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Svante August Arrhenius was the first to calculate global climate sensitivity to changes in atmospheric CO2 concentration. He was also the first to calculate the anthropogenic rate of CO2 buildup in the modern atmosphere. There is apparently an inconsistency, however, between the references to these estimates [e.g., Uppenbrink, 1996] and the real numbers Arrhenius derived in his later works. The citations of Arrhenius' calculations are usually based on the work published in 1896 [Arrhenius, 1896]. In this paper Arrhenius reported that CO2 doubling should increase the Earth's mean temperature by 5–6°C. In the same ear, he estimated that it would take about 3000 y ears for mankind to double the atmospheric concentration through the burning of fossil fuels [Arrhenius, 1896]. However, the 1896 paper was not his last publication on the problem of global warming.

Solar Variability, Weather, and Climate reassesses the question of solar variability and its effects on weather and climate, taking into account new measurements and more recent theories of the earth's atmosphere. The papers, which make up this book, were presented at an American Geophysical Union meeting in December 1978. Besides a review of the current basic knowledge on the topic, fundamental questions requiring additional research form the basis of the conclusions and recommendations. Eight papers, five stating the background and three the possible mechanisms, comprise the book. Solar, weather, and climate variability and evidence of the effect of solar variations on the atmosphere are reviewed. Solar variability is recognized to exist at different time scales (from minutes to decades), and these variations cover a broad range of the spectral irradiance (from X rays and extreme ultraviolet to the centimeter wavelengths). Regarding total luminosity, the parts of the solar constant that are known to vary constitute less than 1% of the total budget of energy that the earth receives from the sun and is far less than the total energy required to force direct changes in atmospheric circulation. Moreover, the variable portions of the solar output are mainly absorbed or dissipated in the upper atmosphere. Thus, for known solar changes to perturb the dynamics of the troposphere they must work through mechanisms that are complex and indirect. A number of such possible dynamic, radiative, chemical, and electrical couplings of solar inputs through various regions of the atmosphere are discussed in chapters 6, 7, and 8.

In two recent papers, R. W. Spencer and W. D. Braswell (Remote Sens., 3(8), 1603– 1613, doi:10.3390/rs3081603, 2011) (SB) and R. S. Lindzen and Y.-S. Choi (Asia Pac. J. Atmos. Sci., 47(4), 377–390, doi:10.1007/s13143-011-0023-x, 2011) (LC) argue that clouds act as a primary initiator of surface temperature changes in Earth's climate system. The two sets of authors reached this conclusion by developing a method that tries to determine the Earth's surface temperature by calculating how much energy is stored in the ocean's upper layers, how much of this heat is transferred to the rest of the climate system, how clouds affect the rate at which energy escapes Earth's atmosphere, and how the surface's energy flux changes with temperature. Both studies spurred substantial debate within the media and the public, with the research by SB causing the editor of the journal in which it was published to resign, claiming it should not have been accepted by the journal. Assessing the two studies,Dessler found what he suggests are a number of methodological errors.

[1] George Colvin Reid, a pioneering solar and climate scientist, passed away at his home in Boulder, Colo., on 6 May 2011 after a brief battle with pancreatic cancer. George was 81. His legacy includes an impressive and prolific scientific career that spanned nearly 60 years. George was a world leader in atmospheric science with an exceptionally broad understanding of atmospheric phenomena encompassing both dynamics and chemistry. Early in his career, George wrote a number of influential papers with Harold Leinbach, Gordon Little, and Colin Hines on energetic particles in solar flares and the effect of such particles on the Earth's atmosphere. He and Harold Leinbach coined the often quoted phrase “polar cap absorption” and its acronym “PCA,” which have entered the lexicon of atmospheric science to describe the interaction of solar flares on the Earth's atmosphere at high latitudes. As his career progressed, his research interests expanded to include solar energetic particles, solar influences on the upper atmosphere, ion chemistry in the upper atmosphere, noctilucent clouds, the dynamics and chemistry of the middle atmosphere, the mechanisms of global climate change with emphasis on the tropics, and the influence of solar variability on the lower atmosphere and ocean temperatures.

It is frequently stated in textbooks and scholarly articles that the surface temperature of Earth is 33°C warmer than it would be without the atmosphere and that this difference is due to the greenhouse effect. This Forum shows that the atmosphere effect leads to warming of only 20°C. This new conclusion requires a revision to all of the relevant literature in K-12, undergraduate, and graduate education material and to science papers and reports.

The ratio of carbon-14 (14C) to carbon in the dissolved inorganic carbon (ΣCO2) of California's Mono Lake has continued to rise at a rate far faster than expected from the invasion of bomb-test14C-labeled atmospheric CO2. Two explanations can be given. One is that the invasion rate of carbon dioxide from the atmosphere is 5 or so times higher than that for chemically inert gases. The second is tha Mono Lake has been used as a site for clandestine disposal of radiocarbon. In this paper, we attempt to reconstruct the radiocarbon history of the lake by invoking the addition of radiocarbon-free CO2 from the volcanic center that lies beneath the lake and the invasion of bomb-test tagged CO2 from above.

It is a pleasure and an honor to present the citation to John M. Wahr for the Charles A. Whitten Medal, which is an award for outstanding achievement in research on the form and dynamics of the Earth. John has made fundamental advances in many areas of dynamics, including time-variable gravity, Earth rotation, Earth and ocean tides, interaction of the atmosphere and ocean with the Earth, postglacial deformation, and nutation. He has published papers in geodesy, geodynamics, seismology, geomagnetism, hydrology, cryospheric sciences, oceanography, atmospheric sciences, planetary sciences, and even general relativity. John is a major intellectual leader in much of geophysics with a heavy emphasis on global-scale problems involving the fluid envelope. John broke new ground with his work in the application of geodetic data to geophysical problems, including global tides, barometric response of the oceans, and Earth rotation. His unique contributions came from developing the theory, and modeling Earth tides, nutations, and various other types of rotational and deformational motion. Both the Earth tide model and the nutation model served as the adopted international standards for almost 20 years. His cutting-edge work on time-variable gravity has enabled him to blaze a new trail for interdisciplinary geodesy.

Current concern is focused on the consequences of global warming as the atmospheric level of carbon dioxide (CO2) increases. But adding CO2 to the atmosphere has some potential benefits. As considered in this paper, published research supports the view that a moderate increase in the atmospheric CO2 level could prevent the initiation of another ice age. The amount of C02 resulting from the use of the world's fossil fuel reserves should be sufficient to provide this protection for thousands of years.

In the article, New Findings about Auroras Confirm Importance of Ionosphere in Space Weather (Eos, December 22,1998), the author states that imaging riometers respond mainly to keV electrons. It is more correct to say that they respond mainly to electrons of 10s to 100s keV. The absorption frequently maximizes at about 90 km altitude, and an electron giving maximum production at 90 km must enter the atmosphere with energy about 50 keV. The evidence comes from observations by rocket and by incoherent-scatter radar, together with direct comparisons between radiowave absorption in the auroral zone and electron spectra measured at geosynchronous orbit. Yamagishi et al. [1998] are quoted as finding that absorption events are far more common in winter than in summer. I have not been able to find this statement in the Yamagishi paper; moreover, conjugate-point studies show that near the maximum of the absorption zone the events are almost invariably conjugate that is, they are seen in both hemispheres. They do, however, tend to be more intense in the winter hemisphere. Yamagishi et al.s Table 1 gives the numbers of events that are more intense in one hemisphere or the other, and those results are not inconsistent with the earlier work on this point [Hargreaves and Cowley, 1967; Hargreaves, 1969]. Osepian and Smirnova [1997] argue that the seasonal difference may be explained by seasonal changes in the effective recombination coefficient because of variations in the properties of the neutral air.

The continental surfaces comprise one of several interacting components of the climate system. Therefore, they play a role in the natural fluctuations and anthropogenic changes of regional and global climate. In light of the importance of land-atmosphere interactions to climate, the Atmospheric Sciences and Hydrology sections cosponsored a special session on land surface processes and climate variability at the AGU 1991 Fall Meeting in San Francisco. The focus was on physical interactions between the continents and the atmosphere through exchanges of mass, energy, and momentum, with an emphasis on the relevance of those interactions to natural and anthropogenic variations of climate and continental hydrology. The call for papers requested reports on process-oriented, model-based, and observational studies of the influence of land-surface processes on atmospheric variability, land-surface response to atmospheric variations, and climatic sensitivity to changes of the continental surfaces.

The symposium was jointly organized by the International Association of Meteorology and Atmospheric Physics (IAMAP) and by the International Association of Geomagnetism and Aeronomy (IAGA). It was cosponsored by SCOSTEP, COSPAR, and by the following IAMAP Commissions: ICACGP, IOC, and IRC. The large number of contributions, about 160 papers presented in 11 half-day sessions, reflects the increasing activity in middle atmosphere research and the growing interest of scientists from many nations, including the developing countries, in efficient communications in this field. The sessions contained contributions about (1) solar UV flux, photochemical processes, and related chemistry; (2) remote sensing; (3) dynamics, including troposphere coupling; (4) the strato-meso-thermosphere system and solar-terrestrial relationships; (5) climatology of the middle atmosphere; (6) gravity waves, turbulence, and related transport; (7) modeling, including the radiation budget; (8) trace species; (9) ions and aerosols; (10) electrodynamics; and (11) aeronomic phenomena in the mesopause region, including noctilucent clouds.

Two controversial papers in the April issue of Geophysical Research Letters by a group from the University of Iowa offer a new picture of the earth's upper atmosphere and the source of water on the earth and other planets. Louis A. Frank and colleagues John B. Sigwarth and John D. Craven proposed that the earth may be seeing an influx of as many as 20 small comets per minute, each weighing perhaps 100 tons. Since comets contain a great deal of water ice, such a phenomenon could add significant amounts of water to the earth's atmosphere in a short time.

Since the earliest days of the U.S. Space Program, concerns have been raised regarding the atmospheric perturbations that might be caused by the exhaust products of large rocket engines. In 1964 a comprehensive review of the subject was published by Kellogg [1964] in which the space science community was alerted to the many possible ways that rocket ‘pollutants’ could have environmental impacts. The final impression left by Kellogg's paper was that the terrestrial atmosphere was sufficiently dense to absorb any conceivable shock that an aerospace technology might reasonably be expected to build—even to the point of the giant Saturn V rockets envisioned for the Apollo Program. In the 15 years that have passed since Kellogg's assessment, very little evidence was found to suggest that rocket effluents were in fact perilous to our environment. A reappraisal of all published accounts of rocket-induced modifications of the atmosphere since Sputnik 1 (M. Mendillo, unpublished manuscript, 1979) reveals that hardly a dozen accounts exist describing specific aeronomic perturbations associated with the many hundreds of rocket launches that have occurred since 1957. There are good reasons for this: (1) The vast majority of rockets launched in the last 2 decades were relatively small ones, and thus the exhaust emissions amounted to no more than very minor additions of essentially trace species. (2) Of the large rockets (Saturns, Atlas/Centaurs, SL-4/Soyuz) the overwhelming majority of launches carried payloads into low earth orbit (h < 200 km), where the typical exhaust products (H20, H2, CO2, N2, and O2,) were again relatively inconspicuous additions to ambient conditions. (3) Large-rocket launches made by U.S. agencies generally occur at the Kennedy Space Flight Center, thereby insuring that rocket ascent trajectories occur over water—conditions hardly conducive to atmospheric monitoring via ground-based facilities.

Having devoured Holland's earlier book on the modern state of ocean and atmosphere chemical reservoirs, The Chemistry of the Atmosphere and Oceans (Wiley-Interscience, New York, 1978), and having read several of the stimulating papers that derived from his work on the promised companion volume, concerned with the history of atmospheric and ocean chemistry, I eagerly anticipated publication of The Chemical Evolution of the Atmosphere and Oceans. It has been published, and I am not disappointed, nor will the education of any graduate student or practing professional in the earth or ocean sciences be complete without thorough study of this long-awaited book. There is nothing else that resembles it in subject matter, comprehensiveness, and thoughtful and objective analysis of data and of old and new ideas in the field. Holland has devoted space and consideration in his book to the different episodes in atmospheric and ocean chemical history of the earth roughly in proportion to the relative duration of each episode. This, of course, means that the treatment of the relatively data-rich Phanerozoic interval is more terse than the sections on the Precambrian. Yet Holland handles the paucity of data for the Precambrian with flair and appropriate conjecture. In fact, it is in this part of the book that his impressive intellect shines.