Davey Tree Flipbooks

12 THE DAVEY BULLETIN | November/December 2021 TREES AND CLIMATE CHANGE The Davey Institute's Climate Change Fact Sheet series summarizes effects of climate change projected to impact the tree care industry over the next 30 to 70 years. The average surface temperature of Earth has increased 2 degrees Fahrenheit since the beginning of the 20th century with most of that warming happening within the past 40 years. By the end of this century, temperatures across the U.S. are projected to increase by another 3-11°F. Impacts of this warming are readily apparent and include annual average temperature increases, precipitation changes, sea-level rise, greater storm intensity, pest pressure and a longer wildfire season – all of which affect tree health. The nature and magnitude of these impacts vary across the country. The Institute's fact sheets are regionally based and highlight the further projected impacts of climate change as they are forecast to be experienced in your communities. Many of these environmental impacts identified by the Institute – such as warmer, drier summers – will be experienced by multiple U.S. regions, but the varied, cumulative impacts may be regionally unique. This illustration summarizes key U.S. region impacts of climate change identified by the Institute's fact sheet series. To read a fact sheet for a U.S. region, or the series' executive summary, go to: https://www.davey.com/climate NORTHWEST IMPACTS Insect outbreaks, particularly bark beetle, and wildfires are changing the composition of forests and dramatically increasing tree mortality. Precipitation patterns are becoming much more variable. Average precipitation is projected to increase in winter and spring and decrease in summer. SOUTHWEST U.S. IMPACTS Warming and drying of the climate have contributed to increased wildfire frequency, duration, and season length. These factors will result in more acres burned each year, greatly reducing the tree population. NORTHERN GREAT PLAINS IMPACTS Summer drought, decreased snowpack, shrinking glaciers, and increased evapotranspiration in the Northern Great Plains have decreased the average flow rate of rivers and streams in recent decades. Furthermore, agricultural irrigation has depleted ground water in the High Plains Aquifer System on which the water supply of parts of the region, including Nebraska, are highly dependent. Limits on municipal water supplies may result in irrigation restrictions, which will present challenges for tree health maintenance when physiological demands for water are amplified by increasing temperatures and evapotranspiration. SOUTHERN GREAT PLAINS IMPACTS As plant growth begins earlier in the spring and summers become hotter and extreme heat more frequent, soil is becoming drier with increasing evapotranspiration. These trends will intensify stress experienced by trees, resulting in their increased susceptibility to secondary pests such as wood-borers, vascular wilt and canker pathogens. MIDWEST U.S. IMPACTS States throughout the Midwest, like all parts of the U.S., have experienced increases in annual average temperatures over the last century, but Minnesota has experienced warming of more than 3 degrees Fahrenheit – making it one of the fastest warming areas of the continental U.S. Meanwhile, southern Minnesota and Ohio are predicted to experience 5 to 15 more days per year with temperatures exceeding 95 degrees, with Illinois expected to experience 15 to 20 more days above 95 degrees. Warming Midwest winters are leading to changes in USDA plant hardiness zones. Increasing temperatures and more frequent summer drought are predicted to accelerate the northward migration of some tree species with more heat and drought tolerance. VISION

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