Climate change indicators in the United States, 2014

Background/Question/Methods

One important way to track and communicate the causes and effects of climate change is through the use of indica­tors. An indicator, such as a record of Arctic sea ice extent, represents the state or trend of certain envi­ronmental conditions over a given area and a specified period of time. Environmental indicators are used to help monitor environmental trends, track key factors that influence the environ­ment, and identify effects on ecosystems and society. Building on previous efforts, we have developed and updated a system of climate change indicators for the US. The purpose of this work is to track and document climate change in the US, and to provide a tool to communicate to broad audiences, including policymakers and the public. Our team has worked with peer-reviewed data from various government agencies, academic institutions, and others to identify metrics for a set of indicators that is essential to characterize climate change in the US. Potential indicators were screened and chosen using a standard set of criteria that considered usefulness, objectivity, data quality, transparency, ability to meaningfully com­municate, and relevance to climate change. Feedback from a diverse group of scientists, research­ers, and communications experts helped to inform the communication of results.  

Results/Conclusions

This effort currently consists of 30 indicators, each describing trends related to the causes and effects of climate change. They focus primarily on the US, but some present global trends to provide context or a basis for comparison, and others have a regional focus. Four new indicators were added (Wildfires, Lyme Disease, Water Levels and Temperatures in the Great Lakes, and Heating/Cooling Degree Days) and others were updated with new data. The indicators span six categories: Greenhouse Gases, Weather and Climate, Oceans, Snow and Ice, Health and Society, and Ecosystems. In addition to presenting observations and trends, the indicators high­light the far-reaching significance of climate change and the possible consequences for people, the envi­ronment, and society. For example, temperatures are rising, snow and rainfall patterns are shifting, and bird wintering ranges are showing Northward movement. Each indicator features five elements: background, description, key points, summary of limitations or constraints, and information on the underlying data sources. Results are presented in a print and web-based report designed to inform readers' understanding of climate change. It also provides a tool for scientists, analysts, decision-makers, educators, and others to assess environmental trends, support science-based decision-making and communication, and evaluate climate-related policies and programs.