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Climate Parameter Variability
Published in Saeid Eslamian, Faezeh Eslamian, Handbook of Drought and Water Scarcity, 2017
It is evident that a change of the Earth’s energy budget has strong consequences on the climate system and, thus, also on drought occurrence. Of the incoming solar shortwave radiation (SWR), about half is absorbed by the Earth’s surface. The fraction of SWR reflected back to space by gases and aerosols, by clouds, and by the Earth’s surface (albedo) is approximately 30%, and about 20% is absorbed in the atmosphere. Surface albedo is changed by changes in vegetation or land surface properties, snow or ice cover, and ocean color. In particular, surface albedo is the ratio between reflected and incident solar flux at the surface and it varies with the surface cover. For example, most forests are darker (i.e., lower albedo) than grasses and croplands, which are darker than barren land and desert.
Photoelectrocatalytic Carbon Dioxide Reduction to Value-Added Products
Published in Anirban Das, Gyandshwar Kumar Rao, Kasinath Ojha, Photoelectrochemical Generation of Fuels, 2023
Paras Kalra, Cini M. Suresh, Rashid, Pravin P. Ingole
Carbon dioxide being a greenhouse gas absorbs heat radiated from the earth’s land and ocean surfaces which are warmed by sunlight and released gradually over time. A definite amount of greenhouse gas keeps the earth safe from freezing, while an increase in its concentration outbalances the earth’s energy budget by trapping additional heat and hence increasing the average temperature [1]. The burning of fossil fuels, the conventional source of energy, has been adding an increased amount of CO2 into the atmosphere. According to a study by the National Ocean and Atmospheric Administration (Figure 5.1), “The global average atmospheric carbon dioxide in 2019 was 409.8 parts per million (ppm for short), with a range of uncertainty of plus or minus 0.1 ppm. Carbon dioxide level today is higher than at any point in at least the past 800,000 years” [2]. Due to such a drastic increase in the anthropogenic production of CO2 into the atmosphere, we have seen some of the warmest days in recent years. The consequences of global warming are seen through extreme weather conditions, natural disasters, rising sea levels, melting icebergs, desertification, increased number of wildfires, and acidification of oceans only to name a few [3]. In order to reach the goal of limiting temperature rise close to 1.5°C, the global greenhouse emissions need to fall by 7.6% each year over the next decade. Specifically speaking about the CO2 emissions, the global net anthropogenic carbondioxide emissions need to fall by about 45% from 2010 levels by 2030 to reach a “net zero” by 2050 [4]. This would mean reducing further CO2 emissions to the maximum and also balancing the rest, by removing the existing CO2 from the atmosphere by decarbonizing, carbon sequestration, and carbon recycling, which are the three main categories that we need to work on [5].
Sources, intensities, and implications of subsurface warming in times of climate change
Published in Critical Reviews in Environmental Science and Technology, 2023
Maximilian Noethen, Hannes Hemmerle, Peter Bayer
Enhanced greenhouse gas emissions yield an imbalance in Earth’s energy budget. Due to their great impact on climate change, priority is set on their effect on atmospheric global warming. Only around 5% of the excess heat is taken up by land (von Schuckmann et al., 2020) which manifests in trailing in-situ underground warming when compared to temperature trends in the atmosphere (Arias et al., 2021). Without surface warming, the thermal regime in shallow ground would be equilibrated and only respond to the seasonal oscillation in surface temperature in the top few meters (Taylor & Stefan, 2009). Meanwhile, the effects of global warming manifest down to depths of up to 100 m (Harris & Chapman, 1997; Lachenbruch & Marshall, 1986). Subsurface warming in response to atmospheric climate change is superimposed by human encroachment that changes the energy balance at the land surface. Especially in densely populated areas the thermal impact of direct anthropogenic land use is often more pronounced than the warming in response to climate change (Eggleston & McCoy, 2015). This has been measured worldwide in boreholes and groundwater wells, revealing a highly heterogeneous picture of man-made spatial and temporal temperature variations that chiefly represent interferences of multiple coexisting heat sources (Benz et al., 2017). Local heat accumulation in the ground can be magnitudes higher than in the atmosphere, but is transferred at much lower rates. As a consequence, recent anthropogenic warming imprints as a persistent signature in the subsurface (Pollack et al., 1998). Beneath many cities, the agglomeration of a multitude of anthropogenic heat sources evolved so-called subsurface urban heat islands, with higher intensity and temperature stability than the far better-known surface and atmospheric urban heat islands (Ferguson & Woodbury, 2007; Menberg, Bayer, et al., 2013; Oke, 1973; among others).