[MCN] Climate change: Is it too late?
lance at wildrockies.org
Tue Aug 7 10:36:50 EDT 2018
The key question here is too late for what?
It’s obviously too late to halt the combustion of fossil fuels before it raises the planet’s temperature. And it’s been well understood that, even if we stopped burning fossil fuels, the leading greenhouse gas, carbon dioxide, remains in the atmosphere for 1,000 years <https://www.forest-trends.org/wp-content/uploads/imported/0812721106.full_Solomon_CO2.pdf> once we dump it there, and lingering effects may persist for thousands of years beyond that <https://journals.ametsoc.org/doi/10.1175/2008JCLI2554.1>. Carbon dioxide levels have risen measurably since pre-industrial times, so it’s already too late to prevent long-enduring heat above pre-industrial times.
The positive feedback effect
It’s also been well understood that a greater danger would surface if positive feedbacks add more heat above that created by combustion of fossil fuels, making a bad situation worse <<https://www.dw.com/en/when-nature-harms-itself-five-scary-climate-feedback-loops/a-43649814 <https://www.dw.com/en/when-nature-harms-itself-five-scary-climate-feedback-loops/a-43649814>>>.
The earliest example is Arhennius’ 19th Century prediction that heat-driven loss of snow and ice would add its own warming effect, simply by reducing the amount of incoming solar reflected back into space.
We are now seeing his predicted loss of ice and snow, and science has been working out exactly how much new heat we’re getting as a consequence.
Experts have identified other positive feedbacks, including soil shift from source to sink, and heightened risk of fire. There’s recently been reasonable evidence that, like the loss of ice and snow, these two feedbacks are also underway, now, already.
The carbon dioxide release by these feedbacks will of course push the heat to even higher levels, and this even greater heat will also last at least 1,000 years, and will serve to maintain the positive feedbacks.
So it seems reasonable to me that now it’s too late to stop a thousand years of positive feedbacks.
Nobody gets to take refuge in uncertainty
The trouble with climate uncertainty, says Michael Mann, is that it cuts both ways. Yes, things may not turn out as badly as expected, and that hope provides refuge for some who would rather think the unthinkable.
But yes, too, Mann has said, things may turn out even worse than expected, making uncertainty no refuge at all. “Uncertainty,” Mann said more recently, “is not our friend, despite what the contrarians would have you think <<https://www.newyorker.com/science/elements/how-climate-change-contributed-to-this-summers-wildfires <https://www.newyorker.com/science/elements/how-climate-change-contributed-to-this-summers-wildfires>>>.”
“The climate scientist James Hansen has called two-degree warming “a prescription for long-term disaster.”
Robert Watson, a former director of the United Nations Intergovernmental Panel on Climate Change, has argued that three-degree warming is the realistic minimum.
The prospect of a five-degree warming has prompted some of the world’s leading climate scientists to warn of the end of human civilization.”
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