Climate Scientist Mann on 400 ppm CO2

Climate Scientists Michael Mann, author of The Hockey Stick and the Climate Wars: Dispatches from the Front Lines, interviewed on Democracy Now:

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Professor Mann Rocks. The threats and false accusations levelled at Prof. Mann and his colleagues are a true sign of the bankrupt nature of the pseudo-sceptics' deceitful and wholly bogus arguments. There has been a concerted effort to discredit Professor Mann, the perpetrators need to be caught and punished.

Prof. Mann's and his colleagues' 'Hockey-stick' has been amply validated, confirmed and extended by numerous subsequent studies.
For instance: http://www.skepticblog.org/2013/04/17/the-hockey-stick-slaps-back/

Dr. Mann is precisely correct that the Keystone XL pipeline must not be approved and that for it to be approved sends the wrong signal. The US is falling behind China in terms of renewable energy and that should be a cause for embarrassment. Renewable energy is desirable for many reasons including energy independence and not supporting objectionable foreign regimes.

As a species we need to reduce our impact, by numerous means, energy-efficiency, insulation, renewable energy, nuclear. All fossil carbon needs to remain in the ground.