RAL SEMINAR: Perspectives on Multi-facet Impacts of Global Warming to the Hydrosphere & Cryosphere

Man has benefited from consuming shared resources such as air and freshwater and return their wastes back into the shared resources. However, tragedy arises when man fails to recognize that consumptive activities of some could lead to a significant impact of many - the destruction of the integrity of shared resources, such as the current global predicament of climate change impact on the hydrosphere and cryosphere. In recent decades, the world has suffered significant environmental changes such as hydrologic extremes, melting glaciers and ice caps, wet lands drying and shrinking, sea level rise, forest fires, and many natural disasters causing serious damage, massive property losses and even deaths, such as the 2013 Alberta flood of Canada, Congo flood of 2019-2020, European floods of 2021 in Belgium, Germany, the Netherlands, and Switzerland, and many others. A warmer climate means the atmosphere will be loaded with more water vapor which is fuel for developing intensive storms and hurricanes. Conversely, rising temperature can also give rise to prolonged moisture deficit or droughts in arid/semi-arid regions, resulting in loss of multibillion dollar revenues from agriculture, leading to famine and even humanitarian crisis, such as that of Nigeria and Somalia in 2017.

Perspectives on the global energy balance, greenhouse effects and examples of observed changes to the hydrosphere will be presented. Future climate scenarios projected by general circulation models (GCMs) of the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC, 2013), and that of the 6th Coupled Model Intercomparison Project (CMIP6) of IPCC (2021), and case studies based on regional climate models and land surface schemes will be discussed. The discussions will also include possible implications to the future global climate, hydrology, and water resources under the impacts of climate change. Besides climate change impact to the hydrosphere, the cryosphere is also undergoing rapid changes during the 20th and the early 21st Century, such as significant retreat of glaciers worldwide; thinning of Arctic sea-ice extent and thickness by about 40% in late summer in recent decades; snow cover of the Northern Hemisphere decreased by about 10% in area since global observations by satellites began in the late 1960s; degradations of permafrost detected in some polar and sub-polar regions, and the total 20th Century global average sea level rise was about 0.17m. Possible implications to the future global hydrosphere and cryosphere under climate change impact and practical adaptation strategies to mitigate such impacts will be discussed.