Sea levels are projected to rise faster than previously thought – as much as 10 feet within the next 50 years – precipitating an undeniable and irreversible effect on coastal cities like New York and Miami, according to a new study by 17 of the world's top climate change experts.
This suggests rates of glacial melt have been drastically underestimated and that large numbers of people resideing now in the very areas that could be underwater within just a few decades will need to be relocated.
"We conclude that continued high emissions will make multi-meter sea level rise practically unavoidable and likely to occur this century. Social disruption and economic consequences of such large sea level rise could be devastating. It is not difficult to imagine that conflicts arising from forced migrations and economic collapse might make the planet ungovernable, threatening the fabric of civilization."
Using this approach, the paper concludes:
"Humanity faces near certainty of eventual sea level rise of at least Eemian proportions, 15 5–9 m, if fossil fuel emissions continue on a business-as-usual course, e.g., IPCC scenario A1B that has CO2 ? 700 ppm in 2100."
(NB: Eemian refers to the most recent interglacial period of the Pleistocene in northern Europe.)
Who is threatened?
"It is unlikely that coastal cities or low-lying areas such as Bangladesh, European lowlands, and large portions of the United States eastern coast and northeast China plains (Fig. S22) could be protected against such large sea level rise."
But that's not all. The report predicts:
"Storms conjoin with sea level rise to cause the most devastating coastal damage. Our simulations imply increasing storm strengths for such situations, as a stronger temperature gradient caused by ice melt increases baroclinicity and provides energy for more severe weather events."
What's more:
"Effects of freshwater injection and resulting ocean stratification are occurring sooner in the real world than in our model."
It adds a note for policymakers:
"We conclude that the 2?C global warming 'guardrail', affirmed in the Copenhagen Accord (2009), does not provide safety, as such warming would likely yield sea level rise of several meters along with numerous other severely disruptive consequences for human society and ecosystems."
The report strongly questions whether "global temperature is the most fundamental metric for global climate in the 21st century".
It says the real challenge is to stabilize the climate is "to remove Earth's energy imbalance, which is now about +0.6 W m?2"; i.e., there is more energy coming in than going out.
Hansen repeats his long held view that to achieve this "requires reducing atmospheric CO2 20 from ? 400 to ? 350 ppm (Hansen et al., 2008, 2013a)". In short, "that fossil fuel CO2 emissions must be reduced as rapidly as practical".
This is now seen as extremely unlikely to achieve. The challenge for those threatened areas, then, is to relocate citizens and make the areas more resilient, especially in reation to sea level rise and storm surges.
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