Here is a preprint for our forthcoming chapter in the Encyclopedia of Climate System Science. Our perspective is that ice sheet, ocean circulation and global carbon cycle are critical to the development of ice ages, which are not simply caused by changes in Earth’s orbit as Milankovitch would have it.
Here is a preprint for our forthcoming chapter in the Encyclopedia of Climate System Science. Our perspective is that ice sheet, ocean circulation and global carbon cycle are critical to the development of ice ages, which are not simply caused by changes in Earth’s orbit as Milankovitch would have it.
Radiocarbon (14C) is produced in the atmosphere and spreads through the surface carbon cycle before, you guessed it, radioactive decay. Hence the name, radiocarbon. In contrast, carbon spit out from Earth’s interior is 14C-free and can thus produce a “negative 14C anomaly” in the region of release. Working with Pat Rafter at USF and my former PhD student Ryan Green (now at Equatic), we reconstruct and simulate a major 14C anomaly in the Gulf of California.
We find two main pulses of maybe 800PgC total carbon release during the end of the last ice age, but smaller 14C anomalies persist to the modern day. We also find that the carbon release did not cause ocean acidification or significantly increase CO2, because it was neutralized by a equimolar pulse of alkalinity release to the ocean. Our results lead us to conclude that this highly unusual instance of large scale neutralized-carbon release could be an important geologic analogue for Ocean Alkalinity Enhancement (OAE) as means for marine Carbon Dioxide Removal (mCDR) in the ongoing challenge to mitigate anthropogenic climate change and ocean acidification.
Our four papers on the topic (left to right): (1) detailed reconstructions of deglacial 14C anomalies in the Gulf of California, (2) global carbon cycle constraints on geologic carbon release during the deglacial period, (3) mass balance and pH constraints in simulating regional impacts of carbon release, and (4) regional assessment of 14C anomalies since the last ice age. This inferred release of neutralized carbon remains a challenge to our current paradigm of the global carbon cycle, but it does not significantly affect our understanding of the ice age carbon cycle or our ability to reconstruct ocean circulation using 14C.
Today I was interviewed by Mira Shah of carbon economics on her Signals of Change podcast. Mira had questions about our carbon cycle research and how it may inform sustainable management of the environment going forward.
In a new chapter for the third edition of the Treatise on Geochemistry with Kat Allen and Sandy Kirtland Turner, we systematically analyze the dynamics that couple climate and carbon cycle through CO2 radiative forcing. This includes the first analytical derivation of the silicate weathering timescale. The relevant context of proxy systems for climate and carbon cycle and terminology for coupled climate-carbon cycle change is intended to introduce Earth System science.
