What's New Archive

NOAA and NASA researchers have found that Earth’s energy imbalance approximately doubled during the 14-year period from 2005 to 2019. Earth's climate is determined by a delicate balance between how much of the Sun's radiative energy is absorbed in the atmosphere and at the surface and how much thermal infrared radiation Earth emits to space. A positive energy imbalance means the Earth system is gaining energy, causing the planet to heat up. The doubling of the energy imbalance is the topic of a recent study, the results of which were published June 15 in Geophysical Research Letters.

Scientists compared data from two independent measurements. NASA's Clouds and the Earth's Radiant Energy System (CERES) suite of satellite sensors measure how much energy enters and leaves Earth's system. In addition, data from a global array of ocean floats, called Argo, enable an accurate estimate of the rate at which the world’s oceans are heating up. Since approximately 90 percent of the excess energy from an energy imbalance ends up in the ocean, the overall trends of incoming and outgoing radiation should broadly agree with changes in ocean heat content.

"The two very independent ways of looking at changes in Earth's energy imbalance are in really, really good agreement, and they're both showing this very large trend, which gives us a lot of confidence that what we're seeing is a real phenomenon and not just an instrumental artifact, " said Norman Loeb, lead author for the study and principal investigator for CERES at NASA's Langley Research Center in Hampton, Virginia. "The trends we found were quite alarming in a sense."

Increases in emissions of greenhouse gases such as carbon dioxide and methane due to human activity trap heat in the atmosphere, capturing outgoing radiation that would otherwise escape into space. The warming drives other changes, such as snow and ice melt, and increased water vapor and cloud changes that can further enhance the warming. Earth’s energy imbalance is the net effect of all these factors. In order to determine the primary factors driving the imbalance, the investigators used a method that looked at changes in clouds, water vapor, combined contributions from trace gases and the output of light from the Sun, surface albedo (the amount of light reflected by the Earth's surface), tiny atmospheric particles called aerosols, and changes in surface and atmospheric temperature distributions.

The study finds that the doubling of the imbalance is partially the result an increase in greenhouse gases due to human activity, also known as anthropogenic forcing, along with increases in water vapor are trapping more outgoing longwave radiation, further contributing to Earth’s energy imbalance. Additionally, the related decrease in clouds and sea ice lead to more absorption of solar energy.

The researchers also found that a flip of the Pacific Decadal Oscillation (PDO) from a cool phase to a warm phase likely played a major role in the intensification of the energy imbalance. The PDO is a pattern of Pacific climate variability. Its fingerprint includes a massive wedge of water in the eastern Pacific that goes through cool and warm phases. This naturally occurring internal variability in the Earth system can have far-reaching effects on weather and climate. An intensely warm PDO phase that began around 2014 and continued until 2020 caused a widespread reduction in cloud coverage over the ocean and a corresponding increase in the absorption of solar radiation.

"It's likely a mix of anthropogenic forcing and internal variability," said Loeb. "And over this period they're both causing warming, which leads to a fairly large change in Earth's energy imbalance. The magnitude of the increase is unprecedented."

Loeb cautions that the study is only a snapshot relative to long-term climate change, and that it's not possible to predict with any certainty what the coming decades might look like for the balance of Earth's energy budget. The study does conclude, however, that unless the rate of heat uptake subsides, greater changes in climate than are already occurring should be expected.

"The lengthening and highly complementary records from Argo and CERES have allowed us both to pin down Earth’s energy imbalance with increasing accuracy, and to study its variations and trends with increasing insight, as time goes on." said Gregory Johnson, co-author on the study and physical oceanographer at the National Oceanic and Atmospheric Administration's Pacific Marine Environmental Laboratory in Seattle, Washington. "Observing the magnitude and variations of this energy imbalance are vital to understanding Earth’s changing climate."

Read the original articles posted by NASA Langley.

The U.S. West Coast continental shelf is known to host methane bubble streams, formerly thought to be rare. However, results of a recently published paper indicate that nearly 3,500 methane bubble streams, clustered into more than 1,300 methane emission sites, emanate from the seafloor from the Strait of Juan de Fuca in the north to the Mendocino Fracture Zone off northern California in the south, in an area known as the Cascadia Margin. Derived from data collected during multibeam mapping surveys on Ocean Exploration Trust's Exploration Vessel (E/V) Nautilus, the University of Washington's Research Vessel (R/V) Thompson, NOAA Ship Rainier and historical data, the discovery sheds new light on the extent and distribution of seafloor methane seeps. These seeps may provide important habitat for marine life and could play an important role in ocean warming.

The results, published in Frontiers of Earth Science by scientists from the Oregon State University-NOAA Cooperative Institute for Marine Resources Studies (CIMRS) with PMEL's Earth-Ocean Interactions Program, University of Washington, U.S. Naval Research Lab at Stennis Space Center, and Ocean Exploration Trust, provide a major contribution to the first systematic “baseline” survey of methane seeps published over such a large area, representing over 40% of the 93,000 square kilometers (35,900 square miles) of the U.S. Cascadia margin.

Until recently, the number and distribution of methane seep sites in the northeast Pacific across depth and latitude was very poorly known, with previous estimates of methane seeps, based largely on historical fisheries survey data, suggesting about a thousand seeps existed along the U.S. Cascadia Margin.

In the Frontiers of Earth Science paper, scientists present the analyses of detailed seafloor and co-registered acoustic water column data from eight large-scale multibeam sonar surveys on the U.S. Cascadia Margin with previous historical data. The analyses resulted in a remarkably detailed view of where the 3,500 bubble streams (clustered into 1,300 methane emission sites) are located as well as the seafloor features associated with the seeps.

The methane sites are concentrated in water depths less than 800 meters (2,625 feet), although sites are also found in water as deep as 2,070 meters (6,790 feet) and as shallow as 40 meters (130 feet). In waters along the Cascadia Margin, methane hydrate is stable at depths greater than about 500 meters (1,640 feet) and is unstable at shallower depths.

The importance of these methane seeps goes beyond the numbers. These seeps host chemosynthetic communities, build rocky carbonate hard grounds that are essential fish habitat, and release an unknown quantity of methane to the ocean and potentially to the atmosphere, where it acts as a powerful greenhouse gas. This new seep compilation provides a baseline to evaluate possible future increasing methane gas flux as ocean waters warm and drive what is known as the methane hydrate stability zone deeper, releasing additional methane from its ice-like form.

As methane seeps are likely ubiquitous on most or all continental margins, this study literally provides a map for more detailed studies of the ecological importance of methane seeps along the west coast of the United States.

The database of all the combined methane bubble streams and clustered emission sites is publicly available on PMEL Earth Ocean Interaction Program website

What’s next: 

This summer and fall, some of the co-authors and other members of NOAA PMEL, University of Washington, and Oregon State University will participate in another Nautilus Cascadia Margin expedition as well as in the West Coast Ocean Acidification expedition aboard NOAA Ship Ron Brown. More data will be acquired for addition to this new database in order to better understand any potential impacts of methane seeps in the water column and to test new technologies.

Originally posted on NOAA Ocean Exploration. 

The Beaufort Gyre in the western Arctic Ocean is the largest oceanic freshwater reservoir in the Northern Hemisphere. It has increased its freshwater content by 40% over the past two decades. The fate of the excess freshwater and how and where this water will flow into the Atlantic Ocean is important for local and global ocean conditions. A new paper in Nature Communications, researchers from the University of Washington, NOAA's Pacific Marine Environmental Laboratory and the Department of Energy Los Alamos National Laboratory, show that a historical release during 1983-1996 freshened the western Labrador Sea by as much as 0.2 parts per thousand. The results imply that a future release of the current high volume of Beaufort Gyre freshwater could even be more impactful. 

This study is the first that quantifies the fate of the Beaufort Gyre freshwater after it is released and its downstream impact. The study shows that this freshwater travels through the Canadian Archipelago to reach the Labrador Sea, rather than through the wider marine passageways that connect to seas in Northern Europe. The results are based on passive tracers implemented in a global intermediate-resolution ocean sea-ice model, which is performed at the High Performance Computing facility at Los Alamos National Laboratory. 

“The Canadian Archipelago is a major conduit between the Arctic and the North Atlantic,” said lead author Jiaxu Zhang, a UW postdoctoral researcher at the Cooperative Institute for Climate, Ocean and Ecosystem Studies who began this work at Los Alamos National Laboratory. “In the future, if the winds get weaker and the freshwater gets released, there is a potential for this high amount of water to have a big influence in the Labrador Sea region.”

The finding has implications for the Labrador Sea marine environment, since Arctic water tends to be fresher but also rich in nutrients. This pathway also affects larger oceanic currents, namely a conveyor-belt circulation in the Atlantic Ocean in which colder, heavier water sinks in the North Atlantic and comes back along the surface as the Gulf Stream. Fresher, lighter water entering the Labrador Sea could slow that overturning circulation.

“We know that the Arctic Ocean has one of the biggest climate change signals,” said co-author Wei Cheng at the UW-based Cooperative Institute for Climate, Ocean and Atmosphere Studies. “Right now this freshwater is still trapped in the Arctic. But once it gets out, it can have a very large impact."

The exact impact is unknown. The study focused on past events, and current research is looking at where today’s freshwater buildup might end up and what changes it could trigger.

Read the full University of Washington News Release.

Shelled pteropods, microscopic free-swimming sea snails, are widely regarded as indicators for ocean acidification because research has shown that their fragile shells are vulnerable to increasing ocean acidity. Sometimes called sea butterflies because of how they appear to flap their “wings” as they swim through the water column, fat-rich pteropods are an important food source for organisms ranging from other plankton to juvenile salmon to whales. They make shells by fixing calcium carbonate in ocean water to form an exoskeleton. 

A new study, published in the journal Scientific Reports, shows that pteropods sampled off the coasts of Washington and Oregon made thinner shells than those in offshore waters. Along the coast, upwelling from deeper water layers brings cold, carbon dioxide-rich waters of relatively low pH to the surface. The research team of Dutch and American scientists found that the shells of pteropods collected in this upwelling region were 37 percent thinner than ones collected offshore.

 “It appears that pteropods make thinner shells where upwelling brings water that is colder and lower in pH to the surface, ” said lead author Lisette Mekkes of Naturalis Biodiversity Centers and the University of Amsterdam in the Netherlands. Mekkes added that while some shells also showed signs of dissolution, the change in shell thickness was particularly pronounced, demonstrating that acidified water interfered with pteropods’ ability to build their shells. 

The scientists examined shells of pteropods collected during the 2016 NOAA Ocean Acidification Program research cruise in the northern California Current Ecosystem onboard the NOAA Ship Ronald H. Brown. Shell thicknesses of 80 of the tiny creatures - no larger than the head of a pin - were analyzed using 3D scans provided by micron-scale computer tomography, a high-resolution X-ray technique. The scientists also examined the shells with a scanning electron microscope to assess if thinner shells were a result of dissolution. They also used DNA analysis to make sure the examined specimens belonged to a single population.  

 "Pteropod shells protect against predation and infection, but making thinner shells could also be an adaptive or acclimation strategy," said  Katja Peijnenburg,  group leader at Naturalis Biodiversity Center. "However, an important question is  how long can pteropods continue making thinner shells in rapidly acidifying waters?"

The California Current Ecosystem along the West Coast is especially vulnerable to ocean acidification because it not only absorbs carbon dioxide from the atmosphere, but is also bathed by seasonal upwelling of carbon-dioxide rich waters from the deep ocean. In recent years these waters have grown increasingly corrosive as a result of the increasing amounts of atmospheric carbon dioxide absorbed into the ocean. 

“Our research shows that within two to three months, pteropods transported by currents from the open-ocean to more corrosive nearshore waters have difficulty building their shells,” said Nina Bednarsek, a research scientist from the Southern California Coastal Water Research Project in Costa Mesa, California, a coauthor of the study. 

Over the last two-and-a-half centuries, scientists say, the global ocean has absorbed approximately 620 billion tons of carbon dioxide from emissions released into the atmosphere by burning fossil fuels, changes in land-use, and cement production, resulting in a process called ocean acidification.

“The new research provides the foundation for understanding how pteropods and other microscopic organisms are actively affected by progressing ocean acidification and how these changes can impact the global carbon cycle and ecological communities,” said Richard Feely, NOAA Pacific Marine Environmental Laboratory and chief scientist for the cruise.

This research was supported by NOAA’s Ocean Acidification Program  and the Netherlands Organization for Scientific Research. Story originally posted on NOAA Research.