Jack Longman, Benjamin Mills, Andrew Merdith

The emplacement of large igneous provinces (LIPs) is known to have been a driver of climate change in Earth’s past, particularly during the breakup of Pangaea. However, the balance between climate warming through CO2 emission and climate cooling through increased weathering is poorly understood. To better understand the role of LIP emplacement on long-term climate change, we utilize a coupled climate-biogeochemical model which considers the holistic impact of LIPs through both degassing of CO2 and enhancement of local continental weathering rates. Of the 7 LIPs during the breakup phase of Pangea (approximately between 300 and 150 Ma), only the Central Atlantic Magmatic Province (CAMP) drives long-term cooling in our model, and this is a minor effect despite emplacement of a very large surface area in the humid tropics. Similarly, only the CAMP imparts a clear stepwise change in the long-term strontium isotope record whereas the other LIPs of this period do not. Due to relatively small areal extents, and emplacement often outside the tropical weathering zone, we conclude that most LIPs have no significant global cooling effect on multimillion year timescales.