** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** CLIMATE CHANGE IS ALREADY HAVING A PROFOUND IMPACT ON AGRICULTURE AROUND THE WORLD. CROP LOSSES DUE TO EXTREME HEAT ARE PROJECTED TO RISE SUBSTANTIALLY THROUGH THE END OF THE CENTURY. WHETHER AND HOW FARMERS WILL ADAPT TO HIGH TEMPERATURES ARE THEREFORE CRUCIAL POLICY QUESTIONS.IRRIGATION REPRESENTS A KEY FORM OF AGRICULTURAL CLIMATE ADAPTATION. FOR EXAMPLE, HOT TEMPERATURES CAUSE SUBSTANTIAL CROP LOSSES IN THE RAINFED EASTERN U.S. WHERE IRRIGATION IS LESS COMMON, BUT NOT IN THE IRRIGATION-DEPENDENT WESTERN U.S. HOWEVER, DESPITE ITS IMPORTANCE FOR AGRICULTURE--AND ITS SUSCEPTIBILITY TO CLIMATE CHANGE--THE ROLE OF GROUNDWATER REMAINS UNDERSTUDIED. IN PARTICULAR, LITTLE IS KNOWN ABOUT THE EXTENT TO WHICH FARMERS CAN USE GROUNDWATER TO ADAPT TO CLIMATE CHANGE, SINCE MEASURING GROUNDWATER EXTRACTION IS DIFFICULT. MOREOVER, UNDERSTANDING THE ROLE OF GROUNDWATER AS A SOURCE OF CLIMATE ADAPTATION IS BECOMING INCREASINGLY URGENT, AS UNDERGROUND AQUIFERS ARE BEING RAPIDLY DEPLETED AROUND THE GLOBE. THE GOAL OF THIS PROJECT IS TO EMPIRICALLY ASSESS THE IMPORTANCE AND SUSTAINABILITY OF ADAPTIVE IRRIGATION UNDER CLIMATE CHANGE.WE HAVE THREE OBJECTIVES THAT WILL CONTRIBUTE TO OUR KNOWLEDGE ABOUT THE LINKAGES BETWEEN AGRICULTURE, GROUNDWATER, AND CLIMATE CHANGE IN THE UNITED STATES. OBJECTIVE 1 IS TO ESTIMATE THE LINK BETWEEN EXTREME HEAT AND ADAPTIVE IRRIGATION. OBJECTIVE 2 IS TO PREDICT GROUNDWATER STOCK DYNAMICS UNDER CLIMATE CHANGE. OBJECTIVE 3 IS TO ANALYZE THE RELATIONSHIP BETWEEN CROP INSURANCE AND WATER USE. IN MEETING THESE THREE OBJECTIVES, WE WILL LEVERAGE HIGH-RESOLUTION DATA AND EMPLOY RIGOROUS ECONOMETRIC METHODS TO PRODUCE RESULTS THAT ARE BOTH ACADEMICALLY INTERESTING AND POLICY RELEVANT.