According to a hypothesis proposed in the 1985 global warming was suggested to increase the risk of frost damage to trees in the boreal and temperate regions Cannell et al 1985; Hänninen et al 2006 So

According to a hypothesis proposed in 1985, global warming was suggested to increase the risk of frost damage to trees in the boreal and temperate regions (Cannell et al., 1985; Hänninen, et al., 2006). Subsequent studies have provided mixed results, with some showing little increase in frost damage in temperate conditions, while others have observed an increase in the boreal forests (Hänninen, et al., 1991; Kellomäki et al., 1995; Kramer et al., 1994). However, despite some studies indicating a decrease in frost damage (Parker et al., 2021), the possibility of severe frost damage still exists (Saxe et al., 2001). The findings of the current study align with these prior research findings, indicating that the impact of global warming on frost damage is complex and varies across different regions.

The geographical distribution of spring frost events analyzed in this study revealed changes in the Northern Hemisphere. While the overall area impacted by spring frosts has decreased over time, the changes were not uniform across the examined areas. In fact, the number of spring frosts has increased in many regions, as clearly demonstrated in this study. These findings support previous research that suggests the frequency of extreme climate events, such as late spring frosts, is expected to increase with climate change (Sangüesa-Barreda et al., 2021; Vitesse et al., 2019). Furthermore, the increasing coefficient of determination of linear regression from 1983-2016 to 1948-1982 indicates a strengthening correlation between global temperature anomaly and the number of spring frost events in recent decades. This suggests that the relationship between global warming and spring frost events has become more pronounced over time.

In addition to changes in frequency, the occurrences of spring frost events have also shifted northward. This aligns with previous findings that higher-latitude regions experience more severe spring frosts (Francis et al., 2012; Zohner et al., 2020). The northward shift of spring frosts is further supported by research in phenology and agricultural production. Studies on the frequency of frosts at budbreak have shown a decrease in the risk of spring frosts in lower-latitude regions like Spain, but an increase in higher-latitude regions like Germany (Leolini et al., 2018). Similarly, research on apple blooming has indicated an increased risk of spring frosts in Switzerland (higher latitude), but a slightly decreased risk in Italy (lower latitude) (Unterberger et al., 2018). Projections for the evolution of spring frost risk to apple production have also highlighted higher risks in higher-latitude regions like Great Britain and Finland compared to lower-latitude regions like Italy and France (Cannell et al., 1986; Eccel et al., 2009; Hofmann et al., 2013; Kaukoranta et al., 2010; Unterberger et al., 2018). These studies underscore the heterogeneity in the risk of spring frosts and provide further support for the conclusion that spring frosts have shifted northward.

In summary, the impact of global warming on frost damage to trees is complex and varies across different regions. While some studies have shown little increase in frost damage in temperate conditions, others have observed an increase in the boreal forests. The current study's findings align with prior research, indicating that the frequency of spring frost events has increased in many areas, although the overall area impacted has decreased. Furthermore, there is a strengthening correlation between global temperature anomaly and the number of spring frost events, suggesting a more pronounced relationship with climate change in recent decades. The northward shift of spring frosts is supported by research in phenology and agricultural production, which demonstrate a higher risk of spring frosts in higher-latitude regions. These findings highlight the need for further research and adaptation strategies to mitigate the potential impacts of spring frosts in a changing climate.