Observational constraints indicate risk of drying in the Amazon basin

Shiogama, Hideo; Emori, Seita; Hanasaki, Naota; Abe, Manabu; Masutomi, Yuji; Toko, Kiyoshi; Nozawa, Takashi

doi:10.1038/ncomms1252

Cited by 59 publications

(47 citation statements)

References 36 publications

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“…Beyond this model consensus, however, substantial uncertainties in the current assessments given uncertainty in climate feedbacks and climate sensitivity to anthropogenic forcing remain. They arise from many sources including the limited ability of coupled ocean-atmosphere general circulation models (OAGCMs) to capture the presentclimate global patterns of temperature and precipitation as well as local vegetation-climate feedbacks Shiogama et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Predicting the response of the Amazon rainforest to persistent drought conditions under current and future climates: a major challenge for global land surface models

Joetzjer¹,

Delire²,

Koshiro³

et al. 2014

Geosci. Model Dev.

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Abstract. While a majority of global climate models project drier and longer dry seasons over the Amazon under higher CO 2 levels, large uncertainties surround the response of vegetation to persistent droughts in both present-day and future climates. We propose a detailed evaluation of the ability of the ISBA CC (Interaction Soil-Biosphere-Atmosphere Carbon Cycle) land surface model to capture drought effects on both water and carbon budgets, comparing fluxes and stocks at two recent throughfall exclusion (TFE) experiments performed in the Amazon. We also explore the model sensitivity to different water stress functions (WSFs) and to an idealized increase in CO 2 concentration and/or temperature. In spite of a reasonable soil moisture simulation, ISBA CC struggles to correctly simulate the vegetation response to TFE whose amplitude and timing is highly sensitive to the WSF. Under higher CO 2 concentrations, the increased wateruse efficiency (WUE) mitigates the sensitivity of ISBA CC to drought. While one of the proposed WSF formulations improves the response of most ISBA CC fluxes, except respiration, a parameterization of drought-induced tree mortality is missing for an accurate estimate of the vegetation response. Also, a better mechanistic understanding of the forest responses to drought under a warmer climate and higher CO 2 concentration is clearly needed.

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Section: Introductionmentioning

confidence: 99%

Predicting the response of the Amazon rainforest to persistent drought conditions under current and future climates: a major challenge for global land surface models

Joetzjer¹,

Delire²,

Koshiro³

et al. 2014

Geosci. Model Dev.

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show abstract

“…As noted in the introduction, metrics that are related to future projections have been sought (Hall and Qu 2006;Boe et al 2009;Shiogama et al 2011). Though it is beyond the scope of the present study, it will be valuable to assess briefly whether the simple metrics defined in this study may have any relevance to future projection.…”

Section: Discussionmentioning

confidence: 97%

“…It has been pointed out that most of such straightforward metrics as area-mean biases and root-mean-square errors for the present day climate do not necessarily be applicable well to future projections (Whetton et al 2007;Abe et al 2009;Girogi and Coppola 2010;Knutti et al 2010). Recently, e¤orts have been devoted to finding metrics that can connect current climate reproducibility reasonably to future projection (Hall and Qu 2006;Boe et al 2009;Shiogama et al 2011), where these metrics are expected to reduce uncertainty in future projections based on ensembles of climate models. In addition, a new paradigm of a statistically indistinguishable ensemble has been proposed (Annan and Hargreaves 2010), which di¤ers from the particular paradigm we adopt here that ensemble members are assumed to be distributed around the true climate.…”

Section: Introductionmentioning

confidence: 99%

Relationship of the Reproducibility of Multiple Variables among Global Climate Models

Nishii

Miyasaka

Nakamura

et al. 2012

Journal of the Meteorological Society of Japan

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Numerous e¤orts have been made for evaluating the performance of global climate models with such expectation that those models with higher reproducibility of the current climate should provide more reliable projections of climate changes into the future. Attempts have been made to define a single general metric through which the overall performance of a global climate model can be assessed. On the basis of general metrics defined through several techniques of multivariate analysis, the present study compares global climate models from a viewpoint of their reproducibility of climatological-mean fields of multiple variables. The analyses indicate that a reproducibility of a particular variable is not necessarily independent of that of others, which may bring redundant information into a general metric. The model reproducibility in upper and mid-tropospheric temperature and lower-tropospheric humidity, for example, tends to be anti-correlated with that in upper and mid-tropospheric humidity. It is argued that attention has to be paid to this kind of trade-o¤ relationships among some variables and resultant redundancy in synthesizing multiple metrics. A possibility is suggested that an arbitrary selection of variables can yield some redundant information of variables. The redundancy is, however, found to exert no serious influence on the quality of a general metric as long as it is based on the su‰cient number of variables. In our attempt to evaluate the climate models by introducing general performance metrics with reduced redundancy of variables, the overall model ranking is found rather insensitive to the specific definition of the metric.

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“…Evaluating the credibility of future projections is becoming an increasingly important issue. Some studies constrain projections using observations, suggesting that the models performing well in a present-day climate predict more converged future changes (Walsh et al 2008;Smith and Chandler 2010;Shiogama et al 2011). Abe et al (2009) show that the similarities observed in the precipitation distribution among the models in the present-day climate is significantly correlated with the similarities observed in the projected precipitation change over the tropics (15 S-15 N).…”

Section: Introductionmentioning

confidence: 97%

Inter-Model Differences of Future Precipitation Changes in CMIP3 and MIROC5 Climate Models

Hirota

Takayabu

2012

Journal of the Meteorological Society of Japan

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The projected changes in annual mean precipitation and large-scale circulations between the two periods 1981-2000 and 2081-2100 obtained from the Coupled Model Intercomparison Project phase 3 (CMIP3) and version 5 of the Model for Interdisciplinary Research on Climate (MIROC5), which is a newly developed model and not included in CMIP3, are investigated over tropical oceans (30 S-30 N). We first evaluate skill scores for precipitation reproducibility, based on which five highest and lowest score models (HSMs and LSMs) are selected from 24 CMIP3 models. The score of MIROC5 is higher than that of any CMIP3 model without flux adjustment. While the HSMs, the LSMs, and MIROC5 commonly show precipitation increase over the equatorial central to eastern Pacific region, and weakening of the Walker circulation in future projections; the magnitudes of these changes are significantly larger in the HSMs than in the LSMs. This di¤erence in the magnitudes of the changes between in HSMs and in LSMs is consistent with the di¤erent sensitivities of deep convection to the environmental humidity in the mid-lower troposphere. The vertical structure of the vertical velocity changes indicates that the precipitation increase around 160 E-150 W in the HSMs and LSMs is associated with deep convection, whereas that in MIROC5 is associated with middle-level convection.

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Observational constraints indicate risk of drying in the Amazon basin

Cited by 59 publications

References 36 publications

Predicting the response of the Amazon rainforest to persistent drought conditions under current and future climates: a major challenge for global land surface models

Predicting the response of the Amazon rainforest to persistent drought conditions under current and future climates: a major challenge for global land surface models

Relationship of the Reproducibility of Multiple Variables among Global Climate Models

Inter-Model Differences of Future Precipitation Changes in CMIP3 and MIROC5 Climate Models

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