The climate fact no one will admit: 2 °C warming is inevitable

[OKIsItJustMe]

11. The climate policy narrative for a dangerously warming world

http://www.nature.com/nclimate/journal/v4/n3/full/nclimate2148.html

[font face=Serif][font size=5]The climate policy narrative for a dangerously warming world[/font]

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Nature Climate Change 4, 164–166 (2014) doi:10.1038/nclimate2148
Published online 26 February 2014

[font size=3]It is time to acknowledge that global average temperatures are likely to rise above the 2 °C policy target and consider how that deeply troubling prospect should affect priorities for communicating and managing the risks of a dangerously warming climate.

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http://www.voxeu.org/article/improbable-2-c-global-warming-target

[font face=Serif][font size=5]The improbable 2°C global warming target[/font]

Carlo Carraro, Emanuele Massetti 03 September 2009

[font size=3]Mitigating global warning is a pressing and daunting task for the world’s major economies. This column says that the 2°C target set by G8 leaders is both politically and technologically unrealistic. It argues they must adopt more realistic targets and long-term commitments to adaptation plans.

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Hansen et al. (2008)
http://arxiv.org/abs/0804.1126

[font face=Serif][font size=5]Target Atmospheric CO₂: Where Should Humanity Aim?[/font]

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[font size=2]Abstract: Paleoclimate data show that climate sensitivity is ~3°C for doubled CO₂, including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6°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, the planet being nearly ice-free until CO₂ fell to 450 ± 100 ppm; barring prompt policy changes, that critical level will be passed, in the opposite direction, within decades. 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, but likely less than that. 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.[/font]

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2.4. Warming “in the pipeline”

The expanded time scale for the industrial era (Fig. 2) reveals a growing gap between actual global temperature (purple curve) and equilibrium (long-term) temperature response based on the net estimated climate forcing (black curve). Ocean and ice sheet response times together account for this gap, which is now 2.0°C.

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