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Natural Science Papers by Martin Claussen
Das Ziel des 2. Hamburger Klimaberichtes (2HKB) ist es, das wissenschaftliche Wissen über den ver... more Das Ziel des 2. Hamburger Klimaberichtes (2HKB) ist es, das wissenschaftliche Wissen über den vergangenen, den derzeitigen und den zukünftig möglichen Klimawandel und seine Wirkung in der Metropolregion Hamburg und Norddeutschland zu dokumentieren und zusammenzufassen. 2011 erschien der erste „Klimabericht für die Metropolregion Hamburg“ (1HKB) erstellt von einer Autorengruppe des KlimaCampus Hamburg und externen Partnern. Dieses Projekt wurde von Hans von Storch initiiert, vom Norddeutschen Küsten- und Klimabüro (HZG) organisiert und im Rahmen des Klima-Exzellenzclusters CliSAP (Integrated Climate System Analysis and Prediction) der Universität Hamburg und ihren außeruniversitären Partnern gefördert. Der Bericht sollte das Wissen über den regionalen Klimawandel in der Metropolregion Hamburg, mögliche Klimafolgen in der Region und mögliches Management, wie es in wissenschaftlichen Publikationen belegt ist, sichten und im Hinblick auf Konsens und Dissens bewerten.
Vorbilder dieses Wissensberichtes waren auf globaler Ebene der IPCC-Bericht und auf regionaler Ebene der BACC-Report „BALTEX Assessment of Climate Change in the Baltic Sea Basin“, der als erster regionaler Wissensbericht 2008 veröffentlicht wurde. Der 1. HKB spiegelt den Stand des Wissens im Sommer 2009 wider, da für den Bericht Material gesichtet wurde, das vor dem 1. August 2009 veröffentlicht worden war. Etwa 3 Jahre nach Erscheinen dieses Klimaberichtes wurde von den Partnern des KlimaCampus Hamburg im Herbst 2014 beschlossen, einen zweiten Bericht zu erarbeiten. Dieser 2. Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg und Norddeutschland – liegt nun vor. Das Material des ersten Berichtes wurde kritisch vor dem Hintergrund neuer Erkenntnisse analysiert. Neue Themen, die im ersten Bericht aufgrund fehlender Forschung keine Berücksichtigung fanden, wurden aufgegriffen. Das vorliegende Buch dokumentiert den Forschungsstand bis Oktober 2015.
Papers by Martin Claussen
Contributions to atmospheric physics, 1982
Journal of Advances in Modeling Earth Systems, 2019
Klimabericht für die Metropolregion Hamburg, 2010
Geophysical Research Letters, 2009
Abstract. By using a climate system model of intermediate complexity, we have simulated longterm ... more Abstract. By using a climate system model of intermediate complexity, we have simulated longterm natural climate changes occurring over the last 9000 years. The paleo-simulations in which the model is driven by orbital forcing only, i.e., by changes in insolation caused by changes in the Earth's orbit, are compared with sensitivity simulations in which various scenarios of increasing atmospheric CO 2 concentration are prescribed. Focussing on climate and vegetation change in northern Africa, we recapture the strong greening of the Sahara in the early and mid-Holocene (some 9000-6000 years ago), and we show that some expansion of grassland into the Sahara is theoretically possible, if the atmospheric CO 2 concentration increases well above pre-industrial values and if vegetation growth is not disturbed. Depending on the rate of CO 2 increase, vegetation migration into the Sahara can be rapid, up to 1/10th of the Saharan area per decade, but could not exceed a coverage of 45%. In...
By coupling an atmospheric general circulation model asynchronously with an equilibrium vegetatio... more By coupling an atmospheric general circulation model asynchronously with an equilibrium vegetation model, manifold equilibrium solutions of the atmosphere^biosphere system have been explored. It is found that under present-day conditions of the Earth's orbital parameters and sea-surface temperatures, two stable equilibria of vegetation patterns are possible: one corresponding to present-day sparse vegeta-tion in the Sahel, the second solution yielding savannah which extends far into the south-western part of the Sahara. A similar picture is obtained for conditions during the last glacial maximum (21 000 years before present (BP)). For the mid-Holocene (6000 years BP), however, the model ¢nds only one solution: the green Sahara.We suggest that this intransitive behaviour of the atmosphere^biosphere is related to a westward shift of the Hadley^Walker circulation. A conceptual model of atmosphere^vegetation dynamics is used to interpret the bifurcation as well as its change in ter...
In this overview two definitions of climate are presented, from the meteorological point of view ... more In this overview two definitions of climate are presented, from the meteorological point of view and from the climate system’s point of view. The origin of climate change is discussed, i.e., externally forced variability and free, or internal variability that is caused without external trigger by internal instabilities of the system. Both, forced and free variability can appear as periodic, randomly quasi-periodic, and abrupt climate change. Finally, various possibilities of climate forecast are considered.
Earth System Dynamics Discussions
A major link between climate and humans in Northern Africa, and the Sahel in particular, is land ... more A major link between climate and humans in Northern Africa, and the Sahel in particular, is land use and associated land cover change, mainly where subsistence farming prevails. Here we assess possible feedbacks between the type of land use and harvest intensity and climate by analyzing a series of idealized GCM experiments using the MPI-ESM. The base line for these experiments is a simulation forced by the RCP8.5 scenario which includes strong greenhouse gas emissions and anthropogenic land cover changes. The anthropogenic land cover changes in the RCP8.5 scenario include a mixture of pasture and agriculture. In subsequent simulations, we replace the entire area affected by anthropogenic land cover change in the region between the Sahara in the North and the Guinean Coast in the South (4 to 20° N) by either pasture or agriculture, respectively. In a second setup we vary the amount of harvest in case of agriculture. The RCP8.5 base line simulation reveals strong changes in mean ...
Climate of the Past Discussions
The recently proposed global monsoon hypothesis interprets monsoon systems as part of one global-... more The recently proposed global monsoon hypothesis interprets monsoon systems as part of one global-scale atmospheric overturning circulation, implying a connection between the regional monsoon systems and an in-phase behaviour of all northern hemispheric monsoons on annual timescales (Trenberth et al., 2000). Whether this concept can be applied to past climates and variability on longer timescales is still under debate, because the monsoon systems exhibit different regional characteristics such as different seasonality (i.e. onset, peak, and withdrawal). To investigate the interconnection of different monsoon systems during the pre-industrial Holocene, five transient global climate model simulations have been analysed with respect to the rainfall trend and variability in different sub-domains of the Afro-Asian monsoon region. Our analysis suggests that on millennial timescales with varying orbital forcing, the monsoons do not behave as a tightly connected global system. According to t...
Earth System Dynamics Discussions
In Earth system model simulations we find different carbon cycle sensitivities for recent and gla... more In Earth system model simulations we find different carbon cycle sensitivities for recent and glacial climate. This result is obtained by comparing the transient response of the terrestrial carbon cycle to a fast and strong atmospheric CO<sub>2</sub> concentration increase (roughly 1000ppm) in C<sup>4</sup>MIP type simulations starting from climate conditions of the Last Glacial Maximum (<q>LGM</q>) and from Pre-Industrial times (<q>PI</q>). The sensitivity β to CO<sub>2</sub> fertilization is larger in the LGM experiment during most of the simulation time: The fertilization effect leads to a terrestrial carbon gain in the LGM experiment almost twice as large as in the PI experiment. The larger fertilization effect in the LGM experiment is caused by the stronger initial CO<sub>2</sub> limitation of photosynthesis, implying a stronger potential for its release upon CO<sub>2</sub> concentration increas...
Earth System Dynamics Discussions, 2012
Das Ziel des 2. Hamburger Klimaberichtes (2HKB) ist es, das wissenschaftliche Wissen über den ver... more Das Ziel des 2. Hamburger Klimaberichtes (2HKB) ist es, das wissenschaftliche Wissen über den vergangenen, den derzeitigen und den zukünftig möglichen Klimawandel und seine Wirkung in der Metropolregion Hamburg und Norddeutschland zu dokumentieren und zusammenzufassen. 2011 erschien der erste „Klimabericht für die Metropolregion Hamburg“ (1HKB) erstellt von einer Autorengruppe des KlimaCampus Hamburg und externen Partnern. Dieses Projekt wurde von Hans von Storch initiiert, vom Norddeutschen Küsten- und Klimabüro (HZG) organisiert und im Rahmen des Klima-Exzellenzclusters CliSAP (Integrated Climate System Analysis and Prediction) der Universität Hamburg und ihren außeruniversitären Partnern gefördert. Der Bericht sollte das Wissen über den regionalen Klimawandel in der Metropolregion Hamburg, mögliche Klimafolgen in der Region und mögliches Management, wie es in wissenschaftlichen Publikationen belegt ist, sichten und im Hinblick auf Konsens und Dissens bewerten.
Vorbilder dieses Wissensberichtes waren auf globaler Ebene der IPCC-Bericht und auf regionaler Ebene der BACC-Report „BALTEX Assessment of Climate Change in the Baltic Sea Basin“, der als erster regionaler Wissensbericht 2008 veröffentlicht wurde. Der 1. HKB spiegelt den Stand des Wissens im Sommer 2009 wider, da für den Bericht Material gesichtet wurde, das vor dem 1. August 2009 veröffentlicht worden war. Etwa 3 Jahre nach Erscheinen dieses Klimaberichtes wurde von den Partnern des KlimaCampus Hamburg im Herbst 2014 beschlossen, einen zweiten Bericht zu erarbeiten. Dieser 2. Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg und Norddeutschland – liegt nun vor. Das Material des ersten Berichtes wurde kritisch vor dem Hintergrund neuer Erkenntnisse analysiert. Neue Themen, die im ersten Bericht aufgrund fehlender Forschung keine Berücksichtigung fanden, wurden aufgegriffen. Das vorliegende Buch dokumentiert den Forschungsstand bis Oktober 2015.
Contributions to atmospheric physics, 1982
Journal of Advances in Modeling Earth Systems, 2019
Klimabericht für die Metropolregion Hamburg, 2010
Geophysical Research Letters, 2009
Abstract. By using a climate system model of intermediate complexity, we have simulated longterm ... more Abstract. By using a climate system model of intermediate complexity, we have simulated longterm natural climate changes occurring over the last 9000 years. The paleo-simulations in which the model is driven by orbital forcing only, i.e., by changes in insolation caused by changes in the Earth's orbit, are compared with sensitivity simulations in which various scenarios of increasing atmospheric CO 2 concentration are prescribed. Focussing on climate and vegetation change in northern Africa, we recapture the strong greening of the Sahara in the early and mid-Holocene (some 9000-6000 years ago), and we show that some expansion of grassland into the Sahara is theoretically possible, if the atmospheric CO 2 concentration increases well above pre-industrial values and if vegetation growth is not disturbed. Depending on the rate of CO 2 increase, vegetation migration into the Sahara can be rapid, up to 1/10th of the Saharan area per decade, but could not exceed a coverage of 45%. In...
By coupling an atmospheric general circulation model asynchronously with an equilibrium vegetatio... more By coupling an atmospheric general circulation model asynchronously with an equilibrium vegetation model, manifold equilibrium solutions of the atmosphere^biosphere system have been explored. It is found that under present-day conditions of the Earth's orbital parameters and sea-surface temperatures, two stable equilibria of vegetation patterns are possible: one corresponding to present-day sparse vegeta-tion in the Sahel, the second solution yielding savannah which extends far into the south-western part of the Sahara. A similar picture is obtained for conditions during the last glacial maximum (21 000 years before present (BP)). For the mid-Holocene (6000 years BP), however, the model ¢nds only one solution: the green Sahara.We suggest that this intransitive behaviour of the atmosphere^biosphere is related to a westward shift of the Hadley^Walker circulation. A conceptual model of atmosphere^vegetation dynamics is used to interpret the bifurcation as well as its change in ter...
In this overview two definitions of climate are presented, from the meteorological point of view ... more In this overview two definitions of climate are presented, from the meteorological point of view and from the climate system’s point of view. The origin of climate change is discussed, i.e., externally forced variability and free, or internal variability that is caused without external trigger by internal instabilities of the system. Both, forced and free variability can appear as periodic, randomly quasi-periodic, and abrupt climate change. Finally, various possibilities of climate forecast are considered.
Earth System Dynamics Discussions
A major link between climate and humans in Northern Africa, and the Sahel in particular, is land ... more A major link between climate and humans in Northern Africa, and the Sahel in particular, is land use and associated land cover change, mainly where subsistence farming prevails. Here we assess possible feedbacks between the type of land use and harvest intensity and climate by analyzing a series of idealized GCM experiments using the MPI-ESM. The base line for these experiments is a simulation forced by the RCP8.5 scenario which includes strong greenhouse gas emissions and anthropogenic land cover changes. The anthropogenic land cover changes in the RCP8.5 scenario include a mixture of pasture and agriculture. In subsequent simulations, we replace the entire area affected by anthropogenic land cover change in the region between the Sahara in the North and the Guinean Coast in the South (4 to 20° N) by either pasture or agriculture, respectively. In a second setup we vary the amount of harvest in case of agriculture. The RCP8.5 base line simulation reveals strong changes in mean ...
Climate of the Past Discussions
The recently proposed global monsoon hypothesis interprets monsoon systems as part of one global-... more The recently proposed global monsoon hypothesis interprets monsoon systems as part of one global-scale atmospheric overturning circulation, implying a connection between the regional monsoon systems and an in-phase behaviour of all northern hemispheric monsoons on annual timescales (Trenberth et al., 2000). Whether this concept can be applied to past climates and variability on longer timescales is still under debate, because the monsoon systems exhibit different regional characteristics such as different seasonality (i.e. onset, peak, and withdrawal). To investigate the interconnection of different monsoon systems during the pre-industrial Holocene, five transient global climate model simulations have been analysed with respect to the rainfall trend and variability in different sub-domains of the Afro-Asian monsoon region. Our analysis suggests that on millennial timescales with varying orbital forcing, the monsoons do not behave as a tightly connected global system. According to t...
Earth System Dynamics Discussions
In Earth system model simulations we find different carbon cycle sensitivities for recent and gla... more In Earth system model simulations we find different carbon cycle sensitivities for recent and glacial climate. This result is obtained by comparing the transient response of the terrestrial carbon cycle to a fast and strong atmospheric CO<sub>2</sub> concentration increase (roughly 1000ppm) in C<sup>4</sup>MIP type simulations starting from climate conditions of the Last Glacial Maximum (<q>LGM</q>) and from Pre-Industrial times (<q>PI</q>). The sensitivity β to CO<sub>2</sub> fertilization is larger in the LGM experiment during most of the simulation time: The fertilization effect leads to a terrestrial carbon gain in the LGM experiment almost twice as large as in the PI experiment. The larger fertilization effect in the LGM experiment is caused by the stronger initial CO<sub>2</sub> limitation of photosynthesis, implying a stronger potential for its release upon CO<sub>2</sub> concentration increas...
Earth System Dynamics Discussions, 2012
Umweltwissenschaften Und Schadstoff Forschung, 2003