Target atmospheric CO2: Where should humanity aim?

By J. Hansen, M. Sato, P. Kharecha, D. Beerling, R. Berner, V. Masson‐Delmotte, M. Pagani, M. Raymo, D. Royer, J. C. Z. N. Giss and 7 more. 2008

1,345 citations recorded by the source corpus.

Paleoclimate data show that climate sensitivity is ~3 deg-C for doubled CO2, including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6 deg-C for doubled CO2 for the range of climate states between glacial conditions and ice-free Antarctica. Decreasing CO2 was the main cause of a cooling trend that began 50 million years ago, large scale glaciation occurring when CO2 fell to 450 +/- 100 ppm, a level that will be exceeded within decades, barring prompt policy changes. If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm. The largest uncertainty in the target arises from possible changes of non-CO2 forcings. An initial 350 ppm CO2 target may be achievable by phasing out coal use except where CO2 is captured and adopting agricultural and forestry practices that sequester carbon. If the present overshoot of this target CO2 is not brief, there is a possibility of seeding irreversible catastrophic effects.

Subfields: Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/4757c5bf5b07e2367948a9cc51c619ea4cd20650

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In Global and Planetary Change

Citations in the corpus

The Century Ahead: Searching for Sustainability (2010, background): “This would give an approximately 70 percent chance of meeting the 2 °C temperature change constraint [16]; some stress that even lower concentrations levels may be necessary [17].”
GLOBAL SURFACE TEMPERATURE CHANGE (2010, background): “A problem with that prescription is the danger that the climate system could pass tipping points that cause major climate changes to proceed largely out of humanity’s control [Hansen et al., 2008].”
Fossil fuel depletion and socio-economic scenarios: An integrated approach (2014, background): “…to at most 350 ppm if humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted (Hansen et al., 2011, 2008; Rockström et al., 2009).20 In fact, if high concentration levels are maintained during a certain time, anthropogenic…”
Black soot and the survival of Tibetan glaciers (2009, background): “If coal emissions were phased out over the next two decades, and if unconventional fossil fuels, such as tar sands and oil shale, were not developed, atmospheric CO2 could peak at 400–425 ppm and conceivably return to a level of 350 ppm or less via improved forestry and agricultural practices (27).”
High Earth-system climate sensitivity determined from Pliocene carbon dioxide concentrations (2010, background): “However, this value incorporates only relatively rapid feedbacks such as changes in atmospheric water vapour concentrations, and the distributions of sea ice, clouds and aerosol”
Beyond Copenhagen: mitigating climate change and achieving food security through soil carbon sequestration (2010, background): “This low hanging fruit, a win-win option of C sequestration in terrestrial ecosystems with a sink capacity of reducing the atmospheric CO2 concentration by 50 ppm by 2100 (Hansen et al. 2008), should have been high on the agenda of the COP-15 meeting in Copenhagen in December 2009.”
The future tourism mobility of the world population: Emission growth versus climate policy (2011, background): “Other authors have reasoned that the long-term CO2 concentration levels necessary to avoid dangerous interference with the climate system should not exceed 350 ppm (Hansen et al., 2008).”
Australia's Biodiversity and Climate Change (2010, background): “Mean temperature change above the 2°C level, with the associated changes in other aspects of climate, will lead to escalating loss of biodiversity with little or no chance of avoiding or reducing losses via adaptation (Hansen et al. 2008; IPCC 2007b; van Vliet and Leemans 2006).”
An Antarctic view of Beryllium-10 and solar activity for the past millennium (2011, background): “As explained by Damon and Sternberg (1989), and Goslar (2001) , the total quantity of carbon included in the model (‘carbon inventory’) affects the attenuation introduced by the model.”
Exploitation of renewable energy for sustainable development and overcoming power crisis in Bangladesh (2014, neutral): “Bangladesh is already in potential hazardous zone such as sea level rise and climate change because of this GHG phenomenon [77].”