Day 4: Carbon Feedback Cycle

Today you will learn from expert guest Pierre Friedlingstein about carbon feedback cycles, why thy exist, and how we might positively influence them to solve climate change.

Summary

Guest: Pierre Friedlingstein

Professor Pierre Friedlingstein is a Fellow of the Royal Society. He holds a Chair in Mathematical Modelling of the Climate System at the University of Exeter. His research interests are in the field of global biogeochemical cycles and their interaction with the climate system.

More specifically, he is interested in the coupling between  climate change and the major biogeochemical cycles over the historical period and in the future. He identified the positive feedback between climate change and carbon cycle and developed a mathematical framework for climate-carbon feedbacks analysis.

Pierre coordinates the annual Global Carbon Budget of the Global Carbon Project (GCP), and also co-lead the  coupled climate carbon cycle intercomparison project (C4MIP).

He is member of the Joint Steering Committee (JSC)  of the World Climate Research Programme (WCRP).

He has been actively involved in climate assessment through his participation in the Intergovernmental Panel on Climate Change (IPCC) since 1994. He was lead author for the IPCC Fifth Assessment Report for both Working group I and the Synthesis Report.

Follow Pierre:

• LinkedIn
• X
• Website

Explain succinctly what the carbon feedback cycle is from first principles.

The carbon cycle is a natural system. Ocean and land sinks take in CO2 from the atmosphere through photosynthesis of biomass. When that plant material dies, it decomposes with a fraction of the CO2 going into the soil or deep ocean and a fraction returning to the atmosphere.

Why does the carbon feedback cycle exist? What role does this system play in our lives?

And when there's no perturbation from human activities, this is more or less a steady state. It's a natural system.

Humans emit CO2 into the atmosphere when we are burning fossil fuels or burning coal, oil and gas, and all of these CO2 goes into the atmosphere.

That CO2 stays in the atmosphere for hundreds of years disrupting the natural carbon cycle system.

Because of this increase in CO2 concentration in the atmosphere, you have an increase in the flux that goes into carbon sinks like the ocean.  

Likewise on the land in the forest ecosystem, for example, if you have more CO2 in the atmosphere, there is more photosynthesis, more growth of the ecosystem.

How does the carbon feedback cycle interact with the problem of climate change?

CO2 has been relatively stable in the atmosphere until the last century, when humans began emitting CO2 in the atmosphere, creating an increase in the feedback cycle and greenhouse effect leading to a warming climate.

Warming of the climate also has an impact on the carbon cycle creating a second type of feedback:

If you have larger warming, you reduce the flux of CO2 that goes into  the ocean.

• There's less CO2 going into the ocean now because the oceans are warming.
• The warming of the ocean reduce  the uptake of carbon from the ocean.

If you have larger warming, you reduce the intake of CO2 by forests and land ecosystems.

• Warming leads to increase the composition and respiration for microbial activity in the soil so the carbon doesn't stay in the soil as long.

Ocean and land sinks do help with reducing the intensity at which humans are emitting carbon into the atmosphere; however, their efficiency is reducing as the climate continues to warm.

How might we positively influence this system to help solve climate change?

To improve the carbon feedback cycle we must:

• Reduce emissions: the faster we do reduce emissions, the faster we will reduce the warming and the impact of warming on land and marine ecosystems.
• Stop deforestation: not only does deforestation means that we emit CO2 into the atmosphere because we're cutting trees, and in these trees we're storing lots of carbon, but also we reduce the amount of forests that can sequester carbon.

‍

Additional Resources

• The Intergovernmental Panel on Climate Change
• Carbon cycle feedbacks and future climate change by Pierre Friedlingstein

‍

Top Skills To Learn

Our guest recommends learning the following skills:

• Numerical skills & climate modeling: math, statistics, numerical modeling, coding, machine learning and AI.

‍

Activity

Activity: Feedback Loop Analysis

Choose a specific climate-related scenario involving both positive and negative feedback loops. Research the components of these feedback loops and how they interact. Create a written analysis or visual representation that explains the feedback mechanisms and their potential implications for the climate system.

‍

Skill Lesson Mastered

Demonstrate mastery of the knowledge and skills presented in this lesson by applying it to the above activity. If, and only if, you have a full understanding and have mastered the knowledge and skills presented in this lesson, select the next lesson in the navigation.