The ozone layer in the upper atmosphere is a natural feature of the earth's environment. It performs several important functions, including shielding the earth from damaging solar ultraviolet radiation. Far from being static, ozone concentrations rise and fall under the forces of photochemical production, catalytic chemical destruction, and fluid dynamical transport. Human activities are projected to deplete substantially stratospheric ozone through anthropogenic increases in the global concentrations of key atmospheric chemicals. Human-induced perturbations may be occurring already.

One hundred fifty years ago, on 22 April 1863, the U.S. National Academy of Sciences (NAS) held its first meeting. The founding of the academy was but one of an impressive array of federal actions that would prepare the United States of America for a bright future. During the dark days of 1862 and 1863, mired in a bloody and intense Civil War, Congress passed, and President Lincoln signed, the Morrill Act, creating a system of Land Grant Colleges. The Act greatly enhanced access to higher education for Americans and promoted scientific and technical research in the coming generations. In the same period, Congress authorized the completion of the Transcontinental Railroad, and President Lincoln issued the Emancipation Proclamation. Only a few months later, President Lincoln and Congress took another major step to advance the young nation by creating NAS, a bold way to elevate American science and to incorporate science into the U.S. future. This was a remarkable set of government actions during very tough times.

Recent enthusiam for science in the United States is cause for celebration, but it's also food for thought: What can scientists do to build on this new excitement and support? If the U.S. Congress and administration are to continue to advance science research and education and to rely on science in policy-making, then scientists must do much more to show how science works and how scientific research contributes to the nation.

The National Academy of Sciences is an honorific society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. This Viewpoint explores the interconnection between scientific research and policy making in developing a climate policy.

Hacked Electronic Records of Climate Scientists at the University of East Anglia's Climate Research Unit (UEA/CRU) led to worldwide publicity during the December 2009 Copenhagen climate change convention. UEA is conducting a formal investigation to determine whether UEA scientists manipulated or suppressed data or otherwise acted unprofessionally. My reading of the vast scientific literature on climate change is that our understanding is undiminished by this incident; but it has raised concern about the standards of science and has damaged public trust in what scientists do.

Extant data from measurements of halogens in the atmosphere are reviewed in the following categories: gaseous chlorine compounds (inorganic and organic), particulate chloride and chloride in precipitation, gaseous bromine compounds (inorganic and organic), particulate bromide and bromide in precipitation, gaseous iodine compounds (inorganic and organic), iodine in particles and in precipitation, gaseous fluorine compounds (inorganic and organic), and fluoride in particles and precipitation. The roles that these data and other unavailable data play in defining global cycles of the halogens are discussed. Speciation of the halogen gases in the troposphere is very uncertain: the only inorganic species detected by species‐specific methods are HCl and SF6. More specific data are available on organic forms that contain halogens. Key species of gaseous halogens, either established or suspected to be important, are listed along with key processes that need investigation. Heterogeneous reactions, both gas‐to‐particle and particle‐to‐gas processes, precipitation removal, and sea‐salt aerosol generation and fractionation processes need quantitative investigation to allow progress in estimating halogen sources and sinks. Where practical, as with stratospheric inorganic chlorine gases, quantitative comparisons are made between measured and predicted concentrations. Copyright © 1981 by the American Geophysical Union.

This paper is a brief survey of a portion of the research on trace constituents in the stratosphere and mesosphere between 1971 and 1974. A primary motivation for much of the stratospheric research came from the realization that man's activities may influence global climate and the atmospheric ozone content, our shield against certain UV wavelengths. A great deal of progress has been reported in understanding both the present background stratosphere and the responses to be expected from additions of nitrogen oxides, water, and chlorine oxides, especially with respect to ozone. Trace constituents in the mesosphere have been modeled and measured to increase our understanding of the physics and chemistry of the mesosphere but also to relate mesospheric composition and transport to ionospheric processes at higher altitudes, to D region ion chemistry, and to upper stratospheric composition. Copyright © 1975 by the American Geophysical Union.