First direct observation of carbon dioxide's increasing greenhouse effect at the Earth's surface

February 25, 2015

Scientists have observed an increase in carbon dioxide's greenhouse effect at the Earth's surface for the first time. The researchers, led by scientists from the US Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), measured atmospheric carbon dioxide's increasing capacity to absorb thermal radiation emitted from the Earth's surface over an eleven-year period at two locations in North America. They attributed this upward trend to rising CO2 levels from fossil fuel emissions.

The influence of atmospheric CO2 on the balance between incoming energy from the Sun and outgoing heat from the Earth (also called the planet's energy balance) is well established. But this effect has not been experimentally confirmed outside the laboratory until now. The research is reported Wednesday, Feb. 25, in the advance online publication of the journal Nature.

The results agree with theoretical predictions of the greenhouse effect due to human activity. The research also provides further confirmation that the calculations used in today's climate models are on track when it comes to representing the impact of CO2.

The scientists measured atmospheric carbon dioxide's contribution to radiative forcing at two sites, one in Oklahoma and one on the North Slope of Alaska, from 2000 to the end of 2010. Radiative forcing is a measure of how much the planet's energy balance is perturbed by atmospheric changes. Positive radiative forcing occurs when the Earth absorbs more energy from solar radiation than it emits as thermal radiation back to space. It can be measured at the Earth's surface or high in the atmosphere. In this research, the scientists focused on the surface.

They found that CO2 was responsible for a significant uptick in radiative forcing at both locations, about two-tenths of a Watt per square meter per decade. They linked this trend to the 22 parts-per-million increase in atmospheric CO2 between 2000 and 2010. Much of this CO2 is from the burning of fossil fuels, according to a modeling system that tracks CO2 sources around the world.

"We see, for the first time in the field, the amplification of the greenhouse effect because there's more CO2 in the atmosphere to absorb what the Earth emits in response to incoming solar radiation," says Daniel Feldman, a scientist in Berkeley Lab's Earth Sciences Division and lead author of the Nature paper.

"Numerous studies show rising atmospheric CO2 concentrations, but our study provides the critical link between those concentrations and the addition of energy to the system, or the greenhouse effect," Feldman adds.

He conducted the research with fellow Berkeley Lab scientists Bill Collins and Margaret Torn, as well as Jonathan Gero of the University of Wisconsin-Madison, Timothy Shippert of Pacific Northwest National Laboratory, and Eli Mlawer of Atmospheric and Environmental Research.

The scientists used incredibly precise spectroscopic instruments operated by the Atmospheric Radiation Measurement (ARM) Climate Research Facility, a DOE Office of Science User Facility. These instruments, located at ARM research sites in Oklahoma and Alaska, measure thermal infrared energy that travels down through the atmosphere to the surface. They can detect the unique spectral signature of infrared energy from CO2.

Other instruments at the two locations detect the unique signatures of phenomena that can also emit infrared energy, such as clouds and water vapor. The combination of these measurements enabled the scientists to isolate the signals attributed solely to CO2.

"We measured radiation in the form of infrared energy. Then we controlled for other factors that would impact our measurements, such as a weather system moving through the area," says Feldman.

The result is two time-series from two very different locations. Each series spans from 2000 to the end of 2010, and includes 3300 measurements from Alaska and 8300 measurements from Oklahoma obtained on a near-daily basis.

Both series showed the same trend: atmospheric CO2 emitted an increasing amount of infrared energy, to the tune of 0.2 Watts per square meter per decade. This increase is about ten percent of the trend from all sources of infrared energy such as clouds and water vapor.

Based on an analysis of data from the National Oceanic and Atmospheric Administration's CarbonTracker system, the scientists linked this upswing in CO2 -attributed radiative forcing to fossil fuel emissions and fires.

The measurements also enabled the scientists to detect, for the first time, the influence of photosynthesis on the balance of energy at the surface. They found that CO2 -attributed radiative forcing dipped in the spring as flourishing photosynthetic activity pulled more of the greenhouse gas from the air.
-end-
The scientists used the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility located at Berkeley Lab, to conduct some of the research.

The research was supported by the Department of Energy's Office of Science.

Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit http://www.lbl.gov.

DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at science.energy.gov/.

DOE/Lawrence Berkeley National Laboratory

Related Solar Radiation Articles from Brightsurf:

Sheer protection from electromagnetic radiation
A printable ink that is both conductive and transparent can also block radio waves.

What membrane can do in dealing with radiation
USTC recently found that polymethylmethacrylate (PMMA) and polyvinyl chloride (PVC) can release acidic substance under γ radiation, whose amount is proportional to the radiation intensity.

First measurements of radiation levels on the moon
In the current issue (25 September) of the prestigious journal Science Advances, Chinese and German scientists report for the first time on time-resolved measurements of the radiation on the moon.

Merging solar cell and liquid battery produces long-lasting solar storage
Combining liquid chemical battery technology with perovskite solar cells has led to a new record in solar energy conversion within a single device.

Merging solar cell and liquid battery produces efficient, long-lasting solar storage
Chemists at the University of Wisconsin-Madison and their collaborators have created a highly efficient and long-lasting solar flow battery, a way to generate, store and redeliver renewable electricity from the sun in one device.

New biomaterial could shield against harmful radiation
Northwestern University researchers have synthesized a new form of melanin enriched with selenium.

The effectiveness of a heating system is validated, heating air from solar radiation
The device, which takes advantage of heat generated on the outer layer of building facades, could cover the heating required to ventilate a building for up to 75% of the days in a cold season.

Solar wind samples suggest new physics of massive solar ejections
A new study led by the University of Hawai'i (UH) at Mānoa has helped refine understanding of the amount of hydrogen, helium and other elements present in violent outbursts from the Sun, and other types of solar 'wind,' a stream of ionized atoms ejected from the Sun.

Nimotuzumab-cisplatin-radiation versus cisplatin-radiation in HPV negative oropharyngeal cancer
Oncotarget Volume 11, Issue 4: In this study, locally advanced head and neck cancer patients undergoing definitive chemoradiation were randomly allocated to weekly cisplatin - radiation {CRT arm} or nimotuzumab -weekly cisplatin -radiation {NCRT arm}.

Breaking up amino acids with radiation
A new experimental and theoretical study published in EPJ D has shown how the ions formed when electrons collide with one amino acid, glutamine, differ according to the energy of the colliding electrons.

Read More: Solar Radiation News and Solar Radiation Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.