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Ocean Climate Changes
Published in Donat-P. Häder, Kunshan Gao, Aquatic Ecosystems in a Changing Climate, 2018
The strong temperature increase in the Arctic has resulted in a sharp decline of the Arctic sea ice extent (Fig. 3.4) which was on the order of 9.1% per decade between 1979 and 2006 (Stroeve et al. 2007). Most climate models project a continuation of this trend during the current century in response to greenhouse gas forcing (McKenna et al. 2016). Between 1979 and 2017 the Arctic sea ice volume has lost 73.5% when averaged for September of each year (http://climatestate.com/2014/01/26/arctic-death-spiral-1979–2013-sea-ice-decline-deglaciation (ClimateState.com). Recent sea ice models and satellite images suggest that the first ice-free summer will occur before 2020 (Overland and Wang 2013), while the Fifth IPCC report estimates an ice-free summer around 2050 using scenario AR5. The receding ice cover allowed new shipping routes across the Arctic Ocean opening the North East passage which had unsuccessfully been searched for, for several centuries (Howell et al. 2017). The sea ice decline is augmented by a positive feedback called polar amplification: snow and ice cover reflect 50–70% of the incoming solar radiation. When the ice and snow have melted the open water and soil have a much higher absorption (~ 6% reflection) which results in a further heating (Screen and Francis 2016). In addition to a shrinking sea ice cover, the Arctic ice has been found to decrease in thickness as indicated by submarine and ICESAT measurements (Kwok and Rothrock 2009).
Ice bottom evolution derived from thermistor string-based ice mass balance buoy observations
Published in International Journal of Digital Earth, 2023
Zeliang Liao, Yubing Cheng, Ying Jiang, Mengmeng Li, Bin Cheng, Stein Sandven
Unlike other materials, water has three phases that exist simultaneously in nature. Of these three phases, ice constitutes the smallest proportion, yet it represents an essential component of Earth’s cryosphere system. The largest portion of ice exists in the polar region. Polar amplification (known as air temperature increases faster in polar regions than in the rest of the world) extensively alters the phase change of water and further impacts global climate (Feldl and Merlis 2021; Holland and Landrum 2021; Smith et al. 2019). A fundamental topic that has been investigated for decades is the snow and ice mass balance for natural water bodies (Lei et al. 2022; Wagner and Frame 2015; Wever et al. 2021). Quantification of the ice thickness (IT) evolution is the main challenge in understanding the ice mass balance because this process involves comprehensive air–ice-water interactions that impact the climate. This topic has been tackled across a large spatial and temporal scale by investigating sea ice thickness (SIT) in the Arctic Ocean (Johannessen et al. 2022; Lang, Yang, and Kaas 2017; Rantanen et al. 2022). On a local scale, the research objective is often targeted at the evolution of air-snow-ice-water interactions (Kwok 2018; Provost et al. 2017), among which the thermodynamic processes of freezing and ablation of the ice thickness are of particular interest because they play key roles in determining the ice thickness.
Climate change and extreme weather: A review focusing on the continental United States
Published in Journal of the Air & Waste Management Association, 2021
The influence of climate change on mid-latitude storms involves competing effects (Robinson and Booth 2018; Shaw et al. 2016). On the one hand, global warming has, and presumably will continue to, warm high latitudes more than the tropics, especially in the Northern Hemisphere (IPCC 2013). This so-called polar amplification of global warming reduces the equator-pole temperature gradient in the lower atmosphere, most strongly in winter, but also in summer (Barnes and Polvani 2015). At the same time temperature gradients are projected to increase in the upper troposphere, due to warming of the tropical upper troposphere. At the same time, the increase in water vapor in a warmer atmosphere, again, a result of the Clausius-Clapeyron relation, means that more latent heat can be released in these storms, which contributes to their intensification. As with other weather extremes, resolution poses an obstacle to capturing these effects in global climate models. While the dry dynamics of mid-latitude storms are presumably well resolved within global climate models, much of the precipitation, and thus release of latent heat, is organized on spatial scales of tens of kilometers. As a result, the development of mid-latitude storms is enhanced when they are simulated with finer grids than in global models, and this sensitivity to grid resolution is associated with the representation of precipitation and its contribution to storm dynamics (Willison, Robinson, and Lackmann 2013). It has been known for many years that latent heat release is crucial to the development of explosively deepening cyclones (Kuo and Reed 1988), so it is not surprising that the occurrence of such “bomb” cyclones in models is resolution dependent, with nearly twice as many such rapidly deepening storms found at a grid resolution of 20 km, compared to a typical global climate model grid scale of 140 km (Jiaxiang et al. 2020).