| 1. |
- Pereira, Laura M., et al.
(författare)
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From fAIrplay to climate wars : making climate change scenarios more dynamic, creative, and integrative
- 2021
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Ingår i: Ecology and Society. - 1708-3087. ; 26:4
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Tidskriftsartikel (refereegranskat)abstract
- Understanding possible climate futures that include carbon dioxide removal (CDR) and solar radiation modification (SRM) requires thinking not just about staying within the remaining carbon budget, but also about politics and people. However, despite growing interest in CDR and SRM, scenarios focused on these potential responses to climate change tend to exclude feedbacks between social and climate systems (a criticism applicable to climate change scenarios more generally). We adapted the Manoa Mash Up method to generate scenarios for CDR and SRM that were more integrative, creative, and dynamic. The method was modified to identify important branching points in which different choices in how to respond to climate change (feedbacks between climate and social dynamics) lead to a plurality of climate futures. An interdisciplinary group of participants imagined distant futures in which SRM or CDR develop into a major social-environmental force. Groups received other seeds of change, such as Universal Basic Income or China's Belt and Road Initiative, and surprises, such as permafrost collapse that grew to influence the course of events to 2100. Groups developed narratives describing pathways to the future and identified bifurcation points to generate families of branching scenarios. Four climate-social dynamics were identified: motivation to mitigate, moral hazard, social unrest, and trust in institutions. These dynamics could orient toward better or worse outcomes with SRM and CDR deployment (and mitigation and adaptation responses more generally) but are typically excluded from existing climate change scenarios. The importance of these dynamics could be tested through the inclusion of social-environmental feedbacks into integrated assessment models (IAM) exploring climate futures. We offer a step-by-step guide to the modified Manoa Mash-up method to generate more integrative, creative, and dynamic scenarios; reflect on broader implications of using this method for generating more dynamic scenarios for climate change research and policy; and provide examples of using the scenarios in climate policy communication, including a choose-your-own adventure game called Survive the Century (https://survivethecentury.net/), which was played by over 15,000 people in the first 2 weeks of launching.
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| 2. |
- Pugh, Thomas A.M., et al.
(författare)
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Understanding the uncertainty in global forest carbon turnover
- 2020
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 17:15, s. 3961-3989
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Tidskriftsartikel (refereegranskat)abstract
- The length of time that carbon remains in forest biomass is one of the largest uncertainties in the global carbon cycle, with both recent historical baselines and future responses to environmental change poorly constrained by available observations. In the absence of large-scale observations, models used for global assessments tend to fall back on simplified assumptions of the turnover rates of biomass and soil carbon pools. In this study, the biomass carbon turnover times calculated by an ensemble of contemporary terrestrial biosphere models (TBMs) are analysed to assess their current capability to accurately estimate biomass carbon turnover times in forests and how these times are anticipated to change in the future. Modelled baseline 1985-2014 global average forest biomass turnover times vary from 12.2 to 23.5 years between TBMs. TBM differences in phenological processes, which control allocation to, and turnover rate of, leaves and fine roots, are as important as tree mortality with regard to explaining the variation in total turnover among TBMs. The different governing mechanisms exhibited by each TBM result in a wide range of plausible turnover time projections for the end of the century. Based on these simulations, it is not possible to draw robust conclusions regarding likely future changes in turnover time, and thus biomass change, for different regions. Both spatial and temporal uncertainty in turnover time are strongly linked to model assumptions concerning plant functional type distributions and their controls. Thirteen model-based hypotheses of controls on turnover time are identified, along with recommendations for pragmatic steps to test them using existing and novel observations. Efforts to resolve uncertainty in turnover time, and thus its impacts on the future evolution of biomass carbon stocks across the world's forests, will need to address both mortality and establishment components of forest demography, as well as allocation of carbon to woody versus non-woody biomass growth.
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| 3. |
- Tang, Guoping, et al.
(författare)
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Estimating potential forest NPP, biomass and their climatic sensitivity in New England using a dynamic ecosystem model
- 2010
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Ingår i: Ecosphere. - 2150-8925. ; 1:6, s. 1-20
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedAccurate estimation of forest net primary productivity (NPP), biomass, and their sensitivity to changes in temperature and precipitation is important for understanding the fluxes and pools of terrestrial carbon resulting from anthropogenically driven climate change. The objectives of this study were to (1) estimate potential forest NPP and biomass for New England using a regional ecosystem model, (2) compare modeled forest NPP and biomass with other reported data for New England, and (3) examine the sensitivity of modeled forest NPP to historical climatic variation. We addressed these objectives using the regional ecosystem model LPJ-GUESS implemented with eight plant functional types representing New England forests. We ran the model using 30-arc second spatial resolution climate data in monthly time-steps for the period 1901-2006. The modeled forest NPP and biomass were compared to empirically-based MODIS and FIA estimates of NPP and U.S. forest biomass. Our results indicate that forest NPP in New England averages 428 g C.m(-2).yr(-1) and ranges from 333 to 541 g C.m(-2).yr(-1) for the baseline period (1971-2000), while forest biomass averages 135 Mg/ha and ranges from 77 to 242 Mg/ha. Modeled forest biomass decreased at a rate of 0.11 Mg/ha (R-2 = 0.74) per year in the period 1901-1949 but increased at a rate of 0.25 Mg/ha (R-2 = 0.95) per year in the period 1950-2006. Estimates of NPP and biomass depend on forest type: spruce-fir had the lowest mean of 395 g C.m(-2).yr(-1) and oak forest had the highest mean of 468 g C.m(-2).yr(-1). Similarly, forest biomass was highest in oak (153 Mg/ha) and lowest in red-jack pine (118 Mg/ha) forests. The modeled NPP for New England agrees well with FIA-based estimates from similar forests in the mid-Atlantic region but was smaller than MODIS NPP estimates for New England. Nevertheless, the modeled inter-annual variability of NPP was strongly correlated with the MODIS NPP data. The modeled biomass agrees well with U.S. forest biomass data for New England but was less than FIA-based estimates in the mid-Atlantic region. For the region as a whole, the modeled NPP and biomass are within the ranges of MODIS-and FIA-based estimates. Forest NPP was sensitive to changes in temperature and precipitation: NPP was positively related to temperatures in April, May and October but negatively related to summer temperature. Increases in precipitation in the growing season enhanced forest NPP.
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| 4. |
- Tang, Guoping, et al.
(författare)
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Potential future dynamics of carbon fluxes and pools in New England forests and their climatic sensitivities: A model-based study
- 2014
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Ingår i: Global Biogeochemical Cycles. - 0886-6236. ; 28:3, s. 286-299
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Tidskriftsartikel (refereegranskat)abstract
- Projections of terrestrial carbon (C) dynamics must account for interannual variation in ecosystem C exchange associated with climate change, increasing atmospheric CO2 concentration, and species dynamics. We used a dynamic ecosystem model to (i) project the potential dynamics of C in New England forests under nine climate change scenarios (CCSs) for the 21st century and (ii) examine the sensitivity of potential C dynamics to changes in climate and atmospheric CO2 concentration. Our results indicated that forest net primary productivity (NPP) and soil heterotrophic respiration (RH) averaged 428 and 279gC/m(2)/yr and New England forests sequestered CO2 by 149gC/m(2)/yr in the baseline period (1971-2000). Under the nine future CCSs, NPP and RH were modeled to increase by an average rate of 0.85 and 0.56gC/m(2)/yr(2) during 1971-2099. The asymmetric increase in NPP and RH resulted in New England forests sequestering atmospheric CO2 at a net rate of 0.29gC/m(2)/yr(2) with increases in vegetation and soil C. Simulations also indicated that climate warming alone decreases NPP, resulting in a net efflux of C from forests. In contrast, increasing precipitation by itself stimulates CO2 sequestration by forests. At the individual cell level, however, changes in temperature or precipitation can either positively or negatively affect consequent C dynamics. Elevation of CO2 levels was found to be the biggest driver for modeled future enhancement of C sequestration. Without the elevation of CO2 levels, climate warming has the potential to change New England forests from C sinks to sources in the late 21st century. Key Points Carbon sequestration in New England forests Complexity of climatic sensitivities of carbon dynamics Future potential carbon dynamics
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| 5. |
- Tang, Guoping, et al.
(författare)
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The potential transient dynamics of forests in New England under historical and projected future climate change
- 2012
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Ingår i: Climatic Change. - : Springer Science and Business Media LLC. - 0165-0009 .- 1573-1480. ; 114:2, s. 357-377
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Tidskriftsartikel (refereegranskat)abstract
- Projections of vegetation distribution that incorporate the transient responses of vegetation to climate change are likely to be more efficacious than those that assume an equilibrium between climate and vegetation. We examine the non-equilibrium dynamics of a temperate forest region under historic and projected future climate change using the dynamic ecosystem model LPJ-GUESS. We parameterized LPJ-GUESS for the New England region of the United Sates utilizing eight forest cover types that comprise the regionally dominant species. We developed a set of climate data at a monthly-step and a 30-arc second spatial resolution to run the model. These datasets consist of past climate observations for the period 1901-2006 and three general circulation model projections for the period 2007-2099. Our baseline (1971-2000) simulation reproduces the distribution of forest types in our study region as compared to the National Land Cover Data 2001 (Kappa statistic = 0.54). Under historic and nine future climate change scenarios, maple-beech-basswood, oaks and aspen-birch were modeled to move upslope at an estimated rate of 0.2, 0.3 and 0.5 m yr(-1) from 1901 to 2006, and continued this trend at an accelerated rate of around 0.5, 0.9 and 1.7 m yr(-1) from 2007 to 2099. Spruce-fir and white pine-cedar were modeled to contract to mountain ranges and cooler regions of our study region under projected future climate change scenarios. By the end of the 21(st) century, 60% of New England is projected to be dominated by oaks relative to 21% at the beginning of the 21(st) century, while northern New England is modeled to be dominated by aspen-birch. In mid and central New England, maple-beech-basswood, yellow birch-elm and hickories co-occur and form novel species associations. In addition to warming-induced northward and upslope shifts, climate change causes more complex changes in our simulations, such as reversed conversions between forest types that currently share similar bioclimatic ranges. These results underline the importance of considering community interactions and transient dynamics in modeling studies of climate change impacts on forest ecosystems.
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