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NASA Antarctica image: By Dave Pape — own work, using Blue Marble data. Public Domain.

Wildlife, conservation, and satellites.

How a view from space is teaching us more about life on earth.

Images of earth taken by satellites orbiting our planet are helping us learn more about our natural world — from entirely new discoveries, to realisations that we massively underestimated how many trees there are. As technology improves and the spatial resolution of these images increases — along with our ability to process massive amounts of data — the potential uses of satellite imagery are growing more ambitious and more exciting. As someone who’s fascinated by wildlife, I decided to share a few of my favourite stories that illustrate how these artificial eyes in the sky are expanding our knowledge about the species we share our planet with, and how we can protect them.

Satellites, poo and penguins.

I don’t know what it is about zoologists but we cannot resist a good poo story, and this is probably my favourite.

Peter Fretwell, a mapping expert at the British Antarctic Survey, made a “fortuitous” discovery whilst studying Landsat satellite images of the Antarctic. He’d noticed big brown patches in the otherwise white landscape and feeling curious, he decided to investigate what they could be. It turned out that he was looking at the tell-tale signs of huge penguin colonies! The brown patches were penguin poo, or to call it by its more scientific name, guano.

Can you see spot where the penguins have been?

Although it’s not possible to see individual penguins in a Landsat satellite image, penguins live in large social groups and during the breeding season, the patch of ice they live on can get quite messy. By examining the images, Peter and his team were able to identify 10 new colonies of Emperor Penguin (Aptenodytes forsteri), in addition to the 28 colonies that we already knew about.

The Emperor Penguin is the tallest of all the penguin species. Image: Public domain — Michael Van Woert, NOAA NESDIS, ORA.

One part of this story that really stood out for me was finding out that this discovery was made using images that were freely available. At the time, Peter was quoted as saying,

“If this data wasn’t free, we would never have been able to do our research.”

For me this really highlights the importance of open data in solving our biggest conservation challenges.

Since the discovery that penguin guano can be seen from space, the use of satellite imagery to monitor species has become more common, especially now the resolution and quality of images is increasing. In 2012 the British Antarctic Survey published the first ever census of a penguin population to be taken from space. The census was made possible by the availability of Very High Resolution (VHR) satellite images that are detailed enough to allow the counting of individual penguins. And in case you were wondering, there are 595,000 Emperor Penguins in Antarctica and the number of colonies we know about has risen to 46!

But the story doesn’t end there. People who spend a lot of time studying birds have figured out that each species has its own guano ‘signature’ and it’s possible to distinguish different species just by looking at a satellite image of their breeding colony. In fact, you can tell when the birds are breeding because younger chicks have darker guano that gradually gets lighter as they grow. Armed with this knowledge, Peter and his team have also used satellite images of Antarctica to map the breeding sites of all the seabird colonies in the region with 50 or more breeding pairs. Species include the Kelp Gull (Larus dominicanus), Skuas, and the Southern Giant Petrel (Macronectes giganteus).

Monitoring birds in this way means we can observe what’s happening in places that are hard for humans to access. It’s also cheaper and more efficient to use satellite images than to send people into the field.

Satellites and trees.

Using satellite images to monitor deforestation is already a well-known application of satellite imagery but up until a few years ago, we were massively underestimating how many trees there are on our planet. Estimates had put the number at 400 billion, which would work out at 61 trees per person if you were to share them out equally between everyone alive today.

But when a team led by Thomas Crowther at the Yale School of Forestry and Environmental Studies used a combination of ground surveys and satellite images to investigate the true number of trees, they discovered the figure is more like 3.4 trillion, which works out at 422 trees per person! That’s 11 times more than the number of stars in our galaxy!

The Operational Land Imager (OLI) on Landsat 8 captured this image of the Cal Madow in the Sanaag province of Somaliland on June 27, 2015. Credit: Credit: NASA Earth Observatory image by Joshua Stevens, using Landsat data from the U.S. Geological Survey.

So why do we need to know how many trees there are? Well, by looking at the distribution of those trees we can understand better the impact of climate, topography, and human activities on trees. For example, tropical and subtropical regions are home to 42.8% of trees, so if we choose places to protect based on the density of trees, this would be a good place to start. The study also calculated that human activities are responsible for the loss of 15 billion trees every year. With more accurate numbers at our fingertips we can get a better idea of how much carbon is being stored by the trees we have — which is really important information if we are serious about meeting national and international climate targets.

Satellites and coral reefs.

I can honestly say that learning to dive on Australia’s Great Barrier Reef was a life-changing experience for me. I was 19 years old and had plans to study Genetics at university, but after seeing the amazing diversity of life hidden beneath the surface of the ocean, I switched to Zoology. Even today I have vivid memories of tiny gobies darting in and out of their burrows and purple nudibranchs dancing between the corals.

A view of the Great Barrier Reef from space. What a beauty. Image courtesy NASA/GSFC/LaRC/JPL, MISR Team.

Fast forward 13 years later and my heart is breaking as I watch the decline of the Great Barrier Reef. The extent of bleaching across the reef is unprecedented and it’s a clear sign that something is very, very wrong. To help the reef, we need to gather information quickly about what’s happening and satellite images offer an opportunity to make it easier and faster to keep track of changes.

Using satellite images to monitor coral reefs is nothing new: Landsat images have been used to observe coral reefs since 1984 but as satellite technology has advanced, and our ability to process data has improved, we can paint a much more accurate picture of what’s happening beneath the waves. Now it’s possible to do more than just map the location of a reef — we can determine how healthy it is by picking out bleaching events and new algae growth, which are signs that the reef is sick or dying.

A project that launched last year, Sen2Coral, is developing an open source algorithm that makes use of openly available Sentinel-2 satellite images. The aim is make the algorithm available to everyone who wants to use it so we can make the most of the Sentinel-2 images in our conservation work. Climate change is the greatest threat to coral reefs and the bleaching that occurs when sea temperatures rise is a visible, undeniable sign of the damage it can cause. If we are going to tackle it, we need to work together — and making information such as satellite imagery open and available is our best hope of finding the answers we desperately need.

To infinity and beyond.

It’s amazing that technology far above is answering questions about life beneath our feet. Satellite imagery gives us access to information we didn’t have before and assists us as we tackle important environmental issues. Knowing what’s happening in our world right now makes it easier for us to see when populations and habitats start to decline and gives us the chance to figure out why it’s happening. It could help us choose which places and populations should be given priority when it comes to conservation efforts, and provide the information we need to judge if our efforts are working. For places like the Great Barrier Reef, time is running out. The action we take now is vital to their survival and satellite images have an important part to play.



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