How satellite data helps study climate change
Gazing into the distance from the height of the third floor will allow you to look more broadly at the neighborhood than from sidewalk level. It is easier to see the buildings a few streets away, to see what is behind the trees.
It’s the same if we look at the world from orbit – we’re able to see constantly occurring changes on a larger scale – both in terms of terrain, but also over a longer period of time. The balcony from which we take a picture may be obscured by another building, while the view from orbit would never be so obscured – having satellite image processing software, we are able to easily compare two pictures from two different time periods.
Climate changes are not something that can be easily observed. They do not occur in a single year, and the weather has a very strong influence on what happens. For these reasons, climate change must be analyzed on a large scale – over a long period of time and over a large area. In today’s article, we will discuss how satellite data can help researchers study and address climate change.
It is said that the Amazon is the lungs of the Earth. Unfortunately, there is constant logging in this forest, but not only that – the amount of rainforest is decreasing all over the world. The logging is caused by the desire for timber, space to grow fruits or vegetables, and also to create new space for grazing cattle.
The problem is not only a decrease in the number of trees, which create oxygen and absorb carbon dioxide from the atmosphere, but also a decrease in the habitat of various animal species – mammals, birds, and reptiles. Biological systems are incredibly fragile – the extinction of one species due to human activity can lead to the extinction of another species.
Satellite images are able to incredibly quickly and accurately detect areas where logging is taking place, often illegally – then there is a chance to stop such endeavor. An additional aspect is the ability to study over a longer period of time new plantings – based on various indicators (like NDVI), scientists are even able to assess the health of planted forests.
As temperatures rise, changes occur most rapidly in the polar regions. It is possible to distinguish for the main contributing mechanisms, which are particularly visible from orbit – the extent of the ice sheet and the detachment of part of the glacier.
Seasonal changes in the extent of Arctic ice are a natural phenomenon – it is logical that in summer in the Northern Hemisphere the exposure to the sun is greater, so the amount of Arctic ice decreases. In winter, this process reverses and the ice increases. Unfortunately, over the years, it has happened that in some seasons there has been far less ice than the multi-year average indicates. Changes are also taking place in the other hemisphere – sometimes you can read that another iceberg has broken away from Antarctica. Such texts are usually accompanied by a satellite image that shows the scale of the problem.
The detachment of icebergs can lead to the movement of ice to warmer waters, where it melts faster, leading to a steady rise in water levels. What’s more, such mountains are also a direct threat to humans – one of their victims, after all, was the Titanic.
Fires occur everywhere – both in urban areas, but also in dense forests, in hard-to-reach terrain where it is difficult to assess the extent of the damage – satellite imagery can then come to the rescue. It goes without saying that not every fire is caused by climate change, nevertheless, with drier and warmer weather, it is definitely easier to accidentally start a fire.
Mapping fires based on satellite data is, for example, used in Google Maps, which are used by virtually everyone. Marking an area on a map can save the lives of those in the area. In addition, it is important to detect a fire as soon as possible – and locating it accurately can make it easier for emergency services.
Rising sea levels
Sea level rise is one of the more characteristic effects of a warming climate. Scientists are able to study this phenomenon using data from satellites using radar. They are able to detect sea level changes of 2 cm over 100 km.
Covering 70% of the Earth’s surface, the oceans are a very large store of energy. According to NASA, they have absorbed 90% of the heat caused by global warming. The effect of storing so much energy is rising sea levels (caused even by thermal expansion), accelerated melting of glaciers, coral bleaching, unraveling of the biosphere, or intensified hurricanes, which „draw” energy from the heated water sheets. In addition, scientists say that this year’s El Niño, a cyclical weather phenomenon, may be stronger than usual.
In the last 15 years, the Earth, and therefore mostly the oceans, have accumulated as much heat as in the previous 45 years. In April 2023, the oceans reached a record warm temperature. Overall, compared to pre-industrial times, the average water temperature has risen by as much as 0.9 degrees Celsius.
One of the satellites observing the oceans is SWOT – Surface Water and Ocean Topography, which was launched in December 2022 by a Falcon 9 rocket into a sun-synchronous orbit. It is a joint project between the U.S. NASA, France’s CNES and the Canadian and British space agencies. The goal of the mission will be to provide data on sea level heights, sea currents, and study how the oceans absorb heat and carbon dioxide.