Preprints
https://doi.org/10.5194/esd-2021-43
https://doi.org/10.5194/esd-2021-43

  24 Jun 2021

24 Jun 2021

Review status: a revised version of this preprint was accepted for the journal ESD and is expected to appear here in due course.

Climate change in the High Mountain Asia in CMIP6

Mickaël Lalande1, Martin Ménégoz1, Gerhard Krinner1, Kathrin Naegeli2, and Stefan Wunderle2 Mickaël Lalande et al.
  • 1Univ. Grenoble Alpes, CNRS, IRD, G-INP, IGE, 38000 Grenoble, France
  • 2Institute of Geography and Oeschger Center for Climate Change Research, University of Bern, 3012 Bern, Switzerland

Abstract. Climate change over High Mountain Asia (HMA, including the Tibetan Plateau) is investigated over the period 1979–2014 and in future projections following the four shared socioeconomic pathways SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5. The skill of 26 CMIP6 models is estimated for near-surface air temperature, snow cover extent and total precipitation, and 10 of them are used to describe their projections until 2100. Similarly to previous CMIP models, this new generation of GCMs shows a mean cold bias over this area reaching −1.9 [−8.2 to 2.9] °C (90 % confidence interval) in comparison with the CRU observational dataset, associated with a snow cover mean overestimation of 12 [−13 to 43] %, corresponding to a relative bias of 52 [−53 to 183] % in comparison with the NOAA CDR satellite dataset. The temperature and snow cover model biases are more pronounced in winter. Simulated precipitation rates are overestimated by 1.5 [0.3 to 2.9] mm day−1, corresponding to a relative bias of 143 [31 to 281] %, but this might be an apparent bias caused by the undercatch of solid precipitation in the APHRODITE observational reference. For most models, the cold surface bias is associated with an overestimation of snow cover extent, but this relationship does not hold for all models, suggesting that the processes of the origin of the biases can differ from one model to another one. A significant correlation between snow cover bias and surface elevation is found, and to a lesser extent between temperature bias and surface elevation, highlighting the model weaknesses at high elevation. The models performing the best for temperature are not necessarily the most skillful for the other variables, and there is no clear relationship between model resolution and model skill. This highlights the need for a better understanding of the physical processes driving the climate in this complex topographic area, as well as for further parameterization developments adapted to such areas. A dependency of the simulated past trends to the model biases is found for some variables and seasons, however, some highly biased models fall within the range of observed trends suggesting that model bias is not a robust criterion to discard models in trend analysis. The HMA median warming simulated over 2081–2100 with respect to 1995–2014 ranges from 1.9 [1.2 to 2.7] °C for SSP1-2.6 to 6.5 [4.9 to 9.0] °C for SSP5-8.5. This general warming is associated with a relative median snow cover extent decrease from −9.4 [−16.4 to −5.0] % to −32.2 [−49.1 to −25.0] % and a relative median precipitation increase from 8.5 [4.8 to 18.2] % to 24.9 [14.4 to 48.1] % by the end of the century in these respective scenarios. The warming is 11 % higher over HMA than over the other Northern Hemisphere continental surfaces excluding the Arctic area. Seasonal temperature, snow cover and precipitation changes over HMA show a linear relationship with the Global Surface Air Temperature (GSAT), except for summer snow cover that shows a slower decrease at strong levels of GSAT.

Mickaël Lalande et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on esd-2021-43', Anonymous Referee #1, 20 Jul 2021
    • AC1: 'Reply on RC1', Mickaël Lalande, 13 Aug 2021
  • RC2: 'Comment on esd-2021-43', Anonymous Referee #2, 25 Jul 2021
    • AC2: 'Reply on RC2', Mickaël Lalande, 13 Aug 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on esd-2021-43', Anonymous Referee #1, 20 Jul 2021
    • AC1: 'Reply on RC1', Mickaël Lalande, 13 Aug 2021
  • RC2: 'Comment on esd-2021-43', Anonymous Referee #2, 25 Jul 2021
    • AC2: 'Reply on RC2', Mickaël Lalande, 13 Aug 2021

Mickaël Lalande et al.

Mickaël Lalande et al.

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Short summary
Climate change over High Mountain Asia is investigated with CMIP6 climate models. A general cold bias is found in this area, often related to a snow cover overestimation in the models. Ensemble experiments generally encompass the past observed trends, suggesting that even biased models can reproduce the trends. Depending on the future scenario, a warming from 1.9 to 6.5 °C, associated with a snow cover decrease and precipitation increase is expected at the end of the XXIth century.
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