April 19, 2021
From a space perspective, NASA’s fleet of Earth observation satellites is working with those of partner agencies and international agencies to study and illuminate connections between ecosystems that are continents apart, or right next door. With a global perspective, scientists can observe how factors such as deforestation, climate change and disasters affect forests and other plants – while studying how changes in vegetation affect air quality, waterways and climate. Vegetation is the primary source of energy for almost all life on earth. Hence, it is important to monitor it and predict how it could be affected by climate change.
In the Amazon region, NASA earth scientists monitor forests and pass this data on to local decision-makers. NASA data provides information on tree cutting for agriculture and livestock, as well as the effects of the drought on tree mortality. People cut forests and then ignite the stacks of trees and other vegetation, leading to forest fires that can be detected with instruments such as the thermal imaging camera on the Suomi nuclear power plant satellite. In 2020, these sensors detected where 1.4 million fires had occurred. The fires create smoke that drifts across the continent and can be seen from space.
Using instruments that collect images of the earth’s surface, researchers can also track the extent of these fires and forest clearings over the years and even decades. NASA and the US Geological Survey’s joint Landsat mission, which launched its first satellite in 1972 and scheduled to launch Landsat 9 in September 2021, will allow scientists to track changing patterns of deforestation, showing them how farming practices on small family farms have changed in the Amazon to massive ranching operations.
The Amazon is the largest tropical rainforest in the world, almost the size of the continental United States. But every year there is even less of this forest. Today’s deforestation across the Amazon border consists of tractors and bulldozers clearing large swaths to make room for livestock and harvest on an industrial scale. Landsat satellite data is used to map land cover in Brazil with a historical perspective up to 1984. Credits: NASA Goddard Space Flight Center Download this video in HD formats from NASA Goddard’s Scientific Visualization Studio
Plant Health Tracking from Space
Satellites can tell how “green” an area is – and show the health of plants growing in a given location. While fires, deforestation, and drought are causing the tropical Amazon to be less green, the warming temperatures in the Arctic are causing the tundra and boreal regions to become greener. Using 87,000 Landsat images spanning nearly three decades, scientists determined that a third of the land cover of Canada and Alaska in 2012 looked different than 1985. With warmer temperatures and longer growing seasons, shrubs on grassy tundras become denser, transforming what they looked like from space.
Since plants absorb carbon dioxide from the air during photosynthesis to make food, a greener Arctic could result in less greenhouse gas being released into the atmosphere. However, a recent study using satellite data and computer models found that increased carbon uptake in the Arctic is offset by a decline in the tropics. There, warmer global temperatures have resulted in a drier atmosphere. That means less rainfall and more drought in places like the Amazon, resulting in a decline in tree growth and an increase in tree mortality – and less carbon from the atmosphere. The scientists discovered that the availability of water could soon also limit the vegetation in the Arctic. As forests expand or are cut down, researchers use data from instruments like MODIS and satellites like Landsat to measure their extent and health.
A new set of NASA instruments in space also measures forest health. The Global Ecosystem Dynamics Investigation (GEDI) instrument on board the International Space Station uses lasers to measure the height of trees and enables researchers to study how ecosystems are changing and how carbon and water cycles change in a warming climate. The Altitude Satellite 2 for Ice, Clouds and Land (ICESat-2) uses a similar technique to measure altitude and can reach higher latitudes to also detect changes in the Arctic biomes. The Ecosystem Spaceborne Thermal Radiometer Experiment on the Space Station (ECOSTRESS) measures the temperature of plants to determine their water consumption and health.
From the forest to the farm
While climate change affects the growth and health of vegetation, naturally occurring weather patterns also affect it. NASA Harvest scientists are studying the relationships between weather patterns in El Niño / La Niña and agricultural conditions and crop yields in eastern and southern Africa. During the El Niño years, winds and currents in the equatorial Pacific cause water to pool against South America and affect weather conditions around the globe – even in Africa. The researchers found that southern Africa tends to have lower crop yields during the El Niño phases, while East Africa has higher crop yields during these years. Knowing about these relationships can help farmers and policy makers prepare for a particular season.
NASA satellites and science are also helping US farmers monitor and track their crops. When farmers have more information on rainfall, crop health, and other data, they will get information they use to manage the extreme weather events that are increasing due to climate change, as well as relocating planting areas and other impacts such as early freezes and heavier spring rains. The U.S. Department of Agriculture estimates and tracks crop production through farmer surveys and soil observations, using Landsat data, NASA computer models, and other geoscientific resources to provide a comprehensive overview. They also use MODIS tools to monitor daily vegetation health – all to determine what the crop yield will be and in which areas problems could arise.
The same satellites can also help scientists track the undesirable products of some agricultural fields, including runoff that flows into waterways. Farms, forests, tundra – all these overgrown ecosystems connect with other spheres of our home planet.
By Kate Ramsayer
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Last updated: April 19, 2021
Editor: Kate Ramsayer
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