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By NASA
Earth (ESD) Earth Explore Climate Change Science in Action Multimedia Data For Researchers About Us 4 min read
NASA Study: Crops, Forests Responding to Changing Rainfall Patterns
Earth’s rainy days are changing and plant life is responding. This visualization shows average precipitation for the entire globe based on more than 20 years of data from 2000 to 2023. Cooler colors indicate areas that receive less rain. Warm colors receive more rain. NASA’s Scientific Visualization Studio A new NASA-led study has found that how rain falls in a given year is nearly as important to the world’s vegetation as how much. Reporting Dec. 11 in Nature, the researchers showed that even in years with similar rainfall totals, plants fared differently when that water came in fewer, bigger bursts.
In years with less frequent but more concentrated rainfall, plants in drier environments like the U.S. Southwest were more likely to thrive. In humid ecosystems like the Central American rainforest, vegetation tended to fare worse, possibly because it could not tolerate the longer dry spells.
Scientists have previously estimated that almost half of the world’s vegetation is driven primarily by how much rain falls in a year. Less well understood is the role of day-to-day variability, said lead author Andrew Feldman, a hydrologist and ecosystem scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Shifting precipitation patterns are producing stronger rainstorms — with longer dry spells in between — compared to a century ago.
“You can think of it like this: if you have a house plant, what happens if you give it a full pitcher of water on Sunday versus a third of a pitcher on Monday, Wednesday, and Friday?” said Feldman. Scale that to the size of the U.S. Corn Belt or a rainforest and the answer could have implications for crop yields and ultimately how much carbon dioxide plants remove from the atmosphere.
Blooms in Desert
The team, including researchers from the U.S. Department of Agriculture and multiple universities, analyzed two decades of field and satellite observations, spanning millions of square miles. Their study area encompassed diverse landscapes from Siberia to the southern tip of Patagonia.
Yellow wildflowers and orange poppies carpet the desert following a wet winter for the Antelope Valley in California. NASA/Jim Ross They found that plants across 42% of Earth’s vegetated land surface were sensitive to daily rainfall variability. Of those, a little over half fared better — often showing increased growth — in years with fewer but more intense wet days. These include croplands as well as drier landscapes like grasslands and deserts.
In contrast, broadleaf (e.g., oak, maple, and beech) forests and rainforests in lower and middle latitudes tended to fare worse under those conditions. The effect was especially pronounced in Indo-Pacific rainforests, including in the Philippines and Indonesia.
Statistically, daily rainfall variability was nearly as important as annual rainfall totals in driving growth worldwide.
Red Light, Green Light
The new study relied primarily on a suite of NASA missions and datasets, including the Integrated Multi-satellitE Retrievals for GPM (IMERG) algorithm, which provides rain and snowfall rates for most of the planet every 30 minutes using a network of international satellites.
To gauge plant response day to day, the researchers calculated how green an area appeared in satellite imagery. “Greenness”, also known asthe Normalized Difference Vegetation Index, is commonly used to estimate vegetation density and health. They also tracked a faint reddish light that plants emit during photosynthesis, when a plant absorbs sunlight to convert carbon dioxide and water into food, its chlorophyll “leaks” unused photons. This faint light is called solar-induced fluorescence, and it’s a telltale sign of flourishing vegetation.
Growing plants emit a form of light detectable by NASA satellites orbiting hundreds of miles above Earth. Parts of North America appear to glimmer in this visualization, depicting an average year. Gray indicates regions with little or no fluorescence; red, pink, and white indicate high fluorescence. NASA Scientific Visualization Studio Not visible bythe naked eye, plant fluorescence can be detected by instruments aboard satellites such as NASA’s Orbiting Carbon Observatory-2 (OCO-2). Launched in 2014, OCO-2 has observed the U.S. Midwest fluorescing strongly during the growing season.
Feldman said the findings highlight the vital role that plants play in moving carbon around Earth — a process called the carbon cycle. Vegetation, including crops, forests, and grasslands, forms a vast carbon “sink,” absorbing excess carbon dioxide from the atmosphere.
“A finer understanding of how plants thrive or decline day to day, storm by storm, could help us better understand their role in that critical cycle,” Feldman said.
The study also included researchers from NASA’s Jet Propulsion Laboratory in Southern California, Stanford University, Columbia University, Indiana University, and the University of Arizona.
By Sally Younger
NASA’s Earth Science News Team
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Last Updated Dec 11, 2024 Related Terms
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By NASA
6 min read
NASA-ISRO Radar Mission to Provide Dynamic View of Forests, Wetlands
NISAR will use radar to study changes in ecosystems around the world, such as this forest in Tikal National Park in northern Guatemala, to understand how these areas are affected by climate change and human activity, and the role they play in the global carbon cycle.Credit: USAID NISAR will help researchers explore how changes in Earth’s forest and wetland ecosystems are affecting the global carbon cycle and influencing climate change.
Once it launches in early 2024, the NISAR radar satellite mission will offer detailed insights into two types of ecosystems – forests and wetlands – vital to naturally regulating the greenhouses gases in the atmosphere that are driving global climate change.
NISAR is a joint mission by NASA and ISRO (Indian Space Research Organisation), and when in orbit, its sophisticated radar systems will scan nearly all of Earth’s land and ice surfaces twice every 12 days. The data it collects will help researchers understand two key functions of both ecosystem types: the capture and the release of carbon.
Pictured in this artist’s concept, NISAR, short for NASA-ISRO Synthetic Aperture Radar, marks the first time the U.S. and Indian space agencies have cooperated on hardware development for an Earth-observing mission. Its two radar systems will monitor change in nearly all of Earth’s land and ice surfaces twice every 12 days.Credit: NASA/JPL-Caltech Forests hold carbon in the wood of their trees; wetlands store it in their layers of organic soil. Disruption of either system, whether gradual or sudden, can accelerate the release of carbon dioxide and methane into the atmosphere. Tracking these land-cover changes on a global scale will help researchers study the impacts on the carbon cycle – the processes by which carbon moves between the atmosphere, land, ocean, and living things.
“The radar technology on NISAR will allow us to get a sweeping perspective of the planet in space and time,” said Paul Rosen, the NISAR project scientist at NASA’s Jet Propulsion Laboratory in Southern California. “It can give us a really reliable view of exactly how Earth’s land and ice are changing.”
Tracking Deforestation
Forestry and other land-use changes account for about 11% of net human-caused greenhouse gas emissions. NISAR’s data will improve our understanding of how the loss of forests around the world influences the carbon cycle and contributes to global warming.
“Globally, we do not understand well the carbon sources and sinks from terrestrial ecosystems, particularly from forests,” said Anup Das, an ecosystems scientist and co-lead of the ISRO NISAR science team. “So we expect that NISAR will greatly help address that, especially in less dense forests, which are more vulnerable to deforestation and degradation.”
To show the kind of imagery NISAR will produce, researchers pointed to this composite that uses data from two Japanese L-band SAR missions to reveal land-cover change in Brazil’s Xingu River basin between 1996 and 2007. Black shows forest areas converted to farmland before 1996, and red shows additional areas cleared by 2007.Credit: Woodwell Climate Research Center/Earth Big Data LLC. Data courtesy of METI and JAXA. The signal from NISAR’s L-band radar will penetrate the leaves and branches of forest canopies, bouncing off the tree trunks and the ground below. By analyzing the signal that reflects back, researchers will be able to estimate the density of forest cover in an area as small as a soccer field. With successive orbital passes, it will be able to track whether a section of forest has been thinned or cleared over time. The data – which will be collected in early morning and evening and in any weather – could also offer clues as to what caused the change, such as disease, human activity, or fire.
It’s an important set of capabilities for studying vast, often cloud-covered rainforests such as those in the Congo and Amazon basins, which lose millions of wooded acres every year. Fire releases carbon into the air directly, while the deterioration of forests reduces the absorption of atmospheric carbon dioxide.
The data could also help improve accounting of deforestation and forest degradation – as well as forest growth – as countries that rely on logging try to shift toward more sustainable practices, said Josef Kellndorfer, a member of the NISAR science team and founder of Earth Big Data LLC, a provider of large data sets and analytic tools for research and decisions support. “Reducing deforestation and degradation is low-hanging fruit to address a substantial part of the global carbon emission problem,” he added.
Monitoring Wetland Flooding
Wetlands present another carbon puzzle: Swamps, bogs, peatlands, inundated forests, marshes, and other wetlands hold 20 to 30% of the carbon in Earth’s soil, despite constituting only 5 to 8% of the land surface.
When wetlands flood, bacteria go to work digesting organic matter (mostly dead plants) in the soil. Through this natural process, wetlands are the planet’s largest natural source of the potent greenhouse gas methane, which bubbles to the water’s surface and travels into the atmosphere. Meanwhile, when wetlands dry out, the carbon they store is exposed to oxygen, releasing carbon dioxide.
NISAR will track wetland flooding to study how these carbon-rich ecosystems are reacting to climate change. It will generate images like this one from an airborne radar that flew over Peru in 2013. Black indicates water, gray is rainforest, green is low vegetation, and red and pink are flooded plants.Credit: NASA/JPL-Caltech “These are huge reservoirs of carbon that can be released in a relatively short time frame,” said Erika Podest, a NISAR science team member and a carbon cycle and ecosystems researcher at JPL.
Less well understood is how changing temperature and precipitation patterns due to climate change – along with human activities such as development and agriculture – are affecting the extent, frequency, and duration of flooding in wetlands. NISAR will be able to monitor flooding, and with repeated passes, researchers will be able to track seasonal and annual variations in wetlands inundation, as well as long-term trends.
By coupling NISAR’s wetlands observations with separate data on the release of greenhouse gases, researchers should gain insights that inform the management of wetland ecosystems, said Bruce Chapman, a NISAR science team member and JPL wetlands researcher. “We have to be careful to reduce our impact on wetland areas so that we don’t worsen the situation with the climate,” he added.
NISAR is set to launch in early 2024 from southern India. In addition to tracking ecosystem changes, it will collect information on the motion of the land, helping researchers understand the dynamics of earthquakes, volcanic eruptions, landslides, and subsidence and uplift (when the surface sinks and rises). It will also track the movements and melting of both glaciers and sea ice.
More About the Mission
NISAR is an equal collaboration between NASA and ISRO and marks the first time the two agencies have cooperated on hardware development for an Earth-observing mission. JPL, which is managed for NASA by Caltech in Pasadena, leads the U.S. component of the project and is providing the mission’s L-band SAR. NASA is also providing the radar reflector antenna, the deployable boom, a high-rate communication subsystem for science data, GPS receivers, a solid-state recorder, and payload data subsystem. ISRO’s U R Rao Satellite Centre in Bengaluru, which is leading the ISRO component of the mission, is providing the spacecraft bus, the S-band SAR electronics, the launch vehicle, and associated launch services and satellite mission operations.
To learn more about NISAR, visit:
https://nisar.jpl.nasa.gov/
See the NISAR spacecraft in 3D in NASA's interactive Eyes on the Earth News Media Contacts
Andrew Wang / Jane J. Lee
Jet Propulsion Laboratory, Pasadena, Calif.
626-379-6874 / 818-354-0307
andrew.wang@jpl.nasa.gov / jane.j.lee@jpl.nasa.gov
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Last Updated Oct 27, 2023 Related Terms
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By European Space Agency
With more than 100 global leaders at COP26 having pledged to halt and reverse deforestation and land degradation by the end of the decade to help address the climate crisis, the health of the world’s forests is high on the political agenda. ESA’s Biomass mission will soon play a key role in delivering novel information about the of the state of our forests, how they are changing over time, and advance our knowledge of the carbon cycle. With launch scheduled for 2023, the mission is now in its last phases of development, having recently passed several key milestones.
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