This study quantifies global energy consumption and CO₂ emissions from irrigation between 2000 and 2010, revealing that irrigation contributes 216 million metric tons of CO₂ emissions and consumes 1896 petajoules of energy annually, accounting for 15% of agricultural greenhouse gas emissions and energy use. Groundwater pumping accounts for 89% of total irrigation energy consumption, despite only 40% of irrigated agriculture relying on groundwater. Future irrigation expansion could increase energy use by 28%, but efficient and low-carbon irrigation methods could halve energy use and reduce CO₂ emissions by 90%. However, considering country-specific feasibility, global CO₂ emissions may only decrease by 55%. The study also highlights that irrigation contributes significantly to global energy and CO₂ emissions, with Asia having the highest energy intensity and CO₂ emissions intensity per hectare. Groundwater degassing contributes 6 million metric tons of CO₂ annually, with major contributors being India and the United States. Future irrigation expansion under a 3°C warmer climate could increase energy consumption by 536 PJ, representing 28% of current irrigation energy use. Switching to electric pumps could reduce energy-related CO₂ emissions by 7%, with India and Russia being the largest contributors. The study also assesses the feasibility of mitigation options, showing that drip irrigation and low-carbon electricity could significantly reduce emissions, though their effectiveness varies by region. The study provides insights into the energy and CO₂ intensity of irrigation, comparing it with other agricultural activities. Overall, irrigation is a major contributor to agricultural energy and CO₂ emissions, with significant potential for reduction through efficient and low-carbon practices.This study quantifies global energy consumption and CO₂ emissions from irrigation between 2000 and 2010, revealing that irrigation contributes 216 million metric tons of CO₂ emissions and consumes 1896 petajoules of energy annually, accounting for 15% of agricultural greenhouse gas emissions and energy use. Groundwater pumping accounts for 89% of total irrigation energy consumption, despite only 40% of irrigated agriculture relying on groundwater. Future irrigation expansion could increase energy use by 28%, but efficient and low-carbon irrigation methods could halve energy use and reduce CO₂ emissions by 90%. However, considering country-specific feasibility, global CO₂ emissions may only decrease by 55%. The study also highlights that irrigation contributes significantly to global energy and CO₂ emissions, with Asia having the highest energy intensity and CO₂ emissions intensity per hectare. Groundwater degassing contributes 6 million metric tons of CO₂ annually, with major contributors being India and the United States. Future irrigation expansion under a 3°C warmer climate could increase energy consumption by 536 PJ, representing 28% of current irrigation energy use. Switching to electric pumps could reduce energy-related CO₂ emissions by 7%, with India and Russia being the largest contributors. The study also assesses the feasibility of mitigation options, showing that drip irrigation and low-carbon electricity could significantly reduce emissions, though their effectiveness varies by region. The study provides insights into the energy and CO₂ intensity of irrigation, comparing it with other agricultural activities. Overall, irrigation is a major contributor to agricultural energy and CO₂ emissions, with significant potential for reduction through efficient and low-carbon practices.