[Vision2020] Global Warming and Uncertainty: 2-24-15 "Future climate change under RCP emission scenarios with GISS ModelE2"

[Ted Moffett]

Gavin Schmidt took over the helm at Goddard Institute for Space Studies
June 2014 from James Hansen, who served as director of GISS from
1981-2013.  Given GISS is one of the most credible research institutions on
climate science, today I searched for the most recent scientific
publications by Gavin Schmidt, and found the following, published online
less than two months ago

The abstract is pasted in below.  It demonstrates clearly, to my mind, the
probabilistic nature of climate science predictions regarding anthropogenic
climate change.  To expect climate science to make firm predictions and
dates regarding exactly what average global temperature, what Arctic sea
ice extent, what sea level rise etc. the Earth will reach at some exact
date in the future, is to misunderstand the nature of climate science.
That large scale changes will occur can be predicted with a high degree of
confidence, but there is a range of possible outcomes, some very extreme,
some less so, over differing time scales.

Note the year 2500 referenced in the abstract, indicating climate science
modeling over a time scale that some think not scientifically credible!

Given this state of the science, the argument to take action to mitigate
anthropogenic climate change is based on a risk taking analysis.  We might
be lucky and the outcomes will not be as catastrophic... On the other
hand...

It appears those who argue climate science predictions are too undertrain
to justify taking action now to mitigate global warming, suggest we assume
a significant risk of very costly outcomes as acceptable.
-----------------------------------
Future climate change under RCP emission scenarios with GISS ModelE2

http://onlinelibrary.wiley.com/wol1/doi/10.1002/2014MS000403/full
Abstract

We examine the anthropogenically forced climate response for the 21st
century representative concentration pathway (RCP) emission scenarios and
their extensions for the period 2101–2500. The experiments were performed
with ModelE2, a new version of the NASA Goddard Institute for Space
Sciences (GISS) coupled general circulation model that includes three
different versions for the atmospheric composition components: a
noninteractive version (NINT) with prescribed composition and a tuned
aerosol indirect effect (AIE), the TCAD version with fully interactive
aerosols, whole-atmosphere chemistry, and the tuned AIE, and the TCADI
version which further includes a parameterized first indirect aerosol
effect on clouds. Each atmospheric version is coupled to two different
ocean general circulation models: the Russell ocean model (GISS-E2-R) and
HYCOM (GISS-E2-H). By 2100, global mean warming in the RCP scenarios ranges
from 1.0 to 4.5°C relative to 1850–1860 mean temperature in the historical
simulations. In the RCP2.6 scenario, the surface warming in all simulations
stays below a 2°C threshold at the end of the 21st century. For RCP8.5, the
range is 3.5–4.5°C at 2100. Decadally averaged sea ice area changes are
highly correlated to global mean surface air temperature anomalies and show
steep declines in both hemispheres, with a larger sensitivity during winter
months. By the year 2500, there are complete recoveries of the globally
averaged surface air temperature for all versions of the GISS climate model
in the low-forcing scenario RCP2.6. TCADI simulations show enhanced warming
due to greater sensitivity to CO2, aerosol effects, and greater methane
feedbacks, and recovery is much slower in RCP2.6 than with the NINT and
TCAD versions. All coupled models have decreases in the Atlantic
overturning stream function by 2100. In RCP2.6, there is a complete
recovery of the Atlantic overturning stream function by the year 2500 while
with scenario RCP8.5, the E2-R climate model produces a complete shutdown
of deep water formation in the North Atlantic.
---------------------------------------
Vison2020 Post: Ted Moffett
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.fsr.com/pipermail/vision2020/attachments/20150421/edce9844/attachment.html>