My research focuses on climate impacts on vegetation and agriculture. I am interested in understanding the interaction between vegetation and climate system. Future climate scenarios I studied are global warming, solar radiation management and nuclear war.
Contact Information:
14 College Farm Road
New Brunswick, NJ 08901
Sulfate geoengineering has been discussed frequently as anthropogenic global warming is continuing, and currently we lack an adequate mitigation strategy to keep global average temperature from rising to 2°C above the pre-industrial level. With sulfate geoengineering, climate factors important for agriculture will change, including temperature, precipitation, total solar radiation, diffuse radiation, ultraviolet radiation, and surface ozone. I am interested in vegetation (including crops) responses to those unique climate change under sulfate geoengineering using the Community Earth System Model and crop models.
I am also interested in studying nuclear war impacts on global food system. A simulated nuclear war could inject soot into the stratopshere, which would absorb sunlight, decrease global averaged surface temperature for years, and have major impacts on precipitation and solar radiation reaching Earth's surface. This would have a strong impact on agriculture system as well as the fishery. I am collaborating with the AgMIP and the Fish-MIP to estimate global food system change under simulated nuclear wars.
Sam S. Rabin, William J. Sacks, Danica L. Lombardozzi, Lili Xia, and Alan Robock
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Farmers around the world time the planting of their crops to optimize growing season conditions and choose varieties that grow slowly enough to take advantage of the entire growing season while minimizing the risk of late-season kill. As climate changes, these strategies will be an important component of agricultural adaptation. Thus, it is critical that the global models used to project crop productivity under future conditions are able to realistically simulate growing season timing. This is especially important for climate- and hydrosphere-coupled crop models, where the intra-annual timing of crop growth and management affects regional weather and water availability. We have improved the crop module of the Community Land Model (CLM) to allow the use of externally specified crop planting dates and maturity requirements. In this way, CLM can use alternative algorithms for future crop calendars that are potentially more accurate and/or flexible than the built-in methods.
Using observation-derived planting and maturity inputs reduces bias in the mean simulated global yield of sugarcane and cotton but increases bias for corn, spring wheat, and especially rice. These inputs also reduce simulated global irrigation demand by 15%, much of which is associated with particular regions of corn and rice cultivation. Finally, we discuss how our results suggest areas for improvement in CLM and, potentially, similar crop models.
Brendan Clark, Lili Xia, Alan Robock, Simone Tilmes, Jadwiga H. Richter, Daniele Visioni and Sam S. Rabin
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Seyed Vahid Mousavi, Khalil Karami, Simone Tilmes, Helene Muri, Lili Xia, and Abolfazl Rezaei
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Alan Robock, Lili Xia, Cheryl S. Harrison, Joshua Coupe, Owen B. Toon, and Charles G. Bardeen
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Wenfu Tang, Simone Tilmes, David M. Lawrence, Fang Li, Cenlin He, Louisa K. Emmons, Rebecca R. Buchholz, and Lili Xia
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We quantify future changes in wildfire burned area and carbon emissions in the 21st century under four Shared Socioeconomic Pathways (SSPs) scenarios and two SSP5-8.5-based solar geoengineering scenarios with a target surface temperature defined by SSP2-4.5 - solar irradiance reduction (G6solar) and stratospheric sulfate aerosol injections (G6sulfur) - and explore the mechanisms that drive solar geoengineering impacts on fires. This study is based on fully coupled climate-chemistry simulations with simulated occurrence of fires (burned area and carbon emissions) using the Whole Atmosphere Community Climate Model version 6 (WACCM6) as the atmospheric component of the Community Earth System Model version 2 (CESM2). Globally, total wildfire burned area is projected to increase over the 21st century under scenarios without geoengineering and decrease under the two geoengineering scenarios. By the end of the century, the two geoengineering scenarios have lower burned area and fire carbon emissions than not only their base-climate scenario SSP5-8.5 but also the targeted-climate scenario SSP2-4.5.
Geoengineering reduces wildfire occurrence by decreasing surface temperature and wind speed and increasing relative humidity and soil water, with the exception of boreal regions where geoengineering increases the occurrence of wildfires due to a decrease in relative humidity and soil water compared with the present day. This leads to a global reduction in burned area and fire carbon emissions by the end of the century relative to their base-climate scenario SSP5-8.5. However, geoengineering also yields reductions in precipitation compared with a warming climate, which offsets some of the fire reduction. Overall, the impacts of the different driving factors are larger on burned area than fire carbon emissions. In general, the stratospheric sulfate aerosol approach has a stronger fire-reducing effect than the solar irradiance reduction approach.
Daniele Visioni, Ben Kravitz, Alan Robock, Simone Tilmes, Jim Haywood, Olivier Boucher, Mark Lawrence, Peter Irvine, Ulrike Niemeier, Lili Xia, Gabriel Chiodo, Chris Lennard, Shingo Watanabe, John C. Moore, and Helene Muri
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The Geoengineering Model Intercomparison Project (GeoMIP) is a coordinating framework, started in 2010, that includes a series of standardized climate model experiments aimed at understanding the physical processes and projected impacts of solar geoengineering. Numerous experiments have been conducted, and numerous more have been proposed as "test-bed" experiments, spanning a variety of geoengineering techniques aimed at modifying the planetary radiation budget: stratospheric aerosol injection, marine cloud brightening, surface albedo modification, cirrus cloud thinning, and sunshade mirrors. To date, more than 100 studies have been published that used results from GeoMIP simulations. Here we provide a critical assessment of GeoMIP and its experiments.
We discuss its successes and missed opportunities, for instance in terms of which experiments elicited more interest from the scientific community and which did not, and the potential reasons why that happened. We also discuss the knowledge that GeoMIP has contributed to the field of geoengineering research and climate science as a whole: what have we learned in terms of intermodel differences, robustness of the projected outcomes for specific geoengineering methods, and future areas of model development that would be necessary in the future? We also offer multiple examples of cases where GeoMIP experiments were fundamental for international assessments of climate change.
Finally, we provide a series of recommendations, regarding both future experiments and more general activities, with the goal of continuously deepening our understanding of the effects of potential geoengineering approaches and reducing uncertainties in climate outcomes, important for assessing wider impacts on societies and ecosystems. In doing so, we refine the purpose of GeoMIP and outline a series of criteria whereby GeoMIP can best serve its participants, stakeholders, and the broader science community.
Lili Xia, Alan Robock, Kim Scherrer, Cheryl S. Harrison, Benjamin Leon Bodirsky, Isabelle Weindl, Jonas Jägermeyr, Charles G. Bardeen, Owen B. Toon and Ryan Heneghan
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Gal Hochman, Hainan Zhang, Lili Xia, Alan Robock, Aleti Saketh, Dominique Y van der Mensbrugghe and Jonas Jägermeyr
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Charles G. Bardeen, Douglas E. Kinnison, Owen B. Toon, Michael J. Mills, Francis Vitt, Lili Xia, Jonas Jägermeyr, Nicole S. Lovenduski, Kim J. N. Scherrer, Margot Clyne, Alan Robock
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For the first time, we use a modern climate model with interactive chemistry including the effects of aerosols on photolysis rates to simulate the consequences of regional and global scale nuclear wars (injecting 5 and 150 Tg of soot respectively) for the ozone layer and surface ultraviolet (UV) light. For a global nuclear war, heating in the stratosphere, reduced photolysis, and an increase in catalytic loss from the HOx cycle cause a 15 year-long reduction in the ozone column, with a peak loss of 75% globally and 65% in the tropics. This is larger than predictions from the 1980s, which assumed large injections of nitrogen oxides (NOx), but did not include the effects of smoke. NOx from the fireball and the fires provide a small (5%) increase to the global average ozone loss for the first few years. Initially, soot would shield the surface from UV-B, but UV Index values would become extreme: greater than 35 in the tropics for 4 years, and greater than 45 during the summer in the southern polar regions for 3 years. For a regional war, global column ozone would be reduced by 25% with recovery taking 12 years. This is similar to previous simulations, but with a faster recovery time due to a shorter lifetime for soot in our simulations. In-line photolysis provides process specific action spectra enabling future integration with biogeochemistry models and allows output that quantifies the potential health impacts from changes in surface UV for this and other larger aerosol injections.
Phoebe L. Zarnetske, Jessica Gurevitch, Janet Franklin, Peter M. Groffman, Cheryl S. Harrison, Jessica J. Hellmann, Forrest M. Hoffman, Shan Kothari, Alan Robock, Simone Tilmes, Daniele Visioni, Jin Wu, Lili Xia, and Cheng-En Yang
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S. Eastham, S. Doherty, D. Keith, J. H. Richter and Lili Xia
Kim J. N. Scherrer, Cheryl S. Harrison, Ryan F. Heneghan, Eric Galbraith, Charles G. Bardeen, Joshua Coupe, Jonas Jägermeyr, Nicole S. Lovenduski, August Luna, Alan Robock, Jessica Stevens, Samantha Stevenson, Owen B. Toon, and Lili Xia
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Cheng-En Yang, Forrest M Hoffman, Daniel M Ricciuto, Simone Tilmes, Lili Xia, Douglas G MacMartin, Ben Kravitz, Jadwiga H Richter, Michael Mills and Joshua S Fu
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Geoengineering by injecting sulfur dioxide (SO2) into the lower stratosphere has been suggested to reduce anthropogenically induced warming. While impacts of such geoengineering on climate have been investigated in recent decades, few modeling studies have considered biogeochemical feedbacks resulting from such intervention. This study comprehensively characterizes responses and feedbacks of terrestrial ecosystems, from an ensemble of coupled high-resolution Earth system model climate change simulations, under the highest standard greenhouse gas scenario with an extreme geoengineering mitigation strategy. Under this strategy, temperature increases beyond 2020 levels due to elevated anthropogenic carbon dioxide (CO2) were completely offset by the SO2 injection. Carbon cycle feedbacks can alter the trajectory of atmospheric CO2 levels by storing or releasing additional carbon on land and in the ocean, thus moderating or amplifying climate change. We assess terrestrial biogeochemical feedbacks to climate in response to geoengineering, using model output from the Stratospheric Aerosol Geoengineering Large Ensemble (GLENS) project. Results indicate terrestrial ecosystems become a stronger carbon sink globally because of lower ecosystem respiration and diminished disturbance effects under geoengineering. An additional 79 Pg C would be stored on land by the end of the twenty-first century, yielding as much as a 4% reduction in atmospheric CO2 mole fraction without marine biogeochemical feedbacks, compared to the high greenhouse gas scenario without geoengineering.
Daniele Visioni, Eric Slessarev, Douglas G MacMartin, Natalie M Mahowald, Christine L Goodale, and Lili Xia
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The problem of reducing the impacts of rising anthropogenic greenhouse gas on warming temperatures has led to the proposal of using stratospheric aerosols to reflect some of the incoming solar radiation back to space. The deliberate injection of sulfur into the stratosphere to form stratospheric sulfate aerosols, emulating volcanoes, will result in sulfate deposition to the surface. We consider here an extreme sulfate geoengineering scenario necessary to maintain temperatures at 2020 levels while greenhouse gas emissions continue to grow unabated. We show that the amount of stratospheric sulfate needed could be globally balanced by the predicted decrease in tropospheric anthropogenic SO2 emissions, but the spatial distribution would move from industrialized regions to pristine areas. We show how these changes would affect ecosystems differently depending on present day observations of soil pH, which we use to infer the potential for acid-induced aluminum toxicity across the planet.
Yangyang Xu, Lei Lin, Simone Tilmes, Katherine Dagon, Lili Xia, Chenrui Diao, Wei Cheng, Zhili Wang, Isla Simpson, and Lorna Burnell
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To mitigate the projected global warming in the 21st century, it is well-recognized that society needs to cut CO2 emissions and other short-lived warming agents aggressively. However, to stabilize the climate at a warming level closer to the present day, such as the "well below 2°C" aspiration in the Paris Agreement, a net-zero carbon emission by 2050 is still insufficient. The recent IPCC special report calls for a massive scheme to extract CO2 directly from the atmosphere, in addition to decarbonization, to reach negative net emissions at the mid-century mark. Another ambitious proposal is solar-radiation-based geoengineering schemes, including injecting sulfur gas into the stratosphere. Despite being in public debate for years, these two leading geoengineering schemes have not been directly compared under a consistent analytical framework using global climate models.
Here we present the first explicit analysis of the hydroclimate impacts of these two geoengineering approaches using two recently available large-ensemble (>10 members) model experiments conducted by a family of state-of-the-art Earth system models. The CO2-based mitigation simulation is designed to include both emission cuts and carbon capture. The solar-radiation-based mitigation simulation is designed to inject sulfur gas strategically at specified altitudes and latitudes and run a feedback control algorithm to avoid common problems previously identified such as the overcooling of the tropics and large-scale precipitation shifts.
Our analysis focuses on the projected aridity conditions over the Americas in the 21st century in detailed terms of the potential mitigation benefits, the temporal evolution, the spatial distribution (within North and South America), the relative efficiency, and the physical mechanisms. We show that sulfur injection, in contrast to previous notions of leading to excessive terrestrial drying (in terms of precipitation reduction) while offsetting the global mean greenhouse gas (GHG) warming, will instead mitigate the projected drying tendency under RCP8.5. The surface energy balance change induced by sulfur injection, in addition to the well-known response in temperature and precipitation, plays a crucial role in determining the overall terrestrial hydroclimate response. However, when normalized by the same amount of avoided global warming in these simulations, sulfur injection is less effective in curbing the worsening trend of regional land aridity in the Americas under RCP8.5 when compared with carbon capture. Temporally, the climate benefit of sulfur injection will emerge more quickly, even when both schemes are hypothetically started in the same year of 2020. Spatially, both schemes are effective in curbing the drying trend over North America. However, for South America, the sulfur injection scheme is particularly more effective for the sub-Amazon region (southern Brazil), while the carbon capture scheme is more effective for the Amazon region. We conclude that despite the apparent limitations (such as an inability to address ocean acidification) and potential side effects (such as changes to the ozone layer), innovative means of sulfur injection should continue to be explored as a potential low-cost option in the climate solution toolbox, complementing other mitigation approaches such as emission cuts and carbon capture (Cao et al., 2017). Our results demonstrate the urgent need for multi-model comparison studies and detailed regional assessments in other parts of the world.
Simone Tilmes, Douglas G. MacMartin, Jan T. M. Lenaerts, Leo van Kampenhout, Laura Muntjewerf, Lili Xia, Cheryl S. Harrison, Kristen M. Krumhardt, Michael J. Mills, Ben Kravitz, and Alan Robock
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A new set of stratospheric aerosol geoengineering (SAG) model experiments has been performed with Community Earth System Model version 2 (CESM2) with the Whole Atmosphere Community Climate Model (WACCM6) that are based on the Coupled Model Intercomparison Project phase 6 (CMIP6) overshoot scenario (SSP5-34-OS) as a baseline scenario to limit global warming to 1.5 or 2.0°C above 1850-1900 conditions. The overshoot scenario allows us to applying a peak-shaving scenario that reduces the needed duration and amount of SAG application compared to a high forcing scenario. In addition, a feedback algorithm identifies the needed amount of sulfur dioxide injections in the stratosphere at four pre-defined latitudes, 30°N, 15°N, 15°S, and 30°S, to reach three surface temperature targets: global mean temperature, and interhemispheric and pole-to-Equator temperature gradients. These targets further help to reduce side effects, including overcooling in the tropics, warming of high latitudes, and large shifts in precipitation patterns. These experiments are therefore relevant for investigating the impacts on society and ecosystems. Comparisons to SAG simulations based on a high emission pathway baseline scenario (SSP5-85) are also performed to investigate the dependency of impacts using different injection amounts to offset surface warming by SAG. We find that changes from present-day conditions around 2020 in some variables depend strongly on the defined temperature target (1.5°C vs. 2.0°C). These include surface air temperature and related impacts, the Atlantic Meridional Overturning Circulation, which impacts ocean net primary productivity, and changes in ice sheet surface mass balance, which impacts sea level rise. Others, including global precipitation changes and the recovery of the Antarctic ozone hole, depend strongly on the amount of SAG application. Furthermore, land net primary productivity as well as ocean acidification depend mostly on the global atmospheric CO2 concentration and therefore the baseline scenario. Multi-model comparisons of experiments that include strong mitigation and carbon dioxide removal with some SAG application are proposed to assess the robustness of impacts on societies and ecosystems.
Jägermeyr, Jonas, Alan Robock, Joshua Elliott, Christoph Müller, Lili Xia, Nikolay Khabarov, Christian Folberth, Erwin Schmid, Wenfeng Liu, Florian Zabel, Sam S. Rabin, Michael J. Puma, Alison C. Heslin, James Franke, Ian Foster, Senthold Asseng, Charles G.Bardeen, Owen B. Toon, and Cynthia Rosenzweig
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Alan Robock, Owen B. Toon, Charles G. Bardeen, Lili Xia, Hans M. Kristensen, Matthew McKinzie, R. J. Peterson, Cheryl S. Harrison, Nicole S. Lovenduski and Richard P. Turco
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Owen B. Toon, Charles G. Bardeen, Alan Robock, Lili Xia, Hans M. Kristensen, Matthew McKinzie, R. J. Peterson, Cheryl S. Harrison, Nicole S. Lovenduski and Richard P. Turco
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Owen B. Toon, Alan Robock, Michael Mills, Lili Xia, Charles Bardeen
Christopher H. Trisos, Corey Gabriel, Alan Robock, Lili Xia
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Christopher H. Trisos, Giuseppe Amatulli, Jessica Gurevitch, Alan Robock, Lili Xia and Brian Zambri
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Solar geoengineering is receiving increased policy attention as a potential tool to offset climate warming. While climate responses to geoengineering have been studied in detail, the potential biodiversity consequences are largely unknown. To avoid extinction, species must either adapt or move to track shifting climates. Here, we assess the effects of the rapid implementation, continuation and sudden termination of geoengineering on climate velocities-the speeds and directions that species would need to move to track changes in climate. Compared to a moderate climate change scenario (RCP4.5), rapid geoengineering implementation reduces temperature velocities towards zero in terrestrial biodiversity hotspots. In contrast, sudden termination increases both ocean and land temperature velocities to unprecedented speeds (global medians >10 km yr-1) that are more than double the temperature velocities for recent and future climate change in global biodiversity hotspots. Furthermore, as climate velocities more than double in speed, rapid climate fragmentation occurs in biomes such as temperate grasslands and forests where temperature and precipitation velocity vectors diverge spatially by >90°. Rapid geoengineering termination would significantly increase the threats to biodiversity from climate change.
Lili Xia, Peer J. Nowack, Simone Tilmes, and Alan Robock
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Masahiro Sugiyama, Shinichiro Asayama, Atsushi Ishii, Takanobu Kosugi, John C. Moore, Jolene Lin, Penehuro F. Lefale, Wil Burns, Masatomo Fujiwara, Arunabha Ghosh, Joshua Horton, Atsushi Kurosawa, Andy Parker, Michael Thompson, Pak-Hang Wong and Lili Xia
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Owen B. Toon, Alan Robock, Michael Mills and Lili Xia
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Corey J. Gabriel, Alan Robock, Lili Xia, Brian Zambri, and Ben Kravitz
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Reducing insolation has been proposed as a geoengineering response to global warming. Here we present the results of climate model simulations of a unique Geoengineering Model Intercomparison Project Testbed experiment to investigate the benefits and risks of a scheme that would brighten certain oceanic regions. The National Center for Atmospheric Research CESM CAM4-Chem global climate model was modified to simulate a scheme in which the albedo of the ocean surface is increased over the subtropical ocean gyres in the Southern Hemisphere. In theory, this could be accomplished using a stable, nondispersive foam, comprised of tiny, highly reflective microbubbles. Such a foam has been developed under idealized conditions, although deployment at a large scale is presently infeasible. We conducted three ensemble members of a simulation (G4Foam) from 2020 through to 2069 in which the albedo of the ocean surface is set to 0.15 (an increase of 150%) over the three subtropical ocean gyres in the Southern Hemisphere, against a background of the RCP6.0 (representative concentration pathway resulting in +6 W m-2 radiative forcing by 2100) scenario. After 2069, geoengineering is ceased, and the simulation is run for an additional 20 years. Global mean surface temperature in G4Foam is 0.6 K lower than RCP6.0, with statistically significant cooling relative to RCP6.0 south of 30°N. There is an increase in rainfall over land, most pronouncedly in the tropics during the June-July-August season, relative to both G4SSA (specified stratospheric aerosols) and RCP6.0. Heavily populated and highly cultivated regions throughout the tropics, including the Sahel, southern Asia, the Maritime Continent, Central America, and much of the Amazon experience a statistically significant increase in precipitation minus evaporation. The temperature response to the relatively modest global average forcing of -1.5 W m-2 is amplified through a series of positive cloud feedbacks, in which more shortwave radiation is reflected. The precipitation response is primarily the result of the intensification of the southern Hadley cell, as its mean position migrates northward and away from the Equator in response to the asymmetric cooling.
Lili Xia, Alan Robock, Simone Tilmes, and Ryan R. Neely III
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Stratospheric sulfate geoengineering could impact the terrestrial carbon cycle by enhancing the carbon sink. With an 8 Tg yr-1 injection of SO2 to produce a stratospheric aerosol cloud to balance anthropogenic radiative forcing from the Representative Concentration Pathway 6.0 (RCP6.0) scenario, we conducted climate model simulations with the Community Earth System Model - the Community Atmospheric Model 4 fully coupled to tropospheric and stratospheric chemistry (CAM4-chem). During the geoengineering period, as compared to RCP6.0, land-averaged downward visible (300-700 nm) diffuse radiation increased 3.2 W m-2 (11%). The enhanced diffuse radiation combined with the cooling increased plant photosynthesis by 0.07 ± 0.02 µmol C m-2 s-1, which could contribute to an additional 3.8 ± 1.1 Gt C yr-1 global gross primary productivity without explicit nutrient limitation. This increase could potentially increase the land carbon sink. Suppressed plant and soil respiration due to the cooling would reduce natural land carbon emission and therefore further enhance the terrestrial carbon sink during the geoengineering period. This potentially beneficial impact of stratospheric sulfate geoengineering would need to be balanced by a large number of potential risks in any future decisions about the implementation of geoengineering.
Lili Xia, Alan Robock, Michael Mills, Andrea Stenke, and Ira Helfand
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Lili Xia, Alan Robock, Jason Cole, Charles L. Curry, Duoying Ji, Andy Jones, Ben Kravitz, John C. Moore, Helene Muri, Ulrike Niemeier, Balwinder Singh, Simone Tilmes, Shingo Watanabe, and Jin-Ho Yoon
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Geoengineering via solar radiation management could affect agricultural productivity due to changes in temperature, precipitation, and solar radiation. To study rice and maize production changes in China, we used results from 10 climate models participating in the Geoengineering Model Intercomparison Project (GeoMIP) G2 scenario to force the Decision Support System for Agrotechnology Transfer (DSSAT) crop model. G2 prescribes an insolation reduction to balance a 1% a-1 increase in CO2 concentration (1pctCO2) for 50 years. We first evaluated the DSSAT model using 30 years (1978-2007) of daily observed weather records and agriculture practices for 25 major agriculture provinces in China and compared the results to observations of yield. We then created three sets of climate forcing for 42 locations in China for DSSAT from each climate model experiment: (1) 1pctCO2, (2) G2, and (3) G2 with constant CO2 concentration (409 ppm) and compared the resulting agricultural responses. In the DSSAT simulations: (1) Without changing management practices, the combined effect of simulated climate changes due to geoengineering and CO2 fertilization during the last 15 years of solar reduction would change rice production in China by -3.0 ± 4.0 megaton (Mt) (2.4 ± 4.0%) as compared with 1pctCO2 and increase Chinese maize production by 18.1 ± 6.0 Mt (13.9 ± 5.9%). (2) The termination of geoengineering shows negligible impacts on rice production but a 19.6 Mt (11.9%) reduction of maize production as compared to the last 15 years of geoengineering. (3) The CO2 fertilization effect compensates for the deleterious impacts of changes in temperature, precipitation, and solar radiation due to geoengineering on rice production, increasing rice production by 8.6 Mt. The elevated CO2 concentration enhances maize production in G2, contributing 7.7 Mt (42.4%) to the total increase. Using the DSSAT crop model, virtually all of the climate models agree on the sign of the responses, even though the spread across models is large. This suggests that solar radiation management would have little impact on rice production in China but could increase maize production.
Lili Xia, Alan Robock
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A regional nuclear war between India and Pakistan with a 5 Tg black carbon injection into the upper troposphere would produce significant climate changes for a decade, including cooling, reduction of solar radiation, and reduction of precipitation, which are all important factors controlling agricultural productivity. We used the Decision Support System for Agrotechnology Transfer agricultural simulation model to simulate regional nuclear war impacts on rice yield in 24 provinces in China. We first evaluated the model by forcing it with daily weather data and management practices for the period 1980-2008 for 24 provinces in China, and compared the results to observations of rice yields in China. Then we perturbed observed weather data using climate anomalies for a 10-year period from a nuclear war simulation. We perturbed each year of the 30-year climate record with anomalies from each year of the 10-year nuclear war simulations for different regions in China. We found that rice production would decline by an average of 21% for the first 4 years after soot injection, and would slowly recover in the following years. For the next 6 years, the reduction in rice production was about 10%. Different regions responded differently to climate changes from nuclear war. Rice production in northern China was damaged severely, while regions along the south and east coasts showed a positive response to regional nuclear war. Although we might try to adapt to a perturbed climate by enhancing rice planting activity in southern and eastern China or increasing fertilizer usage, both methods have severe limitations. The best solution to avoid nuclear war impacts on agriculture is to avoid nuclear war, and this can only be guaranteed with a nuclear-weapon-free world.
Lili Xia, Yuan Gao
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Lili Xia, Yuan Gao
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Characterization of coastal aerosols is important to the study of the atmospheric input of nutrients to the adjacent marine and the ocean ecosystems. Over a land-ocean transition zone, however, aerosol composition could be strongly modified by anthropogenic emissions and transport processes. This work focuses on examining aerosol properties, in particular chemical composition, particle-size distributions and iron (Fe) solubility, over the US East Coast, an important boundary for the transport of continental substances from North America to the North Atlantic Ocean. Fourteen sets of bulk aerosol samples and three sets of size-segregated aerosol samples were collected in southern New Jersey on the US East Coast during 2007 and 2008. Samples were analyzed by IC, ICP-MS and UV spectroscopy. The major chemical components were nitrate, non-sea-salt sulfate (NSS-sulfate), ammonium, sodium and chloride, accounting for ~70% of the total mass. A typical bimodal mass-size distribution was observed, with the major peak from 0.36 µm to 0.56 µm and the minor one from 3.6 µm to 5.6 µm in diameters. Different individual components showed different mass-size distributions. Pollution-derived substances, such as vanadium and NSS-sulfate of non-biogenic origin, were mostly in the fine mode, while crustal elements, such as aluminum and iron, were mainly in the coarse mode. At this location, the concentrations of soluble ferrous species (Fe(II)s) in aerosols ranged from 50 to 518 pmol m-3, accounting for ~17% of the total Fe (FeT) mass in bulk samples. The average Fe solubility observed at this location was 18%, higher than those over remote oceans. Fe solubility showed an inverse correlation with FeT concentrations, which could be the result of different particle sizes. In addition, high Fe solubility was associated with high molar ratios of NSS-sulfate to FeT and oxalate to FeT, indicating that inorganic and organic acidic components and anthropogenic emissions may highly affect Fe solubility in this region.
