Tuesday, August 1, 2017

Best Case Scenario Is Not Good

Even if we begin immediately to curb CO2 emissions, two studies say that we will reach 2 degrees Celsius or more by the end of the Century.

“Our analysis shows that the goal of 2 degrees is very much a best-case scenario,” said lead author Adrian Raftery, a UW professor of statistics and sociology. “It is achievable, but only with major, sustained effort on all fronts over the next 80 years.”
 The two studies reveal that factoring in current emissions, as well as a wide range of future trends, we may have already locked in a temperature rise surpassing the universally agreed-upon global warming target of 1.5 to 2 degrees Celsius — which the 2015 Paris accord sought to set as an upper limit.
If all the world’s human-derived sources of greenhouse gases stopped today (which obviously will not happen), by 2100 global temperatures would stabilize somewhere between a temp slightly cooler than the current average and about 2.3 degrees higher than preindustrial levels, according to the first study. That report found a 13 percent chance that the hard-won target of 1.5 degrees favored by small island states was already lost.
The second study simulated 100,000 potential future versions of our civilization out to 2100. In only about 1,000 of them, or around 1 percent, did human society move quickly enough to avert a temperature rise of greater than 1.5 degrees. “We’re closer to the margin than we think,” said Adrian Raftery, lead author of the simulation study.
What does 2 degrees Celsius (3.6 F) mean?
Scientists believe that 3.6 degrees is roughly the temperature at which the expansive ice sheets in Greenland and West Antarctica become unstable and melt at an unstoppable rate. If the West Antarctic ice sheet melted entirely, it would raise sea levels by more than 10 feet. If Greenland’s ice sheet melted away, add another 23 feet. It's still a matter of contention how many centuries this would take, but a number of studies this year show these ice sheets melting at an alarming rate. In the last month, four studies show these ice sheets may be more unstable than previous models, which would mean current projections of sea level rise, of up to 4 feet by the century's end, are too conservative. One of these analyses, from NASA and the University of California at Irvine, shows that western Antarctica lost water that's equivalent to the weight of Mt. Everest every two years for the past 21 years. 
This would change the world map as we know it. Some 12.3 million people live on U.S. land that would go underwater if the sea rises by 10 feet. 
Uncontrolled climate change would also fuel greater extremes across the world. We’re already experiencing hotter average temperatures; the first 11 months of 2014 means this year is on track to be the hottest year recorded. Those effects grow even worse in a world that's 7.2 degrees warmer than pre-industrial times. The coolest months in tropical regions are likely to be "substantially warmer than the warmest months in the 20th century," according to the World Bank. The summer months in the Mediterranean, North Africa, and the Middle East will exceed today's heat extremes. Parts of Africa, the Middle East, and South Asia will face devastating droughts as temperatures rise. Food production will plummet and water supplies will be drained, even as the world population rises. No doubt, the frequency and severity of human conflict will rise right along with it.

We may have even less time to stop global warming than we thought

“Frankly, this study does indicate that it may be more of an uphill battle than we previously thought in order to stabilize warming below the commonly defined dangerous limit of 2 degrees Celsius,” said Pennsylvania State University’s Michael Mann, one of the study’s authors.

Most of the land around the Equator will be uninhabitable.  Millions, hundreds of millions, of people will be migrating toward more moderate weather.  And large portions of land now used to feed those people will be barren.  We will be relying on less and less land to feed more and more people.

The social order will likely descent into chaos.  Everyone will be relying locally for survival.

And it will be worse if nothing is done immediately.  A lot is being done to change our reliance on oil and coal, but there continues to be very strong resistance.  That resistance has to be broken, soon.