Predicting Our Climate Future: What We Know, What We Don't Know, And What We Can't Know

“Predicting Our Climate Future is an ambitious exploration of a critical topic.”

The key messages of David Stainforth’s Predicting our Climate Future are that predicting future climate change is extremely difficult, that making the most accurate predictions possible is critical to our ability to thrive—or even survive—in a warming world, and that researchers in different disciplines will need to work together in order to make good decisions based on those predictions.

Stainforth appears to be highly motivated to get those messages out. On the very first page he mentions how much he wants the reader to keep on reading. Alas, it is not entirely clear who that reader should be. While some parts are written for a general audience, the main messages of the book are most relevant to climate-change researchers, their institutions, and their funders. And although there is actually only one math formula in the entire book, several chapters deal with complex mathematical concepts that will try the patience of non-experts.

Accurate climate prediction is indeed difficult. One approach is what Stainforth calls the “look-and-see” method, in which we examine and quantify past climate changes and then extrapolate those forward in time. The problem is that, in the context of anthropogenic climate change, the past isn’t a reliable guide to the future because the rate of change is changing and the mechanisms that are driving that change are also changing. Look-and-see is not the answer to accurately predicting climate changes decades into the future.

The other he calls the “how-it-functions” approach. In this case we do our best to understand everything that affects our climate and drives it to change, and then we write (and re-write, and adjust, and re-adjust) computer models that allow us to step forward in time and predict the likely changes. The main problems here are that we don’t yet fully understand the driving forces, and that the models are so complex that they challenge our computing resources.

Stainforth explains that in order to make the best predictions possible—so that we can make good decisions about how to cope in a world which is likely to have a very different climate—we have to keep working on improving climate models and on expanding the computing power to run them, and we have to do that quickly. He acknowledges that these two goals are mutually exclusive. Developing great climate models and building great computers both take time. Do we act now on the predictions available, he asks, or do we wait for better predictions so that we can plan more appropriate actions?

Stainforth stresses the need for multidisciplinary research to help us navigate the future. By way of illustration he describes a collaboration between an economist, a geographer, and a physicist (himself), and summarizes their findings this way: “If a 500 ppm [CO2] scenario leads to a future global economy which is 1% larger than the business-as-usual scenario [in which CO2 levels would be much higher than 500 ppm] then this indicates that even after allowing for the cost of reducing emissions [so that we don’t exceed 500 ppm], the future is improved in a way that is equivalent to increasing the size of the global economy by 1% forever.” We should be alarmed by this perspective because it ignores the likely tens of millions of deaths and hundreds of millions of displacements that even 500 ppm will lead to, most of them in countries where such tragedies have little impact on the global rate of economic growth. It seems that broader interdisciplinarity is needed.

Predicting Our Climate Future is an ambitious exploration of a critical topic. It is a recommended read for climate scientists, especially those trying to model the future, for the researchers—in many disciplines—that are focused on understanding and forecasting the physical and human impacts of the coming climate changes, and for policy makers engaged in climate issues. It might be an interesting and thought provoking read for those working on the margins of climate change, as well as those just looking in from the outside, as long as they can remain engaged long enough to reach the end.