Lawrence Livermore National Laboratory

Field hydro frac 3D plot

GEOS Team Aims for Exascale Target

October 28, 2016

Massively parallel physics simulations provide Lawrence Livermore with a wealth of data to complement experimental observation. Within the Physical and Life Sciences Directorate, computational geoscience is a cornerstone of the Atmospheric, Earth, and Energy Division's (AEED) efforts to advance energy and environmental technology. Because the nation's security depends in part on energy independence, a Livermore team developed GEOS—a three-dimensional, multi-physics modeling code that addresses problems of subsurface fracturing in rock. A key feature of GEOS is the ability to simulate the evolution of hydraulically driven fractures through rock. Hydraulic fracturing has driven the oil and gas boom over the last decade, but comprehensive understanding of the physical mechanisms that govern the process remains elusive.

LLNL researchers have measured how force moves through 3D granular materials such as sand and soil. Photo by Sean O'Flaherty.

Feeling the force between sand grains

August 24, 2016

For the first time, Lawrence Livermore National Laboratory (LLNL) researchers have measured how forces move through 3D granular materials, determining how this important class of materials might pack and behave in processes throughout nature and industry.

Granular materials such as sand, soil and rice exist everywhere around us. However, scientists and engineers do not yet fully understand how external forces move through these materials. The ability to quantify that force transmission is missing, yet critical in efforts to predict material behavior.

Using X-ray diffraction, computed tomography and new mathematical analysis, the team measured how forces move through a slowly compressed, opaque 3D granular material. The new technique confirmed that forces move spatially through granular materials in patterns that agree with theory and simulations, and tend to behave more uniformly as load is increased.

"Understanding how forces move through granular materials is important for building models and predicting the behavior of geologic materials such as sands and soils (e.g., when they fracture and flow during hydraulic fracturing and when they are penetrated to defeat buried enemy targets)," said Ryan Hurley, a PLS scientist and lead author of the study appearing in the Aug. 19 edition of the journal, Physical Review Letters.

Changes in cloud patterns during the last three decades, which likely have had a warming effect on the planet, sync up with climate model simulations. Image courtesy of NASA Goddard Space Flight Center.

Scientists find evidence for climate change in satellite cloud record

July 11, 2016

Scientists, including researchers from the Atmospheric, Earth and Energy Division of LLNL's Physical and Life Sciences directorate, have found that changes in cloud patterns during the last three decades match those predicted by climate model simulations. These cloud changes are likely to have had a warming effect on the planet.

Records of cloudiness from satellites originally designed to monitor weather are plagued by erroneous variability related to changes in satellite orbit, instrument calibration and other factors, so the team used a new technique to remove the variability from the records. The corrected satellite records exhibited large-scale patterns of cloud change between the 1980s and 2000s that are consistent with climate model predictions, including poleward retreat of mid-latitude storm tracks, expansion of subtropical dry zones and increasing height of the highest cloud tops.

The research from Lawrence Livermore National Laboratory, Scripps Institution of Oceanography, University of California, Riverside, and Colorado State University appears in the July 11 edition of the journal, Nature.

"What this paper brings to the table is the first credible demonstration that the cloud changes we expect from climate models and theory are currently happening," said study lead author Joel Norris, a climate researcher at Scripps.

Researchers have found that the dehydration of chlorite is likely crucial in explaining the high electrical conductivity observed in the Earth's mantle. Image courtesy of Johan Swanepoel via Getty Images.

Research finds clues to uncanny electrical conductivity in Earth's mantle

May 6, 2016

A team of scientists, including one at Lawrence Livermore National Laboratory (LLNL), has found that the dehydration of chlorite is likely to be crucial in explaining the anomalously high electrical conductivity observed in the Earth's mantle.

The high electrical conductivity (EC) in the mantle wedge regions between depths of 40 and 100 km is often attributed to the aqueous fluid released from descending slabs. It is well known that mantle silicate minerals are electrical insulators with large electronic band gaps of around 7.5 to 9.5 electron volts (eV) at room temperature.

Laboratory-based measurements of the electrical conductivity of hydrous phases and aqueous fluids are significantly lower and cannot readily explain the geophysically observed high electrical conductivity. The released aqueous fluid also rehydrates the mantle wedge and stabilizes a suite of hydrous phases, including serpentine and chlorite.

The new research, appearing in the May 6 edition of the journal Science Advances, shows that the EC of chlorite is similar to other hydrous silicate minerals. The EC has a weak or no-pressure dependence but varies significantly with temperature.

"We have measured the electrical conductivity of a natural chlorite at pressures and temperatures relevant for the subduction zone setting," said Davide Novella, a geophysicist at LLNL. "In our experiment, we observed two distinct conductivity enhancements when chlorite is heated to temperatures beyond its thermodynamic stability field. The initial increase in electrical conductivity can be attributed to chlorite dehydration and the release of aqueous fluids. This is followed by a unique, subsequent enhancement of electrical conductivity."

Many clouds surround the Southern Ocean. Lawrence Livermore scientists have found that climate models don't accurately portray clouds and in turn underestimate global warming. Photo courtesy of NASA.

Climate models underestimate global warming by exaggerating cloud 'brightening'

April 7, 2016

Researchers at Lawrence Livermore National Laboratory and Yale University have found that climate models are aggressively making clouds "brighter" as the planet warms. This may be causing models to underestimate how much global warming will occur due to increasing carbon dioxide. The research appears in the April 8 edition of Science.

As the atmosphere warms, clouds become increasingly composed of liquid rather than ice, making them brighter. Because liquid clouds reflect more sunlight back to space than ice clouds, this "cloud phase feedback" acts as a brake on global warming in climate models.

But most models' clouds contain too much ice that is susceptible to becoming liquid with warming, which makes their stabilizing cloud phase feedback unrealistically strong. Using a state-of-the-art climate model, the researchers modified parameters to bring the relative amounts of liquid and ice in clouds into agreement with clouds observed in nature. Correcting the bias led to a weaker cloud phase feedback and greater warming in response to carbon dioxide.

"We found that the climate sensitivity increased from 4 degrees C in the default model to 5-5.3 degrees C in versions that were modified to bring liquid and ice amounts into closer agreement with observation," said Yale researcher Ivy Tan, lead author of the paper.

Lawrence Livermore scientists measured the carbon-14 content of carbon dioxide in air collected by high-altitude balloon flights in 2003, 2004 and 2005. Photo by E. Atlas.

Atmospheric carbon-14 measurements reveal natural production rate by cosmic rays

March 2, 2016

Lawrence Livermore National Laboratory researchers have measured the carbon-14 isotope (14C) produced by cosmic rays in the stratosphere and found its production rate is less than most previous estimates.

The team, led by Kristie Boering of the University of California, Berkeley and including Lawrence Livermore National Laboratory scientists, measured the 14C content of carbon dioxide in air collected by high-altitude balloon flights in 2003, 2004 and 2005, and estimated the contemporary 14C production in the stratosphere, nearly four decades after the Limited Test Ban Treaty restricted atmospheric testing of nuclear weapons.

Atmospheric testing of nuclear weapons in the 1950s and '60s injected massive amounts of 14C into the stratosphere. The amount of weapon 14C at that time was so large that it effectively hid the natural production of 14C by cosmic rays. Now that the weapon 14C has mostly dissipated from the atmosphere, the new measurements enabled the team to estimate the natural 14C source and found it was much lower than most previous estimates. The research appears in a recent edition of the journal Geophysical Research Letters.

"Our estimates are the first that use recent measurements of 14C concentration in the stratosphere to estimate the natural 14C production rate," said LLNL scientist Philip Cameron- Smith, a co-author on the paper. "We confirmed our analysis by simulating 14C with the LLNL atmospheric chemistry-transport model (IMPACT) on the Livermore Computing supercomputers."

Akin to having a fleet of miniature research vessels, the global flotilla of more than 3,000 robotic profiling floats provides crucial information on upper layers of the world's ocean currents. Photo by Alicia Navidad/ CSIRO.

Researcher sheds light on ocean observations

February 24, 2016

Oceanographer Paul Durack  of the Laboratory's Program for Climate Modeling and Intercomparison (PCMDI) recently opined about the importance of ocean salinity observations and needed urgent attention for the ocean observing system in the journal, Nature Climate Change.

The global water cycle — where, when and how it rains, and the corresponding changes to water availability — are as pressing an issue as any when it comes to climate change.

The global ocean is a great place to ascertain observed water cycle changes, as it contains 97 percent of the Earth's water and is where 80 percent of fluxes — water exchanges at the Earth's surface — occur.

The backbone of historical ocean measurements dates back to ocean research undertaken on the original RV Challenger cruise in 1872. Data from subsequent research cruises have been enhanced since 1999 by automated profilers called Argo, and a coherent global network of repeat ocean sampling undertaken by the international GO-SHIP Program. Argo has provided the first continuous, near-global salinity (and temperature) observing system, cycling at 10-day intervals in near real-time and taking measurements for the top 6,600 feet (2,000 meters) at a target density of one float per 3.3 degrees of the global ocean. This has significantly increased measurement coverage and density, particularly for the Southern Hemisphere that has been the focus of recent LLNL research.

Melting glaciers like the Equp Sermia glacier in West Greenland, is contributing to sea level rise, one of the most noticeable effects of global warming. Image courtesy of Michele Koppes, University of British Columbia.

Consequences of today's carbon emissions will linger for thousands of years, study finds

February 8, 2016

The Earth may suffer irreversible damage that could last tens of thousands of years because of the rate humans are emitting carbon into the atmosphere.

In a new study in Nature Climate Change, researchers at Oregon State University, Lawrence Livermore National Laboratory and collaborating institutions found that the longer-term impacts of climate change go well past the 21st century.

"Much of the carbon we are putting in the air from burning fossil fuels will stay there for thousands of years — and some of it will be there for more than 100,000 years," said Peter Clark, an Oregon State University paleoclimatologist and lead author on the article. "People need to understand that the effects of climate change on the planet won't go away, at least not for thousands of generations

LLNL's Benjamin Santer said the focus on climate change at the end of the 21st century needs to be shifted toward a much longer-term perspective.

"Our greenhouse gas emissions today produce climate-change commitments for many centuries to come," Santer said. "Today's actions — or inaction — will have long-term climate consequences for generations of our descendants."

"The long-term view sends the chilling message what the real risks and consequences are of the fossil fuel era," said Thomas Stocker of the University of Bern in Switzerland, who is past co-chair of the Intergovernmental Panel on Climate Change's (IPCC) Working Group I. "It will commit us to massive adaptation efforts so that for many, dislocation and migration becomes the only option."

Pacific and Atlantic southern sections showing upper-ocean warming for the past six decades (1955-2011). Red colors indicate warming and blue colors indicate cooling. Image by Timo Bremer/LLNL.

Livermore scientists find global ocean warming has doubled in recent decades

January 18, 2016

Lawrence Livermore scientists, working with National Oceanic and Atmospheric Administration and university colleagues, have found that half of the global ocean heat content increase since 1865 has occurred over the past two decades.

"In recent decades the ocean has continued to warm substantially, and with time the warming signal is reaching deeper into the ocean," said LLNL scientist Peter Gleckler, lead author of a paper (link is external) published in the journal Nature Climate Change.

Changes in ocean heat storage are important because the ocean absorbs more than 90 percent of the Earth's excess heat increase associated with global warming. The observed ocean and atmosphere warming is a result of continuing greenhouse gas emissions. Quantifying how much heat is accumulating in the Earth system is critical to improving the understanding of climate change already under way and to better assess how much more to expect in decades and centuries to come. It is vital to improving projections of how much and how fast the Earth will warm and seas rise in the future.

Increases in upper ocean temperatures since the 1970s are well documented and associated with greenhouse gas emissions. By including measurements from a 19th century oceanographic expedition and recent changes in the deeper ocean, the study indicates that half of the accumulated heat during the industrial era has occurred in recent decades, with about a third residing in the deeper oceans.

This integrated system would store carbon dioxide in an underground reservoir, with concentric rings of horizontal wells confining the pressurized CO2 beneath the caprock. Stored CO2 displaces brine that flows up wells to the surface where it is heated by thermal plants (e.g., solar farms) and reinjected into the reservoir to store thermal energy.

'Underground battery' could store energy, CO2

January 6, 2016

Meeting the Paris Climate Agreement goal of limiting the increase in the global average temperature to well below two degrees Celsius compared to pre-industrial levels will require increased use of renewable energy and reducing the CO2 intensity of fossil energy use.

The intermittency of when the wind blows and when the sun shines is one of the biggest challenges impeding the widespread integration of renewable energy into electric grids, while the cost of capturing CO2 and storing it permanently underground is a big challenge for decarbonizing fossil energy.

However, researchers from Lawrence Livermore National Laboratory, Ohio State University, University of Minnesota and TerraCOH, Inc. think they've found an answer to both of these problems with a large-scale system that incorporates CO2 sequestration and energy storage.

The team's paper, published in the December issue of Mechanical Engineering magazine, describes a subsurface energy system that could tap geothermal energy, store energy from above-ground sources, and dispatch it to the grid throughout the year like a massive underground battery, while at the same time storing CO2 from fossil-fuel power plants.

"If you want to store the large quantities of renewable energy necessary to balance seasonal supply-demand mismatches and store it efficiently, we believe the best way to do that is underground," said the paper's author, Thomas Buscheck, leader of the Lab's Geochemical, Hydrological and Environmental Sciences Group. "We believe this is a cost-effective way to store the energy long enough so it can be used later."

Buscheck's team's approach involves injecting liquid-like CO2 into underground reservoirs located in sedimentary rock, creating a pressurized plume that pushes brine up production wells to the surface. The brine could be heated and reinjected into the reservoir to store thermal energy, and the resulting pressurized CO2 would act as a shock absorber, enabling the system to be charged or discharged depending on supply and demand. When there's insufficient renewable energy, the pressurized CO2 and brine could be released and converted to power.

Rain showers descending. Photo courtesy of Haley Luna.

Climate models overestimate rainfall increases

December 10, 2015

Lawrence Livermore researchers and collaborators have found that most climate models overestimate the increase in global precipitation due to climate change.

Specifically, the team looked at 25 models and found they underestimate the increase in absorption of sunlight by water vapor as the atmosphere becomes moister, and therefore overestimate increases in global precipitation.

The team found global precipitation increase per degree of global warming at the end of the 21st century may be about 40 percent smaller than what the models, on average, currently predict.

The research appears in the Dec. 10 edition of the journal Nature.

Evaluation of model-predicted global precipitation change with actual precipitation observations is difficult due to uncertainties arising from many sources, including insufficient spatial and historical data coverage. As an alternative approach, the team, made up of LLNL scientist Mark Zelinka and colleagues from the University of California, Los Angeles, including lead author Anthony DeAngelis, evaluated model-simulated global precipitation change through consideration of the physical processes that govern it.

The team found that the increase in global precipitation simulated by models is strongly controlled by how much additional sunlight is absorbed by water vapor as the planet warms: Models in which more sunlight is absorbed by water vapor tend to have smaller increases in precipitation. They demonstrated that model-to-model differences in increased absorption of sunlight were not controlled by how much their humidity increased, but by how much additional sunlight was trapped in the atmosphere for a given increase in humidity. Conveniently, this quantity can be measured from space, allowing the team to assess how well the models capture the physics controlling changes in global precipitation.

cover of Nature vol. 527, 165.

PLS climate scientist reflects on 20 years of climate-change science

November 20, 2015

In a letter to the editors of Nature published in the Nov 12, 2015 edition of that journal, Lab climate scientist Ben Santer reflects on the impact of the 1995 Intergovernmental Panel on Climate Change (IPCC) 2nd Assessment Report, the lessons learned, and progress made since then in detecting and attributing the causes of observed changes in global climate. Santer was the convening lead author for the 8th chapter in the IPCC 2nd Assessment Report, entitled "Detection of climate change and attribution of causes". His letter to Nature is reproduced here.

From left, LLNL postdoc Jianchao Ye works on a lithium ion battery, while Morris Wang looks on. The two are part of a team studying the use of hydrogen for longer-lasting batteries.

Using hydrogen to enhance lithium ion batteries 

November 5, 2015

Lawrence Livermore National Laboratory scientists have found that lithium ion batteries operate longer and faster when their electrodes are treated with hydrogen.

Lithium ion batteries (LIBs) are a class of rechargeable battery types in which lithium ions move from the negative electrode to the positive electrode during discharge and back when charging.

The growing demand for energy storage emphasizes the urgent need for higher-performance batteries. Several key characteristics of lithium ion battery performance -- capacity, voltage and energy density -- are ultimately determined by the binding between lithium ions and the electrode material. Subtle changes in the structure, chemistry and shape of an electrode can significantly affect how strongly lithium ions bond to it.

Through experiments and calculations, the Livermore team discovered that hydrogen-treated graphene nanofoam electrodes in the LIBs show higher capacity and faster transport.

"These findings provide qualitative insights in helping the design of graphene-based materials for high-power electrodes," said Morris Wang, an LLNL materials scientist and co-author of a paper appearing in Nov. 5 edition of Nature Scientific Reports.

"The performance improvement we've seen in the electrodes is a breakthrough that has real world applications," said Jianchao Ye, who is a postdoc staff scientist at the Lab's Materials Science Division, and the leading author of the paper.

This model shows planetesimals accreting to a growing Earth 4.56 billion years ago. Image courtesy of Antoine Pitrou/Institut de Physique du Globe de Parise Physique.

Research lends new view of the Earth's core 

September 22, 2015

There is more oxygen in the core of Earth than originally thought.

Lawrence Livermore geologist Rick Ryerson and international colleagues discovered some new findings about Earth's core and mantle by considering their geophysical and geochemical signatures together.

This research provides insight into the origins of Earth's formation.

Based on the higher oxygen concentration of the core, Ryerson's team concludes that Earth must have accreted material that is more oxidized than the present-day mantle, similar to that of planetesimals such as asteroidal bodies. A planetesimal is an object formed from dust, rock and other materials and can be can be anywhere in size from several meters to hundreds of kilometers.

Earth formed about 4.56 billion years ago over a period of several tens of millions of years through the accretion of planetary embryos and planetesimals. The energy delivered by progressively larger impacts maintained Earth's outer layer and an extensively molten magma ocean. Gravitational separation of metal and silicate within the magma ocean results in the planet characterized by a metallic core and a silicate mantle.

The formation of Earth's core left behind geophysical and geochemical signatures in the core and mantle that remain to this day. In the past, core formation models have only attempted to address the evolution of core and mantle compositional signatures separately rather than looking for a joint solution.

Two workers oversee the emplacement of the canister that contained the chemical explosive charge for Source Physics Experiment-4 Prime at the Nevada National Security Site.

Laboratory's role in underground explosives tests will help nation's detection capabilities 

June 11, 2015

A Lawrence Livermore National Laboratory (LLNL) team played a leading role in fielding the recent Source Physics Experiment (SPE-4 Prime) detonated at the Nevada National Security Site (NNSS).

The SPE tests, including the most recent one on May 21, consist of a series of seven underground, high-explosive field tests in hard rock that are designed to improve the United States' ability to detect and identify low-yield nuclear explosions amid the clutter of conventional explosions and small earthquakes.

"As nuclear monitoring scientists, we are very excited by the new data from SPE-4 Prime," said Bill Walter, the SPE scientific leader for LLNL and the SPE-5 chief scientist. "It is the most over-buried field explosion in granite from which we have ever obtained data, and the data return and quality look excellent.

"We will be able to compare this new data with the prior SPE shots, which were shallower, allowing us to directly measure and understand the role that the interactions of the Earth's surface play in generating the signals we observe."

High-speed photograph of a controlled surface explosion at Kirtland Air Force Base in Albuquerque, New Mexico, similar to the explosions at White Sands Missile Range were used in a study of seismic signals to detect above-ground explosions.

Photo credit:
Defense Threat Reduction Agency (DTRA) Counter-WMD Test Support Division (CXT)

PLS researchers use seismic signals to track above-ground explosions 

May 20, 2015

Lawrence Livermore researchers have determined that a tunnel bomb explosion by Syrian rebels was less than 60 tons as claimed by sources.

Using seismic stations in Turkey, PLS scientists Michael Pasyanos and Sean Ford created a method to determine source characteristics of near-earth surface explosions. They found the above-ground tunnel bomb blast under the Wadi al-Deif Army Base near Aleppo last spring was likely not as large as originally estimated and was closer to 40 tons.

Seismology has long been used to determine the source characteristics of underground explosions, such as yield and depth, and plays a prominent role in nuclear explosion monitoring. But now some of the same techniques have been modified to determine the strength and source of near and above-ground blasts.

Researchers sample soil at the Pendleton Research Station (Columbia Basin Agricultural Research Center, Oregon State University.) Photo by Markus Kleber.

Soil organic matter vulnerable to climate change 

March 31, 2015

Soil organic matter, long thought to be a semi-permanent storehouse for ancient carbon, may be much more vulnerable to climate change than previously thought.

Plants direct between 40 percent and 60 percent of photosynthetically fixed carbon to their roots and much of this carbon is secreted and then taken up by root-associated soil microorganisms. Elevated carbon dioxide (CO2) concentrations in the atmosphere are projected to increase the quantity and alter the composition of root secretions released into the soil.

In new research in the March 30, 2015 edition of the journal, Nature Climate Change , Lawrence Livermore scientists and collaborators found that the common root secretion, oxalic acid, can promote soil carbon loss by an unconventional mechanism — freeing organic compounds from protective associations with minerals.

Microcapsules containing sodium carbonate solution are suspended on a mesh during carbon dioxide absorption testing.

Microcapsules capture carbon safely 

February 4, 2015

Using the same baking soda found in most grocery stores, Lawrence Livermore scientists, along with colleagues from Harvard University and the University of Illinois at Urbana-Champaign, have created a significant advance in carbon dioxide capture.

The team developed a new type of carbon capture media composed of core-shell microcapsules, which consist of a highly permeable polymer shell and a fluid (made up of sodium carbonate solution) that reacts with and absorbs carbon dioxide (CO2). Sodium carbonate is typically known as the main ingredient in baking soda. The capsules keep the liquid contained inside the core, and allow the CO2 gas to pass back and forth through the capsule shell.

Image of Cantona, one of the largest cities in pre-Columbian Mesoamerica, with a population of 90,000 inhabitants at its peak.

Lawrence Livermore research finds early Mesoamericans affected by climate change 

January 26, 2015

Lawrence Livermore researcher Susan Zimmerman and colleagues analyzed pollen, stable isotopes and elemental concentrations, which serve as proxies of past climatic and environmental conditions, from lake sediments in the region and found evidence of a regional drought between 500 and 1150 AD, about the time Cantona was abandoned.

Ionic liquids (molten salts) are important solvents in the microbial production of biofuels, but can inhibit microbial growth.

Lawrence Livermore scientists discover bacterial resistance to improve biofuel production  

March 26, 2014

Resistance is not futile when it comes to a new method to more efficiently convert biomass to biofuels. New research by scientists from Lawrence Livermore National Laboratory in conjunction with the Joint BioEnergy Institute (JBEI) suggests that a type of bacterial resistance may provide more efficient production of biofuels.

The Earth's average surface air temperature has increased by about 1.4 degrees Fahrenheit since 1900, with much of this increase taking place since the mid-1970s, according to a new report.

Science academies explain global warming in 'plain English' 

February 28, 2014

If emissions of greenhouse gases continue in a business-as-usual manner, future changes in climate will substantially exceed those that have occurred so far, with a warming of the Earth in the range of roughly 5 to 9 degrees Fahrenheit by the end of the century.

LLNL scientist Benjamin Santer and his climbing group ascend Mt. St. Helens in April 1980, about a month before its major eruption.

Volcanoes contribute to recent warming 'hiatus' 

February 23, 2014

Volcanic eruptions in the early part of the 21st century have cooled the planet, according to a study led by Lawrence Livermore National Laboratory. This cooling partly offset the warming produced by greenhouse gases.

A massive crack runs about 18 miles across the Pine Island Glacier's floating tongue, marking the moment of creation for a new iceberg.

Current ice melt rate in Pine Island Glacier may go on for decades 

February 21, 2014

A study of the Pine Island Glacier could provide insight into the patterns and duration of glacial melt. New research by an international team including researchers from LLNL shows that this same glacier also experienced rapid thinning about 8,000 years ago. Using LLNL's Center for Accelerator Mass Spectrometry, Livermore researchers Bob Finkel and Dylan Rood reported that the melting 8,000 years ago was sustained for decades to centuries at an average rate of more than 100 centimeters per year. This is comparable to modern-day melting rates.

Living and fossilized coral are gathered from dives in the Hawaiian Islands.

Change in Pacific nitrogen content tied to climate change 

December 15, 2013

Using deep sea corals gathered near the Hawaiian Islands, a Lawrence Livermore scientist, in collaboration with UC Santa Cruz colleagues, has determined that a long-term shift in nitrogen content in the Pacific Ocean has occurred as a result of climate change.

Lawrence Livermore scientists have found that observed changes in global precipitation are directly affected by human activities.

LLNL scientists find precipitation, global warming link 

November 11, 2013

A new study by Lawrence Livermore National Laboratory scientists shows that observed changes in global (ocean and land) precipitation are directly affected by human activities and cannot be explained by natural variability alone.

Manmade changes such as the increased production of greenhouse gases causes the stratosphere to cool while the mid- to upper troposphere heats up.

LLNL study finds human activity affects vertical structure of atmospheric temperature 

September 17, 2013

Human influences have directly impacted the latitude/altitude pattern of atmospheric temperature. That is the conclusion of a new report by scientists from LLNL and six other scientific institutions.