Joint Global Change Research Institute

About: Joint Global Change Research Institute is a facility organization based out in Riverdale Park, Maryland, United States. It is known for research contribution in the topics: Greenhouse gas & Climate change. The organization has 197 authors who have published 934 publications receiving 62390 citations.

Can radiative forcing be limited to 2.6 Wm−2 without negative emissions from bioenergy AND CO2 capture and storage?

Abstract: Combining bioenergy and carbon dioxide (CO2) capture and storage (CCS) technologies (BECCS) has the potential to remove CO2 from the atmosphere while producing useful energy. BECCS has played a central role in scenarios that reduce climate forcing to low levels such as 2.6 Wm−2. In this paper we consider whether BECCS is essential to limiting radiative forcing (RF) to 2.6 Wm−2 by 2100 using the Global Change Assessment Model, a closely coupled model of biogeophysical and human Earth systems. We show that BECCS can potentially reduce the cost of limiting RF to 2.6 Wm−2 by 2100 but that a variety of technology combinations that do not include BECCS can also achieve this goal, under appropriate emissions mitigation policies. We note that with appropriate supporting land-use policies terrestrial sequestration could deliver carbon storage ranging from 200 to 700 PgCO2-equiavalent over the 21st century. We explore substantial delays in participation by some geopolitical regions. We find that the value of BECCS is substantially higher under delay and that delay results in higher transient RF and climate change. However, when major regions postponed mitigation indefinitely, it was impossible to return RF to 2.6 Wm−2 by 2100. Neither finite land resources nor finite potential geologic storage capacity represented a meaningful technical limit on the ability of BECCS to contribute to emissions mitigation in the numerical experiments reported in this paper.

Significant impacts of irrigation water sources and methods on modeling irrigation effects in the ACME Land Model

Abstract: An irrigation module considering irrigation water source and irrigation method has been incorporated into the ACME Land Model (ALM). Global numerical experiments were conducted to investigate irrigation effects and their sensitivity to irrigation water sources and irrigation methods. All simulations shared the same irrigation soil moisture target constrained by a global census data set of irrigation amounts. Irrigation has large impacts on terrestrial water balances especially in regions with extensive irrigation. Such effects depend on the irrigation water source: surface water-fed irrigation decreases runoff and water table depth, while groundwater-fed irrigation increases water table depth, and increases or decreases runoff depending on the pumping intensity. Irrigation effects also depend significantly on the irrigation method. Flood irrigation applies water in large volumes within short durations, resulting in much larger impacts on runoff and water table depth than drip and sprinkler irrigation. Differentiating the irrigation water source and method is important not only for representing the distinct pathways of how irrigation influences the terrestrial water balances, but also for estimating irrigation water use efficiency. Specifically, groundwater pumping has lower irrigation water use efficiency than irrigation relying on surface water withdrawal only due to enhanced recharge rates. Different irrigation methods also affect water use efficiency, with drip irrigation being the most efficient followed by sprinkler and flood irrigation. Our results highlight the importance of explicitly accounting for irrigation source and irrigation method, which are the least understood and constrained aspects in modeling irrigation water demand, water scarcity, and irrigation effects in Earth System Models.

Nitrous Oxide Emissions from Agricultural Toposequences in Alberta and Saskatchewan

Abstract: Nitrous oxide fluxes from soils are inherently variable in time and space. An improved understanding of this variability is needed to make accurate estimates of N 2 O fluxes at a regional scale. The objectives of this work were to (i) characterize the influence of soillandscape combinations and N application rates on N 2 O emissions and to (ii) determine the contribution of these influences on the estimation of N 2 O emissions at the field scale. We used static chambers and gas chromatography methods to measure N 2 O fluxes and collected ancillary data (mineral N, water soluble C, soil water content, soil temperature) in Canada at Mundare (AB) in the aspen parkland ecoregion and at Swift Current (SK) in the short-grass prairie ecoregion. At Mundare, measurements were taken in 1995 and 1996 by landscape position and land use. At Swift Current, data were collected in 1999 and 2000 by landscape position and N rate. At Mundare, landscape position affected N 2 O emissions but the pattern varied seasonally. During a 46-d period in summer 1995, a flux of 430 g N 2 O-N ha -1 measured in a backslope was greater than the 60 g N 2 O-N ha measured on average in shoulder and depressional areas. The flux pattern changed during a 43-d spring thaw of 1996 when fluxes from depressional areas were greatest (1710 g N 2 O-N ha -1 ). Nitrous oxide emissions from natural areas were small. The emission pattern during summer 1996 was similar to that of 1995 but the fluxes were an order of magnitude larger. At Swift Current, N 2 O fluxes in summer 1999 were affected by topography and N rate. Fluxes were greatest in depressional areas receiving N at 110 kg ha -1 (3140 g N 2 O-N ha -1 ). Use of the area fraction occupied by each landscape position to calculate N 2 O flux increased the estimates of N 2 O fluxes at the field scale in five out of six cases. Further research of N 2 O fluxes in variable landscapes should help elucidate factors controlling N 2 O fluxes from pedon to field scale and thus translate into improved flux estimates at regional scales.

Source attribution of black carbon and its direct radiative forcing in China

Abstract: . The source attributions for mass concentration, haze formation, transport and direct radiative forcing of black carbon (BC) in various regions of China are quantified in this study using the Community Earth System Model (CESM) with a source-tagging technique. Anthropogenic emissions are from the Community Emissions Data System that is newly developed for the Coupled Model Intercomparison Project Phase 6 (CMIP6). Over north China where the air quality is often poor, about 90 % of near-surface BC concentration is contributed by local emissions. Overall, 35 % of BC concentration over south China in winter can be attributed to emissions from north China, and 19 % comes from sources outside China in spring. For other regions in China, BC is largely contributed from nonlocal sources. We further investigated potential factors that contribute to the poor air quality in China. During polluted days, a net inflow of BC transported from nonlocal source regions associated with anomalous winds plays an important role in increasing local BC concentrations. BC-containing particles emitted from East Asia can also be transported across the Pacific. Our model results show that emissions from inside and outside China are equally important for the BC outflow from East Asia, while emissions from China account for 8 % of BC concentration and 29 % in column burden in the western United States in spring. Radiative forcing estimates show that 65 % of the annual mean BC direct radiative forcing (2.2 W m−2) in China results from local emissions, and the remaining 35 % is contributed by emissions outside of China. Efficiency analysis shows that a reduction in BC emissions over eastern China could have a greater benefit for the regional air quality in China, especially in the winter haze season.