Nebraskans for Peace regular columnist, Dr. Bruce Johansen, has written his regular What's HOT in Global Warming? article about the most recent study done by climate scientist Dr. James Hansen and his colleagues.
This article was first published in Nebraskans for Peace March/ April newsletter, and is reprinted with permission.
By Bruce E. Johansen
As our presidential campaign drowns in insults and trivia,
here’s the real news: the world’s coastal cities are on a carbon-dioxide clock.
As the Earth has experienced its warmest winter and early spring in recorded
history, exceeding records in the 121-year instrumental record by an astounding
margin, the scientific debate no longer dwells on whether present levels of
greenhouse-gas emissions in the atmosphere will drown the coasts. The question
is when, and by how much.
During the last few months, an intense El Nino and rising
greenhouse-gas levels have launched temperatures to nearly 5 degrees F. above
20th-century averages. In December, 2015; January, 2016; and February 2016 (the
meteorological winter season), temperatures not only set world records, but did
so by the largest margins (anomalies) since record-keeping began about 1880.
February's global temperature was 1.35 degrees C. above the 1951-1980
average—exceeding the previous record anomaly set in January of 1.13 degrees
C., according to NASA's Goddard Institute for Space Studies. December, 2015 was
1.11 degrees C. above the same set of averages.
"The departures are what we would consider
astronomical," said NOAA climate scientist Jessica Blunden. "It's on land.
It's in the oceans. It's in the upper atmosphere. It's in the lower atmosphere.
The Arctic had record low sea ice. Everything everywhere is a record this
month, except Antarctica," Blunden said. "It's insane." Georgia
Tech climate scientist Kim Cobb added: “When I look at the new February 2016
temperatures, I feel like I'm looking at something out of a sci-fi movie. In a
way we are: it's like someone plucked a value off a graph from 2030 and stuck
it on a graph of present temperatures. It is a portent of things to come, and
it is sobering that such temperature extremes are already on our doorstep.”
Advancing the
Timetable for Sea-level Rise
As radical rises in worldwide temperatures startled
scientists early in 2016, James Hansen and 18 co-authors published a study in
the open-access journal Atmospheric Chemistry and Physics (from the European
Geophysical Union), making a case that several meters in sea-level rise could
take place within a century—not the several hundred years projected by many
scientists. This conclusion is based on a study of paleoclimate during the
Eemian period 120,000 years ago, a situation analogous to today (except that
temperature increases occurred less rapidly then than now).
During the Eemian, Hansen and colleagues assert that excess
heat in the deep oceans rapidly eroded ice in Antarctica and Greenland at an
accelerating pace. This melting was accelerated by a slowing of the Atlantic
Ocean’s meridional circulation that usually distributes heat through the world
ocean. The slowing of ocean circulation caused stagnation of relatively warm
water in some areas in and near the Arctic.
The authors of this study point to maps of worldwide warming
during the winter of 2015-2016 indicating that the only areas with
below-average temperatures were over oceans adjacent to Greenland and
Antarctica, where rapid melting of ice influences the water’s temperature
level. “My interpretation is that this is the beginning,” Hansen said. “And it’s
one or two decades sooner than in our model” (Gillis, 2016). “I think almost
everybody who’s really familiar with both paleo [climatic] and modern
[observations] is now very concerned that we are approaching—if we have not
passed—the points at which we have locked in really big changes for young
people and future generations,” Hansen said.
The 2 Degree C. Limit
“Dangerous”
Limiting global temperature rise to 2 degrees C. (3.6 F.)
over pre-industrial levels (as recommended by recent diplomatic efforts such as
the 2015 Paris accords) will not prevent climate-driven changes forcing
evacuation of many coastal cities, Hansen and colleagues warned.
Hansen and colleagues hypothesized that: “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. Doubling times of
10, 20 or 40 years yield multi-meter sea level rise in about 50, 100 or 200
years. These climate feedbacks aid interpretation of events late in the prior interglacial,
when sea level rose to +6–9 meters with evidence of extreme storms while Earth
was less than 1° C warmer than today. [Climate] modeling, paleoclimate
evidence, and ongoing observations together imply that 2° C global warming
above the pre-industrial level could be dangerous, [including] growing sea
level rise, reaching several meters over a timescale of 50–150 years.”
“Some of the claims in this paper are indeed extraordinary,”
said Michael E. Mann, a climate scientist at Penn State University. “They
conflict with the mainstream understanding of climate change to the point where
the standard of proof is quite high.” However, noting that Hansen and
colleagues often have presaged consensus, Mann said: “I think we ignore James
Hansen at our peril,” Mann said (Gillis, 2016).
Bruce E. Johansen is
Jacob J. Isaacson University Research Professor, Communication and Native
American Studies, University of Nebraska at Omaha. He is at work on a
three-volume encyclopedia on global warming for ABC-CLIO, to be published next
year.
REFERENCES
Gillis, Justin. “Scientists Warn of Perilous Climate Shift
Within Decades, Not Centuries.” New York Times, March 22, 2016.
http://www.nytimes.com/2016/03/23/science/global-warming-sea-level-carbon-dioxide-emissions.html
Hansen, J., M. Sato, P. Hearty, R. Ruedy, M. Kelley, V.
Masson-Delmotte, G. Russell, G. Tselioudis, J. Cao, E. Rignot, I. Velicogn. B.
Tormey, B. Donovan, E. Kandiano, K. von Schuckmann, P. Kharecha, A.N. Legrande,
A. M. Bauer, and K.-W. Lo. “Ice Melt, Sea Level Rise and Superstorms: Evidence
from Paleoclimate Data, Climate Modeling, and Modern Observations That 2 °C
Global Warming Could be Dangerous.” Atmospheric Chemistry and Physics 16(March
22, 2016), 3,761-3812. doi:10.5194/acp-16-3761-2016.
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