Elevation-dependent warming in global climate model simulations at high spatial resolution

Abstract

The enhancement of warming rates with elevation, so-called elevation-dependent warming (EDW), is one of the regional, still not completely understood, expressions of global warming. Sentinels of climate and environmental changes, mountains have experienced more rapid and intense warming trends in the recent decades, leading to serious impacts on mountain ecosystems and downstream. In this paper we use a state-of-the-art Global Climate Model (EC-Earth) to investigate the impact of model spatial resolution on the representation of this phenomenon and to highlight possible differences in EDW and its causes in different mountain regions of the Northern Hemisphere. To this end we use EC-Earth climate simulations at five different spatial resolutions, from ∼ 125 to ∼ 16 km, to explore the existence and the driving mechanisms of EDW in the Colorado Rocky Mountains, the Greater Alpine Region and the Tibetan Plateau-Himalayas. Our results show that the more frequent EDW drivers in all regions and seasons are the changes in albedo and in downward thermal radiation and this is reflected in both daytime and nighttime warming. In the Tibetan Plateau-Himalayas and in the Greater Alpine Region, an additional driver is the change in specific humidity. We also find that, while generally the model shows no clear resolution dependence in its ability to simulate the existence of EDW in the different regions, specific EDW characteristics such as its intensity and the relative role of different driving mechanisms may be different in simulations performed at different spatial resolutions. Moreover, we find that the role of internal climate variability can be significant in modulating the EDW signal, as suggested by the spread found in the multi-member ensemble of the EC-Earth experiments which we use.

Rising mean and extreme near‐surface air temperature across Nepal

“…In this regard, present study can serve as a baseline (Gerlitz et al ., ; Hasson et al ., ; Norris et al ., ; Karki et al ., ; Hasson et al ., ). The climate model simulations can further support in better understanding of the physical processes and mechanisms affecting the spatiotemporal distribution of mean and extreme temperatures, and can particularly be useful for providing future climate change scenarios (Norris et al ., , ; Karki et al ., ; Palazzi et al ., ).…”

“…A decreased snowfall and reduction of snow cover due to a warmer climate lead to a reduced snow albedo, and subsequently, higher absorption of solar radiation at the surface, resulting in enhanced warming in mountain regions (Pepin et al ., ; Minder et al ., ). Such snow albedo‐effect has already been identified as a dominant driver for amplification of warming at high elevations and in the Himalayas (Pepin et al ., ; Palazzi et al ., ). Observed EDW for T max during winter can also be related to significant influence of the snow‐albedo effect.…”

Changing station coverage impacts temperature trends in the Upper Colorado River basin

“…A recent modelling study over the UCRB found that reductions in snow cover drove increases in mean temperature at higher elevations, particularly during spring and summer (Minder et al, ). This finding is corroborated by simulations over the western United States, which find EDW except in the winter (Palazzi et al, ).…”

“…In most months, the reduction in warming in PRISM and Livneh is somewhat greater at middle and high elevations. This pattern is contrary to expectations from the literature, which suggests that high elevations have been warming faster than low elevations worldwide (e.g., Rangwala and Miller, ; Mountain Research Initiative EDW Working Group, ), regionally (Palazzi et al, ), and elsewhere in Colorado (e.g., McGuire et al, ; Minder et al, ). Here we show that known inhomogeneities can explain most of the difference in the late 20th century, but that they cannot explain elevational differences in temperature trends between 1926 and 1990.…”

Temperature Changes in the Maloti-Drakensberg Region: An Analysis of Trends for the 1960–2016 Period

“…Kohler, Wehrli and Jurek [10] maintain that large mountain ranges could be considered as climatic barriers, whose boundaries could shift due to climate change, with dire consequences for ecosystems, especially through habitat changes, as well as through increased frequency of occurrence of natural hazards and disruption of economic activities and land uses. Mountain climates often exhibit spatially complex patterns [11]. This is most evident in their effect on vertical gradients of microclimates, species distribution, availability of natural resources such as water, soil and biological resources and land uses.…”