Space-based ecological observations: the NASA decadal survey

Abstract

In the coming decade, accelerating climate change and human modification of both landscapes and oceans will cause tremendous changes in ecosystem distribution and function. These changes will affect the capacity of ecosystems to provide food, water, healthy living environments, and a range of other services, and they will also affect the rate at which global warming continues to increase. Changes are already occurring in many parts of the world, notably in coastal zones where much of the world's population lives, at high latitudes where climate change is lengthening the snow-free season, and in tropical forests undergoing massive conversions for agricultural expansion and timber extraction. The vast, remote open ocean is experiencing increasing acidity as a result of higher levels of atmospheric CO2 while over-harvesting of fish is leading to global changes in marine ecosystems. Global ecosystem management is a growing challenge for the future. In order to understand and manage ecosystem changes and their feedback to the Earth's climate system, continuous global observations are critical. Space-based observations of ecosystems now span decades and capture variability and trends in ecosystems by studying large areas repeatedly. Observations of the physical environment provide the context for understanding ecosystems' sensitivity to climate change. Measurements such as soil moisture, ocean topography, ocean vector winds, earth radiation, and precipitation are among those needed. The Space Studies Board of the National Research Council has organized a decadal survey study, “Earth observations from space: a community assessment and strategy for the future” (http://qp.nas.edu/decadalsurvey). NASA has used decadal surveys in other disciplines to establish a framework for science priorities and missions, but this is the first attempt to use the process for the Earth sciences, including ecology. Satellite observations and the analyses they provide have an important and growing role in environmental science and management, so the decadal survey will have a major impact in ecology and environmental management. Within this process, the Earth Science and Applications Panel on Ecosystems was appointed to address terrestrial, aquatic, and marine environments. (Although the authors are members of this panel, the views in this editorial are based on personal observations of the process.) The survey will generate recommendations regarding science and applications priorities, identify opportunities afforded by new measurement types and new vantage points, and take a systems approach to observations that encompass the research programs of NASA and the related operational programs of NOAA and the USGS. This study will recommend priority measurements to support research, monitoring, and management during the decade 2005–2015 and beyond. In addition to elucidating fundamental Earth system processes and those underlying environmental change, applications needs also include weather and hydrological forecasting, climate prediction, aviation safety, earthquake prediction, natural resources management, agricultural assessment, homeland security, and infrastructure planning. The ecosystems panel evaluated ecological, technical, and management challenges, identified the contribution of remote observations to research and applications, and reviewed existing plans for ongoing ecologically relevant measurements. The panel strongly supports continuity of critical time series begun with LANDSAT, MODIS, and other sensors, and has tentatively identified four high-priority satellite missions. These research missions will employ new technologies to add new observations. The first new mission focuses on the detection and diagnosis of changes in ecosystem function (productivity, nutrient and water status, invasive species distributions, and coral reef status). The second focuses on terrestrial ecosystem structure and biomass, providing information on woody biomass, horizontal and vertical heterogeneity of forest habitat, and the effects of land use and deforestation on carbon stocks. A third mission will detail changes in CO2 concentration profiles above land and oceans, to quantify the global carbon budget. The fourth will view the coastal zone diurnally from a geostationary orbit to measure coastal ecosystem dynamics, including instances of harmful algal blooms, transport of organic matter, productivity, fisheries, and impacts of pollution episodes. The panel will also make recommendations about the need for new in situ and airborne capability. Remote sensing is used to address global-change ecology, conservation biology and planning, invasive species management, fisheries, wildfire management, precision agriculture, water resource planning, and a host of other ecological problems. The outcome of the decadal survey will influence the ecological satellite data resources available for the future. Interested scientists are strongly encouraged to contact the authors of this editorial or the NRC directly with their views. Bringing the next decade's ecological remote sensing program to fruition will require input, involvement, and support for spaced-based science and funding by ecologists and managers in an environment where many needs compete for limited opportunities. David Schimel, Senior Scientist, National Center for Atmospheric Research, Boulder, CO Inez Fung, Co-Director, Berkeley Institute of the Environment, CA Ruth Defries, Associate Professor, University of Maryland, MD