[Marxism] Study Finds More of Earth Is Hotter and Says Global Warming Is at Work
lnp3 at panix.com
Tue Aug 7 09:06:17 MDT 2012
NY Times August 6, 2012
Study Finds More of Earth Is Hotter and Says Global Warming Is at Work
By JUSTIN GILLIS
(Study is at
The percentage of the earth’s land surface covered by extreme heat in
the summer has soared in recent decades, from less than 1 percent in the
years before 1980 to as much as 13 percent in recent years, according to
a new scientific paper.
The change is so drastic, the paper says, that scientists can claim with
near certainty that events like the Texas heat wave last year, the
Russian heat wave of 2010 and the European heat wave of 2003 would not
have happened without the planetary warming caused by the human release
of greenhouse gases.
Those claims, which go beyond the established scientific consensus about
the role of climate change in causing weather extremes, were advanced by
James E. Hansen, a prominent NASA climate scientist, and two co-authors
in a scientific paper published online on Monday in the Proceedings of
the National Academy of Sciences.
“The main thing is just to look at the statistics and see that the
change is too large to be natural,” Dr. Hansen said in an interview. The
findings provoked an immediate split among his scientific colleagues,
Some experts said he had come up with a smart new way of understanding
the magnitude of the heat extremes that people around the world are
noticing. Others suggested that he had presented a weak statistical case
for his boldest claims and that the rest of the paper contained little
that had not been observed in the scientific literature for years.
The divide is characteristic of the strong reactions that Dr. Hansen has
elicited playing dual roles in the debate over climate change and how to
combat it. As the head of the Goddard Institute for Space Studies in
Manhattan, he is one of NASA’s principal climate scientists and the
primary custodian of its records of the earth’s temperature. Yet he has
also become an activist who marches in protests to demand new government
policies on energy and climate.
The latter role — he has been arrested four times at demonstrations,
always while on leave from his government job — has made him a hero to
the political left, and particularly to college students involved in
climate activism. But it has discomfited some of his fellow researchers,
who fear that his political activities may be sowing unnecessary doubts
about his scientific findings and climate science in general.
Climate-change skeptics routinely accuse Dr. Hansen of manipulating the
temperature record to make global warming seem more serious, although
there is no proof that he has done so and the warming trend has
repeatedly been confirmed by other researchers.
Scientists have long believed that the warming — roughly 2.5 degrees
Fahrenheit over land in the past century, with most of that occurring
since 1980 — was caused largely by the human release of greenhouse gases
from burning fossil fuels. Such emissions have increased the likelihood
of heat waves and some other types of weather extremes, like heavy rains
and snowstorms, they say.
But researchers have struggled with the question of whether any
particular heat wave or storm can be definitively linked to
human-induced climate change.
In the new paper, titled “Perception of Climate Change,” Dr. Hansen and
his co-authors compared the global climate of 1951 to 1980, before the
bulk of global warming had occurred, with the climate of the years 1981
They computed how much of the earth’s land surface in each period was
subjected in June, July and August to heat that would have been
considered particularly extreme in the period from 1951 to 1980. In that
era, they found, only 0.2 percent of the land surface was subjected to
extreme summer heat. But from 2006 to 2011, extreme heat covered from 4
to 13 percent of the world, they found.
“It confirms people’s suspicions that things are happening” to the
climate, Dr. Hansen said in the interview. “It’s just going to get worse.”
The findings led his team to assert that the big heat waves and droughts
of recent years were a direct consequence of climate change. The authors
did not offer formal proof of the sort favored by many climate
scientists, instead presenting what amounted to a circumstantial case
that the background warming was the only plausible cause of those
individual heat extremes.
Dr. Hansen said the heat wave and drought afflicting the country this
year were also a likely consequence of climate change.
Some experts said they found the arguments persuasive. Andrew J. Weaver,
a climate scientist at the University of Victoria in British Columbia
who reviewed the paper before publication, compared the warming of
recent years to a measles outbreak popping up in different places. As
with a measles epidemic, he said, it makes sense to suspect a common cause.
“You can actually start to see these patterns emerging whereby in any
given year more and more of the globe is covered by anomalously warm
events,” Dr. Weaver said.
But some other scientists described the Hansen paper as a muddle.
Claudia Tebaldi, a scientist with an organization called Climate Central
that seeks to make climate research accessible to the public, said she
felt that the paper was on solid ground in asserting a greater overall
likelihood of heat waves as a consequence of global warming, but that
the finding was not new. The paper’s attribution of specific heat waves
to climate change was not backed by persuasive evidence, she said.
Martin P. Hoerling, a researcher with the National Oceanic and
Atmospheric Administration who studies the causes of weather extremes,
said he shared Dr. Hansen’s general concern about global warming. But he
has in the past criticized Dr. Hansen for, in his view, exaggerating the
connection between global warming and specific weather extremes. In an
interview, he said he felt that Dr. Hansen had done so again.
Dr. Hoerling has published research suggesting that the 2010 Russian
heat wave was largely a consequence of natural climate variability, and
a forthcoming study he carried out on the Texas drought of 2011 also
says natural factors were the main cause.
Dr. Hoerling contended that Dr. Hansen’s new paper confuses drought,
caused primarily by a lack of rainfall, with heat waves.
“This isn’t a serious science paper,” Dr. Hoerling said. “It’s mainly
about perception, as indicated by the paper’s title. Perception is not a
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