THE ARCTIC-BOREAL REGION CHARACTERIZED BY VAST EXPANSES OF TUNDRA BOREAL FORESTS AND WETLANDS CONTINUES TO WARM MORE RAPIDLY THAN ELSEWHERE ON EARTH. REGIONAL WARMING ASSOCIATED SHIFTS IN THE ANNUAL NON-FROZEN SEASON AND SIMULTANEOUS CHANGES IN HYDROLOGY CAN GREATLY INCREASE ECOSYSTEM VULNERABILITY TO CHANGE. ABRUPT DISTURBANCES FROM FIRE AND THE RAPID THAW OF PERMAFROST ALSO THREATEN ECOSYSTEM STRUCTURE AND FUNCTION INCLUDING CONTRIBUTIONS TO CARBON BUDGETS AND CLIMATE FORCING. HOW CHANGING ARCTIC-BOREAL SYSTEMS ARE IMPACTING CLIMATE UNDER CONTEMPORARY CONDITIONS IS NOT WELL UNDERSTOOD AND HOW THESE ECOSYSTEMS MIGHT RESPOND UNDER FUTURE CLIMATE REMAINS HIGHLY UNCERTAIN. UNDERSTANDING HOW CHANGES IN ENVIRONMENTAL CONDITIONS AND COMMUNITY STRUCTURE ULTIMATELY AFFECT ATMOSPHERIC RADIATIVE FORCING IS KEY TO IDENTIFYING THE ROLE OF THESE SYSTEMS IN AMPLIFYING OR MITIGATING CLIMATE CHANGE. A PRESSING CHALLENGE IS IMPROVING PROCESS-MODEL ESTIMATES OF CARBON DIOXIDE (CO2) AND METHANE (CH4) GAS EXCHANGE FOR HIGH LATITUDE TERRESTRIAL AND AQUATIC ENVIRONMENTS. MODELING STUDIES CONTINUE TO DISAGREE REGARDING THE: 1) NET CO2 SINK OR SOURCE STATUS FOR THE ARCTIC-BOREAL REGION 2) MAGNITUDES AND SPATIOTEMPORAL DISTRIBUTIONS OF CH4 FLUXES AND COMPONENTS (I.E. CONTRIBUTIONS FROM TERRESTRIAL VS. AQUATIC SYSTEMS EMISSION VS. UPTAKE) 3) REGIONAL TRAJECTORIES OF GAS EXCHANGE GIVEN FUTURE CLIMATE CONDITIONS AND ECOSYSTEM DISTURBANCES. REDUCING UNCERTAINTIES IN ECOSYSTEM CARBON BUDGETS IS NECESSARY TO IMPROVE OUR UNDERSTANDING OF HOW THE ARCTIC-BOREAL ZONE IS RESPONDING TO/IMPACTING CLIMATE. THIS STUDY FIRST FOCUSES ON IMPROVING ESTIMATES OF CO2 AND CH4 EXCHANGE FOR THE ARCTIC-BOREAL REGION THROUGH THE INTEGRATION OF TERRESTRIAL AND AQUATIC FIELD OBSERVATIONS A SUITE OF REMOTE SENSING DATA AND PRODUCTS AND MODELING (BIOGEOCHEMICAL AND ATMOSPHERIC). HERE WE FOCUS ON AN IMPROVED VERSION OF THE DYNAMIC VEGETATION DYNAMIC ORGANIC SOIL TERRESTRIAL ECOSYSTEM MODEL (DVM-DOS-TEM) WITH UPDATED ECOSYSTEM PARAMETERIZATIONS FOR TUNDRA BOREAL FORESTS AND WETLANDS MADE POSSIBLE THROUGH NEW ABOVE SYNTHESIS DATASETS OF CARBON FLUX ECOSYSTEM PROPERTIES AND DISTURBANCE. SITE-LEVEL VALIDATIONS FOR DVM-DOS-TEM WILL EMPLOY A WEALTH OF DATA FROM MONITORING AND VALIDATION SITES WITHIN ALASKA CANADA AND SIBERIA WE WILL ALSO INCORPORATE ADDITIONAL GLOBAL AND REGIONAL (I.E. ABOVE) MODEL BENCHMARKING. TO ASSESS MODEL SKILL/UNCERTAINTY AT THE REGIONAL LEVEL WE WILL USE A WRFSTILT (STOCHASTIC TIME-INVERTED LAGRANGIAN TRANSPORT MODEL DRIVEN BY A POLAR VARIANT OF WEATHER RESEARCH AND FORECASTING MODEL WINDS) APPROACH AND ATMOSPHERIC OBSERVATIONS FROM TALL TOWERS AND AIRCRAFT CAMPAIGNS. FURTHER OUR STUDY INCLUDES A CARBON MODEL INTERCOMPARISON EFFORT TO BETTER IDENTIFY SIMILARITIES AND DIFFERENCES IN CARBON BUDGET ESTIMATES AND ASSOCIATED UNCERTAINTIES ACROSS THE ABOVE DOMAIN AND EASTERN SIBERIA. WE WILL USE OUR NEW 0.25 DEGREE AND 1-KM MONTHLY CO2 AND CH4 FLUX RECORDS (2001-2021) FOR THE ARCTIC-BOREAL REGION SATELLITEINFORMED RECORDS OF FIRE EMISSIONS AND ALBEDO TO IDENTIFY HOW ECOSYSTEMS ARE CONTRIBUTING TO NET RADIATIVE FORCING AND REGIONAL WARMING OR COOLING. OUR FINAL COMPONENT EXPLORES POSSIBLE FUTURE TRAJECTORIES OF NET ECOSYSTEM CARBON BUDGETS (NECB TERRESTRIAL & AQUATIC CARBON FLUX PLUS FIRE EMISSIONS) AND RADIATIVE FORCING UNDER ALTERNATIVE CLIMATE AND DISTURBANCE SCENARIOS THROUGH 2100. THIS RESEARCH DIRECTLY BENEFITS NASA BY PROVIDING IMPROVED UNDERSTANDING OF CLIMATE-CARBON CYCLE-DISTURBANCE FEEDBACKS IN ARCTICBOREAL SYSTEMS THROUGH ENHANCED REGIONAL PROCESS-MODEL ESTIMATES OF NECB NEW RADIATIVE FORCING ASSESSMENTS THAT CONSIDER NECB AND ALBEDO AND NEW EVALUATIONS OF HIGH LATITUDE ECOSYSTEM RESPONSE INCLUDING NECB AND RADIATIVE FORCING UNDER FUTURE CLIMATE SCENARIOS.