Regionalizing global climate models

Pitman, A. J.; Arneth, Almut; Ganzeveld, L.

doi:10.1002/joc.2279

Cited by 65 publications

(41 citation statements)

References 140 publications

(165 reference statements)

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“…1b) Combined effects, human impacts and climate (cf Fig. 1c) A B C D E F G within global climate models can be improved by taking into account local-scale processes (15). Surface water evaporation from man-made reservoirs and reservoir operations causing seasonal regime shifts across multiyears can cause slight changes in annual runoff numbers.…”

Section: Discussionmentioning

confidence: 99%

Global water resources affected by human interventions and climate change

Haddeland

Heinke

Biemans

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

1,125

635

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Humans directly change the dynamics of the water cycle through dams constructed for water storage, and through water withdrawals for industrial, agricultural, or domestic purposes. Climate change is expected to additionally affect water supply and demand. Here, analyses of climate change and direct human impacts on the terrestrial water cycle are presented and compared using a multimodel approach. Seven global hydrological models have been forced with multiple climate projections, and with and without taking into account impacts of human interventions such as dams and water withdrawals on the hydrological cycle. Model results are analyzed for different levels of global warming, allowing for analyses in line with temperature targets for climate change mitigation. The results indicate that direct human impacts on the water cycle in some regions, e.g., parts of Asia and in the western United States, are of the same order of magnitude, or even exceed impacts to be expected for moderate levels of global warming (+2 K). Despite some spread in model projections, irrigation water consumption is generally projected to increase with higher global mean temperatures. Irrigation water scarcity is particularly large in parts of southern and eastern Asia, and is expected to become even larger in the future. ISI-MIP | WaterMIPT errestrial water fluxes are affected by both climate and direct human interventions, e.g., dam operations and water withdrawals. Climate change is expected to alter the water cycle and will subsequently impact water availability and demand. Several hydrologic modeling studies have focused on climate change impacts on discharge in large river basins or global terrestrial areas under naturalized conditions using a single hydrologic model forced with multiple climate projections (1, 2). Recently, hydrological projections from eight global hydrological models (GHMs) were compared (3). In many areas, there was a large spread in projected runoff changes within the climate-hydrology modeling chain. However, at high latitudes there was a clear increase in runoff, whereas some midlatitude regions showed a robust signal of reduced runoff. The study also concluded that the choice of GHM adds to the uncertainty for hydrological change caused by the choice of atmosphere-ocean general circulation models (hereafter called GCMs) (3). Expected runoff increases in the north and decreases in parts of the middle latitudes have been found also when analyzing runoff from 23 GCMs (4).These studies focused on the naturalized hydrological cycle, i.e., the effects of direct human interventions were not taken into account. However, in many river basins humans substantially alter the hydrological cycle by constructing dams and through water withdrawals. Reservoir operations alter the timing of discharge, although mean annual discharge does not necessarily change much. A study with the water balance model (WBM) showed that the impact of human disturbances, i.e., dams and water consumption, in some river basins is equal to or greater...

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Section: Discussionmentioning

confidence: 99%

Global water resources affected by human interventions and climate change

Haddeland

Heinke

Biemans

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

1,125

635

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“…Beyond ecological implications, the proper representation of whether vegetation is dominated by trees, by grasses, or by a tree-grass mix will also affect important surface characteristics that are of relevance to regional climate: amongst others, short-wave albedo, evapotranspiration rates from soil and vegetation, canopy conductance, and Bowen ratio (Pitman et al, 2011;Scheffer et al, 2005). Fire influences climate also by being a major source of atmospherically shortlived trace gases (especially ozone) and organic as well as black carbon aerosols (Janhäll et al, 2010;Langmann et al, 2009; see also Fig.…”

Section: Biogeosciencesmentioning

confidence: 99%

Future challenges of representing land-processes in studies on land-atmosphere interactions

et al. 2012

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Abstract. Over recent years, it has become increasingly apparent that climate change and air pollution need to be considered jointly for improved attribution and projections of human-caused changes in the Earth system. Exchange processes at the land surface come into play in this context, because many compounds that either act as greenhouse gases, as pollutant precursors, or both, have not only anthropogenic but also terrestrial sources and sinks. And since the fluxes of multiple gases and particulate matter between the terrestrial biota and the atmosphere are directly or indirectly coupled to vegetation and soil carbon, nutrient and water balances, quantification of their geographic patterns or changes over time requires due consideration of the underlying biological processes. In this review we highlight a number of critical aspects and recent progress in this respect, identifying in particular a number of areas where studies have shown that accounting for ecological process understanding can alter global model projections of land-atmosphere interactions substantially. Specifically, this concerns the improved quantification of uncertainties and dynamic system responses, including acclimation, and the incorporation of exchange processes that so far have been missing from global models even though they are proposed to be of relevance for our understanding of terrestrial biota-climate feedbacks. Progress has also been made regarding studies on the impacts of land use/land cover change on climate change, but the absence of a mechanistically based representation of human responseprocesses in ecosystem models that are coupled to climate models limits our ability to analyse how climate change or air pollution in turn might affect human land use. A more integrated perspective is necessary and should become an active area of research that bridges the socio-economic and biophysical communities.

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“…In turn, the atmospheric photooxidation of isoprene affects the atmospheric chemical composition including ozone and aerosol particulate matter that contribute to air pollution and modify Earth's radiation budget [Unger, 2012]. Large-scale perturbations to isoprene emission may provide a powerful lever on regional climate and even trigger feedback to global climate [Pitman et al, 2012]. Therefore, understanding isoprene emission response to global change on climatically relevant spatiotemporal scales (e.g., 100-40,000 km and > months) is a critically important research area [Arneth et al, 2007a;Beerling et al, 2011;Heald et al, 2009;Lathiere et al, 2005;Liao et al, 2009;Naik et al, 2004;Sanderson et al, 2003;Valdes et al, 2005].…”

Section: Introductionmentioning

confidence: 99%

Isoprene emission variability through the twentieth century

Unger

2013

JGR Atmospheres

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[1] A biochemical model of isoprene emission embedded within a global chemistry-climate simulation framework is applied to investigate the transient response to environmental change over the past century. In the model, the isoprene production is directly coupled to photosynthesis and depends on intercellular carbon dioxide concentration (CO 2 ), atmospheric CO 2 , and canopy temperature. Sensitivity runs are performed to isolate the relative roles of individual global change drivers: CO 2 , physical climate, and anthropogenic land cover change (ALCC). Between 1880 and 2000, atmospheric CO 2 increased by~30% from 291 to 370 ppmv, global average surface air temperature increased by 0.7°C, and the crop cover fraction of vegetated land area more than doubled from 15 to 37%. Over the past century, isoprene emission has decreased globally by 20% from 534 to 449 Tg C/yr, while gross primary productivity has increased by 15% from 107 to 124 Pg C/yr mostly due to CO 2 fertilization. In terms of individual drivers, the global isoprene source increased by 7% due to the atmospheric CO 2 concentration rise (including the opposing effects of CO 2 fertilization and CO 2 inhibition), decreased by 22% due to ALCC, and increased by only 3% due to physical climate change. Thus, ALCC is the dominant driver of isoprene emission change. Modeled global isoprene emissions were higher in the preindustrial than in the present day. In the industrial era, isoprene emission change represents a human-induced climate forcing, analogous to land use-driven CO 2 emission, not a climate feedback because temperature-driven increase was a relatively weak driver of isoprene emission change from 1880 to 2000.

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Regionalizing global climate models

Cited by 65 publications

References 140 publications

Global water resources affected by human interventions and climate change

Global water resources affected by human interventions and climate change

Future challenges of representing land-processes in studies on land-atmosphere interactions

Isoprene emission variability through the twentieth century

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