Appendix 5
Reference Document 5-2
days (i.e., consecutive days without rainfall), increasing the intensity of naturally occurring droughts in the future (Runkel et al. 2022). Although, hydrological droughts have become less frequent in eastern regions of the country since the 19th century, higher increases in evapotranspiration (the processes by which water is transferred to the atmosphere from Earth’s surface) have generally made the Southeast more drought-prone than the Northeast (Hoffman, 2023). However, future changes in the annual number of consecutive extreme dry days in North Carolina are fortunately not projected to increase substantially: by 1 to 3% by 2025-2049, and by 1 to 4% by 2050-2074 depending on ecoregions and emission scenario (Alder 2024). Table 11 summarizes historical observed and future projections of extremely hot days (maximum temperatures ≥95°F) under different SSP scenarios and at GWL 2 (3.6°F warmer than the1991-2020 time period) for North Carolina ecoregions; while Figure 13 shows the change in the projected the number of extremely hot days in North Carolina at GWL of 1.5 (2.7°F warmer than the 1991-2020 time period) and GWL 2 (3.6°F warmer than the1991-2020 time period). Overall, the projections used in the NCA5 indicate that the number of extremely hot days (maximum temperatures ≥95°F) will increase across North Carolina, with the most pronounced increases occurring in the southern, inland portions of the state, though the magnitude of change often varies greatly by GWL or SSP scenario and location within the state. Winter temperatures are the fastest warming season in most of the U.S. In general, the number of extremely cold days (i.e., days with low temperatures of at least 32°F or lower) in North Carolina is predicted to decrease (Table 8). Winter conditions are key drivers of individual species performance and community composition in terrestrial habitats because species vary in susceptibility to these winter drivers (Williams et al., 2014). Shorter and warmer winters may cause species range shifts that would allow for warm-adapted species to dominate and shift distributions of cold-adapted species. For example, overwintering bird populations are responding to warming climate (e.g., poleward shifts) by favoring the formation of winter bird communities dominated by warm-adapted species instead of cold- adapted species (Princé and Zuckerberg, 2014; Osland et al., 2021). Additionally, winter conditions (e.g., snowfall, low temperatures) have a major effect on ecological processes such as litter decomposition, mineralization rates, nutrient leaching and gas fluxes in the soil and hydrological processes. Winter soil freezing also affects insect and microbial communities for the subsequent warm season (Campbell et al., 2005). Overall, projections used in the NCA5 indicate that the number of extremely cold days (days with low temperatures of ≤ 32°F) will decrease across North Carolina, with the most pronounced decreases occurring throughout the southern and coastal parts of the state, but the magnitude of change often varies greatly by GWL or SSP scenario and location within the state (Table 12; Figure 14). If the Earth surpasses a GWL of 1.5 (2.7°F) or 2 (3.6°F) for a sustained period of time, the number of days where the temperature reaches 32°F or lower (freezing temperatures) will decrease across the state, compared to the years between 1991 and 2020 (Table 12). In North Carolina, the majority of years between 2000 to 2020 have been characterized by warm-season drought conditions. However, little change in total annual precipitation is projected over this century, although the timing and intensity of precipitation events will change (Hoffman et al., 2023). However, increases in temperature will cause more rapid loss of soil moisture during consecutive dry days,
2025 NC Wildlife Action Plan
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