MultiPlanetary


Stunning Galaxy Bracelet

Half off thru June 21.

$20.00



NASA JPL

EARTH

Satellites Show How Earth’s Water Cycle Is Ramping Up as Climate Warms

This image shows a forest giving off moisture into the air, or transpiring. When combined with moisture that evaporates from the land, both processes drive evapotranspiration, a key branch of the water cycle. As the climate warms, these processes are expected to intensify. Credit: Acarapi / Adobe Stock

NASA scientists have studied 17 years of gravity observations of our planet to understand how the global water cycle is changing.

The rate at which plants and the land surface release moisture into the air has increased on a global scale between 2003 and 2019. These processes are collectively known as evapotranspiration, and a new NASA study has calculated its increase by using observations from gravity satellites.

By gauging the mass change of water between the oceans and the continents, the researchers determined that evapotranspiration’s rate of increase is up to two times higher than previous estimates. This is important because evapotranspiration represents a critical branch of the global water cycle – a cycle that creates the conditions for life on land.

While it is known that a warming climate should increase the rate of evapotranspiration, accurate global measurements have, until now, been elusive.

“Our study found that evapotranspiration has increased by about 10% since 2003, which is more than previously estimated, and is mostly due to warming temperatures,” said Madeleine Pascolini-Campbell, a postdoctoral researcher at NASA’s Jet Propulsion Laboratory in Southern California, who led the study. “We hope that this information about the water cycle will help to better inform the development and validation of climate models.”

But how does the rate of evapotranspiration affect the global water cycle? As moisture from the oceans circulates through the atmosphere, a portion falls as precipitation over the continents. Some of this water goes into rivers as runoff, and some seeps into soils. The remaining water evaporates from the land and transpires from plants back into the air.

Finding that evapotranspiration is increasing at a faster rate than previously known has implications for understanding how climate change could impact Earth in the future. As the world warms, evapotranspiration will accelerate, speeding up the drying of land and vegetation. Weather patterns can also be affected: Increased evaporation from land can create droughts in some regions. This is a symptom of a warming world that can have major consequences for ecosystems and human societies as stress on surface and groundwater supplies increases.

“Images of melting glaciers and shrinking ice sheets are a palpable way for us to understand the impacts of global warming,” said Pascolini-Campbell. “But dramatic changes are also happening to other key components of our planet’s water cycle that aren’t so visible, such as when water evaporates from the land before it can enter the rivers as runoff.”

The Gravity of Water

To get a global estimate of how evapotranspiration is changing, researchers found a new way to leverage data collected by the pair of Gravity Recovery and Climate Experiment (GRACE) satellites that operated from 2002 to 2017, and the successor pair, GRACE Follow-On, that launched in 2018. The GRACE mission was launched by NASA and the German Aerospace Center (DLR), and GRACE-FO is a partnership between NASA and German Research Centre for Geosciences (GFZ).

Because water has mass and therefore contributes to the Earth’s gravity signal, these spacecraft are exquisitely sensitive to the movement of water around the world, from tracking changes in ice sheets to water stored on land to variations in ocean mass. Seeing an opportunity, the researchers studied the 17-year dataset from GRACE and GRACE-FO to see if it was possible to tease out the gravitational signal associated with the movement of water by evapotranspiration.

“With the combined record of GRACE and GRACE-FO, we now have a long-enough observational record to be able to monitor these critical signs of global change,” said JT Reager, a JPL scientist and an investigator on the study. “When the gravity signal decreases, it means the land is losing water. Some of that loss is through rivers flowing back into the oceans, but the rest of it goes up into the atmosphere as evapotranspiration.”

By subtracting all the water mass outputs from the inputs over land and then calculating the residual mass of water, the researchers were able to estimate the rate of evapotranspiration. They did this by subtracting independent estimates of global river discharge (in other words, the rate of water flowing through rivers to the ocean) and GRACE and GRACE-FO satellite data (that reveal the local changes in water mass on and in the ground) from global precipitation measurements to find out the mass of water being lost to the atmosphere.

Due to observational and measurement challenges, global estimates of evapotranspiration are typically approximated using models or by taking measurements from individual locations and then scaling those measurements up. But these methods can be prone to error. By measuring global mass changes using gravity satellite observations, however, the researchers were able to get a more precise estimate for the rate of global evapotranspiration.

Using this method, they found that evapotranspiration increased from 405 millimeters (about 16 inches) per year in 2003 to 444 millimeters (about 17.5 inches) per year in 2019. That represents an upward trend of 2.30 millimeters (about 0.1 inches) per year –a 10% increase – with a corresponding uncertainty of 0.5 millimeters (0.02 inches) per year, or 2%.

“For years, we’ve been looking for a way to measure gross changes in the global water cycle, and finally we’ve found it,” said Reager. “The magnitude of the evapotranspiration increases really surprised us: This is a sizable signal indicating our planet’s water cycle is changing.”

These results add to a growing body of research about our planet’s water cycle while also underlining the importance of continuity for Earth observations. Continuous satellite observations by satellites with a global view of water mass changes provide the long record necessary to observe the changing planet over the decades. These observations also help scientists track year-to-year variability in the water cycle caused by climate change and natural cycles.

The study, titled: “A 10% increase in global land evapotranspiration from 2003 to 2019,” was published May 26 in Nature. In addition to JPL, NASA’s Goddard Space Flight Center, in Greenbelt, Maryland, contributed to this research.

JPL managed the GRACE mission and manages the GRACE-FO mission for NASA’s Earth Science Division of the Science Mission Directorate at NASA Headquarters in Washington. Based on Pasadena, California, Caltech manages JPL for NASA.

RELATED NEWS

ROBOTICS.Robotic Navigation Tech Will Explore the Deep OceanEARTH.Caldera Collapse Increases the Size and Duration of Volcanic EruptionsEARTH.International Cutting-Edge SWOT Satellite to Survey the World’s WaterEARTH.In a First, Scientists Map Particle-Laden Rivers in the SkyASTEROIDS AND COMETS.NASA to Participate in Tabletop Exercise Simulating Asteroid ImpactCLIMATE CHANGE.NASA-Built Instrument Will Help to Spot Greenhouse Gas Super-EmittersEARTH.NASA Satellites Detect Signs of Volcanic Unrest Years Before EruptionsTECHNOLOGY.POINTER: Seeing Through Walls to Help Locate FirefightersCLIMATE CHANGE.After COVID-19 Delay, Delta-X Field Campaign Begins in LouisianaASTEROIDS AND COMETS.NASA Analysis: Earth Is Safe From Asteroid Apophis for 100-Plus Years

EXPLORE MORE

IMAGE.Nubian Sandstone Aquifer, Egypt

IMAGE.Lake Oroville, CA, 2014

IMAGE.St. Pierre, France

IMAGE.Fluorescence Map of a Greenland Borehole

IMAGE.Preparing WATSON for Borehole Descent

IMAGE.WATSON’s Field Test in Greenland

IMAGE.Suez Canal Crisis

IMAGE.Namibia Dunes

RELATED NASA SITES

Basics of Spaceflight

Climate Kids

Earth / Global Climate Change

Exoplanet Exploration

Mars Exploration

Solar System Exploration

Space Place

NASA’s Eyes Visualization Project

Voyager Interstellar Mission

NASA

Caltech

Home

NASA Science Mission Directorate

NASA SCIENCESHARE THE SCIENCE

Leadership Team

The Office of the Associate Administrator for NASA’s Science Mission Directorate (SMD) is responsible for directing and overseeing the nation’s space research program in Earth and space science. The Directorate engages the external and internal science community to define and prioritize science questions and seeks to expand the frontiers of five broad scientific pursuits: Earth Science, Planetary Science, Biological and Physical Sciences, Heliophysics, and Astrophysics.

Through a variety of robotic observatory and explorer craft, and through sponsored research, the Directorate provides virtual human access to the farthest reaches of space and time, as well as practical information about changes on our home planet.

Dr. Thomas Zurbuchen portrait

Dr. Thomas Zurbuchen
Associate Administrator

Sandra Connelly Portrait

Sandra E. Connelly
Deputy Associate Administrator

Dr. Michael New Portrait

Dr. Michael New
Deputy Associate Administrator for Research

Kearns_Joel-2019_300_PHOTO_4 (002) v2.jpg

Dr. Joel Kearns
Deputy Associate Administrator for Exploration

Photo of Dr. Wanda Peters

Dr. Wanda Peters
Deputy Associate Administrator for Programs

Karen Flynn Portrait

Karen Flynn
Deputy Associate Administrator for Management

Science Division Directors

The SMD Division Directors lead NASA scientists and engineers across the globe in the development and operations of over 100 missions/year.

Dr. Paul Hertz

Dr. Paul Hertz
Astrophysics Division Director

Dr. Craig Kundrot Portrait

Dr. Craig Kundrot
Biological and Physical Sciences Division Director

Karen St. Germain Portrait

Dr. Karen M. St. Germain
Earth Science Division Director

Dr. Nicola Fox Portrait

Dr. Nicola Fox
Heliophysics Division Director

John Lee Portrait

John Lee
Joint Agency Satellite Division Director

Dr. Lori Glaze Portrait

Dr. Lori Glaze
Planetary Science Division Director

Program Directors

Gregory Robinson Portrait

Gregory Robinson
James Webb Space Telescope Program Director

Jeff Gramling Portrait

Jeff Gramling
Mars Sample Return Program Director

Other Division Directors

Holly Degn Portrait

Holly Degn
Resource Management Division Director

Kristen Erickson Portrait

Kristen J. Erickson
Science Engagement and Partnerships Division Director

Branch Chiefs

Ellen Gersten Portrait

Ellen Gertsen
Chief of the Administration Branch

Dr. Jens Freely

Dr. Jens Feeley
Chief of Policy Branch

Senior Communication

Photo of woman standing in front of a screen.

Karen Fox
Senior Science Communications Officer

Stay Connected

NASA Official: Dr. Mamta Patel Nagaraja


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: