The Abyssal Share: Deep-Ocean Warming Below 2,000 m in Earth's Energy Imbalance and in Thermosteric Sea-Level Rise

How much heat is the ocean below 2,000 m taking up, and what does it contribute to sea-level rise? Basin warming rates of 0.02-0.10 C/decade applied uniformly to the deep volume give 31-153% of the 0.9 W/m2 planetary imbalance, proving those rates are not volume means. A layer-resolved integral gives 34.5 TW (0.0676 W/m2, 7.5% of the imbalance, combined bracket 3-12%) below 2,000 m, and, with the thermal expansion coefficient evaluated at pressure, 0.116 mm/yr of thermosteric rise (9.7% of the total thermosteric rate, bracket 7-14%). The abyss is a tenth-scale term in both budgets. AI use disclosed: this work was prepared with the assistance of an artificial intelligence system, Dave, which carried out the computation in the deposited compute.py and assisted with drafting; the author takes responsibility for the question, inputs and conclusions.