[Vision2020] GISS's Gavin Schmidt: NY Times 10-24-18: "How Scientists Cracked the Climate Change Case"

Ted Moffett starbliss at gmail.com
Sun Oct 28 21:48:09 PDT 2018


New York Times article copied lower down--

Vision2020 Post: Ted Moffett
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I was very surprised to discover Schmidt, in this very short opinion piece,
emphasized the well documented trend in atmospheric temperatures showing
stratospheric cooling coupled with tropospheric warming as evidence of
greenhouse gas (CO2) related warming of Earth's climate, as opposed to, for
example, solar output increases.  I've been repeating this evidence for
years as critical to the science on this issue.

I guess the liberal academic elitist scientists successfully brainwashed my
gullible mind, which is to be expected given their nefarious influence in
college classes at the University of Idaho!  As a local politician who
labeled global warming a "liberal scam" recently stated "“Latah County,
particularly the university, greater *Moscow* area, is a *cesspool of
liberalism*,”
http://dnews.com/local/foreman-calls-moscow-area-cesspool-of-liberalism/article_ff576b30-4853-11e8-a501-23ce20056068.html

But I often wonder about the efficacy of science based reasoning to
influence the attitudes of people who appear unconvinced that human impacts
on global warming are a major cause of this serious problem, or even that
there is a major problem at all?

My anecdotal experience is that science based arguments are ineffectual.
For likely purely subjective personal inclinations, I continue to assume
people are rational fact based creatures influenced by science and logic.
That a blatant global warming science denying propagandist assumed power as
the most powerful person on Earth indicates I am wrong.

Some deeply involved in solutions to anthropogenic global warming warn
against even mentioning "global warming" when promoting, for example, solar
power for homes, given the very emotional bias against addressing an issue
that has become almost synonymous with "liberal big government"
propaganda!  Mention long-term electricity bill savings, or keeping the
lights on during a power outage, but not solving global warming!

Goddard Institute for Space Studies director Gavin Schmidt, commenting on
Realclilmate.org
http://www.realclimate.org/index.php/archives/2018/10/cracking-the-climate-change-case/
regarding his recent New York Times column "How Scientists Cracked the
Climate Change Case" stated:  "But asking how many people are helped to be
persuaded by articles like this is a valid question, and I don’t really
know the answer. Anyone?"
------------------------------------
https://www.nytimes.com/2018/10/24/opinion/climate-change-global-warming-trump.html

How Scientists Cracked the Climate Change Case

The biggest crime scene on the planet is the planet. We know the earth is
warming, but who or what is causing it?

By Gavin Schmidt

Dr. Schmidt is the director of the NASA Goddard Institute for Space Studies.

   - Oct. 24, 2018

The latest report <http://www.ipcc.ch/report/sr15/> from the world’s
climate scientists has made clear the size of the challenge if the world is
to stay below the global warming limit hoped for in the Paris climate
agreement <https://nyti.ms/2m2gTxH>. Unfortunately, with current trends we
are likely to cross this threshold within the next two decades because we
are already two-thirds of the way there.

But how do we know what is driving these climate trends? It comes down to
the same kind of detective work that typifies a crime scene investigation,
only here we are dealing with a case that encompasses the whole world. Let
me give you my view, which does not necessarily represent the position of
NASA or the federal government.

For the past 100 years we have documented good, independently confirmed
observations of change at the surface of the planet, and for the past 40
years satellites and comprehensive measuring efforts have provided a much
fuller view of changes throughout the earth system. These observations show
clearly that among other things, the surface of the planet has warmed, the
upper atmosphere has cooled, the oceans are gaining an enormous amount of
heat, sea level is rising, Arctic ice has greatly receded and glaciers
around the world are in retreat.

Scientists have no shortage of suspects for the causes of climate change.
Over the 4.5-billion-year history of the planet, almost anything that might
have happened has happened, sometimes many times over. The sun has
brightened and sometimes dimmed, massive volcanic eruptions have occurred,
the planet’s orbit has wobbled, the continents have moved, the land surface
has been remade, the composition of the atmosphere and its ability to trap
and reflect solar and terrestrial radiation has altered, ocean circulations
have sputtered and stopped, and we have been struck, at least once, by a
mass-extinction-inducing asteroid.

Each of these events left a unique fingerprint of change on the climate
system, with impacts reaching from the upper atmosphere 30 miles high to
the deep ocean four miles down, from the tropics to the poles, and in the
sediments laid down in the geological record. To track down the culprit of
any one specific climate change involves piecing together the
contemporaneous fingerprints and tracking them back to the plausible causes.

For changes since the beginning of the 20th century we don’t need to worry
about asteroids or moving continents, but we know there have been natural
changes in earth’s orbit, variations in the sun’s brightness and volcanic
activity. There are some new suspects too. Human activity has deforested,
replanted and irrigated large areas of land, added pollution to the skies,
depleted the ozone layer and, yes, changed the concentrations of key
greenhouse gases in the atmosphere. Carbon dioxide levels are up 40 percent
<https://www.ipcc.ch/report/graphics/index.php?t=Assessment%20Reports&r=AR5%20-%20WG1&f=Chapter%2006>,
methane has more than doubled, and we’ve introduced some purely synthetic
compounds that are many times more potent than either of those but are
fortunately present in lower, but growing, concentrations.

Like forensic detectives, climate scientists have developed a new array of
tools in recent decades designed to skillfully calculate what the
fingerprints of these changes look like, and more important, how they
differ from one another. It turns out that increases in solar activity
produce warming throughout the atmosphere, while carbon dioxide increases
cooling in the upper atmosphere and warms the surface. Variations in ocean
circulation distribute heat, while changes in the sun or in greenhouse
gases change the total heat amount in the system. Air pollution, volcanoes
and irrigation all cool the climate, while rising greenhouse gases warm it.
Ozone depletion has increased the speed of the winds around Antarctica,
affecting ocean circulation and sea ice.

But even taking into account uncertainties in the amount of air pollution
in the 19th century or in estimating global temperatures through time,
scientists have concluded that the current warmth is impossible to explain
without human contributions. It is on a par with the likelihood that a DNA
match at a crime scene is purely coincidental. Moreover, when we include
the multiplicity of human effects, we match them with the observed trends
at the surface, in the Arctic, in the ocean and aloft. The dominant factor
that emerges is the rise in greenhouse gases, which we know comes mainly
from the burning of fossil fuels and deforestation.

Even more convincingly, these trends aren’t just being attributed in
hindsight. The rate of surface warming was predicted
<https://www.carbonbrief.org/analysis-how-well-have-climate-models-projected-global-warming>
in the 1980s, the cooling in the upper atmosphere was forecast in a 1967
scientific paper
<https://journals.ametsoc.org/doi/abs/10.1175/1520-0469%281967%29024%3C0241%3ATEOTAW%3E2.0.CO%3B2>,
and specific measurements <https://www.nature.com/articles/35066553> from
space indicate that the total greenhouse effect has been enhanced exactly
as theory would predict.

When this is all put together, the conclusions are inescapable: Without
human activities the planet would not have warmed over the past century.
When scientists include all of the effects that humans have had on the
climate system, they can match them with these many independent and varied
observations. Our best assessment is therefore that humans, at least the
ones responsible for the bulk of carbon dioxide emissions, have been
responsible for all of the recent trends in global temperatures.

The forensics have spoken, and we are to blame.

Gavin Schmidt is a climate scientist and director of the NASA Goddard
Institute for Space Studies in New York.
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