primarily because of the influence of aerosols on Earth’s climate system.

How close are we to the red mark?

• GHG emissions have led to average atmospheric carbon dioxide concentrations being about 410 ppm as opposed to the 350 ppm level considered a ‘safe’ limit
• Currently the atmospheric concentration of CO2 (the leading greenhouse gas) is approximately 398.55 parts per million (ppm).
• The current average annual rate of increase of 1.92 ppm means we could reach the point of no return by 2042.

How can the idea of sustainability benefit?

• The idea of sustainability has been embedded in the human imagination for a very long time and is expressed through our ideas of nature, society, economy, environment and future generations.
• In thinking about these planetary limits then, researchers and policymakers should reflect on multiple systems and the linkages among them
• Well planned step-by-step or transformative changes must be considered to keep the planet safe for the future.
• Transformative changes must be considered to keep Earth safe for the future