Climate change is increasingly influencing the length of day (LOD) variations, with significant implications for Earth's rotation and oblateness. The study shows that the LOD trend increased from 0.3 to 1.0 ms/cy in the 20th century but accelerated to 1.33 ± 0.03 ms/cy since 2000. This acceleration is attributed to surface mass transport caused by melting ice sheets and glaciers, which increases Earth's oblateness. Glacial Isostatic Adjustment (GIA) contributes a decreasing LOD trend of -0.80 ± 0.10 ms/cy, which helps constrain mantle viscosity. The sum of GIA and lunar tidal friction explains the secular LOD trend observed over the past three millennia. Under high emission scenarios, the climate-induced LOD rate may reach 2.62 ± 0.79 ms/cy by 2100, surpassing lunar tidal friction as the main contributor to long-term LOD variations. The study highlights the unprecedented impact of climate change on Earth's rotation and oblateness, with implications for timekeeping and space navigation. Climate-induced LOD changes are projected to continue increasing, with the rate expected to reach levels twice as high as current values, significantly affecting Earth's rotational dynamics. The findings underscore the importance of understanding and mitigating climate change impacts on Earth's systems.Climate change is increasingly influencing the length of day (LOD) variations, with significant implications for Earth's rotation and oblateness. The study shows that the LOD trend increased from 0.3 to 1.0 ms/cy in the 20th century but accelerated to 1.33 ± 0.03 ms/cy since 2000. This acceleration is attributed to surface mass transport caused by melting ice sheets and glaciers, which increases Earth's oblateness. Glacial Isostatic Adjustment (GIA) contributes a decreasing LOD trend of -0.80 ± 0.10 ms/cy, which helps constrain mantle viscosity. The sum of GIA and lunar tidal friction explains the secular LOD trend observed over the past three millennia. Under high emission scenarios, the climate-induced LOD rate may reach 2.62 ± 0.79 ms/cy by 2100, surpassing lunar tidal friction as the main contributor to long-term LOD variations. The study highlights the unprecedented impact of climate change on Earth's rotation and oblateness, with implications for timekeeping and space navigation. Climate-induced LOD changes are projected to continue increasing, with the rate expected to reach levels twice as high as current values, significantly affecting Earth's rotational dynamics. The findings underscore the importance of understanding and mitigating climate change impacts on Earth's systems.