Thursday, November 28, 2019

Climate Tipping Points Are Closer Than We Think, Scientists Warn

By Bob Berwyn, InsideClimate News
Nov 27, 2019

Humans are playing Russian roulette with Earth's climate by ignoring the growing risk of tipping points that, if passed, could jolt the climate system into "a new, less habitable 'hothouse' climate state," scientists are warning ahead of the annual UN climate summit.


The scientists focused on nine parts of the climate system susceptible to tipping points, some of them interconnected:

  • Arctic sea ice, which is critical for reflecting the sun's energy back into space but is disappearing as the planet warms.
  • The Greenland Ice Sheet, which could raise sea level 20 feet if it melts.
  • Boreal forests, which would release more carbon dioxide (CO2) than they absorb if they die and decay or burn.
  • Permafrost, which releases methane and other greenhouse gases as it thaws.
  • The Atlantic Meridional Overturning Circulation, a key ocean current, which would shift global weather patterns if it slowed down or stopped.
  • The Amazon rainforest, which could flip from a net absorber of greenhouse gases to a major emitter.
  • Warm-water corals, which will die on a large scale as the ocean warms, affecting commercial and subsistence fisheries.
  • The West Antarctic Ice Sheet, which would raise sea level by at least 10 feet if it melted entirely and is already threatened by warming from above and below.
  • Parts of the East Antarctic Ice Sheet that would also raise sea level significantly if they melted.


The Emissions Gap Report—an annual assessment of global pledges to cut greenhouse gas emissions—shows that countries' current pledges under the Paris climate agreement will still raise global temperatures 3.2°C (5.8°F) by the end of the century, well beyond the Paris goal of limiting warming to well below 2°C (3.6°F). The Production Gap Report shows that the amount of oil, gas and coal that countries already plan to produce will lead to 50 percent more fossil fuels produced by 2030 than would be allowable to stay under 2°C warming.

The Earth is now warming faster and CO2 levels "are increasing at rates that are an order of magnitude higher than at the end of the last ice age," when rapid climate change destabilized the climate quickly, the scientists wrote in the Nature commentary.

"To err on the side of danger is not a responsible option," they wrote.

No comments:

Post a Comment