How does the carbon cycle directly dictate the future of our climate? This is the first of three micro-lectures broadcast as part of the Climate at the crossroads live lesson (see links below). Dr Mike O'Sullivan from the University of Exeter breaks down the mechanics of the carbon cycle and explains the critical difference between the fast and slow cycles. Discover how human activities have bypassed natural timelines by injecting slow-moving fossil carbon directly into the fast cycle, and learn about the "free" climate mitigation services currently provided by our land and oceans.

Dr O'Sullivan tackles the complex concept of positive feedback loops, explaining how rising temperatures threaten to weaken these natural carbon sinks and accelerate warming. Crucially, the lecture concludes with a powerful, science-backed message of human agency: according to the latest climate models, the moment we stop emissions, global warming stops.

Key Topics Covered: 

• The fast vs slow carbon cycle
• Land and ocean carbon sinks
• Human perturbation of natural systems
• Positive feedback loops in climate change
• Climate modelling and the power of zero emissions

Other videos in this micro-lecture series 

Coral biodiversity and climate change by Prof Peter Mumby, University of Queensland

Tipping points - from peril to prosperity by Dr Tom Powell, University of Exeter