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A Determination of the Cloud Feedback from Climate Variations over the Past Decade
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Estimates of Earth's climate sensitivity are uncertain, largely because of uncertainty in the
long-term cloud feedback. I estimated the magnitude of the cloud feedback in response to short-term
climate variations by analyzing the top-of-atmosphere radiation budget from March 2000 to February
2010. Over this period, the short-term cloud feedback had a magnitude of 0.54 T 0.74 (2s) watts
per square meter per kelvin, meaning that it is likely positive. A small negative feedback is possible,
but one large enough to cancel the climate’s positive feedbacks is not supported by these observations.
Both long- and short-wave components of short-term cloud feedback are also likely positive.
Calculations of short-term cloud feedback in climate models yield a similar feedback. I find no
correlation in the models between the short- and long-term cloud feedbacks.
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Beyond Predictions: Biodiversity Conservation in a Changing Climate
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Climate change is predicted to become a major threat to biodiversity in the 21st century,
but accurate predictions and effective solutions have proved difficult to formulate. Alarming
predictions have come from a rather narrow methodological base, but a new, integrated science
of climate-change biodiversity assessment is emerging, based on multiple sources and
approaches. Drawing on evidence from paleoecological observations, recent phenological and
microevolutionary responses, experiments, and computational models, we review the insights that
different approaches bring to anticipating and managing the biodiversity consequences of
climate change, including the extent of species’ natural resilience. We introduce a framework
that uses information from different sources to identify vulnerability and to support the design of
conservation responses. Although much of the information reviewed is on species, our framework
and conclusions are also applicable to ecosystems, habitats, ecological communities, and
genetic diversity, whether terrestrial, marine, or fresh water.
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The Hot Summer of 2010: Redrawing the Temperature Record Map of Europe
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The summer of 2010 was exceptionally warm in eastern
Europe and large parts of Russia. We provide evidence
that the anomalous 2010 warmth that caused adverse
impacts exceeded the amplitude and spatial extent of the
previous hottest summer of 2003. 'Mega-heatwaves' such
as the 2003 and 2010 events broke the 500-yr long
seasonal temperature records over approximately 50% of
Europe. According to regional multi-model experiments,
the probability of a summer experiencing 'megaheatwaves'
will increase by a factor of 5 to 10 within the
next 40 years. However, the magnitude of the 2010 event
was so extreme that despite this increase, the occurrence
of an analogue over the same region remains fairly
unlikely until the second half of the 21st century.
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Climate Outlook Looking Much The Same, or Even Worse
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Climate scientists have been feverishly preparing analyses for inclusion in the fifth climate assessment report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) due out in 2013. At the meeting, they gave colleagues a peek at where climate science stands 5 years after their last push to inform the authoritative international evaluation . The climate models are bigger and more sophisticated
than ever, speakers reported, but they are yielding the same wide range of possible warming and precipitation changes as they did 5 years ago. But when polled on other areas of concern, researchers say they see more trouble ahead than the previous IPCC assessment had, though less than some scientists had feared
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Carbon Storage with Benefits
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Biochar—a material related to charcoal—has the potential to benefit farming as well as mitigate climate change.
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Biotic Multipliers of Climate Change
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A focus on species interactions may improve predictions of the effects of climate change
on ecosystems.
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Enhanced Seasonal Exchange of CO2 by Northern Ecosystems Since 1960
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Seasonal variations of atmospheric carbon dioxide (CO2) in the Northern Hemisphere have increased since the 1950s, but sparse observations have prevented a clear assessment of the patterns of long-term change and the underlying mechanisms. We compare recent aircraft-based observations of CO2 above the North Pacific and Arctic Oceans to earlier data from 1958 to 1961 and find that the seasonal amplitude at altitudes of 3 to 6 km increased by 50% for 45° to 90°N but by less than 25% for 10° to 45°N. An increase of 30 to 60% in the seasonal exchange of CO2 by northern extratropical land ecosystems, focused on boreal forests, is implicated, substantially more than simulated by current land ecosystem models. The observations appear
to signal large ecological changes in northern forests and a major shift in the global carbon cycle.
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A Reconstruction of Regional and Global Temperature for the Past 11,300 Years
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Surface temperature reconstructions of the past 1500 years suggest that recent warming is
unprecedented in that time. Here we provide a broader perspective by reconstructing regional
and global temperature anomalies for the past 11,300 years from 73 globally distributed
records. Early Holocene (10,000 to 5000 years ago) warmth is followed by ~0.7°C cooling
through the middle to late Holocene (<5000 years ago), culminating in the coolest temperatures
of the Holocene during the Little Ice Age, about 200 years ago. This cooling is largely
associated with ~2°C change in the North Atlantic. Current global temperatures of the past
decade have not yet exceeded peak interglacial values but are warmer than during ~75% of
the Holocene temperature history. Intergovernmental Panel on Climate Change model projections
for 2100 exceed the full distribution of Holocene temperature under all plausible greenhouse
gas emission scenarios.
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Climate Change Conversations
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THE THOUSANDS OF PRESENTATIONS AT NEXT WEEK’S MEETING OF THE AMERICAN CHEMICAL SOCIETY (ACS) in New Orleans exemplify one of the many ways scientists converse among themselves
about the most recent advances in science. Science and technology continue to reshape the
world we live in, and appreciating how these changes, both intended and unintended, come
about is a necessity for all citizens in a democratic society. Scientists have a responsibility to
help their fellow citizens understand what science and technology can and cannot do for them
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Assemblage Time Series Reveal Biodiversity Change but Not Systematic Loss
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The extent to which biodiversity change in local assemblages contributes to global biodiversity
loss is poorly understood. We analyzed 100 time series from biomes across Earth to ask how diversity
within assemblages is changing through time. We quantified patterns of temporal a diversity, measured
as change in local diversity, and temporal b diversity, measured as change in community composition.
Contrary to our expectations, we did not detect systematic loss of a diversity. However, community
composition changed systematically through time, in excess of predictions from null models.
Heterogeneous rates of environmental change, species range shifts associated with climate change,
and biotic homogenization may explain the different patterns of temporal a and b diversity.
Monitoring and understanding change in species composition should be a conservation priority.
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