近日，瑞士苏黎世联邦理工学院
据了解，冰盖和全球冰川的融化导致海平面上升，两极到赤道的物质输送增加了地球的扁率，并导致白昼长度(LOD)增加。
研究人员通过对1900年以来地球表面质量变化的观测和重建，发现20世纪气候引起的LOD趋势在0.3-1.0ms/cy之间徘徊，但自2000年以来已经加速到1.33±0.03ms/cy。研究进一步表明，地表质量输运解释了过去30年观测到的地球扁率加速趋势。研究得到了由冰川均衡调整(GIA)引起的LOD下降趋势的独立测量值-0.80±0.10ms/cy，这为地幔粘度提供了限制。
GIA速率和月球潮汐摩擦的总和充分解释了LOD的长期趋势，这种趋势是从当代气候变化开始之前的过去三千年日食记录中推断出来的。本研究对高排放情景下未来气候变暖的预测表明，到2100年，气候引起的LOD速率可能达到2.62±0.79ms/cy，超过月球潮汐摩擦，成为LOD长期变化的最重要因素。
附：英文原文
Title: The increasingly dominant role of climate change on length of day variations
Author: Shahvandi, Mostafa Kiani, Adhikari, Surendra, Dumberry, Mathieu, Mishra, Siddhartha, Soja, Benedikt
Issue&Volume: 2024-7-15
Abstract: The melting of ice sheets and global glaciers results in sea-level rise, a pole-to-equator mass transport increasing Earth’s oblateness and resulting in an increase in the length of day (LOD). Here, we use observations and reconstructions of mass variations at the Earth’s surface since 1900 to show that the climate-induced LOD trend hovered between 0.3 and 1.0 ms/cy in the 20th century, but has accelerated to 1.33 ± 0.03 ms/cy since 2000. We further show that surface mass transport fully explains the accelerating trend in the Earth oblateness observed in the past three decades. We derive an independent measure of the decreasing LOD trend induced by Glacial Isostatic Adjustment (GIA) of -0.80 ± 0.10 ms/cy, which provides a constraint for the mantle viscosity. The sum of this GIA rate and lunar tidal friction fully explains the secular LOD trend that is inferred from the eclipse record in the past three millennia prior to the onset of contemporary climate change. Projections of future climate warming under high emission scenarios suggest that the climate-induced LOD rate may reach 2.62 ± 0.79 ms/cy by 2100, overtaking lunar tidal friction as the single most important contributor to the long-term LOD variations.
DOI: 10.1073/pnas.2406930121
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2406930121