The uncertain climate footprint of wetlands under human pressure
Petrescu, A.J. ; Lohila, A. ; Tuovinen, J.P. ; Baldocchi, D.D. ; Desai, A.R. ; Veenendaal, E.M. ; Schrier-Uijl, A. - \ 2015
Proceedings of the National Academy of Sciences of the United States of America 112 (2015)15. - ISSN 0027-8424 - p. 4594 - 4599.
methane emissions - carbon-dioxide - peatlands - ecosystem - fluxes - variability - dynamics - drainage - balance - cycle
Significant climate risks are associated with a positive carbon–temperature feedback in northern latitude carbon-rich ecosystems, making an accurate analysis of human impacts on the net greenhouse gas balance of wetlands a priority. Here, we provide a coherent assessment of the climate footprint of a network of wetland sites based on simultaneous and quasi-continuous ecosystem observations of CO2 and CH4 fluxes. Experimental areas are located both in natural and in managed wetlands and cover a wide range of climatic regions, ecosystem types, and management practices. Based on direct observations we predict that sustained CH4 emissions in natural ecosystems are in the long term (i.e., several centuries) typically offset by CO2 uptake, although with large spatiotemporal variability. Using a space-for-time analogy across ecological and climatic gradients, we represent the chronosequence from natural to managed conditions to quantify the “cost” of CH4 emissions for the benefit of net carbon sequestration. With a sustained pulse–response radiative forcing model, we found a significant increase in atmospheric forcing due to land management, in particular for wetland converted to cropland. Our results quantify the role of human activities on the climate footprint of northern wetlands and call for development of active mitigation strategies for managed wetlands and new guidelines of the Intergovernmental Panel on Climate Change (IPCC) accounting for both sustained CH4 emissions and cumulative CO2 exchange.
Atmospheric CH4 in the first decade of the 21st century: Inverse modeling analysis using SCIAMACHY satellite retrievals and NOAA surface measurements
Bergamaschi, P. ; Houweling, S. ; Segers, A. ; Krol, M.C. ; Frankenberg, C. ; Scheepmaker, R.A. ; Dlugokencky, E. ; Wofsy, S.C. ; Kort, E.A. ; Sweeney, C. ; Schuck, T. ; Brenninkmeijer, C. ; Chen, H. ; Beck, V. ; Gerbig, C. - \ 2013
Journal of Geophysical Research: Atmospheres 118 (2013)13. - ISSN 2169-897X - p. 7350 - 7369.
growth-rate - methane emissions - carbon-dioxide - northern-hemisphere - data assimilation - transport model - variability - chemistry - climate - troposphere
The causes of renewed growth in the atmospheric CH4 burden since 2007 are still poorly understood and subject of intensive scientific discussion. We present a reanalysis of global CH4 emissions during the 2000s, based on the TM5-4DVAR inverse modeling system. The model is optimized using high-accuracy surface observations from NOAA ESRL's global air sampling network for 2000-2010 combined with retrievals of column-averaged CH4 mole fractions from SCIAMACHY onboard ENVISAT (starting 2003). Using climatological OH fields, derived global total emissions for 2007-2010 are 16-20 Tg CH4/yr higher compared to 2003-2005. Most of the inferred emission increase was located in the tropics (9-14 Tg CH4/yr) and mid- latitudes of the northern hemisphere (6-8 Tg CH4/yr), while no significant trend was derived for Arctic latitudes. The atmospheric increase can be attributed mainly to increased anthropogenic emissions, but the derived trend is significantly smaller than estimated in the EDGARv4.2 emission inventory. Superimposed on the increasing trend in anthropogenic CH4 emissions are significant inter-annual variations (IAV) of emissions from wetlands (up to +/- 10 Tg CH4/yr), and biomass burning (up to +/- 7 Tg CH4/yr). Sensitivity experiments, which investigated the impact of the SCIAMACHY observations (versus inversions using only surface observations), of the OH fields used, and of a priori emission inventories, resulted in differences in the detailed latitudinal attribution of CH4 emissions, but the IAV and trends aggregated over larger latitude bands were reasonably robust. All sensitivity experiments show similar performance against independent shipboard and airborne observations used for validation, except over Amazonia where satellite retrievals improved agreement with observations in the free troposphere.
Diet effects on urine composition of cattle and N20 emissions
Dijkstra, J. ; Oenema, O. ; Groenigen, J.W. van; Spek, J.W. ; Vuuren, A.M. van; Bannink, A. - \ 2013
Animal 7 (2013)S2. - ISSN 1751-7311 - p. 292 - 302.
nitrous-oxide emissions - milk urea concentration - hippuric-acid content - lactating dairy-cows - environmental-impact - purine derivatives - methane emissions - protein-synthesis - aromatic-acids - benzoic-acid
Ruminant production contributes to emissions of nitrogen (N) to the environment, principally ammonia (NH3), nitrous oxide (N2O) and di-nitrogen (N2) to air, nitrate (NO3 -) to groundwater and particulate N to surface waters. Variation in dietary N intake will particularly affect excretion of urinary N, which is much more vulnerable to losses than is faecal N. Our objective is to review dietary effects on the level and form of N excreted in cattle urine, as well as its consequences for emissions of N2O. The quantity of N excreted in urine varies widely. Urinary N excretion, in particular that of urea N, is decreased upon reduction of dietary N intake or an increase in the supply of energy to the rumen microorganisms and to the host animal itself. Most of the N in urine (from 50% to well over 90%) is present in the form of urea. Other nitrogenous components include purine derivatives (PD), hippuric acid, creatine and creatinine. Excretion of PD is related to rumen microbial protein synthesis, and that of hippuric acid to dietary concentration of degradable phenolic acids. The N concentration of cattle urine ranges from 3 to 20 g/l. High-dietary mineral levels increase urine volume and lead to reduced urinary N concentration as well as reduced urea concentration in plasma and milk. In lactating dairy cattle, variation in urine volume affects the relationship between milk urea and urinary N excretion, which hampers the use of milk urea as an accurate indicator of urinary N excretion. Following its deposition in pastures or in animal houses, ubiquitous microorganisms in soil and waters transform urinary N components into ammonium (NH4 +), and thereafter into NO3 - and ultimately in N2 accompanied with the release of N2O. Urinary hippuric acid, creatine and creatinine decompose more slowly than urea. Hippuric acid may act as a natural inhibitor of N2O emissions, but inhibition conditions have not been defined properly yet. Environmental and soil conditions at the site of urine deposition or manure application strongly influence N2O release. Major dietary strategies to mitigating N2O emission from cattle operations include reducing dietary N content or increasing energy content, and increasing dietary mineral content to increase urine volume. For further reduction of N2O emission, an integrated animal nutrition and excreta management approach is required.
Uncertainty in future N2O emissions due to land use change and socio-economic developments
Nol, L. ; Verburg, P.H. ; Moors, E.J. - \ 2012
Journal of Environmental Management 94 (2012)1. - ISSN 0301-4797 - p. 78 - 90.
nitrous-oxide emissions - methane emissions - scenario development - water-table - soil - uncertainty - inventory - model - scale - agriculture
Better insight in the possible range of future N2O emissions can help to construct mitigation and adaptation strategies and to adapt land use planning and management to climate objectives. The Dutch fen meadow landscape is a hotspot of N2O emission due to high nitrogen inputs combined with moist peat soils due to land use change. Socio-economic developments in the area are expected to have major impacts on N2O emission. The goals of this study are to estimate changes in N2O emissions for the period 2006–2040 under three different scenarios for the Dutch fen meadow landscape (rural production, rural fragmentation, and rural multifunctionality) and to quantify the share of different emission sources. Three scenarios were constructed and quantified based on the Story-And-Simulation approach. The rural production and the rural fragmentation scenarios are characterized by globalization and a market-oriented economy; in the rural production scenario dairy farming has a strong competitive position in the study region, while under the rural fragmentation scenario agriculture is declining. Under the rural multifunctionality scenario, the global context is characterized by regionalization and stronger regulation toward environmental issues. The N2O emission decreased between 2006 and 2040 under all scenarios. Under the rural production scenario, the N2O emission decreased by 7%. Due to measures to limit peat mineralization and policies to reduce agricultural emissions, the rural multifunctionality scenario showed the largest decrease in N2O emissions (44%). Under the rural fragmentation scenario, in which the dairy farming sector is diminished, the emission decreased by 33%. Compared to other uncertainties involved in N2O emission estimates, the uncertainty due to possible future land use change is relatively large and assuming a constant emission with time is therefore not appropriate.
The impact of slurry application technique on nitrous oxide emission from agricultural soils
Velthof, G.L. ; Mosquera, J. - \ 2011
Agriculture, Ecosystems and Environment 140 (2011)1-2. - ISSN 0167-8809 - p. 298 - 308.
distikstofmonoxide - emissie - broeikasgassen - bemesting - landbouwgronden - dierlijke meststoffen - toedieningswijzen - nitrous oxide - emission - greenhouse gases - fertilizer application - agricultural soils - animal manures - application methods - volatile fatty-acids - cattle slurry - pig slurry - methane emissions - surface application - animal production - mineral nitrogen - grassland soil - gas emissions - arable land
Direct nitrous oxide (N2O) emissions from fertilized soils are generally estimated using emission factors. However, the emission factors for N2O emission of applied slurry are not well quantified. The effect of slurry application technique on N2O emission was quantified in field experiments in the Netherlands in order to derive N2O emission factors for (shallow) injected and surface-applied cattle and pig slurries. Fluxes of N2O were measured using a closed flux chamber technique and a photo-acoustic infra-red gasmonitor. Fluxes of N2O were measured 64–83 times on grassland on sandy and clay soils and maize land on sandy soil, in the period 2007–2009. There were large differences in total N2O emission between the years, and differences between treatments were not consistent over the years and sites. The average emission factor of all treatments and years (n = 35) was 0.9% of the N applied, which is close to the default IPCC emission factor of 1%. However, the range in emission was large, i.e. from -0.2% to 7.0%. The average emission factor for grassland was 1.7% of the N applied for calcium ammonium nitrate (CAN), 0.4% for shallow injected cattle slurry, and 0.1% for surface-applied cattle slurry. For maize land, the average emission factor for CAN was 0.1% of the N applied, for injected cattle slurry 0.9% and for surface-applied cattle slurry 0.4%. The emission factors for pig slurry applied to maize land were higher than for cattle slurry; 3.6% for injected pig slurry and 0.9% for surface-applied pig slurry. Increasing the N application rate on maize land resulted in higher emission factors for CAN, injected cattle slurry, and injected pig slurry. Concluding, on both grassland and maize land (shallow) injection of slurry increased the average emission factor of N2O in comparison to surface application. Differentiation of N2O emission factors which takes specific factors into account, such as N type and rate and application technique, can improve the quantification of N2O emission from agricultural soils and is needed to derive most efficient options for mitigation. --------------------------------------------------------------------------------
Assessing CH4 and CO2 emissions from wetlands in the Drenthe province, The Netherlands: a modelling approach
Petrescu, A.J. ; Huissteden, J. van; Vries, F. de; Bregman, E.P.H. ; Scheper, A. - \ 2009
Netherlands journal of geosciences 88 (2009)2. - ISSN 0016-7746 - p. 101 - 116.
veengronden - grondwaterspiegel - bodemchemie - methaan - kooldioxide - emissie - modellen - ecohydrologie - natuurgebieden - drenthe - peat soils - water table - soil chemistry - methane - carbon dioxide - emission - models - ecohydrology - natural areas - drenthe - greenhouse-gas balance - methane emissions - management
Assessment of land use related greenhouse gas (GHG) emissions on larger spatial scales is usually achieved by modelling. Surface flux measurements are expensive and measurement locations too widely scattered to serve as spatially reliable flux estimates. Here we assess CO2 and CH4 fluxes from wetland nature reserves in the Dutch province of Drenthe, using the PEATLAND-VU model. Since surface flux observations in the province are absent and cannot be obtained in a short (
Pig slurry treatment modifies slurry composition, N2O, and CO2 emissions after soil incorporation
Bertora, C. ; Alluvione, F. ; Zavattaro, L. ; Groenigen, J.W. van; Velthof, G.L. ; Grignani, C. - \ 2008
Soil Biology and Biochemistry 40 (2008)8. - ISSN 0038-0717 - p. 1999 - 2006.
nitrous-oxide emission - microbial biomass carbon - 2 grassland soils - cattle slurry - ammonia volatilization - anaerobic-digestion - agricultural soils - methane emissions - livestock slurry - organic-carbon
The treatment of manures may improve their agricultural value and environmental quality, for instance with regards to greenhouse gases mitigation and enhancement of carbon (C) sequestration. The present study verified whether different pig slurry treatments (i.e. solid/liquid separation and anaerobic digestion) changed slurry composition. The effect of the slurry composition on N2O and CO2 emissions, denitrification and soil mineral nitrogen (N), after soil incorporation, was also examined during a 58-day mesocosm study. The treatments included a non-treated pig slurry (NT), the solid fraction (SF), and the liquid fraction (LF) of a pig slurry and the anaerobically digested liquid fraction (DG). Finally, a non-fertilized (N0) and a treatment with urea (UR) were also present. The N2O emissions measured represented 4.8%, 2.6%, 1.8%, 1.0% and 0.9% of N supplied with slurry/fertilizer for NT, LF, DG, SF and UR, respectively. Cumulative CO2 emissions ranged from 0.40 g CO2-C kg¿1 soil (0.38 Mg CO2-C ha¿1) to 0.80 g CO2-C kg¿1 soil (0.75 Mg CO2-C ha¿1). They were highest for SF (56% of C applied), followed by NT (189% of C applied), LF (337% of C applied) and DG (321% of C applied). Ammonium was detected in the soil for all treatments only at day one, while nitrate concentration increased linearly from day 15 to day 58, at a rate independent of the type of slurry/fertilizer applied. The nitrate recovery at day 58 was 39% of the N applied for NT, 19% for SF, 52% for LF, 67% for DG, and 41% for UR. The solid fraction generally produced higher potential denitrification fluxes (75.3 for SF, 56.7 for NT, 53.6 for LF, 47.7 for DG and 39.7 mg N2O + N2-N kg¿1 soil for UR). The high variability of actual denitrification results obfuscated any treatment effect. We conclude that treatment strongly affects slurry composition (mainly its C, fibre and NH4+ content), and hence N2O and CO2 emission patterns as well as denitrification processes and nitrate availability. In particular, the solid fraction obtained after mechanical separation produced the most pronounced difference, while the liquid fraction and the anaerobically digested liquid fraction did not show significant difference with respect to the original slurry for any of the measured parameters. Combining data from the different fractions we showed that separation of slurry leads to reduced N2O emissions, irrespective of whether the liquid fraction is digested or not. Furthermore, our results suggested that the default emission factor for N2O emissions inventory is too low for both the non-treated pig slurry and its liquid fraction (digested or not), and too high for the separated solid fraction and urea
Effect of land cover data on nitrous oxide inventory in fen meadows
Nol, L. ; Verburg, P.H. ; Heuvelink, G.B.M. ; Molenaar, K. - \ 2008
Journal of Environmental Quality 37 (2008)3. - ISSN 0047-2425 - p. 1209 - 1219.
distikstofmonoxide - emissie - broeikasgassen - landgebruik - veenweiden - gegevensanalyse - groene hart - nitrous oxide - emission - greenhouse gases - land use - peat grasslands - data analysis - groene hart - methane emissions - classification accuracy - spatial variability - grazed pastures - gas emissions - n2o emission - rice fields - use maps - model - soil
Landscape representations based on land cover databases differ significantly from the real landscape. Using a land cover database with high uncertainty as input for emission inventory analyses can cause propagation of systematic and random errors. The objective of this study was to analyze how different land cover representations introduce systematic errors into the results of regional N2O emission inventories. Surface areas of grassland, ditches, and ditch banks were estimated for two polders in the Dutch fen meadow landscape using five land cover representations: four commonly used databases and a detailed field map, which most closely resembles the real landscape. These estimated surface areas were scaled up to the Dutch western fen meadow landscape. Based on the estimated surface areas agricultural N2O emissions were estimated using different inventory techniques. All four common databases overestimated the grassland area when compared to the field map. This caused a considerable overestimation of agricultural N2O emissions, ranging from 9% for more detailed databases to 11% for the coarsest database. The effect of poor land cover representation was larger for an inventory method based on a process model than for inventory methods based on simple emission factors. Although the effect of errors in land cover representations may be small compared to the effect of uncertainties in emission factors, these effects are systematic (i.e., cause bias) and do not cancel out by spatial upscaling. Moreover, bias in land cover representations can be quantified or reduced by careful selection of the land cover database
CO2 exchange and carbon balance in two grassland sites on eutrophic drained peat soils
Veenendaal, E.M. ; Kolle, O. ; Leffelaar, P.A. ; Schrier-Uijl, A.P. ; Huissteden, J. van; Walsem, J.D. van; Moller, F. ; Berendse, F. - \ 2007
Biogeosciences 4 (2007)6. - ISSN 1726-4170 - p. 1027 - 1040.
kooldioxide - netto ecosysteem koolstofbalans - veengebieden - eddy-covariantie - melkveehouderijsystemen - graslanden - nederland - carbon dioxide - net ecosystem carbon balance - peatlands - eddy covariance - dairy farming systems - grasslands - netherlands - ecosystem-atmosphere exchange - dioxide exchange - interannual variability - spatial variability - seasonal-variation - methane emissions - flux measurements - wet grasslands - water-vapor - net carbon
In this study we investigated the role of intensive and extensive dairy farm practices on CO2 exchange and the carbon balance of peatlands by means of eddy covariance (EC) measurements. Year long EC measurements were made in two adjacent farm sites on peat soil in the western part of the Netherlands. One site (Stein) is a new meadow bird reserve and is managed predominantly by mowing in June and August. The second site (Oukoop) is an intensive dairy farm.
In this study we investigated the role of intensive and extensive dairy farm practices on CO2 exchange and the carbon balance of peatlands by means of eddy covariance (EC) measurements. Year long EC measurements were made in two adjacent farm sites on peat soil in the western part of the Netherlands. One site (Stein) is a new meadow bird reserve and is managed predominantly by mowing in June and August. The second site (Oukoop) is an intensive dairy farm. Maximum photosynthetic uptake of the grass sward (range 2 to 34 mu mol CO2 m(-2) s(-1)) showed a close and similar linear relationship with Leaf Area Index (LAI; range 1 to 5) except in maturing hay meadows, where maximum photosynthetic uptake did not increase further. Apparent quantum yield varied between 0.02 and 0.08 (mean 0.045) mu mol CO2 mu mol(-1) photons at both sites and was significantly correlated with LAI during the growth season. Ecosystem Respiration at 10 degrees C (R-10) calculated from the year round data set was 3.35 mu mol CO2 m(-2) s(-1) at Stein and 3.69 mu mol CO2 m(-2) s(-1) at Oukoop. Both sites were a source of carbon in winter and a sink during summer with net ecosystem exchange varying between 50 to 100 mmol CO2 m(-2) d(-1) in winter to below -400 mmol CO2 m(-2) d(-1) in summer. Periodically, both sites became a source after mowing. Net annual ecosystem exchange (NEE) for Stein was -5.7 g C m(-2) a(-1) and for Oukoop 133.9 g C m(-2) a(-1). When biomass removal, manure applications and estimates of methane emissions ware taken into account, both eutrophic peat meadows are a strong source for C around 420 g C m(-2) a(-1).
Monitoring GHG from manure stores on organic and conventional dairy farms
Sneath, R.W. ; Beline, F. ; Hilhorst, M.A. ; Peu, P. - \ 2006
Agriculture, Ecosystems and Environment 112 (2006)2-3. - ISSN 0167-8809 - p. 122 - 128.
methane emissions - slurry - livestock
Organic farming methods are claimed to be more environmentally friendly than conventional methods and the EU MIDAIR project had an overall aim to compare emissions from organic dairy farming with conventional methods of milk production. Manure stores are the second largest source of methane emissions (after enteric fermentation) on European dairy farming. The aim of this project was to measure green house gas (GHG) emissions from manures in covered and uncovered slurry stores and farm yard manure (FYM) heaps. The chosen method for measuring these emissions was the tracer ratio method, using sulphur hexafluoride (SF6) as the tracer gas, the limitations of this method prevented successful measurements being made on some of the stores and a modified method was used on the covered stores. The difference in concentration of the upwind and downwind samples and interfering sources were limiting factors. FYM emission measurements were successful only when the manure was stored indoors. Methane emissions were successfully measured over a 12 month period from the uncovered slurry stores. Emission rates from the uncovered slurry stores on the conventional farm and the organic farm ranged from 14.4 to 49.6 and from 12.4 to 42.3 g C m(-3) d(-1), respectively, with the mean CH4 emission rates of 35 and 26 g C m(-3) d(-1). On both farms, nitrous oxide emissions were close to zero. Methane emissions measured from the indoor organic FYM in summer were 17.1 g C m(-3) d(-1) and the nitrous oxide emission was 411 mg N m(-3) d(-1). The covered slurry stores were in such close proximity to other GHG sources that the tracer ratio method was unsuitable and the air-injection method was adopted. The measured emissions from covered slurry stores of CH4, CO2 and NH3 were, respectively, 14.9 g C m(-3) d(-1), 12.9 g C m(-3) d(-1) and 18.6 mg NH3 m(-2) d(-1) of slurry in February and 12.0 g C m(-3) d(-1), 9.5 g C m(-3) d(-1) and 335 mg NH3 m(-2) d(-1) slurry in March. No nitrous oxide production could be measured. (c) 2005 Elsevier B.V. All rights reserved.
Multimodel ensemble simulations of present-day and near-future tropospheric ozone
Stevenson, D.S. ; Dentener, F.J. ; Schultz, M.G. ; Ellingsen, K. ; Noije, T.P.C. van; Wild, O. ; Zeng, G. ; Amann, M. ; Atherton, C.S. ; Bell, N. ; Bergmann, D.J. ; Bey, I. ; Butler, T. ; Cofala, J. ; Collins, W.J. ; Derwent, R.G. ; Doherty, R.M. ; Drevet, J. ; Eskes, H.J. ; Fiore, A.M. ; Gauss, M. ; Hauglustaine, D.A. ; Horowitz, L.W. ; Isaksen, I.S.A. ; Krol, M.C. ; Lamarque, J.F. ; Lawrence, M.G. ; Montanaro, V. ; Muller, J.F. ; Pitari, G. ; Prather, M.J. ; Pyle, J.A. ; Rast, S. ; Rodriguez, J.M. ; Sanderson, M.G. ; Savage, N.H. ; Shindell, D.T. ; Strahan, S.E. ; Sudo, K. ; Szopa, S. - \ 2006
Journal of Geophysical Research: Atmospheres 111 (2006). - ISSN 2169-897X - p. D08301 - D08301.
chemistry transport models - general-circulation model - biogenic nox emissions - global chemical-model - aircraft mozaic data - climate-change - nonmethane hydrocarbons - methane emissions - surface ozone - atmospheric chemistry
Global tropospheric ozone distributions, budgets, and radiative forcings from an ensemble of 26 state-of-the-art atmospheric chemistry models have been intercompared and synthesized as part of a wider study into both the air quality and climate roles of ozone. Results from three 2030 emissions scenarios, broadly representing “optimistic,” “likely,” and “pessimistic” options, are compared to a base year 2000 simulation. This base case realistically represents the current global distribution of tropospheric ozone. A further set of simulations considers the influence of climate change over the same time period by forcing the central emissions scenario with a surface warming of around 0.7K. The use of a large multimodel ensemble allows us to identify key areas of uncertainty and improves the robustness of the results. Ensemble mean changes in tropospheric ozone burden between 2000 and 2030 for the 3 scenarios range from a 5% decrease, through a 6% increase, to a 15% increase. The intermodel uncertainty (±1 standard deviation) associated with these values is about ±25%. Model outliers have no significant influence on the ensemble mean results. Combining ozone and methane changes, the three scenarios produce radiative forcings of -50, 180, and 300 mW m-2, compared to a CO2 forcing over the same time period of 800–1100 mW m-2. These values indicate the importance of air pollution emissions in short- to medium-term climate forcing and the potential for stringent/lax control measures to improve/worsen future climate forcing. The model sensitivity of ozone to imposed climate change varies between models but modulates zonal mean mixing ratios by ±5 ppbv via a variety of feedback mechanisms, in particular those involving water vapor and stratosphere-troposphere exchange. This level of climate change also reduces the methane lifetime by around 4%. The ensemble mean year 2000 tropospheric ozone budget indicates chemical production, chemical destruction, dry deposition and stratospheric input fluxes of 5100, 4650, 1000, and 550 Tg(O3) yr-1, respectively. These values are significantly different to the mean budget documented by the Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (TAR). The mean ozone burden (340 Tg(O3)) is 10% larger than the IPCC TAR estimate, while the mean ozone lifetime (22 days) is 10% shorter. Results from individual models show a correlation between ozone burden and lifetime, and each model's ozone burden and lifetime respond in similar ways across the emissions scenarios. The response to climate change is much less consistent. Models show more variability in the tropics compared to midlatitudes. Some of the most uncertain areas of the models include treatments of deep tropical convection, including lightning NO x production; isoprene emissions from vegetation and isoprene's degradation chemistry; stratosphere-troposphere exchange; biomass burning; and water vapor concentrations.
Multimodel simulations of carbon monoxide: Comparison with observations and projected near-future changes
Shindell, D.T. ; Faluvegi, G. ; Stevenson, D.S. ; Krol, M.C. ; Emmons, L.K. ; Lamarque, J.F. ; Petron, G. ; Dentener, F.J. ; Ellingsen, K. ; Schultz, M.G. ; Wild, O. ; Amann, M. ; Atherton, C.S. ; Bergmann, D.J. ; Bey, I. ; Butler, T. ; Cofala, J. ; Collins, W.J. ; Derwent, R.G. ; Doherty, R.M. ; Drevet, J. ; Eskes, H.J. ; Fiore, A.M. ; Gauss, M. ; Hauglustaine, D.A. ; Horowitz, L.W. ; Isaksen, I.S.A. ; Lawrence, M.G. ; Montanaro, V. ; Muller, J.F. ; Pitari, G. ; Prather, M.J. ; Pyle, J.A. ; Rast, S. ; Rodriguez, J.M. ; Sanderson, M.G. ; Savage, N.H. ; Strahan, S.E. ; Sudo, K. ; Szopa, S. ; Unger, N. ; Noije, T.P.C. van; Zeng, G. - \ 2006
Journal of Geophysical Research: Atmospheres 111 (2006). - ISSN 2169-897X - 24 p.
chemical-transport model - stratosphere-troposphere exchange - general-circulation model - aircraft mozaic data - nonmethane hydrocarbons - ozone simulations - methane emissions - western pacific - climate-change - 3-d models
We analyze present-day and future carbon monoxide (CO) simulations in 26 state-of-the-art atmospheric chemistry models run to study future air quality and climate change. In comparison with near-global satellite observations from the MOPITT instrument and local surface measurements, the models show large underestimates of Northern Hemisphere (NH) extratropical CO, while typically performing reasonably well elsewhere. The results suggest that year-round emissions, probably from fossil fuel burning in east Asia and seasonal biomass burning emissions in south-central Africa, are greatly underestimated in current inventories such as IIASA and EDGAR3.2. Variability among models is large, likely resulting primarily from intermodel differences in representations and emissions of nonmethane volatile organic compounds (NMVOCs) and in hydrologic cycles, which affect OH and soluble hydrocarbon intermediates. Global mean projections of the 2030 CO response to emissions changes are quite robust. Global mean midtropospheric (500 hPa) CO increases by 12.6 +/- 3.5 ppbv (16%) for the high-emissions (A2) scenario, by 1.7 +/- 1.8 ppbv (2%) for the midrange (CLE) scenario, and decreases by 8.1 +/- 2.3 ppbv (11%) for the low-emissions (MFR) scenario. Projected 2030 climate changes decrease global 500 hPa CO by 1.4 +/- 1.4 ppbv. Local changes can be much larger. In response to climate change, substantial effects are seen in the tropics, but intermodel variability is quite large. The regional CO responses to emissions changes are robust across models, however. These range from decreases of 10-20 ppbv over much of the industrialized NH for the CLE scenario to CO increases worldwide and year-round under A2, with the largest changes over central Africa (20-30 ppbv), southern Brazil (20-35 ppbv) and south and east Asia (30-70 ppbv). The trajectory of future emissions thus has the potential to profoundly affect air quality over most of the world's populated areas.
Upscaling regional emissions of greenhouse gases from rice cultivation: methods and sources of uncertainty
Verburg, P.H. ; Bodegom, P.M. van; Denier van der Gon, H.A.C. ; Bergsma, A. ; Breemen, N. van - \ 2006
Plant Ecology 182 (2006)1-2. - ISSN 1385-0237 - p. 89 - 106.
methane emissions - atmospheric methane - water management - ch4 emission - paddy soils - fields - model - china - variability - sensitivity
One of the important sources of greenhouse gases is the emission of methane from rice fields. Methane emission from rice fields is the result of a complex array of soil processes involving plant-microbe interactions. The cumulative effects of these processes at the level of individual plants influence the global atmospheric composition and make it necessary to expand our research focus from small plots to large landscapes and regions. However, present extrapolations (`upscaling¿) are tenuous at best because of methodological and practical problems. The different steps taken to calculate regional emission strengths are discussed and illustrated by calculations for a case-study in the Philippines. The applicability of high quality, process-based, models of methane emission at the level of individual plants is limited for regional analysis by their large data requirements. Simplified models can be used at the regional level but are not able to capture the complex emission situation. Data availability and model accuracy are therefore often difficult to match. Other common sources of uncertainty are the quality of input data. A critical evaluation of input data should be made in every upscaling study to assess the suitability for calculating regional emissions. For the case-study we show effects of differences in input data caused by data source and interpolation technique. The results from the case-study and similar studies in literature indicate that upscaling techniques are still troublesome and a cause of large uncertainties in regional estimates. The results suggest that some of the stumbling blocks in the conventional upscaling procedure are almost impassable in the near future. Based on these results, a plea is made for meso-level measurements to calibrate and validate upscaling methods in order to be better able to quantify and reduce uncertainties in regional emission estimates
Effects of elevated CO2 and N deposition on CH4 emissions from European mires
Silvola, J. ; Saarnio, S. ; Foot, J. ; Sundh, I. ; Greenup, A. ; Heijmans, M.M.P.D. ; Ekberg, A. ; Mitchell, E.P. ; Breemen, N. van - \ 2003
Global Biogeochemical Cycles 17 (2003)2 - 1068. - ISSN 0886-6236 - p. 37 - 1-37-12.
atmospheric carbon-dioxide - methane emissions - boreal mire - raised co2 - northern peatlands - water-table - nitrogen deposition - bog vegetation - forest soils - temperature
 Methane fluxes were measured at five sites representing oligotrophic peatlands along a European transect. Five study plots were subjected to elevated CO2 concentration (560 ppm), and five plots to NH4NO3 (3 or 5 g N yr(-1)). The CH4 emissions from the control plots correlated in most cases with the soil temperatures. The depth of the water table, the pH, and the DOC, N and SO4 concentrations were only weakly correlated with the CH4 emissions. The elevated CO2 treatment gave nonsignificantly higher CH4 emissions at three sites and lower at two sites. The N treatment resulted in higher methane emissions at three sites (nonsignificant). At one site, the CH4 fluxes of the N-treatment plots were significantly lower than those of the control plots. These results were not in agreement with our hypotheses, nor with the results obtained in some earlier studies. However, the results are consistent with the results of the vegetation analyses, which showed no significant treatment effects on species relationships or biomass production.
Nitrous oxide emission from animal manures applied to soil under controlled conditions
Velthof, G.L. ; Kuikman, P.J. ; Oenema, O. - \ 2003
Biology and Fertility of Soils 37 (2003). - ISSN 0178-2762 - p. 221 - 230.
volatile fatty-acids - methane emissions - cattle slurry - pig slurry - laboratory conditions - surface application - grassland - injection - nitrate - carbon
Animal manures may differ strongly in composition and as a result may differ in the emission of N2O following application to soil. An incubation study was carried out to assess the effects of type of mineral N fertilizer and manure, application technique and application rate on N2O emission from a sandy soil with low organic matter content. Fluxes of N2O were measured 30 times over a 98-day period. The total N2O emission from mineral N fertilizer ranged from 2.1 to 4.0% of the N applied. High emissions were associated with manures with high contents of inorganic N, easily mineralizable N and easily mineralizable C, such as liquid pig manure (7.3-13.9% of the N applied). The emission from cattle slurries ranged from 1.8 to 3.0% and that of poultry manures from 0.5 to 1.9%. The total N2O emission during the experimental period tended to increase linearly with increasing N application rate of NH4NO3 and liquid pig manure. The N2O emission from surface-applied NH4NO3 was significantly smaller than that following the incorporation of NH4NO3 in the soil. The N2O emission from pig manure placed in a row at 5 cm depth was significantly higher than from surface-application and other techniques in which manure was incorporated in the soil. The results show that modification of the composition and application technique may be tools to mitigate emission of N2O