Publicaciones

@article{Estrada2023,

title = {Model emulators for the assessment of regional impacts and risks of climate change: A case study of rainfed maize production in Mexico},

author = {Francisco Estrada and Alma Mendoza and Guillermo Murray and Oscar Calderón-Bustamante and Wouter Botzen and Teresa De León Escobedo and Julián A. Velasco},

url = {https://doi.org/10.3389/fenvs.2023.1027545},

doi = {10.3389/fenvs.2023.1027545},

year  = {2023},

date = {2023-03-01},

urldate = {2023-03-01},

journal = {Frontiers in Environmental Science},

volume = {11},

publisher = {Frontiers Media SA},

keywords = {Climate vulnerability, Earth system models, Maize},

pubstate = {published},

tppubtype = {article}

}

@article{MurrayTortarolo2022,

title = {A Process-Model Perspective on Recent Changes in the Carbon Cycle of North America},

author = {Guillermo Murray-Tortarolo and Benjamin Poulter and Rodrigo Vargas and Daniel Hayes and Anna M. Michalak and Christopher Williams and Lisamarie Windham-Myers and Jonathan A. Wang and Kimberly P. Wickland and David Butman and Hanqin Tian and Stephen Sitch and Pierre Friedlingstein and Mike O'Sullivan and Peter Briggs and Vivek Arora and Danica Lombardozzi and Atul K. Jain and Wenping Yuan and Roland Séférian and Julia Nabel and Andy Wiltshire and Almut Arneth and Sebastian Lienert and Sönke Zaehle and Vladislav Bastrikov and Daniel Goll and Nicolas Vuichard and Anthony Walker and Etsushi Kato and Xu Yue and Zhen Zhang and Abhishek Chaterjee and Werner Kurz},

url = {https://doi.org/10.1029/2022jg006904},

doi = {10.1029/2022jg006904},

year  = {2022},

date = {2022-09-01},

urldate = {2022-09-01},

journal = {Journal of Geophysical Research: Biogeosciences},

volume = {127},

number = {9},

publisher = {American Geophysical Union (AGU)},

keywords = {carbon cycle, DGVMs},

pubstate = {published},

tppubtype = {article}

}

@article{MurrayTortarolo2021c,

title = {A breviary of Earth's climate changes using Stephan-Boltzmann law},

author = {Guillermo Nicolás Murray Tortarolo},

url = {https://doi.org/10.20937/atm.53102},

doi = {10.20937/atm.53102},

year  = {2021},

date = {2021-12-01},

urldate = {2021-12-01},

journal = {Atmósfera},

publisher = {Instituto de Ciencias de la Atmosfera y Cambio Climatico},

keywords = {climate change, Extreme climate events},

pubstate = {published},

tppubtype = {article}

}

@article{MurrayTortarolo2021b,

title = {Drought as a driver of Mexico-US migration},

author = {Guillermo N Murray-Tortarolo and Mario Marínez Salgado},

url = {https://doi.org/10.1007/s10584-021-03030-2},

doi = {10.1007/s10584-021-03030-2},

year  = {2021},

date = {2021-01-01},

journal = {Climatic Change},

volume = {164},

number = {3-4},

publisher = {Springer Science and Business Media LLC},

abstract = {Emigration from Mexico to the USA represents one of the largest current socioeconomic phenomena in the world. Climate, and particularly drought, has been identified as a key driver of peak migratory flows between the two nations. However, current existing studies are constrained by a reduced spatial scale (e.g., a single community or municipality) or a short time-window (e.g. <10 years), which limits our long-term nationwide understanding of the climate-migration relationship. To tackle this, we employed high-resolution (municipal-level) and long-term databases (1970–2009), which included nation-level interviews, border patrol apprehensions, and high-resolution precipitation. Our results showed that the decadal and maximum migratory fluxes in these four decades corresponded to years with low precipitation. In particular, the migration of low-income rural farmers tripled during drought, representing as much as a third of all historical migration. It is very likely that rural people were pushed to leave their lands as the result of strongly diminished rainfed agriculture and pastureland production, their main livelihood. Our results suggest that policy oriented to reduce the negative impacts of drought (such as livestock drought insurances and the provisioning of drought-resistant seeds), particularly to marginal farmers in arid ecosystems, could be an effective way to reduce current and future migratory peaks between Mexico and the USA},

keywords = {climate change, drought, Extreme climate events, food security, Migration},

pubstate = {published},

tppubtype = {article}

}

@article{MurrayTortarolo2021,

title = {Seven decades of climate change across Mexico},

author = {Guillermo N Murray-Tortarolo},

url = {https://doi.org/10.20937/atm.52803},

doi = {10.20937/atm.52803},

year  = {2021},

date = {2021-01-01},

journal = {Atmósfera},

publisher = {Centro de Ciencias de la Atmosfera},

keywords = {climate change, Extreme climate events},

pubstate = {published},

tppubtype = {article}

}

@article{MurrayTortarolo2020,

title = {Precipitation extremes in recent decades impact cattle populations at the global and national scales},

author = {Guillermo N Murray-Tortarolo and Víctor J Jaramillo},

url = {https://doi.org/10.1016/j.scitotenv.2020.139557},

doi = {10.1016/j.scitotenv.2020.139557},

year  = {2020},

date = {2020-01-01},

journal = {Science of The Total Environment},

volume = {736},

pages = {139557},

publisher = {Elsevier BV},

keywords = {cattle, climate change, Extreme climate events, livestock},

pubstate = {published},

tppubtype = {article}

}

@article{Quijas2019,

title = {Modelling carbon stock and carbon sequestration ecosystem services for policy design: a comprehensive approach using a dynamic vegetation model},

author = {Sandra Quijas and Alice Boit and Kirsten Thonicke and Guillermo Murray-Tortarolo and Tuyeni Mwampamba and Margaret Skutsch and Margareth Simoes and Nataly Ascarrunz and Marielos Pe{ñ}a-Claros and Laurence Jones and Eric Arets and Víctor J Jaramillo and Elena Lazos and Marisol Toledo and Lucieta G Martorano and Rodrigo Ferraz and Patricia Balvanera},

url = {https://doi.org/10.1080/26395908.2018.1542413},

doi = {10.1080/26395908.2018.1542413},

issn = {26395916},

year  = {2019},

date = {2019-01-01},

journal = {Ecosystems and People},

volume = {15},

number = {1},

pages = {42--60},

publisher = {Taylor & Francis},

abstract = {ABSTRACTEcosystem service (ES) models can only inform policy design adequately if they incorporate ecological processes. We used the Lund-Potsdam-Jena managed Land (LPJmL) model, to address following questions for Mexico, Bolivia and Brazilian Amazon: (i) How different are C stocks and C sequestration quantifications under standard (when soil and litter C and heterotrophic respiration are not considered) and comprehensive (including all C stock and heterotrophic respiration) approach? and (ii) How does the valuation of C stock and C sequestration differ in national payments for ES and global C funds or markets when comparing both approach? We found that up to 65% of C stocks have not been taken into account by neglecting to include C stored in soil and litter, resulting in gross underpayments (up to 500 times lower). Since emissions from heterotrophic respiration of organic material offset a large proportion of C gained through growth of living matter, we found that markets and decision-makers are inadvertently overestimating up to 100 times C sequestrated. New approaches for modelling C services relevant ecological process-based can help accounting for C in soil, litter and heterotrophic respiration and become important for the operationalization of agreements on climate change mitigation following the COP21 in 2015.},

keywords = {decision-makers, DGVMs, ecosystem services},

pubstate = {published},

tppubtype = {article}

}

@article{Jaramillo2019,

title = {The impact of extreme weather events on livestock populations: the case of the 2011 drought in Mexico},

author = {Guillermo N Murray-tortarolo and Víctor J Jaramillo},

url = {https://link.springer.com/article/10.1007/s10584-019-02373-1?utm_source=researcher_app&utm_medium=referral&utm_campaign=MKEF_USG_Researcher_inbound},

doi = {10.1007/s10584-019-02373-1},

year  = {2019},

date = {2019-01-01},

journal = {Climatic Change},

abstract = {textlessh3 class="a-plus-plus"textgreaterAbstracttextless/h3textgreater textlessp class="a-plus-plus"textgreaterExtreme weather events represent a large risk to food production systems. In this study, we evaluated the impacts of the 2011–2012 drought in Mexico, the worst in the last 70 years, on free-ranged livestock populations to link extreme weather events and production. We also considered the potential prevalence of recurring droughts under two contrasting future climate scenarios to examine what could happen over this century. Our results showed that cattle and goat stocks decreased about 3% in response to the drought countrywide. Regionally, the changes in cattle and goat populations generally mimicked the precipitation anomaly, with the strongest reductions across the driest areas in central and northern Mexico. Our work showed that the biophysical and management components of livestock production interact depending on the regions and the type of livestock, leading to a mosaic of spatial responses. It seems that the management of large herds limits the economic viability of drought crisis management options such as the importation of fodder and water, or by moving the animals to other pastures. Sheep herds were much less affected since more than 50% of the total sheep stock is raised in wetter states, which showed a relatively small (~ − 10%) precipitation anomaly during the drought. Under the severe climate change scenario, a greater frequency of extremely dry years (once every 3 years) would have negative impacts on livestock production regionally. Climate change together with already existing trends in overgrazing and soil erosion could further increase the sensitivity of livestock production across the country.textless/ptextgreater textlessp class="a-plus-plus"textgreater textlessspan class="a-plus-plus figure category-standard float-no id-figa"textgreater textlesscaption class="a-plus-plus caption language-en lang-en"textgreater textlessstrong class="a-plus-plus caption-number"textgreaterGraphical abstracttextless/strongtextgreater textlessem class="a-plus-plus caption-content"textgreater textlessdiv class="a-plus-plus simple-para"textgreaterᅟtextless/divtextgreater 

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 textless/captiontextgreater textlessspan class="a-plus-plus media-object id-m-o1"textgreater textlessimg alt="" src="https://static-content.springer.com/image/MediaObjects/10584_2019_2373_Figa_HTML.png" class="a-plus-plus"/textgreater 

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keywords = {cattle, Climate vulnerability, Extreme climate events, livestock},

pubstate = {published},

tppubtype = {article}

}

@article{Murray-Tortarolo2018,

title = {Food security and climate change: the case of rainfed maize production in Mexico},

author = {Guillermo N Murray-Tortarolo and Víctor J Jaramillo and John Larsen},

url = {https://doi.org/10.1016/j.agrformet.2018.02.011},

doi = {10.1016/j.agrformet.2018.02.011},

issn = {01681923},

year  = {2018},

date = {2018-01-01},

journal = {Agricultural and Forest Meteorology},

volume = {253-254},

number = {July 2017},

pages = {124--131},

publisher = {Elsevier},

abstract = {Climate change has altered global rainfall amounts and seasonality. Rainfed crops are particularly dependent on foreseeable rainfall, thus yields of maize, wheat and sorghum have decreased globally. Rainfed maize is the cornerstone of the agriculture in Mexico and the nutrition base of as many as twenty million people. Despite its relevance, the risk that climate change represents for this economic activity has not been studied in our country. We evaluated the link between rainfall variability and maize yields in Mexico across three different time periods: the present, the past 30 years and the remainder of this century (future) with RCPs scenarios. We found that rainfed agriculture was distributed as a function of the dry-season length, occurring in areas with a 4–9 months dry season, thus climate change may alter not only agricultural yields, but also the spatial distribution of land uses. There was a linear correlation (r = 0.45) between mean annual precipitation and rainfed maize production nationally for the period 1980–2012. The correlation was stronger (r = 0.91) during 2005–2012 when high-resolution data were available for the analysis. Correlation values were not homogeneously distributed within the country, although the minimum correlation was 0.35. In the future scenarios, yields were predicted to either not change or to decrease by as much as 10%. The strongest negative impacts were predicted across the Northeast and the South of the country, where yields declined by up to 30% in all scenarios.},

keywords = {Climate vulnerability, Milpa, Rainfed maize, RCPs},

pubstate = {published},

tppubtype = {article}

}

@article{Krause2018,

title = {Large uncertainty in carbon uptake potential of land-based climate-change mitigation efforts},

author = {Andreas Krause and Thomas A M Pugh and Anita D Bayer and Wei Li and Felix Leung and Alberte Bondeau and Jonathan C Doelman and Florian Humpenöder and Peter Anthoni and Benjamin L Bodirsky and Philippe Ciais and Christoph Müller and Guillermo Murray-Tortarolo and Stefan Olin and Alexander Popp and Stephen Sitch and Elke Stehfest and Almut Arneth},

doi = {10.1111/gcb.14144},

issn = {13652486},

year  = {2018},

date = {2018-01-01},

journal = {Global Change Biology},

volume = {24},

number = {7},

pages = {3025--3038},

abstract = {textcopyright 2018 John Wiley & Sons Ltd Most climate mitigation scenarios involve negative emissions, especially those that aim to limit global temperature increase to 2°C or less. However, the carbon uptake potential in land-based climate change mitigation efforts is highly uncertain. Here, we address this uncertainty by using two land-based mitigation scenarios from two land-use models (IMAGE and MAgPIE) as input to four dynamic global vegetation models (DGVMs; LPJ-GUESS, ORCHIDEE, JULES, LPJmL). Each of the four combinations of land-use models and mitigation scenarios aimed for a cumulative carbon uptake of ~130 GtC by the end of the century, achieved either via the cultivation of bioenergy crops combined with carbon capture and storage (BECCS) or avoided deforestation and afforestation (ADAFF). Results suggest large uncertainty in simulated future land demand and carbon uptake rates, depending on the assumptions related to land use and land management in the models. Total cumulative carbon uptake in the DGVMs is highly variable across mitigation scenarios, ranging between 19 and 130 GtC by year 2099. Only one out of the 16 combinations of mitigation scenarios and DGVMs achieves an equivalent or higher carbon uptake than achieved in the land-use models. The large differences in carbon uptake between the DGVMs and their discrepancy against the carbon uptake in IMAGE and MAgPIE are mainly due to different model assumptions regarding bioenergy crop yields and due to the simulation of soil carbon response to land-use change. Differences between land-use models and DGVMs regarding forest biomass and the rate of forest regrowth also have an impact, albeit smaller, on the results. Given the low confidence in simulated carbon uptake for a given land-based mitigation scenario, and that negative emissions simulated by the DGVMs are typically lower than assumed in scenarios consistent with the 2°C target, relying on negative emissions to mitigate climate change is a highly uncertain strategy.},

keywords = {avoided deforestation and afforestation, carbon dioxide removal, land-based mitigation},

pubstate = {published},

tppubtype = {article}

}

@article{Murguia-Flores2018,

title = {Soil Methanotrophy Model (MeMo v1.0): A process-based model to quantify global uptake of atmospheric methane by soil},

author = {Fabiola Murguia-Flores and Sandra Arndt and Anita L Ganesan and Guillermo Murray-Tortarolo and Edward R C Hornibrook},

doi = {10.5194/gmd-11-2009-2018},

issn = {19919603},

year  = {2018},

date = {2018-01-01},

journal = {Geoscientific Model Development},

volume = {11},

number = {6},

pages = {2009--2032},

abstract = {Soil bacteria known as methanotrophs are the sole biological sink for atmospheric methane (CHtextlesssubtextgreater4textless/subtextgreater), a powerful greenhouse gas that is responsible for ~ 20 % of the human-driven increase in radiative forcing since pre-industrial times. Soil methanotrophy is controlled by a plethora of different factors, including temperature, soil texture and moisture or nitrogen content, resulting in spatially and temporally heterogeneous rates of soil methanotrophy. As a consequence, the exact magnitude of the global soil sink, as well as its temporal and spatial variability remains poorly constrained. We developed a process-based model (Methanotrophy Model; MeMo v1.0) to simulate and quantify the uptake of atmospheric CHtextlesssubtextgreater4textless/subtextgreater by soils on the global scale. MeMo builds on previous models by Ridgwell et al. (1999) and Curry (2007) by introducing several advances, including: (1) a general analytical solution of the one-dimensional diffusion-reaction equation in porous media, (2) a refined representation of nitrogen inhibition on soil methanotrophy, and (3) updated factors governing the influence of soil moisture and temperature on CHtextlesssubtextgreater4textless/subtextgreater oxidation rates. We show that the improved representation of these key drivers of soil methanotrophy resulted in a better fit to observational data. A global simulation of soil methanotrophy for the period 1990-2009 using MeMo yielded an average annual sink of 34.3 ± 4.3 Tg CHtextlesssubtextgreater4textless/subtextgreater yrtextlesssuptextgreater−1textless/suptextgreater. Warm and semiarid regions (tropical deciduous forest, dense and open shrubland) had the highest CHtextlesssubtextgreater4textless/subtextgreater uptake rates of 630 and 580 mg CHtextlesssubtextgreater4textless/subtextgreater mtextlesssuptextgreater−2textless/suptextgreater ytextlesssuptextgreater−1textless/suptextgreater, respectively. In these regions, favorable annual soil moisture content (~ 20 % saturation) and low seasonal temperature variations (variations textless ~ 6 textordmasculineC) provided optimal conditions for soil methanotrophy and soil-atmosphere gas exchange. In contrast to previous model analyses, but in agreement with recent observational data, MeMo predicted low fluxes in wet tropical regions because of refinements in describing the influence of excess soil moisture on methanotrophy. Tundra and boreal forest had the lowest simulated CHtextlesssubtextgreater4textless/subtextgreater uptake rates of 179 and 187 mg CHtextlesssubtextgreater4textless/subtextgreater mtextlesssuptextgreater−2textless/suptextgreater ytextlesssuptextgreater−1textless/suptextgreater, respectively, due to their marked seasonality driven by temperature. Soil uptake of atmospheric CHtextlesssubtextgreater4textless/subtextgreater was attenuated by up to 10 % in regions receiving high rates of nitrogen deposition. Globally, nitrogen deposition reduced soil uptake of atmospheric CHtextlesssubtextgreater4textless/subtextgreater by 0.34 Tg ytextlesssuptextgreater−1textless/suptextgreater, which is an order of magnitude lower than reported previously. In addition to improved characterisation of the contemporary soil sink for atmospheric CHtextlesssubtextgreater4textless/subtextgreater, MeMo provides an opportunity to quantify more accurately the relative importance of soil methanotrophy in the global CHtextlesssubtextgreater4textless/subtextgreater cycle in the past and its capacity to contribute to reduction of atmospheric CHtextlesssubtextgreater4textless/subtextgreater levels under future global change scenarios.},

keywords = {metanotrophy, methane},

pubstate = {published},

tppubtype = {article}

}

@article{Salazar2018,

title = {The ecology of peace: preparing Colombia for new political and planetary climates},

author = {Alejandro Salazar and Adriana Sanchez and Juan Camilo Villegas and Juan F Salazar and Daniel Ruiz Carrascal and Stephen Sitch and Juan Dar í and Germ á and Kenneth J Feeley and Lina M Mercado and Paola A Arias and Carlos A Sierra and Maria Rosario del Uribe and Angela Rend M ó and Juan Carlos P é and Guillermo Murray Tortarolo and Daniel Mercado-Bettin and Jos é and Qianlai Zhuang and Jeffrey S Dukes},

url = {https://doi.org/10.1002/fee.1950},

doi = {10.1002/fee.1950},

year  = {2018},

date = {2018-01-01},

journal = {Frontiers in Ecology and the Environment},

volume = {16},

number = {9},

pages = {525--531},

publisher = {Wiley},

keywords = {DGVMs, land-based mitigation},

pubstate = {published},

tppubtype = {article}

}

@article{Murray-Tortarolo2017,

title = {The decreasing range between dry- and wet-season precipitation over land and its effect on vegetation primary productivity},

author = {Guillermo Murray-Tortarolo and Víctor J Jaramillo and Manuel Maass and Pierre Friedlingstein and Stephen Sitch},

doi = {10.1371/journal.pone.0190304},

issn = {19326203},

year  = {2017},

date = {2017-01-01},

journal = {PLoS ONE},

volume = {12},

number = {12},

pages = {1--11},

abstract = {textcopyright 2017 Murray-Tortarolo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. One consequence of climate change is the alteration of global water fluxes, both in amount and seasonality. As a result, the seasonal difference between dry- (p textless 100 mm/month) and wet-season (p textgreater 100 mm/month) precipitation (p) has increased over land during recent decades (1980–2005). However, our analysis expanding to a 60-year period (1950–2009) showed the opposite trend. This is, dry-season precipitation increased steadily, while wet-season precipitation remained constant, leading to reduced seasonality at a global scale. The decrease in seasonality was not due to a change in dry-season length, but in precipitation rate; thus, the dry season is on average becoming wetter without changes in length. Regionally, wet- and dry-season precipitations are of opposite sign, causing a decrease in the seasonal variation of the precipitation over 62% of the terrestrial ecosystems. Furthermore, we found a high correlation (r = 0.62) between the change in dry-season precipitation and the trend in modelled net primary productivity (NPP), which is explained based on different ecological mechanisms. This trend is not found with wet-season precipitation (r = 0.04), These results build on the argument that seasonal water availability has changed over the course of the last six decades and that the dry-season precipitation is a key driver of vegetation productivity at the global scale.},

keywords = {dry season length, Extreme climate events, NPP},

pubstate = {published},

tppubtype = {article}

}

@article{Murray-Tortarolo2016,

title = {The carbon cycle in Mexico: Past, present and future of C stocks and fluxes},

author = {G Murray-Tortarolo and P Friedlingstein and S Sitch and V J Jaramillo and F Murguia-Flores and A Anav and Y Liu and A Arneth and A Arvanitis and A Harper and A Jain and E Kato and C Koven and B Poulter and B D Stocker and A Wiltshire and S Zaehle and N Zeng},

doi = {10.5194/bg-13-223-2016},

issn = {17264189},

year  = {2016},

date = {2016-01-01},

journal = {Biogeosciences},

volume = {13},

number = {1},

pages = {223--238},

abstract = {textlessptextgreaterWe modelled the carbon (C) cycle in Mexico with a process-based approach. We used different available products (satellite data, field measurements, models and flux towers) to estimate C stocks and fluxes in the country at three different time frames: present (defined as the period 2000–2005), the past century (1901–2000) and the remainder of this century (2010–2100). Our estimate of the gross primary productivity (GPP) for the country was 2137 ± 1023 Tg C yrtextlesssuptextgreater−1textless/suptextgreater and a total C stock of 34 506 ± 7483 Tg C, with 20 347 ± 4622 Pg C in vegetation and 14 159 ± 3861 in the soil. textlessbrtextgreatertextless/brtextgreater Contrary to other current estimates for recent decades, our results showed that Mexico was a C sink over the period 1990–2009 (+31 Tg C yrtextlesssuptextgreater−1textless/suptextgreater) and that C accumulation over the last century amounted to 1210 ± 1040 Tg C. We attributed this sink to the COtextlesssubtextgreater2textless/subtextgreater fertilization effect on GPP, which led to an increase of 3408 ± 1060 Tg C, while both climate and land use reduced the country C stocks by −458 ± 1001 and −1740 ± 878 Tg C, respectively. Under different future scenarios the C sink will likely continue over 21st century, with decreasing C uptake as the climate forcing becomes more extreme. Our work provides valuable insights on relevant driving processes of the C-cycle such as the role of drought in marginal lands (e.g. grasslands and shrublands) and the impact of climate change on the mean residence time of C in tropical ecosystems.textless/ptextgreater},

keywords = {carbon cycle, Mexico},

pubstate = {published},

tppubtype = {article}

}

@article{Murray-Tortarolo2016a,

title = {The dry season intensity as a key driver of NPP trends},

author = {Guillermo Murray-Tortarolo and Pierre Friedlingstein and Stephen Sitch and Sonia I Seneviratne and Imogen Fletcher and Brigitte Mueller and Peter Greve and Alessandro Anav and Yi Liu and Anders Ahlström and Chris Huntingford and Sam Levis and Peter Levy and Mark Lomas and Benjamin Poulter and Nicholas Viovy and Sonke Zaehle and Ning Zeng},

doi = {10.1002/2016GL068240},

issn = {19448007},

year  = {2016},

date = {2016-01-01},

journal = {Geophysical Research Letters},

volume = {43},

number = {6},

pages = {2632--2639},

abstract = {textcopyright2016. American Geophysical Union. All Rights Reserved. We analyze the impacts of changing dry season length and intensity on vegetation productivity and biomass. Our results show a wetness asymmetry in dry ecosystems, with dry seasons becoming drier and wet seasons becoming wetter, likely caused by climate change. The increasingly intense dry seasons were consistently correlated with a decreasing trend in net primary productivity (NPP) and biomass from different products and could potentially mean a reduction of 10-13% in NPP by 2100. We found that annual NPP in dry ecosystems is particularly sensitive to the intensity of the dry season, whereas an increase in precipitation during the wet season has a smaller effect. We conclude that changes in water availability over the dry season affect vegetation throughout the whole year, driving changes in regional NPP. Moreover, these results suggest that usage of seasonal water fluxes is necessary to improve our understanding of the link between water availability and the land carbon cycle.},

keywords = {drought, dry season length, land carbon cycle},

pubstate = {published},

tppubtype = {article}

}

@article{Sitch2015,

title = {Recent trends and drivers of regional sources and sinks of carbon dioxide},

author = {S Sitch and P Friedlingstein and N Gruber and S D Jones and G Murray-Tortarolo and A Ahlström and S C Doney and H Graven and C Heinze and C Huntingford and S Levis and P E Levy and M Lomas and B Poulter and N Viovy and S Zaehle and N Zeng and A Arneth and G Bonan and L Bopp and J G Canadell and F Chevallier and P Ciais and R Ellis and M Gloor and P Peylin and S L Piao and C {Le Quéré} and B Smith and Z Zhu and R Myneni},

doi = {10.5194/bg-12-653-2015},

issn = {17264189},

year  = {2015},

date = {2015-01-01},

journal = {Biogeosciences},

volume = {12},

number = {3},

pages = {653--679},

abstract = {textlessptextgreatertextlessstrongtextgreaterAbstract.textless/strongtextgreater The land and ocean absorb on average just over half of the anthropogenic emissions of carbon dioxide (COtextlesssubtextgreater2textless/subtextgreater) every year. These COtextlesssubtextgreater2textless/subtextgreater "sinks" are modulated by climate change and variability. Here we use a suite of nine dynamic global vegetation models (DGVMs) and four ocean biogeochemical general circulation models (OBGCMs) to estimate trends driven by global and regional climate and atmospheric COtextlesssubtextgreater2textless/subtextgreater in land and oceanic COtextlesssubtextgreater2textless/subtextgreater exchanges with the atmosphere over the period 1990–2009, to attribute these trends to underlying processes in the models, and to quantify the uncertainty and level of inter-model agreement. The models were forced with reconstructed climate fields and observed global atmospheric COtextlesssubtextgreater2textless/subtextgreater; land use and land cover changes are not included for the DGVMs. Over the period 1990–2009, the DGVMs simulate a mean global land carbon sink of −2.4 ± 0.7 Pg C yrtextlesssuptextgreater−1textless/suptextgreater with a small significant trend of −0.06 ± 0.03 Pg C yrtextlesssuptextgreater−2textless/suptextgreater (increasing sink). Over the more limited period 1990–2004, the ocean models simulate a mean ocean sink of −2.2 ± 0.2 Pg C yrtextlesssuptextgreater−1textless/suptextgreater with a trend in the net C uptake that is indistinguishable from zero (−0.01 ± 0.02 Pg C yrtextlesssuptextgreater−2textless/suptextgreater). The two ocean models that extended the simulations until 2009 suggest a slightly stronger, but still small, trend of −0.02 ± 0.01 Pg C yrtextlesssuptextgreater−2textless/suptextgreater. Trends from land and ocean models compare favourably to the land greenness trends from remote sensing, atmospheric inversion results, and the residual land sink required to close the global carbon budget. Trends in the land sink are driven by increasing net primary production (NPP), whose statistically significant trend of 0.22 ± 0.08 Pg C yrtextlesssuptextgreater−2textless/suptextgreater exceeds a significant trend in heterotrophic respiration of 0.16 ± 0.05 Pg C yrtextlesssuptextgreater−2textless/suptextgreater – primarily as a consequence of widespread COtextlesssubtextgreater2textless/subtextgreater fertilisation of plant production. Most of the land-based trend in simulated net carbon uptake originates from natural ecosystems in the tropics (−0.04 ± 0.01 Pg C yrtextlesssuptextgreater−2textless/suptextgreater), with almost no trend over the northern land region, where recent warming and reduced rainfall offsets the positive impact of elevated atmospheric COtextlesssubtextgreater2textless/subtextgreater and changes in growing season length on carbon storage. The small uptake trend in the ocean models emerges because climate variability and change, and in particular increasing sea surface temperatures, tend to counter$backslash$$backslash$-act the trend in ocean uptake driven by the increase in atmospheric COtextlesssubtextgreater2textless/subtextgreater. Large uncertainty remains in the magnitude and sign of modelled carbon trends in several regions, as well as regarding the influence of land use and land cover changes on regional trends.textless/ptextgreater},

keywords = {carbon cycle, DGVMs},

pubstate = {published},

tppubtype = {article}

}

@article{Anav2015,

title = {Reviews of Geophysics primary production : A review},

author = {Alessandro Anav and Pierre Friedlingstein and Christian Beer and Philippe Ciais and Anna Harper and Chris Jones and Guillermo Murray-Tortarolo and Dario Papale and Nicholas C Parazoo and Philippe Peylin and Shilong Piao and Stephen Sitch and Nicolas Viovy and Andy Wiltshire and Maosheng Zhao},

doi = {10.1002/2015RG000483.Received},

issn = {87551209},

year  = {2015},

date = {2015-01-01},

journal = {Reviews of Geophysics},

pages = {1--34},

keywords = {DGVMs, ESMs, MTE, satellite},

pubstate = {published},

tppubtype = {article}

}

@article{Valentini2014,

title = {A full greenhouse gases budget of africa: Synthesis, uncertainties, and vulnerabilities},

author = {R Valentini and A Arneth and A Bombelli and S Castaldi and R {Cazzolla Gatti} and F Chevallier and P Ciais and E Grieco and J Hartmann and M Henry and R A Houghton and M Jung and W L Kutsch and Y Malhi and E Mayorga and L Merbold and G Murray-Tortarolo and D Papale and P Peylin and B Poulter and P A Raymond and M Santini and S Sitch and G {Vaglio Laurin} and G R {Van Der Werf} and C A Williams and R J Scholes},

doi = {10.5194/bg-11-381-2014},

issn = {17264170},

year  = {2014},

date = {2014-01-01},

journal = {Biogeosciences},

volume = {11},

number = {2},

pages = {381--407},

abstract = {textlessptextgreatertextlessstrongtextgreaterAbstract.textless/strongtextgreater This paper, developed under the framework of the RECCAP initiative, aims at providing improved estimates of the carbon and GHG (COtextlesssubtextgreater2textless/subtextgreater, CHtextlesssubtextgreater4textless/subtextgreater and Ntextlesssubtextgreater2textless/subtextgreaterO) balance of continental Africa. The various components and processes of the African carbon and GHG budget are considered, existing data reviewed, and new data from different methodologies (inventories, ecosystem flux measurements, models, and atmospheric inversions) presented. Uncertainties are quantified and current gaps and weaknesses in knowledge and monitoring systems described in order to guide future requirements. The majority of results agree that Africa is a small sink of carbon on an annual scale, with an average value of −0.61 ± 0.58 Pg C yrtextlesssuptextgreater−1textless/suptextgreater. Nevertheless, the emissions of CHtextlesssubtextgreater4textless/subtextgreater and Ntextlesssubtextgreater2textless/subtextgreaterO may turn Africa into a net source of radiative forcing in COtextlesssubtextgreater2textless/subtextgreater equivalent terms. At sub-regional level, there is significant spatial variability in both sources and sinks, due to the diversity of biomes represented and differences in the degree of anthropic impacts. Southern Africa is the main source region; while central Africa, with its evergreen tropical forests, is the main sink. Emissions from land-use change in Africa are significant (around 0.32 ± 0.05 Pg C yrtextlesssuptextgreater−1textless/suptextgreater), even higher than the fossil fuel emissions: this is a unique feature among all the continents. There could be significant carbon losses from forest land even without deforestation, resulting from the impact of selective logging. Fires play a significant role in the African carbon cycle, with 1.03 ± 0.22 Pg C yrtextlesssuptextgreater−1textless/suptextgreater of carbon emissions, and 90% originating in savannas and dry woodlands. A large portion of the wild fire emissions are compensated by COtextlesssubtextgreater2textless/subtextgreater uptake during the growing season, but an uncertain fraction of the emission from wood harvested for domestic use is not. Most of these fluxes have large interannual variability, on the order of ±0.5 Pg C yrtextlesssuptextgreater−1textless/suptextgreater in standard deviation, accounting for around 25% of the year-to-year variation in the global carbon budget. textlessbrtextgreatertextlessbrtextgreater Despite the high uncertainty, the estimates provided in this paper show the important role that Africa plays in the global carbon cycle, both in terms of absolute contribution, and as a key source of interannual variability.textless/ptextgreater},

keywords = {carbon cycle, DGVMs},

pubstate = {published},

tppubtype = {article}

}

@article{Anav2013,

title = {Evaluation of land surface models in reproducing satellite derived leaf area index over the high-latitude northern hemisphere. Part II: Earth system models},

author = {Alessandro Anav and Guillermo Murray-Tortarolo and Pierre Friedlingstein and Stephen Sitch and Shilong Piao and Zaichun Zhu},

doi = {10.3390/rs5083637},

issn = {20724292},

year  = {2013},

date = {2013-01-01},

journal = {Remote Sensing},

volume = {5},

number = {8},

pages = {3637--3661},

abstract = {Leaf Area Index (LAI) is a key parameter in the Earth System Models (ESMs) since it strongly affects land-surface boundary conditions and the exchange of matter and energy with the atmosphere. Observations and data products derived from satellite remote sensing are important for the validation and evaluation of ESMs from regional to global scales. Several decades' worth of satellite data products are now available at global scale which represents a unique opportunity to contrast observations against model results. The objective of this study is to assess whether ESMs correctly reproduce the spatial variability of LAI when compared with satellite data and to compare the length of the growing season in the different models with the satellite data. To achieve this goal we analyse outputs from 11 coupled carbon-climate models that are based on the set of new global model simulations planned in support of the IPCC Fifth Assessment Report. We focus on the average LAI and the length of the growing season on Northern Hemisphere over the period 1986–2005. Additionally we compare the results with previous analyses (Part I) of uncoupled land surface models (LSMs) to assess the relative contribution of vegetation and climatic drivers on the correct representation of LAI. Our results show that models tend to overestimate the average values of LAI and have a longer growing season due to the later dormancy. The similarities with the uncoupled models suggest that representing the correct vegetation fraction with the associated parameterizations; is more important in controlling the distribution and value of LAI than the climatic variables.},

keywords = {CMIP5, Earth system models, LAI, Leaf phenology, Remote sensing of vegetation},

pubstate = {published},

tppubtype = {article}

}

@article{Murray-Tortarolo2013,

title = {Evaluation of land surface models in reproducing satellite-derived LAI over the high-latitude northern hemisphere. Part I: Uncoupled DGVMs},

author = {Guillermo Murray-Tortarolo and Alessandro Anav and Pierre Friedlingstein and Stephen Sitch and Shilong Piao and Zaichun Zhu and Benjamin Poulter and Sönke Zaehle and Anders Ahlström and Mark Lomas and Sam Levis and Nicholas Viovy and Ning Zeng},

doi = {10.3390/rs5104819},

issn = {20724292},

year  = {2013},

date = {2013-01-01},

journal = {Remote Sensing},

volume = {5},

number = {10},

pages = {4819--4838},

abstract = {Leaf Area Index (LAI) represents the total surface area of leaves above a unit area of ground and is a key variable in any vegetation model, as well as in climate models. New high resolution LAI satellite data is now available covering a period of several decades. This provides a unique opportunity to validate LAI estimates from multiple vegetation models. The objective of this paper is to compare new, satellite-derived LAI measurements with modeled output for the Northern Hemisphere. We compare monthly LAI output from eight land surface models from the TRENDY compendium with satellite data from an Artificial Neural Network (ANN) from the latest version (third generation) of GIMMS AVHRR NDVI data over the period 1986–2005. Our results show that all the models overestimate the mean LAI, particularly over the boreal forest. We also find that seven out of the eight models overestimate the length of the active vegetation-growing season, mostly due to a late dormancy as a result of a late summer phenology. Finally, we find that the models report a much larger positive trend in LAI over this period than the satellite observations suggest, which translates into a higher trend in the growing season length. These results highlight the need to incorporate a larger number of more accurate plant functional types in all models and, in particular, to improve the phenology of deciduous trees.},

keywords = {Growing season, LAI, Land surface models, Northern hemisphere, Phenology, Trendy},

pubstate = {published},

tppubtype = {article}

}