On Friday, 11 March 2016 19:39:50 UTC, Graham P Davis wrote:

I can't remember whether I recommended the book 'Adventures in the
Anthropocene' by Gaia Vince, but if I didn't I am now.

The book tells of her visits to various parts of the planet and how
they are being affected by climate change. Although parts of it make
you angry at the stupid politicians, there are some uplifting tales of
how local people, when they are given a chance, are finding ways to
counteract the problem.

These solutions are usually very low-tech and can be done very cheaply.
One guy rigged up a wi-fi system covering over 20km using tech that
should only have worked over a few metres. When he told the
manufacturers how he'd done it, they just said it was impossible and
ignored him; it's not just the politicians who are useless tools.

To be fair, she tells of one politician who did a marvellous job - so
the military threw him out.


Graham,

you may have seen that in their March newsletter the RMetSoc announced that they have just produced, in collaboration with NCAS and the RGS, a climate change update booklet for A level geography teachers.

The Summary for the section on Tipping Points reads:

"A climate tipping point is a critical threshold when global or regional climate changes from one stable state to another stable state. The tipping point event may or may not be reversible.
Aspects of the Earth's climate system have tipped in the past, and projections suggest that increasing greenhouse gas concentrations may lead to future tipping points being reached.
The most likely abrupt, but reversible, change to the climate system expected in the 21st century is the decline of Arctic sea-ice, especially in the summer."

And later they write:

"It is likely that the Arctic Ocean will become nearly ice-free in September before 2050. The transition will be abrupt but, if the amount of CO2 in the atmosphere falls, the loss of sea-ice could be reversed within years to decades."

I think we would agree that the Arctic sea ice will be gone well before 2050, and that the reason the transition will be abrupt is because it will be driven by the positive ice-albedo feedback.

That being so, there is no chance of it being reversed if the amount of CO2 falls. The positive feedback will induce a hysteresis where a considerable decrease in CO2 will be needed to restore the sea ice, although when that occurs it too will happen abruptly.

Finally they write:

"The effect of rapid changes to Arctic sea-ice might have consequences throughout the climate system, particularly on cloud cover."

The effects of loss of the Arctic sea ice will not only make us a little cloudier. The warmer Arctic will melt the Greenland ice sheet raising sea level by 7 m, which will lift the West Antarctic ice shelves off their grounding lines. This will remove their buttressing effect on the West Antarctic ice sheet allowing it to slide into the ocean and raise sea level by another 5 m.

You can read it all he

http://www.metlink.org/climate/ipcc-...ipping-points/