THE ATMOSPHERE IS THE INTEGRATOR OF THE EARTH SYSTEM. HUMAN EMISSIONS OF POLLUTANTS AND LONGLIVED GREENHOUSE GASES INTO THE ATMOSPHERE HAVE CAUSED DRAMATIC TRANSFORMATIONS OF THE PLANET ALTERING AIR QUALITY CLIMATE AND NUTRIENT FLOWS IN EVERY ECOSYSTEM. UNDERSTANDING THE GLOBAL ATMOSPHERE REQUIRES AN INTERNATIONAL NETWORK OF SCIENTISTS PROVIDING INTELLECTUAL LEADERSHIP IN AREAS OF ATMOSPHERIC CHEMISTRY THAT NEED TO BE ADDRESSED PROMOTED AND WOULD BENEFIT FROM RESEARCH ACROSS DISCIPLINES AND GEOGRAPHICAL BOUNDARIES. ACKNOWLEDGEMENT OF THIS NEED LED TO THE FORMATION OF THE INTERNATIONAL GLOBAL ATMOSPHERIC CHEMISTRY (IGAC) PROJECT IN 1990. IGAC S MISSION IS TO FACILITATE ATMOSPHERIC CHEMISTRY RESEARCH TOWARDS A SUSTAINABLE WORLD. THIS IS ACHIEVED THROUGH IGAC S THREE FOCAL ACTIVITIES: FOSTERING COMMUNITY BUILDING CAPACITY AND PROVIDING LEADERSHIP. IGAC S PRIORITIES AND ACTIVITIES ARE DETERMINED AND GUIDED BY AN INTERNATIONAL VOLUNTEER SCIENTIFIC STEERING COMMITTEE (SSC). THE IGAC INTERNATIONAL PROJECT OFFICE (IPO) IS PRIMARILY RESPONSIBLE FOR IMPLEMENTING THESE PRIORITIES IN COLLABORATION WITH SSC MEMBERS AND OTHER MEMBERS OF THE INTERNATIONAL ATMOSPHERIC SCIENCE COMMUNITY TO FACILITATE AND FOSTER THEIR EXECUTION. THIS PROPOSAL IS A REQUEST FOR CONTINUED FUNDING IN SUPPORT OF THE IGAC IPO FOR THREE YEARS (1 JULY 2018 - 30 JUNE 2021). INTELLECTUAL MERIT IGAC PROVIDES INTELLECTUAL LEADERSHIP BY IDENTIFYING AND FOSTERING ACTIVITIES ON CURRENT AND FUTURE AREAS WITHIN ATMOSPHERIC CHEMISTRY THAT WOULD BENEFIT FROM RESEARCH ACROSS GEOGRAPHICAL BOUNDARIES AND/OR DISCIPLINES. IGAC S VISION IS TO LINK FUNDAMENTAL SCIENTIFIC RESEARCH ON EMISSIONS ATMOSPHERIC PROCESSES AND ATMOSPHERIC COMPOSITION TO GLOBAL CHANGE AND SUSTAINABILITY ISSUES SUCH AS HUMAN HEALTH CLIMATE ECOSYSTEMS AND HOW INDIVIDUAL AND SOCIETAL RESPONSES FEEDBACK ONTO THE CORE RESEARCH-LED FOCI OF IGAC. BROADER IMPACT IGAC IS AN OPEN INTERNATIONAL COMMUNITY OF ATMOSPHERIC SCIENTISTS ACTIVELY COLLABORATING ACROSS GEOGRAPHICAL BOUNDARIES AND DISCIPLINES IN ORDER TO CONTRIBUTE TO ADDRESSING THE MOST PRESSING GLOBAL CHANGE AND SUSTAINABILITY ISSUES THROUGH SCIENTIFIC RESEARCH. THE IGAC BIENNIAL SCIENCE CONFERENCE AND THE FACILITATION OF NUMEROUS THEMATIC WORKSHOPS EVERY YEAR PROVIDES OPPORTUNITIES TO BUILD COOPERATION AND DISSEMINATE SCIENTIFIC INFORMATION ACROSS THE IGAC INTERNATIONAL COMMUNITY. IGAC BUILDS SCIENTIFIC CAPACITY THROUGH ITS EARLY CAREER PROGRAM AND NATIONAL AND REGIONAL WORKING GROUPS. THE IGAC EARLY CAREER PROGRAM ALLOWS SCIENTISTS TO JOIN AN INTERNATIONAL NETWORK EARLY IN THEIR CAREER. THE IGAC NATIONAL AND REGIONAL WORKING GROUPS CREATE A STRONG COHESIVE COMMUNITY OF ATMOSPHERIC SCIENTISTS IN EMERGING COUNTRIES/REGIONS