paper 1: Irreversible climate change
due to carbon dioxide emissions
● This paper shows that climate change (due to CO2 emission) is irreversible for 1000
yrs after emissions stop. => because ocean T drops very slowly.
● CO2 c now: 385 ppmv (parts per million by volume)
expected level in coming century: 450-600 ppmv
=> if this happens: irreversible dry-season rainfall reductions in regions like those of
the ‘dust-bowl’ era and inexorable sea level rise
● thermal expansion of warming ocean => lower limit to irreversible global sea level
rise of at least 0.4-1.0 m IF CO2 c exceeds 600 ppmv and 0/6-1.9 m for peak CO2 c
exceeding 1000 ppmv.
● effect on sea level rise of glaciers and ice sheets uncertain but can equal or exceed
several meters over next millenium/longer.
● greenhouse gasses increased (human activities!!!)=> threat of irreversible
damage (short AND long term!). Even if all emission stops now, the effects are
long term. UNFCCC tries to stabilize this to minimize effects.
This paper focuses on 2 aspects of the consequences
criteria:
1. Observed changes are already occurring and there is evidence for anthropogenic
contributions to these changes
2. the phenomenon is based upon physical principles thought to be well understood
3. projections are available and broadly robust across models
studied with 2 models: AOGCMs and EMICs
longevity of an atmospheric CO2 perturbation
how long the CO2 stays in the atmosphere
● removing CO2 from the atmosphere: rapid exchange with land biosphere and surface
layer ocean through air-sea exchange and much slower penetration to ocean interior
(ocean is buffer). 80% of the added CO2 is mixed in the ocean, 20% remains in the
atmosphere.
due to carbon dioxide emissions
● This paper shows that climate change (due to CO2 emission) is irreversible for 1000
yrs after emissions stop. => because ocean T drops very slowly.
● CO2 c now: 385 ppmv (parts per million by volume)
expected level in coming century: 450-600 ppmv
=> if this happens: irreversible dry-season rainfall reductions in regions like those of
the ‘dust-bowl’ era and inexorable sea level rise
● thermal expansion of warming ocean => lower limit to irreversible global sea level
rise of at least 0.4-1.0 m IF CO2 c exceeds 600 ppmv and 0/6-1.9 m for peak CO2 c
exceeding 1000 ppmv.
● effect on sea level rise of glaciers and ice sheets uncertain but can equal or exceed
several meters over next millenium/longer.
● greenhouse gasses increased (human activities!!!)=> threat of irreversible
damage (short AND long term!). Even if all emission stops now, the effects are
long term. UNFCCC tries to stabilize this to minimize effects.
This paper focuses on 2 aspects of the consequences
criteria:
1. Observed changes are already occurring and there is evidence for anthropogenic
contributions to these changes
2. the phenomenon is based upon physical principles thought to be well understood
3. projections are available and broadly robust across models
studied with 2 models: AOGCMs and EMICs
longevity of an atmospheric CO2 perturbation
how long the CO2 stays in the atmosphere
● removing CO2 from the atmosphere: rapid exchange with land biosphere and surface
layer ocean through air-sea exchange and much slower penetration to ocean interior
(ocean is buffer). 80% of the added CO2 is mixed in the ocean, 20% remains in the
atmosphere.
