Schlosser
C. Adam
Schlosser
C. Adam
No Thumbnail Available
Search Results
Now showing
1 - 12 of 12
-
ArticleNitrogen effect on carbon-water coupling in forests, grasslands, and shrublands in the arid western United States(American Geophysical Union, 2011-08-25) Felzer, Benjamin S. ; Cronin, Timothy W. ; Melillo, Jerry M. ; Kicklighter, David W. ; Schlosser, C. Adam ; Dangal, Shree R. S.As greenhouse gases, including CO2, accumulate in the atmosphere, the western United States is predicted to undergo large-scale climate warming and reduced summer precipitation in the coming decades. In this study we explore the role of these climate changes with elevated CO2 to determine the plant physiological response on primary productivity and associated feedbacks on evapotranspiration (ET) and runoff using a biogeochemistry model, TEM-Hydro, with downscaled climate data for the western United States from the NCAR CCSM3 A2 scenario. Net primary productivity increases by 32% in forests due to feedbacks between warmer temperatures and enhanced nitrogen mineralization but decreases in shrublands by 24% due to excessive drying and reduced nitrogen mineralization. Warming directly increases nitrogen mineralization rates but indirectly decreases them by reducing soil moisture, so the net effect is highly dependent on climatic conditions within each biome. Increased soil moisture resulting from larger water use efficiency from the elevated CO2 leads to more net nitrogen mineralization in forests, which reduces N-limiting conditions. The effect of CO2 on stomatal conductance is therefore enhanced because of its effect on reducing nitrogen limiting conditions. Runoff decreases over the 21st century by 22% in forests, 58% in grasslands, and 67% in shrublands due to the reduced precipitation in each region but is modulated by the plant-induced changes in ET. The role of moisture limitation is therefore a crucial regulator of nitrogen limitation, which determines the future productivity and water availability in the West.
-
ArticleConsequences of considering carbon–nitrogen interactions on the feedbacks between climate and the terrestrial carbon cycle(American Meteorological Society, 2008-08-01) Sokolov, Andrei P. ; Kicklighter, David W. ; Melillo, Jerry M. ; Felzer, Benjamin S. ; Schlosser, C. Adam ; Cronin, Timothy W.The impact of carbon–nitrogen dynamics in terrestrial ecosystems on the interaction between the carbon cycle and climate is studied using an earth system model of intermediate complexity, the MIT Integrated Global Systems Model (IGSM). Numerical simulations were carried out with two versions of the IGSM’s Terrestrial Ecosystems Model, one with and one without carbon–nitrogen dynamics. Simulations show that consideration of carbon–nitrogen interactions not only limits the effect of CO2 fertilization but also changes the sign of the feedback between the climate and terrestrial carbon cycle. In the absence of carbon–nitrogen interactions, surface warming significantly reduces carbon sequestration in both vegetation and soil by increasing respiration and decomposition (a positive feedback). If plant carbon uptake, however, is assumed to be nitrogen limited, an increase in decomposition leads to an increase in nitrogen availability stimulating plant growth. The resulting increase in carbon uptake by vegetation exceeds carbon loss from the soil, leading to enhanced carbon sequestration (a negative feedback). Under very strong surface warming, however, terrestrial ecosystems become a carbon source whether or not carbon–nitrogen interactions are considered. Overall, for small or moderate increases in surface temperatures, consideration of carbon–nitrogen interactions result in a larger increase in atmospheric CO2 concentration in the simulations with prescribed carbon emissions. This suggests that models that ignore terrestrial carbon–nitrogen dynamics will underestimate reductions in carbon emissions required to achieve atmospheric CO2 stabilization at a given level. At the same time, compensation between climate-related changes in the terrestrial and oceanic carbon uptakes significantly reduces uncertainty in projected CO2 concentration.
-
ArticleProbabilistic forecast for twenty-first-century climate based on uncertainties in emissions (without policy) and climate parameters(American Meteorological Society, 2009-10-01) Sokolov, Andrei P. ; Stone, P. H. ; Forest, C. E. ; Prinn, Ronald G. ; Sarofim, Marcus C. ; Webster, M. ; Paltsev, Sergey ; Schlosser, C. Adam ; Kicklighter, David W. ; Dutkiewicz, Stephanie ; Reilly, John M. ; Wang, C. ; Felzer, Benjamin S. ; Melillo, Jerry M. ; Jacoby, Henry D.The Massachusetts Institute of Technology (MIT) Integrated Global System Model is used to make probabilistic projections of climate change from 1861 to 2100. Since the model’s first projections were published in 2003, substantial improvements have been made to the model, and improved estimates of the probability distributions of uncertain input parameters have become available. The new projections are considerably warmer than the 2003 projections; for example, the median surface warming in 2091–2100 is 5.1°C compared to 2.4°C in the earlier study. Many changes contribute to the stronger warming; among the more important ones are taking into account the cooling in the second half of the twentieth century due to volcanic eruptions for input parameter estimation and a more sophisticated method for projecting gross domestic product (GDP) growth, which eliminated many low-emission scenarios. However, if recently published data, suggesting stronger twentieth-century ocean warming, are used to determine the input climate parameters, the median projected warming at the end of the twenty-first century is only 4.1°C. Nevertheless, all ensembles of the simulations discussed here produce a much smaller probability of warming less than 2.4°C than implied by the lower bound of the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) projected likely range for the A1FI scenario, which has forcing very similar to the median projection in this study. The probability distribution for the surface warming produced by this analysis is more symmetric than the distribution assumed by the IPCC because of a different feedback between the climate and the carbon cycle, resulting from the inclusion in this model of the carbon–nitrogen interaction in the terrestrial ecosystem.
-
ArticleCorrigendum(American Meteorological Society, 2010-04-15) Sokolov, Andrei P. ; Stone, P. H. ; Forest, C. E. ; Prinn, Ronald G. ; Sarofim, Marcus C. ; Webster, M. ; Paltsev, Sergey ; Schlosser, C. Adam ; Kicklighter, David W. ; Dutkiewicz, Stephanie ; Reilly, John M. ; Wang, C. ; Felzer, Benjamin S. ; Melillo, Jerry M. ; Jacoby, Henry D.Corrigendum: Sokolov, A., and Coauthors, 2009: Probabilistic forecast for twenty-first-century climate based on uncertainties in emissions (without policy) and climate parameters. J. Climate, 22, 5175–5204.
-
ArticleDescription and evaluation of the MIT Earth System Model (MESM)(John Wiley & Sons, 2018-08-15) Sokolov, Andrei P. ; Kicklighter, David W. ; Schlosser, C. Adam ; Wang, Chien ; Monier, Erwan ; Brown-Steiner, Benjamin ; Prinn, Ronald G. ; Forest, Chris E. ; Gao, Xiang ; Libardoni, Alex ; Eastham, SebastianThe Massachusetts Institute of Technology Integrated Global System Model (IGSM) is designed for analyzing the global environmental changes that may result from anthropogenic causes, quantifying the uncertainties associated with the projected changes, and assessing the costs and environmental effectiveness of proposed policies to mitigate climate risk. The IGSM consists of the Massachusetts Institute of Technology Earth System Model (MESM) of intermediate complexity and the Economic Projections and Policy Analysis model. This paper documents the current version of the MESM, which includes a two‐dimensional (zonally averaged) atmospheric model with interactive chemistry coupled to the zonally averaged version of Global Land System model and an anomaly‐diffusing ocean model.
-
ArticleThe observed state of the water cycle in the early twenty-first century(American Meteorological Society, 2015-11-01) Rodell, Matthew ; Beaudoing, Hiroko K. ; L’Ecuyer, Tristan S. ; Olson, William S. ; Famiglietti, James S. ; Houser, Paul R. ; Adler, Robert ; Bosilovich, Michael G. ; Clayson, Carol A. ; Chambers, Don P. ; Clark, Edward A. ; Fetzer, Eric J. ; Gao, X. ; Gu, Guojun ; Hilburn, K. A. ; Huffman, George J. ; Lettenmaier, Dennis P. ; Liu, W. Timothy ; Robertson, Franklin R. ; Schlosser, C. Adam ; Sheffield, Justin ; Wood, Eric F.This study quantifies mean annual and monthly fluxes of Earth’s water cycle over continents and ocean basins during the first decade of the millennium. To the extent possible, the flux estimates are based on satellite measurements first and data-integrating models second. A careful accounting of uncertainty in the estimates is included. It is applied within a routine that enforces multiple water and energy budget constraints simultaneously in a variational framework in order to produce objectively determined optimized flux estimates. In the majority of cases, the observed annual surface and atmospheric water budgets over the continents and oceans close with much less than 10% residual. Observed residuals and optimized uncertainty estimates are considerably larger for monthly surface and atmospheric water budget closure, often nearing or exceeding 20% in North America, Eurasia, Australia and neighboring islands, and the Arctic and South Atlantic Oceans. The residuals in South America and Africa tend to be smaller, possibly because cold land processes are negligible. Fluxes were poorly observed over the Arctic Ocean, certain seas, Antarctica, and the Australasian and Indonesian islands, leading to reliance on atmospheric analysis estimates. Many of the satellite systems that contributed data have been or will soon be lost or replaced. Models that integrate ground-based and remote observations will be critical for ameliorating gaps and discontinuities in the data records caused by these transitions. Continued development of such models is essential for maximizing the value of the observations. Next-generation observing systems are the best hope for significantly improving global water budget accounting.
-
ArticlePermafrost degradation and methane : low risk of biogeochemical climate-warming feedback(IOP Publishing, 2013-07-10) Gao, Xiang ; Schlosser, C. Adam ; Sokolov, Andrei P. ; Walter Anthony, Katey M. ; Zhuang, Qianlai ; Kicklighter, David W.Climate change and permafrost thaw have been suggested to increase high latitude methane emissions that could potentially represent a strong feedback to the climate system. Using an integrated earth-system model framework, we examine the degradation of near-surface permafrost, temporal dynamics of inundation (lakes and wetlands) induced by hydro-climatic change, subsequent methane emission, and potential climate feedback. We find that increases in atmospheric CH4 and its radiative forcing, which result from the thawed, inundated emission sources, are small, particularly when weighed against human emissions. The additional warming, across the range of climate policy and uncertainties in the climate-system response, would be no greater than 0.1 ° C by 2100. Further, for this temperature feedback to be doubled (to approximately 0.2 ° C) by 2100, at least a 25-fold increase in the methane emission that results from the estimated permafrost degradation would be required. Overall, this biogeochemical global climate-warming feedback is relatively small whether or not humans choose to constrain global emissions.
-
ArticleClimate impacts of a large-scale biofuels expansion(John Wiley & Sons, 2013-04-28) Hallgren, Willow ; Schlosser, C. Adam ; Monier, Erwan ; Kicklighter, David W. ; Sokolov, Andrei P. ; Melillo, Jerry M.A global biofuels program will potentially lead to intense pressures on land supply and cause widespread transformations in land use. These transformations can alter the Earth climate system by increasing greenhouse gas (GHG) emissions from land use changes and by changing the reflective and energy exchange characteristics of land ecosystems. Using an integrated assessment model that links an economic model with climate, terrestrial biogeochemistry, and biogeophysics models, we examined the biogeochemical and biogeophysical effects of possible land use changes from an expanded global second-generation bioenergy program on surface temperatures over the first half of the 21st century. Our integrated assessment model shows that land clearing, especially forest clearing, has two concurrent effects—increased GHG emissions, resulting in surface air warming; and large changes in the land's reflective and energy exchange characteristics, resulting in surface air warming in the tropics but cooling in temperate and polar regions. Overall, these biogeochemical and biogeophysical effects will only have a small impact on global mean surface temperature. However, the model projects regional patterns of enhanced surface air warming in the Amazon Basin and the eastern part of the Congo Basin. Therefore, global land use strategies that protect tropical forests could dramatically reduce air warming projected in these regions.
-
ArticleCorrection to “Importance of carbon-nitrogen interactions and ozone on ecosystem hydrology during the 21st century”(American Geophysical Union, 2009-08-22) Felzer, Benjamin S. ; Cronin, Timothy W. ; Melillo, Jerry M. ; Kicklighter, David W. ; Schlosser, C. Adam
-
ArticleThe observed state of the energy budget in the early twenty-first century(American Meteorological Society, 2015-11-01) L’Ecuyer, Tristan S. ; Beaudoing, Hiroko K. ; Rodell, Matthew ; Olson, William S. ; Lin, B. ; Kato, S. ; Clayson, Carol A. ; Wood, Eric F. ; Sheffield, Justin ; Adler, Robert ; Huffman, George J. ; Bosilovich, Michael G. ; Gu, Guojun ; Robertson, Franklin R. ; Houser, Paul R. ; Chambers, Don P. ; Famiglietti, James S. ; Fetzer, Eric J. ; Liu, W. Timothy ; Gao, X. ; Schlosser, C. Adam ; Clark, Edward A. ; Lettenmaier, Dennis P. ; Hilburn, K. A.New objectively balanced observation-based reconstructions of global and continental energy budgets and their seasonal variability are presented that span the golden decade of Earth-observing satellites at the start of the twenty-first century. In the absence of balance constraints, various combinations of modern flux datasets reveal that current estimates of net radiation into Earth’s surface exceed corresponding turbulent heat fluxes by 13–24 W m−2. The largest imbalances occur over oceanic regions where the component algorithms operate independent of closure constraints. Recent uncertainty assessments suggest that these imbalances fall within anticipated error bounds for each dataset, but the systematic nature of required adjustments across different regions confirm the existence of biases in the component fluxes. To reintroduce energy and water cycle closure information lost in the development of independent flux datasets, a variational method is introduced that explicitly accounts for the relative accuracies in all component fluxes. Applying the technique to a 10-yr record of satellite observations yields new energy budget estimates that simultaneously satisfy all energy and water cycle balance constraints. Globally, 180 W m−2 of atmospheric longwave cooling is balanced by 74 W m−2 of shortwave absorption and 106 W m−2 of latent and sensible heat release. At the surface, 106 W m−2 of downwelling radiation is balanced by turbulent heat transfer to within a residual heat flux into the oceans of 0.45 W m−2, consistent with recent observations of changes in ocean heat content. Annual mean energy budgets and their seasonal cycles for each of seven continents and nine ocean basins are also presented.
-
ArticleToward a consistent modeling framework to assess multi-sectoral climate impacts(Nature Publishing Group, 2018-02-13) Monier, Erwan ; Paltsev, Sergey ; Sokolov, Andrei P. ; Chen, Y.-H. Henry ; Gao, Xiang ; Ejaz, Qudsia ; Couzo, Evan ; Schlosser, C. Adam ; Dutkiewicz, Stephanie ; Fant, Charles ; Scott, Jeffery ; Kicklighter, David W. ; Morris, Jennifer ; Jacoby, Henry D. ; Prinn, Ronald G. ; Haigh, MartinEfforts to estimate the physical and economic impacts of future climate change face substantial challenges. To enrich the currently popular approaches to impact analysis—which involve evaluation of a damage function or multi-model comparisons based on a limited number of standardized scenarios—we propose integrating a geospatially resolved physical representation of impacts into a coupled human-Earth system modeling framework. Large internationally coordinated exercises cannot easily respond to new policy targets and the implementation of standard scenarios across models, institutions and research communities can yield inconsistent estimates. Here, we argue for a shift toward the use of a self-consistent integrated modeling framework to assess climate impacts, and discuss ways the integrated assessment modeling community can move in this direction. We then demonstrate the capabilities of such a modeling framework by conducting a multi-sectoral assessment of climate impacts under a range of consistent and integrated economic and climate scenarios that are responsive to new policies and business expectations.
-
ArticleImportance of carbon-nitrogen interactions and ozone on ecosystem hydrology during the 21st century(American Geophysical Union, 2009-03-18) Felzer, Benjamin S. ; Cronin, Timothy W. ; Melillo, Jerry M. ; Kicklighter, David W. ; Schlosser, C. AdamThere is evidence that increasing CO2 concentrations have reduced evapotranspiration and increased runoff through reductions in stomatal conductance during the twentieth century. While this process will continue to counteract increased evapotranspiration associated with future warming, it is highly dependent upon concurrent changes in photosynthesis, especially due to CO2 fertilization, nitrogen limitation, and ozone exposure. A new version of the Terrestrial Ecosystem Model (TEM-Hydro) was developed to examine the effects of carbon and nitrogen on the water cycle. We used two climate models (NCAR CCSM3 and DOE PCM) and two emissions scenarios (SRES B1 and A2) to examine the effects of climate, elevated CO2, nitrogen limitation, and ozone exposure on the hydrological cycle in the eastern United States. While the direction of future runoff changes is largely dependent upon predicted precipitation changes, the effects of elevated CO2 on ecosystem function (stomatal closure and CO2 fertilization) increase runoff by 3–7%, as compared to the effects of climate alone. Consideration of nitrogen limitation and ozone damage on photosynthesis increases runoff by a further 6–11%. Failure to consider the effects of the interactions among nitrogen, ozone, and elevated CO2 may lead to significant regional underestimates of future runoff.