by Rob Elmore, @RobElmore on Twitter – September 2012
For the non-climate-scientist reader (and written by one of the
same), this posting aims to highlight input from science writers regarding the
2012 U.S. drought and extensive melting of ice in the Arctic. By presenting
these quotes, the posting is intended to help the reader sort through whether the
2012 news stories on these topics should or should not be regarded as clear
indications of human impacts on climate systems in wide-ranging parts of the
Earth.
(Note: Numbered links below are spelled out as complete web
citations at the end of this posting.)
It’s useful to start with quotes from this (1) recent
“Information Statement” by the American
Meteorological Society, which outlines for scientists
and non-scientists alike some key patterns that weather and climate scientists
have determined regarding drought and Arctic ice conditions. It includes these
quotes:
“Climate models simulate the important aspects of climate and
climate change based on fundamental physical laws of motion, thermodynamics,
and radiative transfer.”
“...climate models have demonstrated skill in reproducing past
climates, and they agree on the broad direction of future climate.”
“Arctic sea ice extent and volume have been decreasing for the
past several decades.”
“The model projections show that the largest warming will occur in
northern polar regions, over land areas, and in the winter season, consistent
with observed trends.”
“For many areas [around the globe], model simulations suggest
there will be a tendency towards more intense rain and snow events separated by
longer periods without precipitation.”
“...model simulations suggest that precipitation will increase in
the far northern parts of North America, and decrease in the southwest and
south-central United States where more droughts will occur.”
“For the longer term, paleoclimatic observations suggest that
droughts lasting decades are possible and that these prolonged droughts could
occur with little warning.”
“Drier conditions in summer, such as those anticipated for the
southern United States and southern Europe, are expected to contribute to more
severe episodes of extreme heat.”
“There is unequivocal evidence that Earth’s...snow cover, mountain
glaciers, and Arctic sea ice are shrinking.”
“Technological, economic, and policy choices in the near future
will determine the extent of future impacts of climate change. Science-based
decisions are seldom made in a context of absolute certainty.”
Drought
Appearing in the Washington
Post, this
(2) article is by James E. Hansen,
who directs the NASA Goddard Institute for Space Studies, and includes these
quotes:
“...a stunning increase in the
frequency of extremely hot summers...”
“Our analysis shows that it is no longer enough
to say that global warming will increase the likelihood of extreme weather and
to repeat the caveat that no individual weather event can be directly linked to
climate change. To the contrary, our analysis shows that, for the extreme hot
weather of the recent past, there is virtually no explanation other than
climate change.”
“The deadly European heat wave of 2003, the fiery Russian heat wave of 2010 and catastrophic droughts in Texas and Oklahoma last year can each be attributed to
climate change.”
“Even with climate change, you will occasionally
see cooler-than-normal summers or a typically cold winter. Don’t let that fool
you.”
“When we plotted the world’s changing
temperatures on a bell curve, the extremes of unusually cool and, even more,
the extremes of unusually hot are being altered so they are becoming both more
common and more severe.”
"There is still time to act and avoid a worsening climate,
but we are wasting precious time."
This
(3) article published by CBC
News (Canadian Broadcasting Corporation) notes:
“This summer, record-breaking temperatures
threw an estimated 62 per cent of America's farms into moderate drought or worse,
according to the U.S. Department of Agriculture.”
"We typically don't see drought intensify
like we did this year."
“...a study published this month in the journal
Nature Climate Change predicts the U.S. will suffer a series of severe droughts
in the next two decades...”
This (4) article
in Wired includes:
‘ “In any single event, it’s hard to really
know if you’re just seeing a natural variation or climate change,” cautioned
climatologist Chris Funk of the University of California, Santa Barbara. With
that caveat, Funk said when asked if human activity exacerbated the drought,
“Tentatively, the answer is yes. To some extent, it is.” ... Funk’s specialty
is the dynamics of sea surface temperatures in the Indian Ocean and western
Pacific Ocean. Over the last century, and in particular the last two decades,
these rose by an average of 1.25 degrees Fahrenheit. Ocean temperature trends
can be tricky to interpret, but there’s little scientific disagreement about
Indian Ocean warming: It’s almost certainly man-made, a result of greenhouse
gases trapping heat in Earth’s atmosphere.‘
‘Bin Guan, a drought specialist at the California Institute of
Technology, struck a cautionary note on early interpretations. “Drought
development is a long, complicated process,” he said. “Its response to
greenhouse gases is more complicated than temperature alone because it’s a
combination of temperature, precipitation, evaporation, soil moisture, and
other conditions.” Whether the current drought’s severity is linked to
greenhouse gas pollution is “difficult to say with certainty,” Guan said. “It
could be a combination of both natural forces and human impact, but we can’t be
sure, at least for now.” ‘
This
(5) transcript of a “Science Friday” interview on NPR (National Public Radio) includes
the following quotes:
“Reporting in the Bulletin
of the American Meteorological Society, researchers write that
extreme heat waves, such as the one last year in Texas, are 20 times more
likely today than they were in the 1960s.”
“Tom Peterson is principal scientist at NOAA's National Climatic
Data Center in Asheville, North Carolina.”
[Tom Peterson:] “You
know, are you asking about the temperature, how warm it got, or are you asking
about the probability of warm temperatures reoccurring? And those can wind up
having different answers, so you have to be very cautious about the
communication. And that's really some of the questions that have been raised by
other scientists is exactly, you know, are we communicating this as precisely,
accurately as we should be? And if you get really precisely accurate, sometimes
people can't really understand you with all the different caveats.”
“...when you have drought, you have less water able to be
evaporated or evapotranspirated from plants, and so more of the energy goes
into sensible heat of warming the soil. So droughts can cause heat waves. At
the same time, a really intense heat wave can cause a drought, because it
fosters so much more evapotranspiration and evaporation of the water off the
soil.”
“...climate prediction is much more akin to understanding the
change of seasonal cycles and the forces that are affecting that, because now
we're seeing - for example, we're seeing spring coming earlier.”
Arctic Ice
This
(6) article from Huffington
Post notes:
“Each year around March, Arctic sea ice begins
its yearly melting period until the extent and volume of ice reach their annual
minimums, usually sometime in mid-September. After that point, new ice forms
until an annual maximum is reached, typically in March of the following year.”
“...the National Snow and Ice Data Center has
reported that from 1979 to 2011, the monthly sea ice extent for September --
the month of the seasonal minimum -- has fallen at a rate of 12 percent per
decade.”
“Less summer ice is not only a consequence of
climate change, but it will also cause further warming: As the summer ice
melts, the light colored ice which reflects the sun's rays back to space is
replaced with dark water which absorbs more heat and warms the oceans further.
This
(7) story in Forbes
includes these quotes:
“As Arctic Ice Reaches Record Low, Meteorologists Name Humans
'Dominant' Cause Of Climate Change”
“Today, the National Snow and Ice Data Center [NSIDC], in
conjunction with NASA, announced today that Arctic sea ice has reached a record
low since the previous record-breaking low in 2007.”
‘ “...in the context of what’s happened in the last several years
and throughout the satellite record, it’s an indication that the Arctic sea ice
cover is fundamentally changing,” NSIDC scientist Walt Meier said in a press release. “The Arctic
used to be dominated by multiyear ice, or ice that stayed around for several
years,” Meier continued. “Now it’s becoming more of a seasonal ice cover and
large areas are now prone to melting out in summer.” ’
This
(8) from the Washington Post
states:
“The Arctic Ocean’s vast, frozen expanse of ice
is rapidly vanishing.”
“The
amount of Arctic sea ice is shrinking each year — and will soon disappear
altogether in the summer months if the planet keeps warming. Since the 1980s, agencies around the world have deployed
satellites to measure the extent of Arctic sea ice...”
“Over the past three decades, the summer Arctic
sea ice extent has declined roughly 40 percent, and the ice has lost significant volume...”
“A new study
in this month’s Environmental Research Letters concludes that between 70 and 95
percent of the Arctic melt since 1979 has been caused by human activity.
Man-made global warming has rapidly heated up the Arctic — the region has been
warming about twice as fast as the global average. (See here for a good explanation of why.)”
“In the past, scientists have underestimated the
pace at which Arctic sea ice would disappear. In 2007, the
Intergovernmental Panel on Climate Change (IPCC) figured we wouldn’t see
ice-free summers in the Arctic until the end of the century or so. But later
observations suggested
that sea-ice extent is shrinking far more quickly than the IPCC had forecast.
It appears that earlier climate models underestimated certain “feedback”
effects.”
This
(9) article from the Wall
Street Journal notes:
“The
Northern Hemisphere's largest expanses of ice have thawed faster and more
extensively this year than scientists have previously recorded. And the summer
isn't over.
“Studies suggest that more of the massive Greenland ice cap has
melted than at any time since satellite monitoring began 33 years ago, while
the Arctic sea's ice is shrinking to its smallest size in modern times.
“ "This year's melting season is a Goliath," said
geophysicist Marco Tedesco, director of the Cryospheric Processes Laboratory at
City University of New York. "The ice is being lost at a very strong
pace." ”
Finally, this
(10) from AFP (Agence France
Presse) by way of the New Zealand
Herald includes the following:
“The sea ice in the Arctic
Ocean has melted to its smallest point ever in a milestone that may show that
worst-case forecasts on climate change are coming true, US scientists said today.”
“The extent of ice observed at the weekend
broke a record set in 2007 and will likely melt further with several weeks of
summer still to come, according to data from the National Snow and Ice Data
Center and the Nasa space agency. The government-backed ice center, based at
the University of Colorado at Boulder, said in a statement that the decline in
summer Arctic sea ice "is considered a strong signal of long-term climate
warming." “
“Michael E. Mann, a lead author of a major UN
report in 2001 on climate change, said the latest data reflected that
scientists who were criticised as alarmists may have shown "perhaps too
great a degree of reticence." "I think, unfortunately, this is an
example that points more to the worst-case scenario side of things," said
Mann, director of the Earth System Science Center at Penn State University. "There
are a number of areas where in fact climate change seems to be proceeding
faster and with a greater magnitude than what the models predicted," Mann
told AFP. "The sea ice decline is perhaps the most profound of those
cautionary tales because the models have basically predicted that we shouldn't
see what we're seeing now for several decades," he added.”
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Web Citations
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