Mar 22, 2016

Ice melt, sea level rise and superstorms: evidence from paleoclimate data,climate modeling, and modern observations that 2 °C global warmingcould be dangerous

Hansen, James, Sato, Makiko, Hearty, Paul, Ruedy, Reto, Kelley, Maxwell, Masson-Delmotte, Valerie, Russell, Gary, Tselioudis, George, Cao, Junji, Rignot, Eric, Velicogna, Isabella, et al
Atmospheric Chemistry and Physics
  • Uses numerical climate simulations, paleoclimate data, and modern observations to study the effect of growing ice melt from Antarctica and Greenland
  • Finds that meltwater tends to stabilize the ocean column, inducing amplifying feedbacks that increase subsurface ocean warming and ice shelf melting
  • States that cold meltwater and induced dynamical effects cause ocean surface cooling in the Southern Ocean and North Atlantic, thus increasing Earth's energy imbalance and heat flux into most of the global ocean's surface
  • States that Southern Ocean surface cooling, while lower latitudes are warming, increases precipitation on the Southern Ocean, increasing ocean stratification, slowing deepwater formation, and increasing ice sheet mass loss
  • Holds that these feedbacks make ice sheets in contact with the ocean vulnerable to accelerating disintegration
  • Hypothesizse that ice mass loss from the most vulnerable ice, sufficient to raise sea level several meters, is better approximated as exponential than by a more linear response
  • Predicts that continued high fossil fuel emissions this century will yield:
  1. cooling of the Southern Ocean, especially in the Western Hemisphere;
  2. slowing of the Southern Ocean overturning circulation, warming of the ice shelves, and growing ice sheet mass loss;
  3. slowdown and eventual shutdown of the Atlantic overturning circulation with cooling of the North Atlantic region;
  4.  increasingly powerful storms; and
  5. nonlinearly growing sea level rise, reaching several meters over a timescale of 50–150 years