Even experts tend to skirt the issue of how much uncertainty remains. When the Intergovernmental Panel on Climate Change (IPCC) discussed the expected "climate sensitivity" of the atmosphere to a doubling of CO₂ at approximately 3^o C, it does not emphasize the substantial uncertainty around that estimate (some estimates range to well over 6^o C. Similarly, there are many discussions about sea levels being most likely to rise by somewhere between 1 and 2 feet by 2100, even though some experts are anticipating more than 10 feet of sea level rise by 2100.

Since Risk = Probability x Consequence, focusing on the most likely climate outcome is misleading when it comes to understanding the nature of climate risk. This is one reason that a risk-neutral Social Cost of Carbon may be as low as $35/ton, while a risk-averse Social Cost of Carbon could be higher than $1,000/ton.

This chapter of Your Climate Change PhD explores the topic of risk, and how it relates to understanding the future of climate change, including:

• The known knowns, known unknowns, and unknown unknowns of climate change
• The relationship of climate uncertainties to risk
• The growing uncertainty associated with climate change impacts and outcomes as climate-relevant probability distributions change
• Exceedance curves as a measure of risk
• Examples of risk-based climate assesslments

In each case you’ll gain insight into the covered topics, and be hyperlinked to curated knowledge collections in the Climate Web.