Column |  Satellites as executioners for the environment and climate

Column | Satellites as executioners for the environment and climate

A few years ago I made an interesting discovery with colleagues from Wales. Namely that the snow in Antarctica sometimes even melts in winter. That’s because of the hairdryer. Air blowing up a mountain forms clouds, rain and snow through forced uplift. The condensation of all that moisture gives the air a lot of energy. Once you reach the top, the air on the leeward side descends, and the energy gained is converted into heating. This effect is sometimes so strong in Antarctica that even in the middle of the pitch-dark polar night, the snow is brought to melting point.

Observations from a measuring mast strategically placed in the snow by us were confirmed by satellites that can see microwave radiation. Snow is white in the microwave range, and meltwater is black. The satellite images allowed us to show that winter melt occurs often, and in several places.

Even though I made this discovery behind a desk in a university building in Utrecht, it still felt a bit like I was somewhere no one had ever been before, in the deep dark Antarctic winter.

Satellites give us eyes to see where we normally can’t see. There are more and more of them, and the optics are getting better and better. But not only that. Increasingly smarter algorithms and automated image recognition are sifting more and more information from the terabytes of pixels collected daily by satellites. Many recent discoveries in glaciology are made thanks to satellites and data techniques.

Greenland and Antarctica are changing very slowly from cold ice caps that trap snow, to warm places with rain, melting snow and refrozen ice crusts. Thanks to our eyes in space, we can increasingly observe and understand these change processes. We thereby improve our models that calculate future melting and associated sea level rise.

Mercilessly exposing

Those all-seeing eyes in space don’t just fuel scientific curiosity. Because satellites do not care about national borders and prohibited areas, they mercilessly expose what is happening in conflict areas (Bocha, Gaza) and have now become indispensable in the coordination of emergency aid (Derna, Gaziantep). There is no looking away anymore. Even the most remote and closed areas become visible from space.

One of the last lawless Wild West areas on Earth is the ocean. A lot of things still happen there out of sight of the authorities. Coke trafficking, human smuggling, piracy. And illegal fishing. Yet satellites also seem to be able to make such activities increasingly visible. The scale of industrial fishing has been extensively mapped this year by a team of US scientists, using the powerful combination of satellite imagery and large-scale data analysis.

They calculated that around three-quarters of commercial fishing vessels worldwide cannot be publicly tracked, especially in Asia and Africa. One of those tracking systems is AIS. In some countries AIS is not mandatory for commercial vessels, but anyone who wants to fish illegally somewhere can simply turn off their transponder and disappear from the radar for a while.

The large inventory of satellite images shows that there is much more fishing going on than you can tell from AIS. For example, in AIS it appears that there are about ten times as many ships fishing in the European part of the Mediterranean as in the African part. But the satellite images show it’s about 50-50. Most African ships cannot be tracked. A small part of this ‘dark fleet’ fishes illegally. Most illegal fishing takes place in the sea between China and North Korea. There is also active fishing in reserves where this is not allowed at all. For example, about five medium to large vessels fish around the Galapagos Islands every week, and twenty in the Great Barrier Reef.

Identify and fine

At the moment it is only possible to say that a ship is fishing illegally somewhere, but not which ship. A satellite now still sees pixels of approximately 15 by 15 meters. If satellites become even better, the time will come when individual ships can be identified and fined. Satellites may help enforce fishing regulations.

In any case, satellites will probably be used increasingly to check whether international climate and environmental legislation is being complied with. Whether illegal logging can be stopped, and whether President Lula will succeed in saving the Brazilian rainforest from destruction, satellites can tell us day by day.

And then there is Tropomi, an instrument largely developed in the Netherlands. This represents a major step towards identifying large, and partly hidden, emitters of greenhouse gases worldwide. Methane leaks, illegal production of CFCs, the ammonia fumes from industrial livestock farming, it is all coming into sharper focus.

Thanks to satellites, we will soon no longer have to rely on the blue eyes of governments, companies and entrepreneurs who have to report emissions and pollution. It can be independently verified from space. Satellites as independent judges represent a major social opportunity and a challenge for science.

Peter Kuipers Munneke is a glaciologist at Utrecht University and weatherman at NOS