Average air temperatures are rising. Climate change has already increased average temperatures enough to shift seasons — spring comes earlier and fall frosts arrive later. These shifts in seasons compel some species to migrate farther north or to higher elevations. While average global air temperatures are warming, historical data also reflects that we are also experiencing more extreme temperature change.
According to the National Climate Assessment: “U.S. average temperature has increased by 1.3°F to 1.9°F since 1895, and most of this increase has occurred since 1970.” Although temperatures are rising, it is important to recognize that temperatures are rising on average. Put another way, climate change increases the likeliness that a specific season or year will be warmer than the historic average. Colder-than-average temperatures are still possible in a climate-changing world; they will simply occur less frequently.
Additionally, the National Climatic Data Center maintains over a century of temperature data and reported that the United States saw unprecedented extreme high and low temperatures in 2014. While record-setting high and low temperatures may continue to occur, EPA reports that long-term data tracking the number of unusually hot (above the 95th percentile) and unusually cold (below the 5th percentile) days that have occurred since 1948 indicates overall warming trends. The 2014 IPCC Climate Change Synthesis Report indicates similar global trends of increases in warm temperature extremes.
Unusually high temperatures have increased in the western United States and in several areas along the Gulf and Atlantic coasts, but decreased in much of the middle of the country. The number of unusually cold days has generally decreased throughout the country (see Figures above). However, the 20th century had many winters with widespread patterns of unusually low temperatures, including a particularly large spike in the late 1970s. Despite some localized anomalies, since the 1980s, unusually cold winter temperatures – particularly very cold nights – have generally become less common.
If the climate were completely stable, one might expect to see highs and lows each accounting for about 50 percent of the records set. However, since the 1970s, record-setting daily high temperatures have become more common than record lows across the United States. The most recent decade had twice as many record highs as record lows, indicating that we are experiencing warming trends.
Warmer average temperatures affect almost everything. Warming trends are reflected in increasing air temperatures and water temperatures, which effect terrestrial and aquatic habitats and species. These impacts may vary by regions and land types. Implications of these impacts for land trusts vary depending on conservation goals, however, in general, warmer average temperatures can present long-term management challenges, especially in regards to preserving a landscape’s native flora and fauna. This is because as average temperatures increase shifting seasons and range shifts affecting species distributions become more likely.
Rising air temperatures are a trigger for many other climate change impacts, such as:
Land trusts are responding to on-the-ground impacts of changing temperatures in various ways. Some groups are changing language in conservation easements to accommodate long-term variations in species and habitats. Others are implementing adaptation projects such as planting trees to shade streams or increasing tree cover in cities to mitigate negative effects of increasing temperatures. In addition to employing strategic conservation planning to reduce risks and enhance resilience, some land trusts are also supporting efforts to mitigate greenhouse gas emissions to reduce the extent of future climate change.
Land trusts must determine the right planning approach for their organization, however, more and more, conservation organizations are working with their communities to identify opportunities to reduce vulnerabilities and prepare for changing temperatures. Agencies are making similar strides to implement projects that reduce risks and plan for resilience by incorporating adaptation, mitigation, and engagement into their strategic goals and objectives. For example, the U.S. Fish and Wildlife Service’s Strategic Plan for Responding to Accelerating Climate Change identifies seven planning and development goals to support sustainable landscapes. Conservation groups are increasingly partnering with agencies as well as other nonprofits and for-profit organizations to respond to this global challenge at local levels.
Resilience describes the ability of a system maintain its functions or “bounce back” through extreme change. By working to identify and reduce potential threats land managers can build resilience and achieve multiple management objectives. Assessing vulnerabilities is a critical step in the strategic conservation planning process that helps land trusts identify key threats to resources. Adaptive management planning enables conservation practitioners to implement interventions to reduce vulnerabilities and to monitor and revise strategies as new information becomes available. There is no one-size-fits-all solution to addressing management challenges associated with warming average temperatures, however, planning that acknowledges vulnerabilities can help land trusts better achieve their conservation objectives.