An isopycnic ocean carbon cycle model

Assmann, Karen M.; Bentsen, Mats; Segschneider, Joachim; Heinze, Christoph

doi:10.5194/gmd-3-143-2010

Cited by 111 publications

(101 citation statements)

References 110 publications

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“…This study is based on an "ensemble of opportunity" comprising 17 Earth system models: NCAR CESM1 (Moore et al, 2013), 5 models from the OCMIP5 framework: NCAR CCSM3-BEC (Collins et al, 2006), NCAR CSM1.4-carbon , BCCR BCM-C (Assmann et al, 2010), IPSL-CM4 (Aumont et al, 2003) and COSMOS (Jungclaus et al, 2006); and 11 CMIP5 models: , CanESM2 , GFDL-ESM2M , HadGEM2-CC and HadGEM2-ES (Palmer and Totterdell, 2001), IPSL-CM5A-LR, IPSL-CM5A-MR and IPSL-CM5B-LR , MIROC-ESM (Watanabe et al, 2011), MPI-ESM-LR and MPI-ESM-MR , and NorESM1-ME .…”

Section: Methodsmentioning

confidence: 99%

Time of emergence of trends in ocean biogeochemistry

2014

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Abstract. For the detection of climate change, not only the magnitude of a trend signal is of significance. An essential issue is the time period required by the trend to be detectable in the first place. An illustrative measure for this is time of emergence (ToE), that is, the point in time when a signal finally emerges from the background noise of natural variability. We investigate the ToE of trend signals in different biogeochemical and physical surface variables utilizing a multimodel ensemble comprising simulations of 17 Earth system models (ESMs). We find that signals in ocean biogeochemical variables emerge on much shorter timescales than the physical variable sea surface temperature (SST). The ToE patterns of pCO 2 and pH are spatially very similar to DIC (dissolved inorganic carbon), yet the trends emerge much faster -after roughly 12 yr for the majority of the global ocean area, compared to between 10 and 30 yr for DIC. ToE of 45-90 yr are even larger for SST. In general, the background noise is of higher importance in determining ToE than the strength of the trend signal. In areas with high natural variability, even strong trends both in the physical climate and carbon cycle system are masked by variability over decadal timescales. In contrast to the trend, natural variability is affected by the seasonal cycle. This has important implications for observations, since it implies that intra-annual variability could question the representativeness of irregularly sampled seasonal measurements for the entire year and, thus, the interpretation of observed trends.

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Section: Methodsmentioning

confidence: 99%

Time of emergence of trends in ocean biogeochemistry

2014

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“…The HAMburg Ocean Carbon Cycle model (HAMOCC;Maier-Reimer, 1993;Maier-Reimer et al, 2005) has been implemented into MICOM by Assmann et al (2010). The HAMOCC version used in NorESM1-ME is further described by Tjiputra et al (2013) and Schwinger et al (2016).…”

Section: The Marine Biogeochemistry Model Micom-hamoccmentioning

confidence: 99%

Amplification of global warming through pH dependence of DMS production simulated with a fully coupled Earth system model

et al. 2017

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Abstract. We estimate the additional transient surface warming T s caused by a potential reduction of marine dimethyl sulfide (DMS) production due to ocean acidification under the high-emission scenario RCP8.5 until the year 2200. Since we use a fully coupled Earth system model, our results include a range of feedbacks, such as the response of marine DMS production to the additional changes in temperature and sea ice cover. Our results are broadly consistent with the findings of a previous study that employed an offline model set-up. Assuming a medium (strong) sensitivity of DMS production to pH, we find an additional transient global warming of 0.30 K (0.47 K) towards the end of the 22nd century when DMS emissions are reduced by 7.3 Tg S yr −1 or 31 % (11.5 Tg S yr −1 or 48 %). The main mechanism behind the additional warming is a reduction of cloud albedo, but a change in shortwave radiative fluxes under clear-sky conditions due to reduced sulfate aerosol load also contributes significantly. We find an approximately linear relationship between reduction of DMS emissions and changes in top of the atmosphere radiative fluxes as well as changes in surface temperature for the range of DMS emissions considered here. For example, global average T s changes by −0.041 K per 1 Tg S yr −1 change in sea-air DMS fluxes. The additional warming in our model has a pronounced asymmetry between northern and southern high latitudes. It is largest over the Antarctic continent, where the additional temperature increase of 0.56 K (0.89 K) is almost twice the global average. We find that feedbacks are small on the global scale due to opposing regional contributions. The most pronounced feedback is found for the Southern Ocean, where we estimate that the additional climate change enhances sea-air DMS fluxes by about 9 % (15 %), which counteracts the reduction due to ocean acidification.

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“…CAM4-Oslo is coupled with the updated version of the Miami Isopycnic Coordinate Ocean Model-MICOM [Assmann et al, 2010]. The sea ice and land models are the same as in the Community Climate System Model version 4 [CCSM4; Gent et al, 2011].…”

Section: Climate Modelmentioning

confidence: 99%

Climate effects of a hypothetical regional nuclear war: Sensitivity to emission duration and particle composition

et al. 2016

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Here, we use a coupled atmospheric-ocean-aerosol model to investigate the plume development and climate effects of the smoke generated by fires following a regional nuclear war between emerging third-world nuclear powers. We simulate a standard scenario where 5 Tg of black carbon (BC) is emitted over 1 day in the upper troposphere-lower stratosphere. However, it is likely that the emissions from the fires ignited by bomb detonations include a substantial amount of particulate organic matter (POM) and that they last more than 1 day. We therefore test the sensitivity of the aerosol plume and climate system to the BC/POM ratio (1:3, 1:9) and to the emission length (1 day, 1 week, 1 month). We find that in general, an emission length of 1 month substantially reduces the cooling compared to the 1-day case, whereas taking into account POM emissions notably increases the cooling and the reduction of precipitation associated with the nuclear war during the first year following the detonation. Accounting for POM emissions increases the particle size in the short-emission-length scenarios (1 day/1 week), reducing the residence time of the injected particle. While the initial cooling is more intense when including POM emission, the long-lasting effects, while still large, may be less extreme compared to the BC-only case. Our study highlights that the emission altitude reached by the plume is sensitive to both the particle type emitted by the fires and the emission duration. Consequently, the climate effects of a nuclear war are strongly dependent on these parameters.

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An isopycnic ocean carbon cycle model

Cited by 111 publications

References 110 publications

Time of emergence of trends in ocean biogeochemistry

Time of emergence of trends in ocean biogeochemistry

Amplification of global warming through pH dependence of DMS production simulated with a fully coupled Earth system model

Climate effects of a hypothetical regional nuclear war: Sensitivity to emission duration and particle composition

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