Global Change: The Earth system
TanDEM-X and TerraSAR-X flying in formation
The twin satellites TerraSAR-X and TanDEM-X fly in close formation only a few hundred metres apart, capturing data for digital elevation models.
Global TanDEM-X forest map
The global TanDEM-X Forest/Non-Forest Map was derived from interferometric radar data and is freely available for scientific applications.
Permafrost region Herschel Island
Herschel Island is located on the northwestern tip of Canada and is characterised by continuous permafrost. The PermASAR radar image acquired in August 2018 reveals vegetation in the L-band frequency range (dark green colour) in the otherwise treeless tundra. The thawing process is also evident along the coasts: In the right part of the picture, broken ice floes float on the sea (violet). On the coast in the left part of the image are traces of mudflows where the thawed soil breaks off and is washed away.
‘Global change’ is not a recently invented term – it has been used since the 1980s to describe changes in the Earth system driven or triggered by human activities. In contrast to climate change, which only deals with one specific issue, global change takes into account a larger range of processes.
Examples are global warming, changes in the composition of the atmosphere, the spread of agricultural land and the consequent loss of natural ecosystems (for example, tropical rainforests) the loss of biodiversity, ocean acidification, the melting of glaciers and parts of the polar ice caps, plastic waste in the oceans, urbanisation (since 2010 more people live in cities than in rural areas), changes in air quality and the increase in vulnerability to natural disasters. Some of these change processes are natural, but many are caused by humans. In some cases, the processes influence one another. Demographic change is a major driver of many of the processes – Earth has a population of approximately 7.5 billion, and the United Nations predicts that it will increase to more than 11 billion by 2100.
Remote sensing to assess changes
Monitoring global change is indispensable and there is no alternative method for understanding change processes, assessing their consequences and, where possible, making socio-political recommendations for action. Remote sensing is the best method for global monitoring. Earth Observation (EO) is the only technology that can perform this monitoring globally, comprehensively and with high spatial and temporal resolution and accuracy – and do this independently of political constraints.
DLR is active in Earth observation – both satellite-based and airborne – on a large scale. The Remote Sensing Technology Institute, the Microwaves and Radar Institute, the Institute of Atmospheric Physics, the Institute of Optical Sensor Systems and the German Remote Sensing Data Center not only address many of the research topics associated with global change but also play leading roles in the related scientific fields. For many years, DLR has been researching global change with a wide variety of missions. It develops archiving and processing technologies, devises algorithms for extracting relevant parameters from EO data and analyses the results.
Manuela BraunGerman Aerospace Center (DLR)Strategy Space R&D
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MOSAiC Arctic expedition – DLR measurement technology for navigation signals will freeze with the Polarstern research vessel in the Arctic OceanThe Polarstern research icebreaker, operated by the Alfred Wegener Institute (AWI), will set sail for the Arctic Ocean on the evening of 20 September 2019. There, it will freeze in the sea ice and drift with it across the Arctic for a year. Researchers from 19 countries have a unique opportunity to conduct experiments and collect data. On 17 and 18 September, before the Polarstern departed from Tromsø, in northern Norway, a team from the German Aerospace Center (DLR) installed a measurement system for receiving and storing raw signals from navigation satellites on board the icebreaker.
Global TanDEM-X forest map is available.Forests are Earth's lungs; they help to reduce greenhouse gas concentrations in the atmosphere and thus counteract global warming, while also providing protection and resources for humans, animals and plants – and they are being lost at an alarming rate. As the view from space reveals, forests cover about one third of Earth’s landmass today. More than half of the world’s forests, which have fallen victim to deforestation since the middle of the 20th century in particular, have already been lost.
High-tech support for humanitarian aidHumanitarian aid organisations are increasingly seeking technological support for their work in crisis and disaster situations. New technologies from fields such as satellite remote sensing, robotics and communications can assist aid workers in rescuing and caring for people as effectively as possible in emergency situations.
Glacier retreat in Antarctica – innovative radar technologies enable improved predictionsThwaites Glacier, one of the most fragile glaciers in western Antarctica, is melting inexorably into the Amundsen Sea at an ever-increasing rate. Until now, it has been responsible for approximately four percent of the global rise in sea level and will cause the oceans to rise by over 65 centimetres in future as its remaining ice melts.
Global 3D elevation model from the TanDEM-X mission now freely availableThe 90-metre TanDEM-X Digital Elevation Model has been released for scientific use and is now available as a global dataset. By providing this data, the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) follows the EU data policy under the Copernicus Earth observation programme, which encourages free and open access to satellite data.