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

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.     

Changing streamflow on Columbia basin tribal lands—climate change and salmon

Over the last 100 years, linear trends of tributary streamflow have changed on Columbia River Basin tribal reservations and historical lands ceded by tribes in treaties with the United States. Analysis of independent flow measures (Seasonal Flow Fraction, Center Timing, Spring Flow Onset, High Flow, Low Flow) using the Student t test and Mann-Kendall trend test suggests evidence for climate change trends for many of the 32 study basins. The trends exist despite interannual climate variability driven by the El Niño–Southern Oscillation and Pacific Decadal Oscillation. The average April—July flow volume declined by 16 %. The median runoff volume date has moved earlier by 5.8 days. The Spring Flow Onset date has shifted earlier by 5.7 days. The trend of the flow standard deviation (i.e., weather variability) increased 3 % to 11 %. The 100-year November floods increased 49 %. The mid-Columbia 7Q10 low flows have decreased by 5 % to 38 %. Continuation of these climatic and hydrological trends may seriously challenge the future of salmon, their critical habitats, and the tribal peoples who depend upon these resources for their traditional livelihood, subsistence, and ceremonial purposes.     

Trade-offs of different land and bioenergy policies on the path to achieving climate targets

Many papers have shown that bioenergy and land-use are potentially important elements in a strategy to limit anthropogenic climate change. But, significant expansion of bioenergy production can have a large terrestrial footprint. In this paper, we test the implications for land use, the global energy system, emissions and mitigation costs of meeting a specific climate target, using a single fossil fuel and industrial sector policy instrument, but with five alternative bioenergy and land-use policy architectures. These scenarios are illustrative in nature, and designed to explore trade-offs. We find that the policies we examined have differing effects on the different segments of the economy. Comprehensive land policies can reduce land-use change emissions, increasing allowable emissions in the energy system, but have implications for the cost of food. Bioenergy penalties and constraints, on the other hand, have little effect on food prices, but result in less bioenergy and thus can increase mitigation costs and energy prices.     

Impacts of agricultural irrigation recharge on groundwater quality in a basalt aquifer system (Washington, USA): a multi-tracer approach

Irrigation in semi-arid agricultural regions can have profound effects on recharge rates and the quality of shallow groundwater. This study coupled stable isotopes (²??, ¹⁸O), age-tracers (³H, CFCs, ¹⁴C), ⁸⁷Sr/⁸⁶Sr ratios, and elemental chemistry to determine the sources, residence times, and flowpaths of groundwater and agricultural contaminants (e.g. NO ₃ ^?C ) in the Saddle Mountains Basalt Aquifer in central Washington, USA, where over 80% of the population depend on groundwater for domestic use. Results demonstrate the presence of two distinct types of water: contaminated irrigation water and pristine regional groundwater. Contaminated irrigation water has high NO ₃ ^?C concentrations (11?C116? mg/l), ⁸⁷Sr/⁸⁶Sr ratios (0.70659?C0.71078) within range of nitrogen-based fertilizers, detectable tritium (2.8?C13.4 TU), CFC ages 20?C40?years, high ??¹⁸O values (?16.9 to ?13.5??), and ??100 percent modern ¹⁴C. Pristine regional groundwater has low NO ₃ ^?C concentrations (1?C5? mg/l), no detectable tritium (??0.8 TU), low ??¹⁸O values (?18.9 to ?17.3??) and ¹⁴C ages from ??15 to 33?ky BP. Nitrogen and oxygen isotopes of NO ₃ ^?C , combined with high dissolved oxygen values, show that denitrification is not an important process in the organic-poor basalt aquifers resulting in transport of high NO ₃ ^?C irrigation water to depths greater than 40?m in less than 30? years.     

Traditional ecologies of the opium poppy and oral history in rural Turkey

Cultivated in the Eastern Mediterranean region for millennia, the opium poppy (Papaver somniferum) was profoundly significant in the economies, ecologies, cultures, and diets of the peoples of many towns and villages of rural Anatolia. When the United States compelled Turkey to eradicate cultivation of the plant in the early 1970s in order to diminish the flow of heroin into America, farmers were obliged to deal with not only changes in their incomes but also profound changes in their relationships with the land and the state. Although Turkish officials later allowed production to resume in a highly controlled manner for pharmaceutical purposes, significant socioeconomic and ecological dimensions of Turkey's poppy-growing communities were forever changed. Interviewing now-retired poppy farmers, I employ oral history as my primary source of historical evidence to reconstruct these past ecologies and associated social relationships and to give voice to the informants.     

Paleoclimate record in the Nubian Sandstone Aquifer,Sinai Peninsula,Egypt

Sixteen groundwater samples collected from production wells tapping Lower Cretaceous Nubian Sandstone and fractured basement aquifers in Sinai were analyzed for their stable isotopic compositions, dissolved noble gas concentrations (recharge temperatures), tritium activities, and ¹⁴C abundances. Results define two groups of samples: Group I has older ages, lower recharge temperatures, and depleted isotopic compositions (adjusted ¹⁴C model age: 24,000–31,000 yr BP; δ¹⁸O: − 9.59‰ to − 6.53‰; δ²H: − 72.9‰ to − 42.9‰; < 1 TU; and recharge T: 17.5–22.0°C) compared to Group II (adjusted ¹⁴C model age: 700–4700 yr BP; δ¹⁸O: − 5.89‰ to − 4.84‰; δ²H: − 34.5‰ to − 24.1‰; < 1 to 2.78 TU; and recharge T: 20.6–26.2°C). Group II samples have isotopic compositions similar to those of average modern rainfall, with larger d-excess values than Group I waters, and locally measurable tritium activity (up to 2.8 TU). These observations are consistent with (1) the Nubian Aquifer being largely recharged prior to and/or during the Last Glacial Maximum (represented by Group I), possibly through the intensification of paleowesterlies; and (2) continued sporadic recharge during the relatively dry and warmer interglacial period (represented by Group II) under conditions similar to those of the present.     

Multi-observation well aquifer test case study: is recovery coincident with the cessation of pumping?

Due to increases in water demand, the City of Kenedy, TX, USA must expand their small drinking water supply in the Gulf Coast aquifer system. Groundwater wells owned by the City of Kenedy, Karnes County, TX were examined to estimate properties for the Jasper aquifer. Conditions of four wells were assessed, after which two wells were rehabilitated and used as pumping wells in aquifer tests. Aquifer tests show that recovery in observation wells was not coincident with the cessation of pumping. Post-pumping data were selectively excluded so that only recovery data were used for analyses. Transmissivity for the Jasper aquifer ranges from 102 to 242 m² d^?1, and storativity ranges from 6.9E?05 to 3.3E?04. Transmissivity computed from recovery data was approximately 25 % higher than transmissivity computed from time-drawdown data. Field measured specific capacities and drawdowns were compared to theoretical specific capacities and drawdowns to calculate pumping well efficiencies in the range of 52.2–99.4 %. This study indicates that water demand for the City of Kenedy could be met by incorporating the tested wells into the water supply system. Future studies should be designed to estimate groundwater recharge rates and a complete water balance for computing a sustainable maximum annual yield.     

H2O–CO2 solubility in mafic alkaline magma: applications to volatile sources and degassing behavior at Erebus volcano, Antarctica

We present new equilibrium mixed-volatile (H₂O–CO₂) solubility data for a phonotephrite from Erebus volcano, Antarctica. H₂O–CO₂-saturated experiments were conducted at 400–700 MPa, 1,190 °C, and ~NNO + 1 in non-end-loaded piston cylinders. Equilibrium H₂O–CO₂ fluid compositions were determined using low-temperature vacuum manometry, and the volatile and major element compositions of the glassy run products were determined by Fourier transform infrared spectroscopy and electron microprobe. Results show that the phonotephrite used in this study will dissolve ~0.8 wt% CO₂ at 700 MPa and a fluid composition of $ X_{{{\text{H}}_{ 2} {\text{O}}}} $ ~0.4, in agreement with previous experimental studies on mafic alkaline rocks. Furthermore, the dissolution of CO₂ at moderate to high $ X_{{{\text{H}}_{ 2} {\text{O}}}}^{\text{fluid}} $ in our experiments exceeds that predicted using lower-pressure experiments on similar melts from the literature, suggesting a departure from Henrian behavior of volatiles in the melt at pressures above 400 MPa. With these data, we place new constraints on the modeling of Erebus melt inclusion and gas emission data and thus the interpretation of its magma plumbing system and the contributions of primitive magmas to passive and explosive degassing from the Erebus phonolite lava lake.     

J2 Invariant Relative Orbits for Spacecraft Formations

An analytic method is presented to establish J ₂ invariant relative orbits. Working with mean orbit elements, the secular drift of the longitude of the ascending node and the sum of the argument of perigee and mean anomaly are set equal between two neighboring orbits. By having both orbits drift at equal angular rates on the average, they will not separate over time due to the J₂ influence. Two first order conditions are established between the differences in momenta elements (semi-major axis, eccentricity and inclination angle) that guarantee that the drift rates of two neighboring orbits are equal on the average. Differences in the longitude of the ascending node, argument of perigee and initial mean anomaly can be set at will, as long as they are setup in mean element space. For near polar orbits, enforcing both momenta element constraints may result in impractically large relative orbits. It this case it is shown that dropping the equal ascending node rate requirement still avoids considerable relative orbit drift and provides substantial fuel savings.This revised version was published online in October 2005 with corrections to the Cover Date.