Wednesday, July 8, 2015

As I Stare at My Smoke-Clouded Sky, a Thought or Two About Tipping Points

Arctic sea ice is vanishing and quite rapidly to boot. The ice cover that once reflected solar radiation, heat, back into space has walked off the job. No brilliant white ice means dark green ocean that is a heat sink. That warming Arctic ocean warms the atmosphere that causes the tundra to dry out and catch fire. As the tundra burns it creates black soot that winds up turning the Greenland Ice Sheet a dirty colour and that accelerates the melting of the ice sheet and sea level rise.

The thawing, burning tundra also exposes the permafrost underneath that, as it thaws, releases massive amounts of once safely sequestered, formerly frozen methane, a very powerful greenhouse gas. As the Arctic ocean warms it also triggers the thawing of ancient, frozen seabed methane clathrates - methane ice if you like - that bubbles to the surface and then onward to the atmosphere.

From rampaging wildfires to tundra fires to ice caps covered in black soot to the release of ancient stores of methane from the permafrost and seabed clathrates these are all the feedback mechanisms your mother those scientists warned you about. They're happening now, not forty years from now, not even twenty years from now.

Have we passed the point of no return. The good news is that's a conversation we're not really having right now. We're still proceeding - although not very quickly and not very well - with talks that assume we're not there yet and can, if we just try hard enough dammit, avoid the worst - maybe.

Today we're at just 0.8 degrees Celsius above pre-industrial levels. We're not at the 1.5C mark yet because that persistent atmospheric greenhouse gas needs time to work its magic. It will and as it does our children and grandchildren will experience the changes in creates.

There are two things that we must understand, and that includes you.

First off. That 1.5C is something we've already bequeathed our kids and theirs. What we need to realize is that emissions are cumulative which means our greenhouse gas emissions from today onward add to that 1.5C. Every tonne of CO2 we emit goes on top of that 1.5C pile. We're experiencing the impacts of barely 0.8C of warming (and it's a real bitch). As today's warming keeps getting hotter, those who follow us will endure a variety of impacts that are even greater, more dangerous, and demanding of new adaptation responses.

Second. These numbers don't include the natural feedback mechanisms we already seem to have triggered. The greenhouse gas emissions they create - CO2 from forest fires, methane released from the permafrost and seabed clathrates - also go atop that 1.5C we have already locked in.

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