Human Impacts on the Carbon Cycle

• human influence on carbon cycle


  - Burning fossil fuels and wood (6-8PgC a year)

  - destruction of natural environments (1.5 PgC a year)
• negative feedback loop


  reduces the effect of change and helps maintain balance
• positive feedback loop


  increases the effect of the change and produces instability
• Changes in carbon ppm

  1790- 280ppm (industrial revolution)

  1958- 317ppm (secondary industrial bloom)

  2023- 419 ppm
• why has the watch had a 1 degree increase?

  because of the increase of carbon dioxide, 138ppm in 223 years
• how many degrees does it take to change biomes?

  2 degrees
• US emissions in 2020

  CO2-79% (4/5ths)

  methane- 11%

  nitrous oxide- 7%

  fluorinated gases- 3%
• Atmospheric CO2 levels


  the highest it has been in 650,000 years
• what % of the pop lives in urban areas?

  50%
• problems with urban areas and heat capture


  suns radiation is absorbed by the dark and vast surfaces of built up areas
• what % of ALL CO2 emissions are contributed by only

  20 cities?

  40%
• what is the upper limit of carbon in the atmosphere?

  1000 years
• obliquity


  The tilt of the Earth's axis
• how much has the seas rises since the 2000s?

  10-25cm
• examples of low lying areas


  -Florida

  -Bangladesh

  -Netherlands
• what would happen if the ice sheets around Greenland and West Antarctica melt?

  a global sea level rise of nearly 6 meters
• Source of U.S carbon dioxide emissions

  Transportation- 1/3 (33%)

  Electrical Power- 1/3 (31%)

  Industry- 16% (metal and chemical production)

  Residential and Commercial- 12% (heaters, central heating)

  Other- 8% (non-fossil fuel combustion)