If your car is headed for a collision, and you don't have time to stop, you don't give up and leave your foot on the accelerator. You take your foot off the accelerator & brake as hard as possible, to minimize the damage. It might mean the difference between breaking your neck and getting a bad whiplash injury.http://thinkprogress.org/climate/2014/12/24/3606755/irreversible-not-unstoppable-climate-change-yet-to-come/
by Joe Romm Posted on December 24, 2014
Unlike Scrooge, we don’t get a spirit to show us what the future holds if we don’t change our ways.
That’s what we have science for. In recent years, observations have confirmed the key projections climate scientists have been making for decades. But some of the most important impacts have been occurring much faster than scientists expected, including sea level rise. As recently as a decade ago, scientists did not expect that the great ice sheets of Greenland and Antarctica would melt enough this century to contribute much to total sea level rise. Now, observations suggest they will be a primary if not the primary driver of sea level rise.
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Yes, it seems unlikely that we will adopt the aggressive but near-zero-net-cost policies needed to stabilize at 450 ppm atmospheric concentrations of carbon dioxide, and then quickly come back to 350 ppm, thanks in large part to the deniers, along with their political pals and media enablers. But the two biggest carbon polluters (China and U.S.) have struck a game-changing deal that could ultimately avoid some of the worst impacts — if other key countries join in and, then all countries pursue even stronger emissions cuts in the coming decades.
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The question of whether it’s “too late,” doesn’t have one purely scientific answer. It does seem clear that the most dangerous carbon-cycle feedback — the defrosting permafrost — hasn’t kicked in yet but likely will within two decades, adding 0.4°F – 1.5°F to total global warming by 2100. On the other hand, part of the West Antarctic ice sheet now does appear close to if not past the point of irreversible collapse. That said, the worst case of sea level rise can still be avoided, as can many other of the most serious impacts.
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Delay is very risky and very, very expensive. As the International Energy Agency has explained, “on planned policies, rising fossil energy use will lead to irreversible and potentially catastrophic climate change.”
“Delaying action is a false economy: for every $1 of investment in cleaner technology that is avoided in the power sector before 2020, an additional $4.30 would need to be spent after 2020 to compensate for the increased emissions.”
Action now will save trillions and trillions of dollars.
Five years ago a NOAA-led paper laid out some alarming predictions for our climate-changed future.
…the climate change that is taking place because of increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop … Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450-600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the “dust bowl” era and inexorable sea level rise.
And we know that large parts of the currently habited and arable land are at risk of turning into Dust Bowls, gravely threatening global food security.
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the climate changes so far, both observed and committed to, are minor compared with the business-as-usual forecast for the end of the century. It’s further emissions we need to worry about. Climate change is like a ratchet, which we wind up by releasing CO2. Once we turn the crank, there’s no easy turning back to the natural climate. But we can still decide to stop turning the crank, and the sooner the better.
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On our current emissions path, CO2 levels in 2100 will hit levels last seen when the Earth was 29°F (16°C) hotter.
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