Evidence of Arctic methane emissions across the mid-Pleistocene

During the Pleistocene, Earth's climate changed dramatically. The mid-Pleistocene transition (MPT; similar to 1.3-0.7 million years (Ma)) featured an important ice volume increase at both poles. The evolution of large Arctic ice sheets caused the sequestration of methane as free gas and hydrates in subseabed sediments. Ice volume changes, associated with variable pressures and temperatures, perturbed those giant reservoirs, causing methane leakages. Here, we present borehole data from the Arctic-Atlantic gateway region, providing foraminiferal stable carbon isotope and source-specific biomarker evidence that reveals three main seafloor leakage episodes that occurred prior to and across the mid-Pleistocene transition. By combining borehole data with hydrate stability modelling, we propose that tectonic stress changes associated with large ice volume early build-up and wastage during the mid-Pleistocene controlled episodic methane leakages from subsurface reservoirs. Our data indicate methane release, showing a potential scenario for vast Arctic areas storing methane that are now affected by ongoing ice volume decrease.

Automated summary

During the Pleistocene, there were significant changes in Earth's climate, leading to increased ice volume and methane leakage. Borehole data from the Arctic-Atlantic gateway region reveals three main seafloor leakage episodes prior to and during the mid-Pleistocene transition. Combining this data with hydrate stability modeling, it is proposed that tectonic stress changes associated with ice volume changes controlled episodic methane leakages.