Key Findings from a National Assessment of Climate Change Impacts on Biodiversity, Ecosystems, and Ecosystem Services

Building on past assessments of how climate change and other stressors are affecting species and ecosystems in the United States, we approach the subject from several different perspectives. First, we review the observed and projected impacts on biodiversity, with a focus on genes, species, and assemblages of species. Next, we examine how climate change is affecting ecosystem structural elements—such as biomass, architecture, and heterogeneity—and functions concerning the fluxes of energy and matter. Third, we review newly emerging research to determine how human activities and a changing climate are likely to alter the delivery of ecosystem services.

We also examine two cross-cutting topics. We recognize that climate change is happening against the backdrop of a wide range of other environmental stressors, many of which have caused dramatic ecosystem degradation already. This broader range of environmental stressors interacts with climate change and human responses to these changes, complicating our abilities to predict and respond to climate change. The second cross-cutting topic is the rapidly advancing field of climate adaptation, where there has been significant progress in developing the conceptual framework, planning approaches, and strategies for safeguarding biodiversity and other ecological resources. At the same time, ecosystem-based adaptation is becoming more prominent as a way to utilize ecosystem services to help human systems adapt to climate change.

Thus, this summary takes a more integrated look at the question of how climate change is affecting our ecological resources, the implications for humans, and possible response strategies.  Key findings from the National Climate Assessment are used to highlight particular challenges facing aquatic species and their habitats.