Climate Change and Observed Climate Trends in the Fort Cobb Experimental Watershed

Abstract

Recurring droughts in the Southern Great Plains of the United States are stressing the landscape, increasing uncertainty and risk in agricultural production, and impeding optimal agronomic management of crop, pasture, and grazing systems. The distinct possibility that the severity of recent droughts may be related to a greenhouse-gas induced climate change introduces new challenges for water resources managers because the intensification of droughts could represent a permanent feature of the future climate. Climate records of the Fort Cobb watershed in central Oklahoma were analyzed to determine if recent decade-long trends in precipitation and air temperature were consistent with climate change projections for central Oklahoma. The historical precipitation record did not reveal any compelling evidence that the recent 20-yr-long decline in precipitation was related to climate change. Also, precipitation projections by global circulation models (GCMs) displayed a flat pattern through the end of the 21st century. Neither observed nor projected precipitation displayed a multidecadal monotonic rising or declining trend consistent with an ongoing warming climate. The recent trend in observed annual precipitation was probably a decade-scale variation not directly related to the warming climate. On the other hand, the observed monotonic warming trend of 0.34°C decade that started around 1978 is consistent with GCM projections of increasing temperature for central Oklahoma.

Can conservation trump impacts of climate change on soil erosion? An assessment from winter wheat cropland in the Southern Great Plains of the United States

“…For agricultural and soil conservation applications, a supplemental downscaling step was necessary to express the projected monthly climate in terms of daily weather data at a particular location within the downscaled GCM grid-box. Synthetic weather generator SYNTOR (Garbrecht et al, 2014) was used to perform this supplemental downscaling (Fig. 2, middle).…”

“…Stochastic weather generator SYNTOR (Garbrecht et al, 2014) was used in this study to downscale the monthly GCM climate predictions to daily weather outcomes at the location of interest within the GCM grid-cell.…”

Uncertainty of Climate Change Impacts on Soil Erosion from Cropland in Central Oklahoma

“…Second, the soil erosion distributions under both emission scenarios overlap significantly, indicating that both emission scenarios have similar impact on soil erosion. It is speculated that this is likely due to climate change in Oklahoma being primarily a change in min/max temperature (9%-34% increase, statistically significant; table 3), not a change in precipitation amount (6%-7% increase, not statistically significant; table 3; and Garbrecht et al, 2014a). Third, the combined uncertainty range of multiple emission scenarios (here RCP4.5 and RCP8.5) is always as large as or larger than that of an individual emission scenario.…”

“…Temperatures are expected to continue to rise due to unabated releases of heat-trapping greenhouse gases (GHG) in the atmosphere (Dore, 2005;Tebaldi et al, 2006;NCADAC, 2009;AMS, 2013;IPCC, 2013). A warmer climate and more frequent and extreme rainfall events generally lead to a disproportional increase in surface runoff and soil erosion by water, thereby altering the extent of soil conservation efforts needed to stay within desirable soil erosion limits (SWCS, 2007;Izaurralde et al, 2011;Zhang et al, 2011;Dabney et al, 2012;Zhang, 2012;Walthall et al, 2013;Garbrecht et al, 2014a). Potential impacts of climate change on soil erosion by water must be estimated to establish the need for development of mitigating and adaptive strategies that maintain a competitive, sustainable, and environmentally responsible agricultural system under changing climatic conditions.…”

Impact of weather and climate scenarios on conservation assessment outcomes

“…The Intergovernmental Panel on Climate Change (IPCC) reported that global climate change was intensifying the hydrologic cycle (IPCC 2007) with projected precipitation and frequency of extremely wet seasons to increase over much of the United States (Christensen et al 2007). Temperatures will continue to rise in the near future (Dore 2005;Tebaldi et al 2006), and precipitation trends are uncertain and may increase or decrease for various locations and seasons (Hayhoe et al 2007;Diodato and Bellocchi 2009;Campbell et al 2011;Garbrecht et al 2014). Intensified precipitation and increased frequency of extreme events would likely result in more runoff, higher soil erosion rates, potentially severe gullying, and related off-site sedimentation problems (SWCS 2007; Zhang et al 2010;Zhang et al 2012;Dabney et al 2012a).…”