Last Updated:
February 28, 2007

GCRIO Program Overview

Library 
Our extensive collection of documents.

Privacy Policy

Archives of the
Global Climate Change Digest
A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999

FROM VOLUME 10, NUMBER 3, MARCH 1997

PROFESSIONAL PUBLICATIONS...
RADIATIVE FORCING

Item #d97mar63

"Further Estimates of Radiative Forcing Due to Tropospheric Ozone Changes," P.M. de F. Forster (Dept. Meteor., Univ. Reading, Reading RG6 6AU, UK; e-mail: piers@met.rdg.ac.uk), C.E. Johnson et al., Geophys. Res. Lett., 23(23), 3321-3324, Nov. 15, 1996.

Estimates made by two 2-D (latitude-height) chemical transport models show large uncertainty, but continue to support the case that tropospheric ozone changes make a substantial contribution (about 15%) to the total greenhouse gas radiative forcing. Results also show that ignoring clouds and the effects of stratospheric adjustment in the radiative forcing calculations overestimates the global average forcing by about 66%.

Item #d97mar64

"Climate Forcing by Stratospheric Ozone Depletion Calculated from Observed Temperature Trends," W. Zhong (Dept. Phys., Imperial College, London SW7 2BZ, UK), R. Tuomi, J.D. Haigh, ibid., 23(22), 3183-3186, Nov. 1, 1996.

Previous studies have concluded that ozone depletion leads to a net negative radiative forcing, estimated by Ramaswamy et al. to be -0.08 W m-2 during the period 1979-1990 (global-annual average). This effect has been considered possible compensation for positive radiative forcing due to anthropogenic greenhouse gases over the same period. More realistic radiation calculations presented here show a much lower value of -0.025 W m-2, although inclusion of some omitted factors would raise this value somewhat.

Item #d97mar65

Special section: Clim. Change, 34(3-4), Nov.-Dec. 1996. Consists of three papers relating to global warming potentials: an editorial comment on two-dimensional models and two papers that employ such models.

"Three-Dimensional Chemistry in the Greenhouse," D.J. Wuebbles (Dept. Atmos. Sci., Univ. Illinois, 105 S. Gregory Ave., Urbana IL 61801), 397-404. Emphasizes that zonally-averaged, 2-D models of atmospheric chemistry and transport processes, such as those used in the following two papers, can provide important insights, but are inadequate for definitive evaluation of tropospheric chemistry processes for a number of reasons that are discussed here.

"Estimates of Indirect Global Warming Potentials for CH4, CO and NOx," J.S. Fuglestvedt (Ctr. for Intl. Climate & Environ. Res. (CICERO), Univ. Oslo, POB 1129 Blindern, N-0317 Oslo, Norway), I.S.A. Isaksen, W.-C. Wang, 405-437.

"Relative Radiative Forcing Consequences of Global Emissions of Hydrocarbons, Carbon Monoxide and NOx from Human Activities Estimated with a Zonally-Averaged Two-Dimensional Model," C.E. Johnson (Meteor. Off., London Rd., Bracknell, Berkshire RG12 2SY, UK), R.G. Derwent, 439-462.

Item #d97mar66

"First Estimates of the Radiative Forcing of Aerosols Generated from Biomass Burning Using Satellite Data," S.A. Christopher (Inst. Atmos. Sci., South Dakota Sch. of Mines & Technol., Rapid City SD 57701; e-mail: sundar@ cloud.ias.sdsmt.edu), D.V. Kilche et al., J. Geophys. Res., 101(D16), 21,265-21,273, Sep. 27, 1996.

Most previous studies have estimated the radiative impact of aerosols from biomass burning by using some form of the radiative transfer equation. This study measures the quantity using a combination of data from two satellite instruments (AVHRR and ERBE), and finds net radiative forcing of about -36 W m-2 for areas with heavy aerosol loading, and about -16 W m-2 for optically thin aerosols.

Item #d97mar67

"Clouds and the Earth's Radiant Energy System (CERES): An Earth Observing System Experiment," B.A. Wielicki (Atmos. Sci. Div., MS-420, NASA-Langley Res. Ctr., Hampton VA 23681), B.R. Barkstrom et al., Bull. Amer. Meteor. Soc., 77(5), 853-868, May 1996.

The CERES program will extend and improve on the Earth Radiation Budget Experiment (ERBE) by flying broadband scanning radiometers on several NASA-EOS satellites starting in 1998 and extending over at least 15 years. CERES will also combine simultaneous cloud property data derived using EOS narrowband imagers to provide a consistent set of cloud/radiation data at the surface and at several selected levels of the atmosphere. [Technical details are available at http://asd-www.larc.nasa.gov/ceres/docs.html]

Item #d97mar68

Two items in Atmos. Environ., 30(10/11), May 1996:

"Radiative Forcing Due to Increased Tropospheric Ozone Concentrations," S. Chalita (Service d'Aéronomie du CNRS, Univ. Paris, 6 Pl. Jussieu, Boite 102, 75252 Paris, Cedex 05, France), D.A. Hauglustaine et al., 1641-1646. To determine their radiative forcing impact, pre-industrial and present-day tropospheric ozone concentrations are simulated by a 3-D chemical transport model in conjunction with a general circulation model. Ozone forcing is regionally heterogeneous with a marked interhemispheric difference; it peaks over the Northern Hemisphere continents in summer and locally reaches more than 1 W m-2. Changes in concentration in the high troposphere have about 10 times more radiative impact than those in the planetary boundary layer. A 10% per decade growth rate of ozone in the future implies an increase of 2 W m-2.

"The Role of Anthropogenic Emissions of NOx on Tropospheric Ozone over the North Atlantic Ocean: A Three-Dimensional, Global Model Study," C.S. Atherton,. .

D.D. Parrish (Aeron. Lab., NOAA, 325 Broadway, Boulder CO 80303) et al., 1739-1749. The model is run with a baseline scenario and one in which North American fossil fuel NOx emissions are reduced 50%. The NOx reduction produces a 30% reduction in the total mass of tropospheric ozone exported from North America to the North Atlantic Ocean.

Item #d97mar69

"The Greenhouse Earth: A View from Space," J.E. Harries (Imperial College of Science, Blackett Lab., Imperial College, London SW7 2BZ, UK), Quart. J. Royal Meteor. Soc., 122(532), 799-818, Apr. 1996 Part B.

A review. Radiative cooling of the Earth in the absence of clouds has recently been shown to be dominated by emission from water vapor in the upper troposphere. The role of clouds is presently less clear, but in both cases, more accurate global observations are needed. The paper is illustrated by data from satellite experiments.

Item #d97mar70

"Impacts of Increased Anthropogenic Emissions in Asia on Tropospheric Ozone and Climate. A Global 3-D Model Study," T. Berntsen (Inst. Geophys., Univ. Oslo, POB 1022, Blindern, 0315 Oslo, Norway), I.S.A. Isaksen et al., Tellus, 48B(1), 13-32, Feb. 1996.

Asia was selected for study because its emissions are rapidly increasing, and there is a large potential for future increases. A doubling of NOx emission leads to ozone increases up to 30% in the upper troposphere. Increased tropospheric ozone causes a positive radiative forcing of about 0.5 W m-2, which is 30-50% of the estimated negative radiative forcing due to the direct effect of sulfate aerosols.

Item #d97mar71

"An Assessment of the Radiative Effects of Anthropogenic Sulfate," C.C. Chuang (Atmos. Sci. Div. L-103, Lawrence-Livermore Natl. Lab., POB 808, Livermore CA 94550; e-mail: cathy@hualien.llnl.gov), J.E. Penner et al., J. Geophys. Res., 102(D3), 3761-3778, Feb. 20, 1997.

Uses a coupled climate-chemistry model with cloud nucleation processes to investigate both direct and indirect sulfate radiative forcings. Estimates a global direct radiative forcing of about -0.4 W m-2, with a maximum over Europe where the strongest anthropogenic sulfur emissions occur. Different approaches for estimating the indirect forcing yield a range of -0.6 to -1.6 W m-2. Simulations indicate that anthropogenic sulfate may cause important increases in reflected solar radiation, which would mask locally the warming from greenhouse gases.

Item #d97mar72

"Climate Implications of Biomass Burning Since the 19th Century in Eastern North America," J.S. Clark (Dept. Botany, Duke Univ., Durham NC 27708), B.J. Stocks, P.J.H. Richard, Global Change Biology, 2(5), 433-442, Oct. 1996.

Recent predictions that tropospheric aerosols have counterbalanced greenhouse warming assume aerosol emissions were low before 1850 and then increased dramatically with industrialization of the Northern Hemisphere and biomass burning in the tropics. This analysis of the lake sediment record of emissions across North America indicates that aerosols could have actually decreased during the 20th century, suggesting that the offset hypothesis requires further analysis using different assumptions of past emissions. [The following entry relates to this topic.]