Assessments of the north hemisphere snow cover response to 1.5 °C and 2.0 °C warming

Abstract

The 2015 Paris Agreement has initialed a goal to pursue the global-mean temperature below 1.5 C, and well below 2 C above pre-industrial levels. As an important surface hydrology variable, the response of snow under different warming levels has not been well investigated. The community earth system model (CESM) project towards 1.5 °C and 2 °C 10 warming targets, combined with CESM large Ensemble project (CESM-LE) brings an opportunity to address this issue. This study provides a comprehensive assessment of snow cover fraction (SCF) and snow area extent (SAE), and the associated Land Surface Air Temperature (LSAT) over North Hemisphere (NH) based on CESM-LE, CESM 1.5 °C and 2 °C projects, as well as CMIP5 historical, RCP2.6 and RCP4.5 products. Results show that the spatiotemporal variations of those modeled products are grossly consistent with the observation. The projected SAE magnitude change in RCP2.6 is comparable to that 15 in 1.5 C, but lower than that in 2 C. The snow cover differences between 1.5 °C and 2 °C are prominent during the second half of 21 st century. Changes in the LSAT and snow cover for 2071-2100 with respect to 1971-2000 exhibit the inconsistently spatial patterns. The contribution of increase in LSAT on the reduction of snow cover differs across seasons with the greatest in boreal autumn (49-55%) and the lowest in boreal summer (10-16%). The snow cover uncertainties induced by the ensemble variability show time invariant across CESM members, but increase with the warming signal 20 among CMIP5 models. This feature reveals that the model physical parameterization plays a predominant role on the long-term snow simulations, while they are less affect by the climate internal variability.

Gathering in an empty house: Arthropod assemblages overwintering in abandoned hornet nests

“…Thus, snowfall may be one of the major factors that cause hornet nests to collapse in winter. It has been predicted that global warming will facilitate reduced snow cover for several regions in the future (Wang et al, 2018). Thus, reduced snow cover with global warming may prevent the destruction of abandoned hornet nests and increase the overwintering success of the arthropod assemblages (mainly spiders) inside, and thus enhance their ecological functions on tree communities.…”

The Relative Contribution of Large-Scale Circulation and Land Surface to Summer Precipitation Over Asian Mid-Low Latitudes

“…This result indicates that the northward movement of the WPSH is the main circulation driving factor, leading to Pr-Circ increasing in northeastern Asia and decreasing on the southeastern coast. The coe cient of determination (CD), de ned as the square of the percentage of squared pattern correlation between component and total Pr (CD = 100%*R 2 ), is adopted here to quantify the contribution of the two components to the total Pr trend (Wang et al 2018). The CD of Pr-Res (88.15%) is much higher than that of Pr-Circ (6.79%), indicating that the Pr-Res dominates the trend of total Pr.…”

Dipole response of early‐summer rainfall in eastern China to 1.5 and 2.0°C global warming

“…To limit anthropogenic influences on climate systems, the 2015 Paris Agreement proposed the target of keeping warming well below 2°C above pre‐industrial levels and pursuing efforts to limit the temperature increase even below 1.5°C (UNFCCC, 2015). Limiting global warming to 1.5°C helps reduce the retreat of glaciers, permafrost, and sea ice and protect plant species (Kraaijenbrink et al ., 2017; Jahn, 2018; Niederdrenk and Notz, 2018; Wang et al ., 2018a). Compared to 2°C warming, the frequency of extreme weather and climate events such as heatwaves (Mishra et al ., 2017; Dosio and Fischer, 2018; Li et al ., 2018b; Zhang et al ., 2018b), droughts (Lehner et al ., 2017; Arnell et al ., 2018), heavy rainfall (Liu et al ., 2017; Mohammed et al ., 2017; Ali and Mishra, 2018; Chen and Sun, 2018; Nangombe et al ., 2018), and extreme El Niño events (Cai et al ., 2014; Wang et al ., 2017) would decrease at 1.5°C warming.…”