Modeling Ecosystem Global Warming Potentials

Climate cooling benefits of cellulosic bioenergy crops from elevated albedo

“…where I sc is the solar constant (1367 W m −2 ), I θ is the extraterrestrial irradiance intensity using the cosine of the solar zenith angle, and d r is the average Earth-Sun distance calculated for each day of the year (see Chen et al, 2021 for a detailed model). The daily zenith angle was derived from NOAA Earth System Research Laboratories for calculating solar radiation (NOAA, 2005).…”

“…However, to reduce bias caused by day‐to‐day differences in cloud cover, T a was manually calculated as the ratio of incoming solar radiation at the top of the atmosphere ( SW TOA ) to that at the surface (SW ↓ ), assuming a same value of upward and downward atmospheric transmittances (Carrer et al, 2018; Sciusco et al, 2020). SW ↓ was obtained from each tower daily, while SW TOA was calculated as:where I sc is the solar constant (1367 W m −2 ), I θ is the extraterrestrial irradiance intensity using the cosine of the solar zenith angle, and d r is the average Earth‐Sun distance calculated for each day of the year (see Chen et al, 2021 for a detailed model). The daily zenith angle was derived from NOAA Earth System Research Laboratories for calculating solar radiation (NOAA, 2005).…”

“…Promoting cellulosic bioenergy crops has been proposed as a way to replace fossil fuels to reduce emissions of greenhouse gases (GHG) to the atmosphere (IPCC, 2022;Robertson et al, 2017Robertson et al, , 2022. Albedo change upon conversion of prior vegetation to cellulosic crops could either attenuate or magnify this benefit depending on its effects on radiative forcing-with the exact magnitude not yet fully resolved because of nonlinear effects, large uncertainties for multi-century processes, and assumptions about changing atmospheric conditions when converting albedo to radiative forcing (Chen et al, 2021). Critically, research on albedo in agricultural landscapes is still severely lacking (Flato et al, 2013;Henderson-Sellers & Wilson, 1983;Ouyang et al, 2022;Smith et al, 2020).…”

“…Land surface albedo ( α s ), the ratio of outgoing shortwave radiation to the incoming shortwave radiation (Henderson‐Sellers, 1980; Henderson‐Sellers & Hughes, 1982; Russel, 1916), is one of the most important measures in radiation and energy budgets (Bright, 2015; Chen et al, 2021). Albedo is a vital indicator of energy partitioning because it reflects solar energy absorbed by a land surface (e.g., grasslands, forest, or urban lands) and then converted to heat, versus the amount reflected back to space with no warming impact (Ollinger et al, 2008).…”

Albedo-Induced Global Warming Impact at Multiple Temporal Scales within an Upper Midwest USA Watershed

“…In Europe, Carrer et al [13] reported that inclusion of cover crops in annual cropping systems could have cooling effects equivalent to a mitigation of −0.03 Mg C eq ha −1 yr −1 , while Lugato et al [14] showed that such mitigation potential due to the inclusion of cover crops could be substantially enhanced by growing high-albedo chlorophyll-deficient cover crops. In southwest Michigan, USA, Chen et al [15] estimated that land conversion from forest to maize (Zea mays L.) can provide a cooling equivalent to a mitigation of −0.043 Mg C eq ha −1 yr −1 due to a 0.051 (i.e., 5.1%) increase in albedo. At watershed scale, Sciusco et al [11] demonstrated that altered landscapes could produce cooling effects relative to the intact, native, late successional forests typical of pre-European settlement and contribute a range of −0.1 to −0.4 Mg C eq ha −1 yr −1 , which is the same order of magnitude of biogeochemical GWI emissions due to many crop management components [16,17].…”