Summit science summary Key facility in Arctic observatory network – increasing use, but also demand for pollution-free sampling environment Unique location on ice sheet provides year-round access to remote, high-elevation Arctic atmosphere & ice sheet Only northern hemisphere location for polar ice sheet intercomparisons with Antarctic Growing science use by multiple geophysical disciplines & aging infrastructure drive need for new investments Vision: Model international research facility – site of leading-edge polar & global multidisciplinary science Long-term geophysical measurements Intensive campaigns: atmospheric & multiple other disciplines Test bed for new sensors & technology Clean scientific observatory, with sustainable infrastructure, renewable energy, minimum pollution, year-round operation for diverse, high-impact science

Nearly 20 years of science at GEOSummit 1989-93: main focus was GISP2 ice core Studies of air-snow exchange for ice-core interpretation & studies of the remote arctic troposphere every year since 1989, involving scientists from dozens of institutions Year-round operations since 2000 & key component of arctic & global atmospheric observation system since 2003 (e.g. GAW, AON, IASOA, NOAA ESRL) Growing demands for scientific use by diverse geophysical disciplines, with some facilities dating back to GISP2, make investments in new infrastructure a high priority.

Ice coring at Summit Peak of the Greenland ice sheet. 72ºN, 38ºW 3,200 masl Sampling for trace metals in snow Peak of the Greenland ice sheet. No significant melting (yet!) GISP2 provided unprecedented high-resolution record of the past 110k yr of Earth’s climate & atmospheric chemistry. Studies of air-snow chemical exchange show both linear & non-linear “transfer functions” Dome protecting GISP2 ice core drill, 1989-93

Atmospheric chemistry at Summit Site for many productive atmospheric measurement campaigns & experiments Production of NOx in sunlit snow, discovered at Summit in 1998, helped launch field of snow photochemistry. Degassing of hydrogen peroxide & formaldehyde from snow create highly oxidizing environment near snow surface. NOAA scientists measure detailed profiles of stratospheric ozone Site for baseline measurements of globally important gases, aerosols in troposphere & stratosphere

Summit in IASOA & AON Illustrative of key role in multiple Arctic & global observing networks Remote ice-sheet location Only high elevation station Regularly samples polar dome air Represents northern hemisphe, free of regional influence