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"Lawrence, David M."
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The experience of revolution in Stuart Britain and Ireland : essays for John Morrill
\"This volume ranges widely across the social, religious and political history of revolution in seventeenth-century Britain and Ireland, from contemporary responses to the outbreak of war to the critique of the post-regicidal regimes; from royalist counsels to Lilburne's politics; and across the three Stuart kingdoms. However, all the essays engage with a central issue - the ways in which individuals experienced the crises of mid seventeenth-century Britain and Ireland and what that tells us about the nature of the Revolution as a whole. Responding in particular to three influential lines of interpretation - local, religious and British - the contributors, all leading specialists in the field, demonstrate that to comprehend the causes, trajectory and consequences of the Revolution we must understand it as a human and dynamic experience, as a process. This volume reveals how the understanding of these personal experiences can provide the basis on which to build up larger frameworks of interpretation\"-- Provided by publisher.
Book
Large influence of soil moisture on long-term terrestrial carbon uptake
Although the terrestrial biosphere absorbs about 25 per cent of anthropogenic carbon dioxide (CO
2
) emissions, the rate of land carbon uptake remains highly uncertain, leading to uncertainties in climate projections
1
,
2
. Understanding the factors that limit or drive land carbon storage is therefore important for improving climate predictions. One potential limiting factor for land carbon uptake is soil moisture, which can reduce gross primary production through ecosystem water stress
3
,
4
, cause vegetation mortality
5
and further exacerbate climate extremes due to land–atmosphere feedbacks
6
. Previous work has explored the impact of soil-moisture availability on past carbon-flux variability
3
,
7
,
8
. However, the influence of soil-moisture variability and trends on the long-term carbon sink and the mechanisms responsible for associated carbon losses remain uncertain. Here we use the data output from four Earth system models
9
from a series of experiments to analyse the responses of terrestrial net biome productivity to soil-moisture changes, and find that soil-moisture variability and trends induce large CO
2
fluxes (about two to three gigatons of carbon per year; comparable with the land carbon sink itself
1
) throughout the twenty-first century. Subseasonal and interannual soil-moisture variability generate CO
2
as a result of the nonlinear response of photosynthesis and net ecosystem exchange to soil-water availability and of the increased temperature and vapour pressure deficit caused by land–atmosphere interactions. Soil-moisture variability reduces the present land carbon sink, and its increase and drying trends in several regions are expected to reduce it further. Our results emphasize that the capacity of continents to act as a future carbon sink critically depends on the nonlinear response of carbon fluxes to soil moisture and on land–atmosphere interactions. This suggests that the increasing trend in carbon uptake rate may not be sustained past the middle of the century and could result in accelerated atmospheric CO
2
growth.
Earth system models suggest that soil-moisture variability and trends will induce large carbon releases throughout the twenty-first century.
Journal Article
Carbon release through abrupt permafrost thaw
The permafrost zone is expected to be a substantial carbon source to the atmosphere, yet large-scale models currently only simulate gradual changes in seasonally thawed soil. Abrupt thaw will probably occur in <20% of the permafrost zone but could affect half of permafrost carbon through collapsing ground, rapid erosion and landslides. Here, we synthesize the best available information and develop inventory models to simulate abrupt thaw impacts on permafrost carbon balance. Emissions across 2.5 million km2 of abrupt thaw could provide a similar climate feedback as gradual thaw emissions from the entire 18 million km2 permafrost region under the warming projection of Representative Concentration Pathway 8.5. While models forecast that gradual thaw may lead to net ecosystem carbon uptake under projections of Representative Concentration Pathway 4.5, abrupt thaw emissions are likely to offset this potential carbon sink. Active hillslope erosional features will occupy 3% of abrupt thaw terrain by 2300 but emit one-third of abrupt thaw carbon losses. Thaw lakes and wetlands are methane hot spots but their carbon release is partially offset by slowly regrowing vegetation. After considering abrupt thaw stabilization, lake drainage and soil carbon uptake by vegetation regrowth, we conclude that models considering only gradual permafrost thaw are substantially underestimating carbon emissions from thawing permafrost.Analyses of inventory models under two climate change projection scenarios suggest that carbon emissions from abrupt thaw of permafrost through ground collapse, erosion and landslides could contribute significantly to the overall permafrost carbon balance.
Journal Article
Deforestation-induced climate change reduces carbon storage in remaining tropical forests
Biophysical effects from deforestation have the potential to amplify carbon losses but are often neglected in carbon accounting systems. Here we use both Earth system model simulations and satellite–derived estimates of aboveground biomass to assess losses of vegetation carbon caused by the influence of tropical deforestation on regional climate across different continents. In the Amazon, warming and drying arising from deforestation result in an additional 5.1 ± 3.7% loss of aboveground biomass. Biophysical effects also amplify carbon losses in the Congo (3.8 ± 2.5%) but do not lead to significant additional carbon losses in tropical Asia due to its high levels of annual mean precipitation. These findings indicate that tropical forests may be undervalued in carbon accounting systems that neglect climate feedbacks from surface biophysical changes and that the positive carbon–climate feedback from deforestation-driven climate change is higher than the feedback originating from fossil fuel emissions.
Warming and drying from deforestation could amplify carbon storage losses in tropical remaining forests. Here the authors report this value to be extra 5.1% in the Amazon and 3.8% in Congo as compared to the direct biomass loss from deforestation.
Journal Article
Diagnosing Present and Future Permafrost from Climate Models
Permafrost is a characteristic aspect of the terrestrial Arctic and the fate of near-surface permafrost over the next century is likely to exert strong controls on Arctic hydrology and biogeochemistry. Using output from the fifth phase of the Coupled Model Intercomparison Project (CMIP5), the authors assess its ability to simulate present-day and future permafrost. Permafrost extent diagnosed directly from each climate model’s soil temperature is a function of the modeled surface climate as well as the ability of the land surface model to represent permafrost physics. For each CMIP5 model these two effects are separated by using indirect estimators of permafrost driven by climatic indices and compared to permafrost extent directly diagnosed via soil temperatures. Several robust conclusions can be drawn from this analysis. Significant air temperature and snow depth biases exist in some model’s climates, which degrade both directly and indirectly diagnosed permafrost conditions. The range of directly calculated present-day (1986–2005) permafrost area is extremely large (∼4–25 × 10⁶ km²). Several land models contain structural weaknesses that limit their skill in simulating cold region subsurface processes. The sensitivity of future permafrost extent to temperature change over the present-day observed permafrost region averages (1.67 ± 0.7) × 10⁶ km² °C−1but is a function of the spatial and temporal distribution of climate change. Because of sizable differences in future climates for the representative concentration pathway (RCP) emission scenarios, a wide variety of future permafrost states is predicted by 2100. Conservatively, the models suggest that for RCP4.5, permafrost will retreat from the present-day discontinuous zone. Under RCP8.5, sustainable permafrost will be most probable only in the Canadian Archipelago, Russian Arctic coast, and east Siberian uplands.
Journal Article
Leveraging the past to prepare for the future of Air Force intelligence analysis
\"This report describes steps the U.S. Air Force can take to help ensure that it has the capability needed to provide intelligence analysis support to a broad range of service and combatant commander needs, including support to ongoing irregular warfare operations, and to conventional warfare with a near-peer competitor. It describes lessons from past operations that have direct implications for Air Force intelligence analysis or that Air Force intelligence analysis could help to address. It also describes future challenges for Air Force intelligence analysis. It makes recommendations related to doctrine, training and career field development, analysis tools, and processes that can help to address the lessons from the past and prepare Air Force intelligence analysts for the challenges of the future\"--Publisher's description.
Book
Permafrost carbon–climate feedback is sensitive to deep soil carbon decomposability but not deep soil nitrogen dynamics
Permafrost soils contain enormous amounts of organic carbon whose stability is contingent on remaining frozen. With future warming, these soils may release carbon to the atmosphere and act as a positive feedback to climate change. Significant uncertainty remains on the postthaw carbon dynamics of permafrost-affected ecosystems, in particular since most of the carbon resides at depth where decomposition dynamics may differ from surface soils, and since nitrogen mineralized by decomposition may enhance plant growth. Here we show, using a carbon–nitrogen model that includes permafrost processes forced in an unmitigated warming scenario, that the future carbon balance of the permafrost region is highly sensitive to the decomposability of deeper carbon, with the net balance ranging from 21 Pg C to 164 Pg C losses by 2300. Increased soil nitrogen mineralization reduces nutrient limitations, but the impact of deep nitrogen on the carbon budget is small due to enhanced nitrogen availability from warming surface soils and seasonal asynchrony between deeper nitrogen availability and plant nitrogen demands. Although nitrogen dynamics are highly uncertain, the future carbon balance of this region is projected to hinge more on the rate and extent of permafrost thaw and soil decomposition than on enhanced nitrogen availability for vegetation growth resulting from permafrost thaw.
Journal Article