Comments 1 to 3:

1. SirCharles at 23:01 PM on 13 April, 2018

   1.5C is already in the pipeline. 2C would imply to cease fossil fuel burning within the next two decades. I wouldn't call that "some reason for hope".
   https://www.youtube.com/watch?v=VbhlWSxcoYg

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2. Riduna at 16:39 PM on 16 April, 2018

   In this video Dr Grinsted expresses the view that a rise of 1.6°C will be a tipping point for eventual loss of the Greenland Ice Sheet.
   We are already less than 0.2°C below that point and will likely exceed it in less than a decade.

   Dr Ramstorf says that we risk SLR of as much as 2 metres by 2100 but suggests that discharge of cold water from ice sheets may be a mitigating factor, slowing mass loss.
   Rignot, Hansen and others argue that discharge of fresh water on the ocean surface will result in formation of warm bottom water hastening, not slowing polar ice mass loss, particularly in West Antarctica where the ice sheet rests on the seabed.

   Dr Hansen has predicted multi-metre median SLR by 2100 as the likely outcome, driven primarily by the rate of mass loss from the polar ice sheets. If decadal doubling of that rate continues to occur – at present it is accelerating – SLR in excess of 3 metres by 2100 seems a more likely outcome.

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3. Doug_C at 16:27 PM on 23 April, 2018

   We also really have to ask what having a largely ice free Arctic ocean in the summer is going to mean for the Greenland ice sheet. Instead of having a very large reflective surface to the north of it, there will likely be a large body of open sea water in the summer at some point almost certainly by mid century.

   Instead of 90% of incoming solar radiation being reflected back into space, the upper levels of the Arctic ocean will be absorbing 90% of that radiation experiencing significant heating in summer.

   This will likely mean much more evaporation of sea water, the ability of the air column to hold water vapour and far different weather patterns. Which could result in higher amounts of rainfall on the surface of the Greenland ice sheet accelerating melting even further. As well as possibly increasing flow of ice into the ocean.

   There are so many dynamics at work here it is going to be difficult to model the responses as once stable systems are thrown into a state of chaos as they transition to a much warmer Arctic and Earth.

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