Of the four main ways that space and sustainability intersect, perhaps the most literal is that space is a location from which to observe the Earth. Space is a powerful vantage point for monitoring the interplay between human activity and environmental health: On-the-ground sensor networks can be difficult to deploy and maintain, and spacecraft can target a variety of temporal and spatial scales. The breadth of satellite capability is illustrated by those that monitor changes in weather, climate, and Earth’s surface. Their data allows people to make a wide range of decisions on how humans interact with nature, ideally with the goal of sustainability in mind.

An everyday example of monitoring from space is weather forecasting. (Note that weather is different from climate, with the key distinction being time.) In the United States, the Geostationary Operational Environmental Satellite (GOES) program tracks clouds, surface temperature, water vapor, and atmospheric structure; Australia relies on the Japanese Himawari satellites for similar information. In both cases, the data are fed into weather forecasting models that generate the weather reports we all check daily. Satellites can also be purpose-built to focus on specific weather phenomena, such as NASA’s CYGNSS constellation, which tracks changes in ocean roughness as a proxy for tropical cyclones. The information provided by weather satellites allows a variety of decisions to be made, ranging from whether you should wear a jacket today or whether a city should be evacuated in advance of a hurricane.

In addition to short-term meteorological predictions, satellites can also provide critical data on long-term changes to climates around the world. A recent World Economic Forum report stated that “half of essential climate variables can only be measured from space.” Scientists use these and many other satellite-derived variables in their global climate models (GCMs) to evaluate a range of scenarios for climate change over different periods of time. The results from GCMs are used in turn by the Intergovernmental Panel on Climate Change to inform policymakers on the latest science, its implications, and potential adaption or mitigation strategies. Besides monitoring global trends, satellites such as MethaneSAT are also increasingly able to pinpoint sources of greenhouse gases, arming corporations and governments with the knowledge needed to create actionable emissions targets to slow the rate of warming.

*Global carbon dioxide and methane concentrations from 2003 to 2019 based on satellite data. (Copernicus Climate Change Service*)

My personal favorite use of space for monitoring the Earth is imaging, which occasionally results in stunning pictures that could be mistaken for abstract art pieces. Satellite imagery of Earth’s surface gives humans a bird’s eye view of our planet and has nearly limitless applications. The world’s longest continuously acquired collection of space-based imagery is from the U.S. Landsat program, which started in 1972 with the launch of Landsat 1; most recently, Landsat 9 was launched in September 2021. Landsat imagery has been used to track land use changes, glacier recession, coral reef health, population growth, deforestation, and many other phenomena at the intersection of human activity and environmental health. Companies such as Planet and Maxar are increasingly providing imagery as a service for both scientific research and businesses, increasing the ways that data from space can be used here on Earth.

*Landsat images show the Aral Sea, lying between Kazakhstan and Uzbekistan, which has been shrinking over decades due to water diversion for agricultural use. (USGS EROS Data Center*)

The common thread through each of these examples—monitoring of Earth’s weather, climate, and surface—is that data collected from space allows people on Earth to make well-informed decisions regarding sustainability. The Biden Administration recognizes this, with 2022 U.S. budget increases for federal agencies that fund climate research such as NASA, NOAA, and the USGS. By deepening our understanding of humanity’s impacts to Earth, policymakers have the proper context in which to change laws and fund solutions, such as in clean technologies that decrease emissions. Furthermore, continued data collection from space provides a mechanism to track the impact of those solutions, which is instrumental in continuing to improve their efficacy in our ongoing race against the most catastrophic impacts of climate change. The criticality of space as a location to monitor sustainability on Earth points to the need to use space itself sustainably as well, a topic I’ll explore in my next post.