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- ItemCarbon dioxide and climate impulse response functions for the computation of greenhouse gas metrics: A multi-model analysis(München : European Geopyhsical Union, 2013) Joos, F.; Roth, R.; Fuglestvedt, J.S.; Peters, G.P.; Enting, I.G.; von Bloh, W.; Brovkin, V.; Burke, E.J.; Eby, M.; Edwards, N.R.; Friedrich, T.; Frölicher, T.L.; Halloran, P.R.; Holden, P.B.; Jones, C.; Kleinen, T.; Mackenzie, F.T.; Matsumoto, K.; Meinshausen, M.; Plattner, G.-K.; Reisinger, A.; Segschneider, J.; Shaffer, G.; Steinacher, M.; Strassmann, K.; Tanaka, K.; Timmermann, A.; Weaver, A.J.The responses of carbon dioxide (CO2) and other climate variables to an emission pulse of CO2 into the atmosphere are often used to compute the Global Warming Potential (GWP) and Global Temperature change Potential (GTP), to characterize the response timescales of Earth System models, and to build reduced-form models. In this carbon cycle-climate model intercomparison project, which spans the full model hierarchy, we quantify responses to emission pulses of different magnitudes injected under different conditions. The CO2 response shows the known rapid decline in the first few decades followed by a millennium-scale tail. For a 100 Gt-C emission pulse added to a constant CO2 concentration of 389 ppm, 25 ± 9% is still found in the atmosphere after 1000 yr; the ocean has absorbed 59 ± 12% and the land the remainder (16 ± 14%). The response in global mean surface air temperature is an increase by 0.20 ± 0.12 °C within the first twenty years; thereafter and until year 1000, temperature decreases only slightly, whereas ocean heat content and sea level continue to rise. Our best estimate for the Absolute Global Warming Potential, given by the time-integrated response in CO2 at year 100 multiplied by its radiative efficiency, is 92.5 × 10−15 yr W m−2 per kg-CO2. This value very likely (5 to 95% confidence) lies within the range of (68 to 117) × 10−15 yr W m−2 per kg-CO2. Estimates for time-integrated response in CO2 published in the IPCC First, Second, and Fourth Assessment and our multi-model best estimate all agree within 15% during the first 100 yr. The integrated CO2 response, normalized by the pulse size, is lower for pre-industrial conditions, compared to present day, and lower for smaller pulses than larger pulses. In contrast, the response in temperature, sea level and ocean heat content is less sensitive to these choices. Although, choices in pulse size, background concentration, and model lead to uncertainties, the most important and subjective choice to determine AGWP of CO2 and GWP is the time horizon.
- ItemRegional projections of temperature and precipitation changes: Robustness and uncertainty aspects(Stuttgart : Gebrueder Borntraeger Verlagsbuchhandlung, 2017) Piniewski, M.; Mezghani, A.; Szczésniak, M.; Kundzewicz, Z.W.This study presents the analysis of bias-corrected projections of changes in temperature and precipitation in the Vistula and Odra basins, covering approximately 90% of the Polish territory and small parts of neighbouring countries in Central and Eastern Europe. The ensemble of climate projections consists of nine regional climate model simulations from the EURO-CORDEX ensemble for two future periods 2021-2050 and 2071-2100, assuming two representative concentration pathways (RCPs) 4.5 and 8.5. The robustness is measured by the ensemble models' agreement on significant changes.We found a robust increase in the annual mean of daily minimum and maximum temperature, by 1-1.4 °C in the near future and by 1.9-3.8 °C in the far future (areal-means of the ensemble mean values). Higher increases are consistently associated with minimum temperature and the gradient of change goes from SWto NE regions. Seasonal projections of both temperature variables reflect lower robustness and suggest a higher future increase in winter temperatures than in other seasons, notably in the far future under RCP 8.5 (by more than 1 °C). However, changes in annual means of precipitation are uncertain and not robust in any of the analysed cases, even though the climate models agree well on the increase. This increase is intensified with rising global temperatures and varies from 5.5% in the near future under RCP 4.5 to 15.2%in the far future under RCP 8.5. Spatial variability is substantial, although quite variable between individual climate model simulations. Although seasonal means of precipitation are projected to considerably increase in all four combinations of RCPs and projection horizons for winter and spring, the high model spread reduces considerably the robustness, especially for the far future. In contrast, the ensemble members agree well that overall, the summer and autumn (with exception of the far future under RCP 8.5) precipitation will not undergo statistically significant changes.
- ItemUncertainty of biomass contributions from agriculture and forestry to renewable energy resources under climate change(Stuttgart : Gebrueder Borntraeger Verlagsbuchhandlung, 2015) Gutsch, M.; Lasch-Born, P.; Lüttger, A.B.; Suckow, F.; Murawski, A.; Pilz, T.
- ItemClimate change impacts on hydrology and water resources(Stuttgart : Gebrueder Borntraeger Verlagsbuchhandlung, 2015) Hattermann, F.F.; Huang, S.; Koch, H.
- ItemConstructing proxy records from age models (COPRA)(München : European Geopyhsical Union, 2012) Breitenbach, S.F.M.; Rehfeld, K.; Goswami, B.; Baldin, J.U.L.; Ridley, H.E.; Kennett, D.J.; Prufer, K.M.; Aquino, V.V.; Asmerom, Y.; Polyak, V.J.; Cheng, H.; Kurths, J.; Marwan, N.Reliable age models are fundamental for any palaeoclimate reconstruction. Available interpolation procedures between age control points are often inadequately reported, and very few translate age uncertainties to proxy uncertainties. Most available modeling algorithms do not allow incorporation of layer counted intervals to improve the confidence limits of the age model in question. We present a framework that allows detection and interactive handling of age reversals and hiatuses, depth-age modeling, and proxy-record reconstruction. Monte Carlo simulation and a translation procedure are used to assign a precise time scale to climate proxies and to translate dating uncertainties to uncertainties in the proxy values. The presented framework allows integration of incremental relative dating information to improve the final age model. The free software package COPRA1.0 facilitates easy interactive usage.
- ItemThe value of remote marine aerosol measurements for constraining radiative forcing uncertainty(Katlenburg-Lindau : EGU, 2020) Regayre, Leighton A.; Schmale, Julia; Johnson, Jill S.; Tatzelt, Christian; Baccarini, Andrea; Henning, Silvia; Yoshioka, Masaru; Stratmann, Frank; Gysel-Beer, Martin; Grosvenor, Daniel P.; Carslaw, Ken S.Aerosol measurements over the Southern Ocean are used to constrain aerosol-cloud interaction radiative forcing (RFaci) uncertainty in a global climate model. Forcing uncertainty is quantified using 1 million climate model variants that sample the uncertainty in nearly 30 model parameters. Measurements of cloud condensation nuclei and other aerosol properties from an Antarctic circumnavigation expedition strongly constrain natural aerosol emissions: default sea spray emissions need to be increased by around a factor of 3 to be consistent with measurements. Forcing uncertainty is reduced by around 7% using this set of several hundred measurements, which is comparable to the 8% reduction achieved using a diverse and extensive set of over 9000 predominantly Northern Hemisphere measurements. When Southern Ocean and Northern Hemisphere measurements are combined, uncertainty in RFaci is reduced by 21 %, and the strongest 20% of forcing values are ruled out as implausible. In this combined constraint, observationally plausible RFaci is around 0.17Wm-2 weaker (less negative) with 95% credible values ranging from-2:51 to-1:17Wm-2 (standard deviation of-2:18 to-1:46Wm-2). The Southern Ocean and Northern Hemisphere measurement datasets are complementary because they constrain different processes. These results highlight the value of remote marine aerosol measurements. © 2020 Laser Institute of America. All rights reserved.
- ItemThe Global Gridded Crop Model Intercomparison: Data and modeling protocols for Phase 1 (v1.0)(München : European Geopyhsical Union, 2015) Elliott, J.; Müller, C.; Deryng, D.; Chryssanthacopoulos, J.; Boote, K.J.; Büchner, M.; Foster, I.; Glotter, M.; Heinke, J.; Iizumi, T.; Izaurralde, R.C.; Mueller, N.D.; Ray, D.K.; Rosenzweig, C.; Ruane, A.C.; Sheffield, J.We present protocols and input data for Phase 1 of the Global Gridded Crop Model Intercomparison, a project of the Agricultural Model Intercomparison and Improvement Project (AgMIP). The project includes global simulations of yields, phenologies, and many land-surface fluxes using 12–15 modeling groups for many crops, climate forcing data sets, and scenarios over the historical period from 1948 to 2012. The primary outcomes of the project include (1) a detailed comparison of the major differences and similarities among global models commonly used for large-scale climate impact assessment, (2) an evaluation of model and ensemble hindcasting skill, (3) quantification of key uncertainties from climate input data, model choice, and other sources, and (4) a multi-model analysis of the agricultural impacts of large-scale climate extremes from the historical record.
- ItemThe PMIP4 contribution to CMIP6 - Part 3: The last millennium, scientific objective, and experimental design for the PMIP4 past1000 simulations(Göttingen : Copernicus GmbH, 2017) Jungclaus, J.H.; Bard, E.; Baroni, M.; Braconnot, P.; Cao, J.; Chini, L.P.; Egorova, T.; Evans, M.; Fidel González-Rouco, J.; Goosse, H.; Hurtt, G.C.; Joos, F.; Kaplan, J.O.; Khodri, M.; Klein Goldewijk, K.; Krivova, N.; Legrande, A.N.; Lorenz, S.J.; Luterbacher, J.; Man, W.; Maycock, A.C.; Meinshausen, M.; Moberg, A.; Muscheler, R.; Nehrbass-Ahles, C.; Otto-Bliesner, B.I.; Phipps, S.J.; Pongratz, J.; Rozanov, E.; Schmidt, G.A.; Schmidt, H.; Schmutz, W.; Schurer, A.; Shapiro, A.I.; Sigl, M.; Smerdon, J.E.; Solanki, S.K.; Timmreck, C.; Toohey, M.; Usoskin, I.G.; Wagner, S.; Wu, C.-J.; Leng Yeo, K.; Zanchettin, D.; Zhang, Q.; Zorita, E.The pre-industrial millennium is among the periods selected by the Paleoclimate Model Intercomparison Project (PMIP) for experiments contributing to the sixth phase of the Coupled Model Intercomparison Project (CMIP6) and the fourth phase of the PMIP (PMIP4). The past1000 transient simulations serve to investigate the response to (mainly) natural forcing under background conditions not too different from today, and to discriminate between forced and internally generated variability on interannual to centennial timescales. This paper describes the motivation and the experimental set-ups for the PMIP4-CMIP6 past1000 simulations, and discusses the forcing agents orbital, solar, volcanic, and land use/land cover changes, and variations in greenhouse gas concentrations. The past1000 simulations covering the pre-industrial millennium from 850 Common Era (CE) to 1849 CE have to be complemented by historical simulations (1850 to 2014 CE) following the CMIP6 protocol. The external forcings for the past1000 experiments have been adapted to provide a seamless transition across these time periods. Protocols for the past1000 simulations have been divided into three tiers. A default forcing data set has been defined for the Tier 1 (the CMIP6 past1000) experiment. However, the PMIP community has maintained the flexibility to conduct coordinated sensitivity experiments to explore uncertainty in forcing reconstructions as well as parameter uncertainty in dedicated Tier 2 simulations. Additional experiments (Tier 3) are defined to foster collaborative model experiments focusing on the early instrumental period and to extend the temporal range and the scope of the simulations. This paper outlines current and future research foci and common analyses for collaborative work between the PMIP and the observational communities (reconstructions, instrumental data).