Assessing impacts of future anthropogenic carbon emissions is currently impeded by uncertainties in our knowledge of equilibrium climate sensitivity to atmospheric carbon dioxide doubling. Previous studies suggest 3 K as best estimate, 2–4.5 K as the 66% probability range, and non-zero probabilities for much higher values, the latter implying a...
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. Shakun,
3
Natalie M. Mahowald,
4
Peter U. 4
Clark,
5
Patrick J. Bartlein,
6
Alan C. Mix,
1
Most of the policy debate surrounding the actions needed to mitigate and adapt to anthropogenic climate change has been framed by observations of the past 150 years as well as climate and sea-level projections for the twenty-first century. The focus on this 250-year window, however, obscures some of the most...
Simulations of past climates require altered
boundary conditions to account for known shifts in the Earth
system. For the Last Glacial Maximum (LGM) and subsequent
deglaciation, the existence of large Northern Hemisphere
ice sheets caused profound changes in surface topography
and albedo. While ice-sheet extent is fairly well
known, numerous...
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or-
bit around the Sun caused Northern Hemisphere ice-sheet re-
treat (Clark et al., 2009; Carlson
Previous Paleoclimate Model Intercomparison Project (PMIP) simulations of the Last Glacial Maximum (LGM) Atlantic Meridional Overturning Circulation (AMOC) showed dissimilar results on transports and structure. Here we analyze the most recent PMIP3 models, which show a consistent increase (on average by 41 ± 26%) and deepening (663 ± 550 m)...
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Glacial Maximum (LGM, 26–19 kyr
before present [Clark et al., 2009]). It is an indicator of the transport
We apply GENMOM, a coupled atmosphere–ocean climate model, to simulate eight equilibrium time
slices at 3000-year intervals for the past 21,000 years forced
by changes in Earth–Sun geometry, atmospheric greenhouse
gases (GHGs), continental ice sheets, and sea level. Simulated
global cooling during the Last Glacial Maximum
(LGM) is 3.8°C and...
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continental ice sheets, GHGs (Clark et
al., 2012), and insolation (Fig. 5). The global average mean
annual
Due to lower sea levels during the Last Glacial Maximum (LGM), tidal energy dissipation was shifted from the shallow margins into the deep ocean. Here using a high-resolution tide model, we estimate that global energy fluxes below 200 m depth were almost quadrupled during the LGM. Applying the energy fluxes to...
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was
about 130m lower than it is today [Clark et al., 2009]. The LGM is one of the best studied time
Questions: Are exotic plant species favoured by non-native ungulate herbivores and disadvantaged by native herbivores in forested rangelands? Do the impacts of ungulates on exotic vs native plants depend on forest management activities such as prescribed fire and stand thinning?
Location: Northeastern Oregon, USA.
Methods: We recorded changes in richness...
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et al. Effects of grazing on plant forest guilds
Acknowledgements
We thank AbeClark, John Cook
Changes in the amount of summer incoming solar radiation (insolation) reaching the Northern Hemisphere are the underlying pacemaker of glacial cycles. However, not all rises in boreal summer insolation over the past 800,000 years resulted in deglaciation to present-day ice volumes, suggesting that there may be a climatic threshold for...
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concentrations during the last deglaciation. Nature 484, 49–55 (2012).
6. Abe-Ouchi, A. et al. Insolation-driven
Background: Prenatal mercury (Hg) exposure is associated with adverse child neurobehavioral
outcomes. Because Hg can interfere with placental functioning and cross the placenta to target the
fetal brain, prenatal Hg exposure can inhibit fetal growth and development directly and indirectly.
Objectives: We examined potential associations between prenatal Hg exposure assessed...
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mental/behavioral and
physical health and disease.
RefeRences
Adkins DE, Clark SL, Åberg K, Hettema JM