Since 1989, the U.S. Global Change Research Program (USGCRP) has submitted annual reports to Congress called Our Changing Planet. The reports describe the status of USGCRP research activities, provide progress updates, and document recent accomplishments. In particular, Our Changing Planet highlights progress and accomplishments in interagency activities. These highlights represent the broad spectrum of USGCRP activities that extend from Earth system observations, modeling, and fundamental research through synthesis and assessment, decision support, and public engagement. Highlights describe the state of science at the time of publication of each yearly report, and may not reflect more recent advances in understanding. The date of publication of the source report is noted on each highlight page.
Interagency observations and analyses show that emissions of the second-most important ozone-depleting substance are back on the decline after a recent surge. Atmospheric measurements show that concentrations of ozone-depleting gases are declining in response to global controls on their production and use enacted under the Montreal Protocol of 1987 and its amendments. The decline since the early 1990s in the atmospheric concentration of trichlorofluoromethane (CFC-11), once widely used as a foaming agent and refrigerant, has been an important component of ozone layer recovery. NOAA and NASA...