2015 Nature CO2 field study recirculated

Daniel R. Feldman and co-authors published the study at the center of the latest social-media posts in *Nature* on Feb. 25, 2015, after using a decade of measurements from U.S. Department of Energy field sites in Oklahoma and Alaska. The paper did not claim to discover the greenhouse effect for the first time. It reported direct observational evidence that rising atmospheric carbon dioxide increased clear-sky downward longwave radiation at Earth’s surface over 2000-2010. The paper’s core result was numerical and narrow. Feldman and colleagues wrote that atmospheric CO2 increased by 22 parts per million between 2000 and 2010 and that the associated clear-sky surface radiative forcing trend at both sites was about 0.2 watts per square meter per decade, with site-specific uncertainties of plus or minus 0.06 and 0.07 W m−2 per decade. ### Which paper are people reposting? (nature.com) *Nature* identified the paper as “Observational determination of surface radiative forcing by CO2 from 2000 to 2010,” by D. R. Feldman, W. D. Collins, P. J. Gero, M. S. Torn, E. J. Mlawer and T. R. Shippert. The journal listed it in volume 519, pages 339-343, with a publication date of March 19, 2015, after online publication in late February 2015. The Lawrence Berkeley National Laboratory-linked record and the U.S. (nature.com) Department of Energy’s OSTI entry describe the paper as empirical evidence that the increase in surface radiative forcing measured at two sites was directly attributable to the increase in atmospheric carbon dioxide over that decade. ### What did the researchers actually measure? The measurements came from Atmospheric Emitted Radiance Interferometer, or AERI, instruments operating at DOE Atmospheric Radiation Measurement sites in the Southern Great Plains and the North Slope of Alaska. (nature.com) The study used those spectra together with ancillary atmospheric measurements and radiative-transfer calculations to isolate the CO2 contribution under clear-sky conditions. (osti.gov) The two locations mattered because they sampled different climates. The Southern Great Plains site represented a mid-latitude continental setting, while the North Slope of Alaska site represented an Arctic marine environment, according to the paper and associated records. ### Does this paper say CO2 alone explains all warming? (osti.gov) The 2015 paper was limited to surface radiative forcing from rising CO2 under clear skies at two long-running observation sites. Feldman and colleagues said surface forcing is distinct from stratosphere-adjusted radiative forcing at the tropopause, though related to it, and presented the work as direct observational evidence for one part of Earth’s energy imbalance. (courses.seas.harvard.edu) The authors also wrote that the observed forcing agreed with model results. That point is one reason the paper has often been cited in discussions about whether radiative-transfer calculations used in climate science match field observations. ### Why does the phrase “first field confirmation” show up in posts? The paper said there had been little direct observational evidence of the radiative impact of increasing atmospheric CO2, despite extensive modeling and theory. (nature.com) Its contribution was to provide observationally based evidence from long-term field measurements, not to overturn decades of atmospheric physics. A University of Wisconsin summary published in 2015 described the work as the first confirmation of increased greenhouse forcing from atmospheric CO2 based on direct observations over a decade, reflecting how the result was framed at the time. (nature.com) ### Where can readers check the original study? The original paper remains posted on *Nature*’s website, and the U.S. Department of Energy’s OSTI database carries a record summarizing the methods, sites and trend values. (nature.com) The paper’s DOI is 10.1038/nature14240. As of September 2, 2026, the recirculating posts point back to a study based on measurements that ended in 2010 and were published in 2015. (ssec.wisc.edu) Readers looking for the underlying source can find the author list, abstract and site details in the journal and DOE records. (nature.com)