Natural landscapes in the Southwestern United States are changing. In recent decades, rising temperatures and drought have led to drier conditions, contributed to large-scale ecological impacts, and affected many plant and animal species across the region. The current and future trajectory of climate change underscores the need for managers and conservation professionals to understand the impacts of these patterns on natural resources. In this regional assessment of the Southwest Climate Change Initiative, we evaluate changes in annual average temperatures from 1951–2006 across major habitats and large watersheds and compare these changes to the number of species of conservation concern that are found within these places.
We found that 80% of habitats in the Southwest have warmed significantly in the past 55 years. Along with other factors, warming very likely contributed to ecological changes in 40% of Southwestern habitats, including changes in the timing of species events, increases in wildfi re activity, widespread insect infestations and forest tree mortality. Those habitats with the highest temperature change and the most species of conservation concern include subalpine forests, piñon-juniper woodlands, sage shrublands, and Colorado Plateau canyonlands and grasslands. At least 119 plant and animal species within these habitats have been affected by climate change.
Additionally, we found that 70% of the watersheds in the Southwest have warmed signifi cantly. Hydrological changes associated with recent warming, including reductions in snowpack and earlier peak stream fl ows, have already been observed in 50% of these watersheds. Warming has been most pronounced within the watersheds that comprise the Colorado River Basin, a regional center for native fi sh diversity that hosts a number of world-renowned national parks and tourist destinations and supplies water for four major cities in the Southwest.
Given that contemporary scientific studies confirm and global climate models project that our environment is becoming drier and warmer, resource managers and conservation professionals now possess suffi cient knowledge to begin adapting to climate change. Management tools already used to restore natural systems, such as mechanical thinning and prescribed fi re, not only reduce fire risk but also build ecosystem resilience to drier conditions. Current planning approaches, including multi-year management plans and adaptive management, are well suited to anticipate and adjust
to a changing environment. Therefore, the most prudent approach is to build upon, reevaluate, and learn from the current set of tools used to maintain and restore forests, grasslands, rivers and wetlands.
In response to the results of our regional assessment, the Southwest Climate Change Initiative convened scientists and managers within four case-study landscape sites. Together, we evaluated how current resource plans, objectives and monitoring protocols could be adjusted to bolster the health and resilience of natural systems given what is currently known about the effects of climate change. Three actionable recommendations emerged from these workshops and this regional assessment:
Modify and expand the use of current management tools to moderate the effects of climate change on rivers, wetlands, and water supply. Examples include strategically-located mechanical thinning and controlled burns to boost snowpack retention and water infiltration in forests; and restoration of vegetation and natural water fl ow patterns in riparian areas and wetlands such that
base fl ows and groundwater recharge are sustained.
Develop climate-smart adaptive management and monitoring protocols. Adjust adaptive management and monitoring protocols to evaluate the effectiveness of management activities designed to address climate change. Reevaluate historical monitoring data sets to understand whether temperature-driven changes to species and ecological process are already occurring within the management area.
Coordinate management of shared resources. Given the regional pattern of recent temperature change—some areas have warmed more rapidly than others—natural resource managers will benefi t by coordinating their activities with others that are managing common resources. Piñon-juniper woodlands for example span the 4-corner region and have experienced a range of temperature change in the last half-century from –1°F to +3°F. Regional and coordinated management of this shared habitat may be the only way to ensure that portions of the habitat can be maintained in a resilient state,
while at the same time, other portions are allowed to transition to another state.
Taking action on these recommendations will be critical for achieving conservation and management goals in the face of a changing climate.
