<p>The Paleocene-Eocene Thermal Maximum (PETM; ∼56 Ma) represents a prominent example of rapid climate-carbon cycle feedback, yet the trigger and tempo of its environmental state change remain controversial. By integrating mercury (Hg) anomalies, carbon isotope (δ¹³C) excursions, and clumped isotope (Δ₄₇) temperature reconstructions from the Egyptian marine Tarfa section, we report a pronounced Hg spike during the PETM onset, implicating pulsed North Atlantic Igneous Province (NAIP) volcanism as a key trigger. Our results are consistent with existing Hg records from across the PETM, indicating a significant increase in volcanic and/or thermogenic Hg release near the onset. However, the Hg signals during the peak warming are largely subdued, suggesting that an alternative carbon source was dominant during this phase. Meanwhile, Δ₄₇ temperature estimates reveal a ∼3 °C warming prior to the PETM, followed by an extreme warming of ∼8 °C (peaking at ∼42 °C) during the PETM main body. This extreme temperature rise, coincident with the maximum negative δ¹³C values, lagged the Hg spike by millennia, suggesting that secondary feedback mechanisms—likely methane hydrates—amplified the warming. Our findings therefore clarify the role of the NAIP in initiating PETM warming and enhance our understanding of how the interaction between deep and shallow carbon reservoirs contributed to extreme climatic warmth.</p>