Millennial variations in atmospheric CO₂ during the early Holocene (11.7–7.4 ka)

<p>We present a new high-resolution record of atmospheric CO<span class="inline-formula">₂</span> from the Siple Dome ice core, Antarctica, over the early Holocene (11.7–7.4 ka) that quantifies natural CO<span class="inline-formula">₂</span> variability on millennial timescales under interglacial climate conditions. Atmospheric CO<span class="inline-formula">₂</span> decreased by <span class="inline-formula">∼10</span> ppm between 11.3 and 7.3 ka. The decrease was punctuated by local minima at 11.1, 10.1, 9.1, and 8.3 ka with an amplitude of 2–4 ppm. Although the explanations of carbon cycle mechanisms remain uncertain due to insufficient paleoclimate records and model simulations, these variations correlate with proxies for solar forcing and local climate in the southeast Atlantic polar front, eastern equatorial Pacific, and North Atlantic. Additional CO<span class="inline-formula">₂</span> measurements using better-quality ice cores and carbon cycle models are needed to confirm the observation.</p>