What are the tipping points that could force runaway climate change?

Tipping point refers to a critical threshold at which a small change in human activity can have large, long-term consequences for the earth’s climate system.  You could compare a tipping point to the proverbial straw that broke the camel’s back.

In 2008, Dr. Timothy Lenton of the University of East Anglia and his colleagues at the Potsdam Institute of Climate Impact Research published a report that concluded that several tipping elements could reach their critical point within this century under anthropogenic climate change. They produced this shortlist of nine tipping elements, with a prediction of the time it would take them to undergo a major transition:

  1. Collapse of the Indian summer monsoon (approx. 1 year)
  2. Melting of Arctic sea-ice (approx. 10 years)
  3. Disruption of the West African monsoon (approx. 10 years)
  4. Dieback of the Boreal Forest (approx. 50 years)
  5. Dieback of the Amazon rainforest (approx. 50 years)
  6. Collapse of the Atlantic Ocean conveyer belt (approx. 100 years)
  7. Increase in the El Nino Southern Oscillation (approx. 100 years)
  8. Decay of the Greenland ice sheet (more than 300 years)
  9. Collapse of the West Antarctic ice sheet (more than 300 years)

These tipping points represent irreversible changes on a human timescale once they pass a certain threshold of change.  The widespread effects of the tipping event would be felt for generations to come. The risk of a tipping point event is increased if global warming exceeds 2C above pre-industrial temperature. According to Dr. Lenton, it is still possible to avoid the tipping points by drastically reducing greenhouse gases; however, we should be prepared to adapt.

Two tipping points affect Manitobans directly.

  • Boreal forest dieback occurs when forests die due to heat and drought conditions, increasing the risk of wildfires. Global warming of 3C to 5C could lead to large-scale dieback of the northern boreal forests within 50 years as trees exposed to hotter summer heat and increasing water stresses would be more vulnerable to diseases and insect infestations.
  • Arctic sea-ice melt exposes a much darker ocean surface that amplifies warming because it absorbs more radiation than white sea-ice. Arctic sea ice is declining much faster than climate models predicted, increasing ice melt in summer and decreasing ice formation in winter.  Warming is further accelerated by a negative feedback loop in which methane is released when permafrost thaws. How will Arctic communities adapt?  Arctic communities are already facing issues such as food insecurity, lack of safe drinking water and damage to infrastructure due to permafrost thaw.   Accelerated rates in permafrost thaw, loss of coastal sea ice and sea level rise will probably force some communities to relocate. Such cultural disruption creates new risks to the health and well-being of Arctic populations.

AMEG says that we have passed tipping point on Arctic sea ice, and that warming Arctic waters is now a stronger driver of CC than CO2, but that it will be succeeded by another driver: methane release. Read more on the AMEG website: www.ameg.me.

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