Structural Cointegration of the Climate--Carbon Feedback: Evidence from the Last 130,000 Years

TL;DR

This study uses millennial-resolution ice-core data to analyze the long-term feedback loop between Antarctic temperature and atmospheric CO2, revealing a strong cointegrated relationship with significant temperature responses to CO2 changes.

Contribution

It provides the first structural cointegration analysis of climate and carbon feedbacks over the last 130,000 years using advanced econometric methods.

Findings

Long-run temperature change of 13.0 K per CO2 doubling

Contemporaneous carbon response of 5.77 ppm/K

Cumulative temperature response of 11.8 K within a millennium

Abstract

Using a gap-free, millennial-resolution ice-core record spanning the last 130,000 years, we identify the feedback architecture between Antarctic temperature and atmospheric CO$_2$. The series are found to be cointegrated, justifying estimation with a Vector Error Correction Model (VECM). The estimated long-run relationship yields a temperature change of 13.0 K per CO$_2$ doubling. Structural identification combining Milankovitch-cycle instrumental variables with the VECM residuals yields a contemporaneous carbon response (CCR) of 5.77 ppm/K, whereas the contemporaneous temperature response (CTR) is statistically indistinguishable from zero. Accounting for lagged feedbacks, the cumulative temperature response within one millennium of CO$_2$ doubling reaches 11.8 K.