Several fascinating new scientific papers have
appeared recently that come to some very different conclusions
about the trend in global average temperature and what causes it.
One concludes that fluctuations in the El Nino explain the current
15-year “pause” in warming and cut future increases in man-made
warming in half; a second finds that once missing data are taken
into account there has been NO pause in warming at all; and a third
reports that natural fluctuations in the Arctic explain the “pause”
which could last until 2030.
So first, in a new
article in the Asia-Pacific Journal of Atmospheric
Science, University of Alabama in Huntsville researchers Roy
Spencer and Danny Braswell use climate models to take into account
the effects that natural variations in the El Nino Southern
Oscillation (ENSO) has on global average temperature trends over
the past 50 years. The ENSO is a phenomenon in which the surface
temperatures over the southern Pacific Ocean fluctuate between hot
and cold phases. According to Phys.org,
they found:
The results suggest that these natural climate cycles change the
total amount of energy received from the sun, providing a natural
warming and cooling mechanism of the surface and the deep ocean on
multi-decadal time scales.“As a result, because as much as 50 percent of the warming since
the 1970s could be attributed to stronger El Niño activity, it
suggests that the climate system is only about half as sensitive to
increasing CO2 as previously believed,” Spencer said.“Basically, previously it was believed that if we doubled the
CO2 in the atmosphere, sea surface temperatures would warm about
2.5 C,” Spencer said. That’s 4.5° F. “But when we factor in the
ENSO warming, we see only a 1.3 C (about 2.3° F) final total
warming after the climate system has adjusted to having twice as
much CO2.” …Spencer said it is reasonable to suspect that the increased La
Niña cooling might be largely responsible for an ongoing “pause” in
global warming that has lasted more than a decade. If that is the
case, weak warming might be expected to revive when this phase of
the El Niño-La Niña cycle shifts back to a warmer El Niño
period.
In contrast, climate catastrophists cite as evidence that things
are worse than they thought a new
study in The Quarterly Journal of the Royal Meteorological
Society by Kevin Cowtan from the University of York and Robert
Way from the University of Ottawa (who both also contribute to the
climate science website Skeptical Science).
The two researchers apply some fancy statistical
jiggering to climate temperature data from the Hadley Centre in the
United Kingdom in an effort to figure out what is going on in the
regions of the globe not well-covered by that dataset. They
report:
The widely quoted trend since 1997 in the hybrid global
reconstruction is two and a half times greater than the
corresponding trend in the coverage-biased HadCRUT4 data. Coverage
bias causes a cool bias in recent temperatures relative to the late
1990s which increases from around 1998 to the present. Trends
starting in 1997 or 1998 are particularly biased with respect to
the global trend. The issue is exacerbated by the strong El Niño
event of 1997-1998, which also tends to suppress trends starting
during those years.
The Guardian
reports that the upshot of their new analysis is:
Both of their new surface temperature data sets show
significantly more warming over the past 16 years than HadCRUT4.
This is mainly due to HadCRUT4 missing accelerated Arctic warming,
especially since 1997.Cowtan & Way investigate the claim of a global surface
warming ‘pause’ over the past 16 years by examining the trends from
1997 through 2012. While HadCRUT4 only estimates the surface
warming trend at 0.046°C per decade during that time, and NASA puts
it at 0.080°C per decade, the new kriging and hybrid data sets
estimate the trend during this time at 0.11 and 0.12°C per decade,
respectively.In other words, there is no 15-year pause in global warming has
all of the current datasets measuring global average temperature
have reported.
And to make things even more “settled,” there is a
new study in Climate Dynamics by Georgia Tech
climatologist Judith Currry and her colleague Marcia Wyatt that
looks at temperature fluctuations in the Arctic region and finds
that they are driven by natural “stadium wave” fluctuations
produced by the Atlantic Multidecadal Oscillation (AMO) and sea ice
extent in the Eurasian Arctic shelf seas. As Newswise
reports the …
…‘stadium-wave’ signal that propagates like the cheer at
sporting events whereby sections of sports fans seated in a stadium
stand and sit as a ‘wave’ propagates through the audience. In like
manner, the ‘stadium wave’ climate signal propagates across the
Northern Hemisphere through a network of ocean, ice, and
atmospheric circulation regimes that self-organize into a
collective tempo.The stadium wave hypothesis provides a plausible explanation for
the hiatus in warming and helps explain why climate models did not
predict this hiatus. Further, the new hypothesis suggests how long
the hiatus might last…“The stadium wave signal predicts that the current pause in
global warming could extend into the 2030s,” said Wyatt,…Curry added, “This prediction is in contrast to the recently
released IPCC AR5 Report that projects an imminent resumption of
the warming, likely to be in the range of a 0.3 to 0.7 degree
Celsius rise in global mean surface temperature from 2016 to 2035.”
…How external forcing projects onto the stadium wave, and whether
it influences signal tempo or affects timing or magnitude of regime
shifts, is unknown and requires further investigation,” Wyatt said.
“While the results of this study appear to have implications
regarding the hiatus in warming, the stadium wave signal does not
support or refute anthropogenic global warming.
Interestingly, the study by Cowtan and Way suggesting that
man-made global warming is continuing apace seems to be getting
much more media attention than are the two suggesting explanations
for why warming has paused and why it might not increase
disastrously in the future. Curious.
Heads up: I will be sending in daily dispatches all next
week from the 19th Conference of the Parties of the United Nations
Framework Convention on Climate Change meeting in Warsaw.
from Hit & Run http://reason.com/blog/2013/11/15/climate-science-is-settled-really
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