Risk vs. Prediction?

My last article was about the need for direct government investment in solving the Climate Crisis. That getting rid of bad subsidies and incentives is helpful, but not enough.

This point was made by Simon Sharpe, who worked on counterterrorism for the UK Foreign Office. But Sharpe made another vital point: A lot of climate crisis information is provided by scientists to government policy makers in the form of prediction.

Prediction is about what is most likely to happen. In his experience with terrorism, he realized that the most likely thing to happen is… nothing!

He learned that from a policy standpoint it is more important to focus on risk: What is the worst that can happen? And then we can ask how likely it is to happen.

Terrorism experts are good at assessing risk. And at communicating it to policy makers. But climate crisis research is done by scientists, who have a very different culture. Scientists typically demand “five sigma” certainty – or about 1 in 3.5 million chance of being wrong.

This creates a language barrier when talking about climate risk. Scientists need to be bolder in talking about the worst case risk. And policy makers need to learn how to ask questions in the language of science.

Sharpe gave the example of the risk of London flooding. England had the good sense 50 years ago to invest in the Thames Barrier to block the threat of an ocean wave or rising tide. It can deal with threats up to five meters. How likely is that to be exceeded?

As the average Earth temperature rises, sea levels are likely to rise for two reasons: Warmer ocean water expands with temperature. And ice and snow on land melts and flows into the ocean. Sometimes quite suddenly, if an entire ice sheet breaks free.

The Intergovernmental Panel on Climate Change (IPCC) forecasts a rise of more than 10 meters over the long term if global Earth temperature rises by more than two degrees Celsius above pre-industrial levels. Unless some even worse catastrophe strikes our planet in the next few years, we are on track to exceed that two-degree rise.

When Sharpe talks to British elected officials about this, they are stunned that no one is talking about it.

A similar problem of risk vs. prediction occurs in the case of meteors possibly striking Earth. Unlike in the case of the climate, the physics is relatively simple.

MIT Professor Richard Binzel presented “A Near-Earth Object (NEO) Hazard Index” to a UN conference in 1995. It was revised and adopted at a 1999 conference in Turin (Torino), Italy, and is now called the Torino Scale of risk of NEOs. The scale goes from 0-10 and it is also color coded.

The scale is also tied to the equivalent megatons of TNT, similar to a nuclear bomb. The Chicxulub impact 66 million years ago is considered a primary cause of the extinction of the dinosaurs. Estimated at 100 million megatons. A solid 10 on the Torino Scale. A 10 means it could wipe out all life as we know it.

The famed 1908 Tunguska impact in Russia was estimated at 3-10 megatons; 8 on the Torino Scale. Such events occur on a time scale of 50-1,000 years and could destroy a city if it hit one.

But the Torino Scale is also tied to the probability of impact. When an NEO is first discovered, the probability is difficult to determine. Further observation usually lowers the probability, indicating the object will miss Earth.

The frequency of impacts can be estimated by looking at moon craters. It seems that the frequency goes inversely to the mass of the meteor. Here is the key point: An extinction event may be once in 100 million years. But it might kill all eight billion people on Earth. Meaning the risk of dying from a meteor is surprisingly large even if the impact probability is low.

Because of the clarity of the meteor threat, scientists and policy makers are working hard on meteor detection and deflection technology. We need that same level of urgency applied to the climate crisis.