Holocene temperatures follow CO2 in southeastern Alaska

Understanding the temperature evolution during the Holocene is crucial for future climate projections. However, a puzzling discrepancy between climate models simulating a warming trend during the second half of the Holocene parallel to the rise in atmospheric CO ₂ concentrations and proxy data suggesting cooling during this period – known as the Holocene temperature conundrum – limits our understanding of how climate will evolve in the future. To solve this conundrum, the inclusion of quantitative paleotemperature records from high-latitude sites, which are extremely rare, is essential. Here, we use the hydrogen isotopic composition of fluid inclusions in speleothems from southeastern Alaska to create a quantitative temperature reconstruction of the entire Holocene. We show that the temperature in southeastern Alaska followed CO ₂, in agreement with modeling results. Because our data show no proxy-model bias, they support a seasonal proxy bias to account for the Holocene temperature conundrum.