Dangerous Climate Change

Sea Level Rise

Below: Satellite radar altimetry indicates an average rate of sea level rise globally of about 3 millimeters per year over the last two decades

 

Cost of sea level rise:

         Loss of land through inundation and erosion

         Displacement of people

         Salt intrusion into freshwater resources

         Increased flooding due to storm surges

         Cost of holding back the sea (where possible)

Summary

1)      Sea level is rising at an average rate of 3mm/year, with half due to thermal expansion, and half due to contributions from melting ice

2)      The sea level rise attributed to melting ice comes from mountain glaciers, the Greenland ice sheet, and West Antarctic ice sheet

3)      Sea level rise of an additional meter (3 feet) by the end of the century would directly impact low lying coastal areas around the world

4)      Estimates of SL rise must account for changing rates of ocean warming and melting of land ice, which depend on complicated feedbacks in the climate system

 

 

The Earth Climate System

“95% certainty that human activities are responsible for most of the warming over the last half century, largely from greenhouse gas emissions” IPCC, 2013

 

 

 

Below: Dangerous Climate Change

         Probability and magnitude of serious climate impacts increases with increasing CO2 in the atmosphere

         ~550 ppm CO2 scales out to an additional global surface temperature increase of >3°C by 2100

 

 

Above: Sources of United States power generation (electricity) since 1950

 

9.CO2_fossil_fuel_emissions-4.png

Above: Worldwide in 2010 about 9 Giga-tons of Carbon (GtC) were emitted from burning fossil fuels as 33 Giga-tons of CO2 gas. Source: NOAA

 

 

Climate impacts

Climate impacts will vary greatly as a result of a region’s

 

          Sensitivity: degree to which a system is affected, either adversely or beneficially

          Adaptive capacity: ability of a system to adapt to climate change to moderate potential damage

          Vulnerability: degree to which a system is susceptible to adverse effects of climate change

 

Above: Monthly global surface air temperature anomalies in degrees Celsius (relative to long term average measured from 1978 to 2013 = 0)

 

 

Summary

  1. “Dangerous Climate Change” implies a threshold level of warming beyond which irreversible damage will occur to our environment.
  2. This threshold level is commonly pegged as being 3 degrees C of additional warming, mainly due to CO2 concentrations rising above 550 ppm (0.055%) in the atmosphere. This level will be reached before the end of this century under ‘business as usual’ scenarios.
  3. Sensitivity, adaptability, and vulnerability are useful concepts for evaluating which parts of the world are most impacted by climate change.
  4. The scientific community has overwhelmingly concluded that anthropogenic warming of Earth’s climate over the last half century is already having significant impacts on sea level, fresh water supply, agriculture, biodiversity, human health, and the global economy.

 

 

SELF-TEST