Assessments of the Northern Hemisphere snow cover response to 1.5 and 2.0 °C warming

Abstract

Abstract. The 2015 Paris Agreement set a goal to pursue a global mean temperature below 1.5 °C and well below 2 °C above preindustrial levels. Although it is an important surface hydrology variable, the response of snow under different warming levels has not been well investigated. This study provides a comprehensive assessment of the snow cover fraction (SCF) and snow area extent (SAE), as well as the associated land surface air temperature (LSAT) over the Northern Hemisphere (NH) based on the Community Earth System Model Large Ensemble project (CESM-LE), the CESM 1.5 and 2 °C projects, and the CMIP5 historical RCP2.6 and RCP4.5 products. The results show that the spatiotemporal variations in those modeled products are grossly consistent with observations. The projected SAE magnitude change in RCP2.6 is comparable to that in 1.5 °C, but lower than that in 2 °C. The snow cover differences between 1.5 and 2 °C are prominent during the second half of the 21st century. The signal-to-noise ratios (SNRs) of both SAE and LSAT over the majority of land areas are greater than 1, and for the long-term period, the dependences of SAE on LSAT changes are comparable for different ensemble products. The contribution of an increase in LSAT to the reduction of snow cover differs across seasons, with the greatest occurring in boreal autumn (49–55 %) and the lowest occurring in boreal summer (10–16 %). The snow cover uncertainties induced by the ensemble variability are invariant over time across CESM members but show an increase in the warming signal between the CMIP5 models. This feature reveals that the physical parameterization of the model plays the predominant role in long-term snow simulations, while they are less affected by internal climate variability.

Multimodel Analysis of Future Land Use and Climate Change Impacts on Ecosystem Functioning

“…To our knowledge, the isolated CC versus LUC effects on future land surface albedo have previously not been analyzed simultaneously, but even the literature on CC-induced changes in future snow cover and albedo is surprisingly scarce. CMIP5 models simulate Northern Hemisphere snow area reductions between 1971-2000 and 2071-2100 of~−5.6 ± 3.2% and −9.7 ± 3.5% in winter and −16.6 ± 13.8% and −25.1 ± 15.5% in summer for RCP2.6 and RCP4.5, respectively (A. H. Wang et al, 2018). This compares to satellite-based…”

“…CMIP5 models simulate Northern Hemisphere snow area reductions between 1971-2000 and 2071-2100 of~−5.6 ± 3.2% and −9.7 ± 3.5% in winter and −16.6 ± 13.8% and −25.1 ± 15.5% in summer for RCP2.6 and RCP4.5, respectively (A. H. Wang et al, 2018). CMIP5 models simulate Northern Hemisphere snow area reductions between 1971-2000 and 2071-2100 of~−5.6 ± 3.2% and −9.7 ± 3.5% in winter and −16.6 ± 13.8% and −25.1 ± 15.5% in summer for RCP2.6 and RCP4.5, respectively (A. H. Wang et al, 2018).…”

Application of the Bias Correction and Spatial Downscaling Algorithm on the Temperature Extremes From CMIP5 Multimodel Ensembles in China

“…Numerous researches had been conducted to understand the potential climate impacts of warming both below and above these threshold levels Wang et al, 2018;Zhang et al, 2018). Numerous researches had been conducted to understand the potential climate impacts of warming both below and above these threshold levels Wang et al, 2018;Zhang et al, 2018).…”

“…Numerous researches had been conducted to understand the potential climate impacts of warming both below and above these threshold levels Wang et al, 2018;Zhang et al, 2018). Wang et al (2018) found that the projected reduction in snow area extent under 1.5°C of warming is lower than that under 2°C of warming during the second half of the 21st century. Wang et al (2018) found that the projected reduction in snow area extent under 1.5°C of warming is lower than that under 2°C of warming during the second half of the 21st century.…”

“…The 2015 Paris Agreement proposed two long-term global goals: holding the increase in global mean temperature to well below 2°C above preindustrial levels and pursuing efforts to limit the temperature increase to 1.5°C . Numerous researches had been conducted to understand the potential climate impacts of warming both below and above these threshold levels Wang et al, 2018;Zhang et al, 2018). Schleussner et al (Schleussner, Rogelj, et al, 2016) revealed that the rate of sea level rise in 2100 would be reduced by about 30% under 1.5°C of warming compared with 2°C of warming.…”