Conservationists have to work around several problems before they can effectively monitor large-scale changes in biodiversity from space.
A main roadblock is the need to establish a space-metric for biodiversity, a consolidated measurement that would incorporate several different datasets. Now, after decades of debate, scientists are nearing agreement about which datasets to include.
New satellites coming online and newly developed sensing technology make the time right for agencies and scientists to move ahead on space-based biodiversity analysis, experts say.
On Christmas Eve in 1968, on their fourth orbit around the moon, the three American astronauts aboard Apollo 8 were startled to see the Earth, a pale blue orb, rising from the darkness. The astronauts hurriedly snapped a picture, the first to be taken of Earth by a person in space. “It was the most beautiful, heart-catching sight of my life,” Frank Borman, the flight’s commander, recalled years later. “This must be what God sees.”
Since the iconic Earthrise photo was taken, our ability to stare at Earth from above has only gotten better. Satellites take high-resolution images and measurements that enable environmental researchers to, among other things, predict weather patterns, track the movements of phytoplankton populations, and monitor active volcanoes.
But so far, environmental scientists aren’t taking full advantage of satellite observation to help fight the intensifying loss of biodiversity. Typically, scientists estimate the biodiversity in an ecosystem by tallying up the number of individuals of different species in a specific area and plugging them into mathematical models. But these results tend to be limited and highly variable.
A vantage point in space could prove invaluable, Nathalie Pettorelli, an ecologist at the Zoological Society of London, told Mongabay. Space-based measurements of biodiversity at varying scales could provide a yardstick of an ecosystem’s overall health and help scientists understand “whole ecosystems and communities and the function that they might perform in a given region and beyond,” she said.
However, conservationists have to work around several problems before they can effectively monitor large-scale changes in biodiversity from space. Right now the organizations that collect the satellite information don’t have explicit partnerships with environmental scientists, which means the limited satellite data that the researchers receive is not continuous over time or specific to the ecologically diverse areas that are of greatest interest.
Access to this information would enable scientists to establish a space-metric for biodiversity, a consolidated measurement that would incorporate several different datasets. After decades of debate, scientists are nearing agreement about which datasets would be the most important to include. But in order to reach a true consensus, they need to collaborate with the data-collecting organizations, Pettorelli said.
Pettorelli and several colleagues penned an op-ed in the journal Nature to kick-start the conversation between scientists and these organizations by suggesting some variables to monitor from space. Together, they anticipate, these metrics could provide an indicator for biodiversity.
Many of the measurements they suggest include aspects of ecosystem function and structure that satellites are already documenting. For instance, the Quickbird satellite, owned by the Colorado-based company DigitalGlobe, and NOAA’s Animal Telemetry Network are sophisticated enough to snap photos of individual plant or animal species, showing researchers their size and distribution.
This may seem like the metric most intuitively related to biodiversity, but many other measurements can give researchers additional information about how an ecosystem functions. For instance, since 1986 the French SPOT mission has mapped swaths of vegetation, indicating which habitats became fragmented over time. Landsat, a joint mission of NASA and the U.S. Geological Survey, gathers information on forest health by calculating how much of an area is covered by leaves, among other data. Fire and flooding information provided by Global Forest Watch (a partner of Mongabay) can show researchers how an ecosystem functions, as well as help identify threats to it. Presumably, satellites launched or used by these institutions — along with others like Google and the European Space Agency — collect lots more useful data. As Pettorelli and her colleagues suggest, these different measurements give researchers a multi-faceted glimpse into the health of ecosystems and the diversity of species that populate them.
Pettorelli told Mongabay that she and her colleagues are proposing a process rather than a solution, similar to the scientific collaboration to determine whether Earth was warming that was first proposed in 1979. The problem of not having an appropriate space metric for biodiversity, Pettorelli and her colleagues write, is “exacerbated by a lack of communication between the ecology and remote-sensing communities.”
Now is the perfect moment for satellites to start measuring biodiversity, Greg Asner, a scientist at the Carnegie Institution for Science, told Mongabay. Fifteen years ago, when many of these satellites were going online, environmental scientists had little idea which metrics could help them calculate biodiversity, and the technology wasn’t sophisticated enough to detect them anyway. Today, the situation has improved. Asner sees Pettorelli’s op-ed as the most recent in a series of publications, conferences, and conversations that have brought scientists closer to an agreement about what variables they should be measuring. He said the metrics mentioned in the op-ed are “close to what people are settling on.”
The technology is much improved, too. Asner takes high-resolution scans from an airplane using an instrument package known as the Airborne Taxonomic Mapping System (AToMS) that can reveal a forest’s structure and biodiversity by detecting plants’ chemical and reflectance properties, among other measures. The souped-up plane gathers data periodically, not continuously as a satellite would, but Asner is working to equip a satellite with an AToMS package.
Such technological advances could be enough of a reason to get space agencies like NASA and the European Space Agency to allocate some of their budget towards biodiversity projects. “It’s the perfect storm of conditions,” Asner said.
More conversations need to happen first between scientists and the data-collecting agencies, according to Pettorelli and her colleagues. They believe that intergovernmental environmental organizations should be the ones to spark that cooperation, like the Secretariat of the Convention on Biological Diversity.
The Secretariat agrees that more needs to be done to align these divergent groups to share more data, Robert Hoft, an environmental affairs officer with the Secretariat, told Mongabay. He said that using satellite data for conservation is on the agenda: the Secretariat is slowly rolling out efforts like those that Pettorelli wants to see. And Secretariat researchers have put out calls to institutions such as universities, science grant agencies, foundations, and government organizations to increase the funding directed toward satellite-based research projects in which scientists and data-gathering agencies can collaborate.
“All [of these organizations] may have different reasons to put up resources for such work: governments need the information and realize this is a cost-effective way to get it; space agencies and Google because it makes use of their capabilities and they can demonstrate doing things of public value; science grant-making bodies because it is neat science,” Hoft told Mongabay. But even with all the data that is already available, without proper funding, conservationists won’t be able to compile the information in a useful way to track biodiversity, he added.
Asner agreed: “The technology is ready to go. The missing part is the decision-makers in places like D.C. need to decide to allocate the funds,” he said.
If conservationists are eventually able to track biodiversity from space, they hope it will help them devise better strategies to prevent too many species from going extinct. And by monitoring the relevant ecosystems consistently, they’ll know whether their strategies are working.
“We have new streams of information coming from new sensors; new satellites are coming online all the time,” Hoft added. “That means we have tons more opportunities to detect change remotely at large scale, and the ability to replicate those observations to see how they change over time.”
But Hoft and Pettorelli said the eyes in the sky won’t replace the need for on-the-ground scrutiny. Satellite data will still need to be supplemented with Earth-based measurements, albeit perhaps with fewer of them.
If conservationists and other stakeholders can hash out a space metric for biodiversity now, they could not only help plan conservation action for the future but also help determine the mission and data collection of future satellites. Several new data-gathering satellite missions are slated to launch in the next few years. NASA’s GEDI mission, to be completed in 2018, will collect information about plant height and biomass. And the agency’s ECOSTRESS mission will launch between 2017 and 2019 to closely examine how plants absorb and release water. Environmental scientists want to start these collaborations before the missions launch in order to make sure they gather the most useful data.
“If we were to make better use of the data we have available, we could be more strategic about how to develop the future constellation of satellites so that we maximize our options of collecting data,” Pettorelli said. “There will always be things you cannot monitor from space, but there’s a lot you can.”
Skidmore, A.K. et al. (2015). Agree on biodiversity metrics to track from space. Nature 523:403–405.