Higher Hydroclimatic Intensity with Global Warming

[1] While changes in land precipitation during the last 50 years have been attributed in part to human influences, results vary by season, are affected by data uncertainty and do not account for changes over ocean. One of the more physically robust responses of the water cycle to warming is the expected amplification of existing patterns of precipitation minus evaporation. Here, precipitation changes in wet and dry regions are analyzed from satellite data for 1988-2010, covering land and ocean. We derive fingerprints for the expected change from climate model simulations that separately track changes in wet and dry regions. The simulations used are driven with anthropogenic and natural forcings combined, and greenhouse gas forcing or natural forcing only. Results of detection and attribution analysis show that the fingerprint of combined external forcing is detectable in observations and that this intensification of the water cycle is partly attributable to greenhouse gas forcing.Citation: Polson, D., G. C. Hegerl, R. P. Allan, and B. Balan Sarojini (2013), Have greenhouse gases intensified the contrast between wet and dry regions?, Geophys. Res. Lett., 40,[4783][4784][4785][4786][4787]

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“…It is also consistent with a wider frequency distribution of precipitation [Lintner et al, 2012;Giorgi et al, 2011;Biasutti, 2013].…”

Section: Introductionsupporting

confidence: 86%

Have greenhouse gases intensified the contrast between wet and dry regions?

Polson

Hegerl

Allan

et al. 2013

Geophysical Research Letters

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“…The observations that support this relationship are not yet enough to establish it clearly. Recent works have reinforced this hypothesis through the enhancement of the probability of extreme warm days and decreases the probability of extreme cold days, and the reduction of wet days and drier conditions in summer over the Mediterranean (Sánchez et al, 2004), or the increase in the dry spells length over the IP (Sánchez et al, 2011) or the hydroclimatic intensity (Giorgi et al, 2011).…”

Section: Discussionmentioning

confidence: 96%

Impacts of projected maximum temperature extremes for C21 by an ensemble of regional climate models on cereal cropping systems in the Iberian Peninsula

Ruiz‐Ramos

Sánchez

Gallardo

et al. 2011

Nat. Hazards Earth Syst. Sci.

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Abstract. Crops growing in the Iberian Peninsula may be subjected to damagingly high temperatures during the sensitive development periods of flowering and grain filling. Such episodes are considered important hazards and farmers may take insurance to offset their impact. Increases in value and frequency of maximum temperature have been observed in the Iberian Peninsula during the 20th century, and studies on climate change indicate the possibility of further increase by the end of the 21st century. Here, impacts of current and future high temperatures on cereal cropping systems of the Iberian Peninsula are evaluated, focusing on vulnerable development periods of winter and summer crops. Climate change scenarios obtained from an ensemble of ten Regional Climate Models (multimodel ensemble) combined with crop simulation models were used for this purpose and related uncertainty was estimated. Results reveal that higher extremes of maximum temperature represent a threat to summer-grown but not to winter-grown crops in the Iberian Peninsula. The study highlights the different vulnerability of crops in the two growing seasons and the need to account for changes in extreme temperatures in developing adaptations in cereal cropping systems. Finally, this work contributes to clarifying the causes of high-uncertainty impact projections from previous studies.

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“…Such effects were deduced for a warmer climate by Trenberth et al (2003) and further elaborated by Trenberth (2011). The relevance of dry spells in diagnosing the intensity of the hydrological cycle was thoroughly discussed and analysed by Giorgi et al (2011). Table 6 analyses the possible future situation in Europe for the RCP scenarios.…”

Section: Precipitationmentioning

confidence: 99%

The Norwegian Earth System Model, NorESM1-M – Part 2: Climate response and scenario projections

et al. 2013

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Abstract. NorESM is a generic name of the Norwegian earth system model. The first version is named NorESM1, and has been applied with medium spatial resolution to provide results for CMIP5 (http://cmip-pcmdi.llnl.gov/cmip5/index. html) without (NorESM1-M) and with (NorESM1-ME) interactive carbon-cycling. Together with the accompanying paper by Bentsen et al. (2012), this paper documents that the core version NorESM1-M is a valuable global climate model for research and for providing complementary results to the evaluation of possible anthropogenic climate change. NorESM1-M is based on the model CCSM4 operated at NCAR, but the ocean model is replaced by a modified version of MICOM and the atmospheric model is extended with online calculations of aerosols, their direct effect and their indirect effect on warm clouds. Model validation is presented in the companion paper (Bentsen et al., 2012). NorESM1-M is estimated to have equilibrium climate sensitivity of ca. 2.9 K and a transient climate response of ca. 1.4 K. This sensitivity is in the lower range amongst the models contributing to CMIP5. Cloud feedbacks dampen the response, and a strong AMOC reduces the heat fraction available for increasing near-surface temperatures, for evaporation and for melting ice. The future projections based on RCP scenarios yield a global surface air temperature increase of almost one standard deviation lower than a 15-model average. Summer sea-ice is projected to decrease considerably by 2100 and disappear completely for RCP8.5. The AMOC is projected to decrease by 12 %, 15-17 %, and 32 % for the RCP2.6, 4.5, 6.0, and 8.5, respectively. Precipitation is projected to increase in the tropics, decrease in the subtropics and in southern parts of the northern extra-tropics during summer, and otherwise increase in most of the extra-tropics. Changes in the atmospheric water cycle indicate that precipitation events over continents will become more intense and dry spells more frequent. Extra-tropical storminess in the Northern Hemisphere is projected to shift northwards. There are indications of more frequent occurrence of spring and summer blocking in the Euro-Atlantic sector, while the amplitude of ENSO events weakens although they tend to appear more frequently. These indications are uncertain because of biases in the model's representation of present-day conditions. Positive phase PNA and negative phase NAO both appear less frequently under the RCP8.5 scenario, but also this result is considered uncertain. Single-forcing experiments indicate that aerosols and greenhouse gases produce similar geographical patterns of response for near-surface temperature and precipitation. These patterns tend to have opposite signs, although with important exceptions for precipitation at low latitudes. The asymmetric aerosol effects between the two hemispheres lead to a southward displacement of ITCZ. Both forcing agents, thus, tend to reduce Northern Hemispheric subtropical precipitation.

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Higher Hydroclimatic Intensity with Global Warming

Cited by 333 publications

References 40 publications

Have greenhouse gases intensified the contrast between wet and dry regions?

Have greenhouse gases intensified the contrast between wet and dry regions?

Impacts of projected maximum temperature extremes for C21 by an ensemble of regional climate models on cereal cropping systems in the Iberian Peninsula

The Norwegian Earth System Model, NorESM1-M – Part 2: Climate response and scenario projections

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