新着論文紹介(2013.12.10) Nature, Science, PNAS
◉Nature
1.Clues to extinction in lava gases
Nature 504, 10 (05 December 2013)
doi:10.1038/504010b
2.Geology: North America's broken heart
A billion years
ago, a huge rift nearly cleaved North America down the middle. And then it
failed. Researchers may be getting close to finding out why.
Jessica Marshall
04 December 2013
3.Climate science: Take more care over glacier facts
Alex S. Gardner
Nature 504, 33 (05 December 2013)
doi:10.1038/504033a
4.Coastal regions
Juliane Mossinger, Michael White & Patrick Goymer
Nature 504, 35 (05 December 2013)
doi:10.1038/504035a
5.North Atlantic warming and the retreat of Greenland's
outlet glaciers
Fiammetta Straneo & Patrick Heimbach
Nature 504, 36–43 (05 December 2013)
doi:10.1038/nature12854
6.Coastal flooding by tropical cyclones and sea-level
rise
Jonathan D. Woodruff, Jennifer L. Irish & Suzana J. Camargo
Nature 504, 44–52 (05 December 2013)
doi:10.1038/nature12855
Mass loss from the
Greenland ice sheet quadrupled over the past two decades, contributing a
quarter of the observed global sea-level rise. Increased submarine melting is
thought to have triggered the retreat of Greenland's outlet glaciers. However,
the chain of events and physical processes remain elusive. Recent evidence
suggests that an anomalous inflow of subtropical waters driven by atmospheric
changes, multidecadal natural ocean variability and a long-term increase in the
North Atlantic's upper ocean heat content since the 1950s all contributed to a
warming of the subpolar North Atlantic. This led, in conjunction with increased
runoff, to enhanced submarine glacier melting.
7.Tidal wetland stability in the face of human impacts
and sea-level rise
Matthew L. Kirwan & J. Patrick Megonigal
Nature 504, 53–60 (05 December 2013)
doi:10.1038/nature12856
8.The changing carbon cycle of the coastal ocean
James E. Bauer, Wei-Jun Cai, Peter A. Raymond, Thomas S. Bianchi, Charles
S. Hopkinson & Pierre A. G. Regnier
Nature 504, 61–70 (05 December 2013)
doi:10.1038/nature12857
We discuss the
sources, exchanges and fates of carbon in the coastal ocean and how
anthropogenic activities have altered the carbon cycle. Recent evidence
suggests that the coastal ocean may have become a net sink for atmospheric
carbon dioxide during post-industrial times. Continued human pressures in coastal
zones will probably have an important impact on the future evolution of the
coastal ocean’s carbon budget.
9.Offshore fresh groundwater reserves as a global
phenomenon
Vincent E.A. Post, Jacobus Groen, Henk Kooi, Mark Person, Shemin Ge &
W. Mike Edmunds
Nature 504, 71–78 (05 December 2013)
doi:10.1038/nature12858
10.Ecosystem-based coastal defence in the face of
global change
Stijn Temmerman, Patrick Meire, Tjeerd J. Bouma, Peter M. J. Herman, Tom
Ysebaert & Huib J. De Vriend
Nature 504, 79–83 (05 December 2013)
doi:10.1038/nature12859
11.Green and golden seaweed tides on the rise
Victor Smetacek & Adriana Zingone
Nature 504, 84–88 (05 December 2013)
doi:10.1038/nature12860
12.Planetary science: Shadows cast on Moon's origin
Tim Elliott & Sarah T. Stewart
Nature 504, 90–91 (05 December 2013)
doi:10.1038/504090a
13.Late-twentieth-century emergence of the El Niño
propagation asymmetry and future projections
Agus Santoso, Shayne McGregor, Fei-Fei Jin, Wenju Cai, Matthew H.
England, Soon-Il An, Michael J. McPhaden & Eric Guilyardi
Nature 504, 126–130 (05 December 2013)
doi:10.1038/nature12683
There is the
asymmetry between SST anomalies during the modest El Nino events and the
extreme El Nino events. They trace the cause of the asymmetry to the variations
in upper ocean currents in the equatorial Pacific. The results shows that
propagation asymmetry is favoured when the westward mean equatorial currents
weaken, as is projected to be the case under global warming. Their analysis suggests
that more frequent emergence of propagation asymmetry will be an indication of
the Earth’s warming climate.
14.Foundering of lower island-arc crust as an
explanation for the origin of the continental Moho
Oliver Jagoutz & Mark D. Behn
Nature 504, 131–134 (05 December 2013)
doi:10.1038/nature12758
◉Science
15.Structure and Composition of the Plate-Boundary Slip Zone for the
2011 Tohoku-Oki Earthquake
Frederick M. Chester, Christie Rowe, Kohtaro Ujiie, James Kirkpatrick,
Christine Regalla, Francesca Remitti, J. Casey Moore, Virginia Toy, Monica
Wolfson-Schwehr, Santanu Bose, Jun Kameda, James J. Mori, Emily E. Brodsky,
Nobuhisa Eguchi, Sean Toczko, and Expedition 343 and 343T Scientists
Science 6 December 2013: 1208-1211.
The mechanics of great subduction earthquakes are influenced by the
frictional properties, structure, and composition of the plate-boundary fault.
We present observations of the structure and composition of
the shallow source
fault of the 2011 Tohoku-Oki earthquake and tsunami from boreholes drilled by
the Integrated Ocean Drilling Program Expedition 343 and 343T.
16.Low Coseismic Shear Stress on the Tohoku-Oki Megathrust Determined
from Laboratory Experiments
Kohtaro Ujiie, Hanae Tanaka, Tsubasa Saito, Akito Tsutsumi, James J.
Mori, Jun Kameda, Emily E. Brodsky, Frederick M. Chester, Nobuhisa Eguchi, Sean
Toczko, and Expedition 343 and 343T Scientists
Science 6 December 2013: 1211-1214.
Large coseismic slip was thought to be unlikely to occur on the shallow
portions of plate-boundary thrusts, but the 11 March 2011 Tohoku-Oki earthquake
[moment magnitude (Mw) = 9.0] produced huge displacements of ~50 meters near
the Japan Trench with a resultant devastating tsunami. To investigate the
mechanisms of the very large fault movements, we conducted high-velocity (1.3
meters per second) friction experiments on samples retrieved from the plate-boundary
thrust associated with the earthquake. The results show a small stress drop
with very low peak and steady-state shear stress. The very low shear stress can
be attributed to the abundance of weak clay (smectite) and thermal
pressurization effects, which can facilitate fault slip. This behavior provides
an explanation for the huge shallow slip that occurred during the earthquake.
17.Low Coseismic Friction on the Tohoku-Oki Fault Determined from
Temperature Measurements
P. M. Fulton, E. E. Brodsky, Y. Kano, J. Mori, F. Chester, T. Ishikawa,
R. N. Harris, W. Lin, N. Eguchi, S. Toczko, and Expedition 343, 343T, and
KR13-08 Scientists
Science 6 December 2013: 1214-1217.
The frictional resistance on a fault during slip controls earthquake
dynamics. Friction dissipates heat during an earthquake; therefore, the fault
temperature after an earthquake provides insight into the level of friction.
The Japan Trench Fast Drilling Project (Integrated Ocean Drilling Program
Expedition 343 and 343T) installed a borehole temperature observatory 16 months
after the March 2011 Tohoku-Oki earthquake across the fault where slip was ~50
meters near the trench. After 9 months of operation, the complete sensor string
was recovered. A 0.31°C temperature anomaly at the plate boundary fault
corresponds to 27 megajoules per square meter of dissipated energy during the
earthquake. The resulting apparent friction coefficient of 0.08 is considerably
smaller than static values for most rocks.
◉PNAS
18.Spontaneous abrupt climate change due to an atmospheric
blocking–sea-ice–ocean feedback in an unforced climate model simulation
Sybren Drijfhout, Emily Gleeson, Henk A. Dijkstra, and Valerie Livina
PNAS 2013 110 (49) 19713-19718; published ahead of print November 18,
2013, doi:10.1073/pnas.1304912110
19.Greenland ice sheet motion insensitive to exceptional meltwater
forcing
Andrew J. Tedstone, Peter W. Nienow, Andrew J. Sole, Douglas W. F.
Mair, Thomas R. Cowton, Ian D. Bartholomew, and Matt A. King
PNAS 2013 110 (49) 19719-19724; published ahead of print November 18,
2013, doi:10.1073/pnas.1315843110
We
use observations of ice motion to examine the surface melt–induced dynamic
response of a land-terminating outlet glacier in south-west Greenland to the
exceptional melting observed in 2012.
We
show that two extreme melt events (98.6% of the Greenland ice sheet surface
experienced melting on July 12 and 79.2% on July 29) and summer ice sheet
runoff ∼3.9σ above the 1958–2011 mean
resulted in enhanced summer ice motion relative to the average melt year of
2009. However, despite record summer melting, subsequent reduced winter ice
motion resulted in 6% less net annual ice motion in 2012 than in 2009. Our
findings suggest that surface melt–induced acceleration of land-terminating
regions of the ice sheet will remain insignificant even under extreme melting
scenarios.
◉Nature
Communications
20. Rapid interhemispheric climate links via the
Australasian monsoon during the last deglaciation
Linda
K. Ayliffe, Michael K. Gagan, Jian-xin Zhao, Russell N. Drysdale, John C.
Hellstrom, Wahyoe S. Hantoro, Michael L. Griffiths, Heather Scott-Gagan, Emma
St Pierre, Joan A. Cowley & Bambang W. Suwargadi
Nature Communications 4, Article number: 2908 doi:10.1038/ncomms3908
Here we present a 230thorium-dated
stalagmite oxygen isotope record of millennial-scale changes in
Australian–Indonesian monsoon rainfall over the last 31,000 years. The record
shows that abrupt southward shifts of the Australian–Indonesian monsoon were
synchronous with North Atlantic cold intervals 17,600–11,500 years ago.
21.Observed thinning of Totten Glacier is linked to coastal polynya
variability
A.
Khazendar, M.P. Schodlok, I. Fenty, S.R.M. Ligtenberg, E. Rignot & M.R. van
den Broeke
Nature Communications 4, Article number: 2857 doi:10.1038/ncomms3857
