When the Sahara was green

Humans are now the main cause of climate change on Earth. Are the climate models we use to predict future change artificially stable? Do we need to re-think explanations for the evolutionary emergence of our ancient human ancestors? 

Answers to these questions lie buried in continentally derived sediments deposited in the deep oceans. 

Properly read, these records reveal dramatic changes in African rainfall and vegetation over geological time controlled by Earth’s orbit of the Sun (Milankovitch Cycles) and abrupt shifts in the temperature of the North Atlantic Ocean. However, none of the climate models currently used to predict 21^st century change can reproduce North African climate for even the most recent geological past (the mid-Holocene). And the predictions they make for African rainfall for the coming decades diverge alarmingly. Ironically, these models appear to show closer agreement with one another when simulating Africa’s climate for the deeper geological past when atmospheric CO₂ levels last approached present day levels (the warm Pliocene, about three and a half million years ago). This is all quite confusing. How can we reconcile these conflicting results? What lessons can we learn? 

I will describe some of the work we have been doing in Southampton to tackle these questions. 

Paul is Professor of Palaeoclimatology in the School of Ocean and Earth Science at the University of Southampton’s Waterfront Campus. Together with his students, he works to understand how Earth's climate system works naturally. He uses what he learns about past changes in climate, to understand the ways in which Earth will respond to human-driven change in the coming decades. Paul has spent almost 2% of his life onboard the scientific drill ship, the JOIDES Resolution. You can learn more about what life is like aboard the JOIDES Resolution during one of these two month-long expeditions here:
https://www.youtube.com/watch?v=A3ot11rBYXM