Our understanding of climate and how it changes is advanced enough to make reasonable decisions, using computer models, about activities such as future energy use and food production. However, for the last four decades, some have been using these models to project catastrophes in the event that governments fail to act. Although many of these projections have been wrong, the doomsayers continue to warn that humanity has 12, 10, or even fewer years left to save society.
These models represent our best current understanding of how the climate works. They have been positively evaluated by the World Climate Research Programme. Yet they are not necessarily correct. For example, a group of scientists at the University of Alabama in Huntsville found that the forecast temperature trends were twice those observed for the tropical upper atmosphere. Other published studies have shown that these same models overestimate global mean surface temperatures, such that observed global temperature trends are often in the lower part of the range of the models predictions.
As early as the late 1980s, the New York Times published projections that global temperatures would rise 3 to 9 degrees Fahrenheit while sea levels would rise 1 to 4 feet by the second quarter of the 21st century. Concern was raised that climate change would cause more droughts and more flooding. The reality has been far from these dire scenarios. The Intergovernmental Panel on Climate Changes Sixth Assessment Report shows more modest warming (less than 1 degree Fahrenheit) and much less sea-level rise (8 inches since 1900, according to NASA). And where heavy precipitation or drought has increased, the confidence in the models is low, according to the same report.
Other dire predictions also have been demonstrably falsifiedfor example, that parts of the globe, including Great Britain, would be relatively snowless by 2020, that the North Pole would be ice-free by the mid-2010s, and even that Mount Kilimanjaros glaciers would disappear by the mid-2010s. In the late 1980s, widespread famines were predicted, followed by the collapse of global agriculture, all by the start of the 21st century. Since that prediction, agricultural output has increased in the Midwest by about 20%.
Finally, a recent study showed that predictions that ocean acidification would decimate fish populations are also proving to be false.
Does all this good news mean that we can ignore the models or that researching them is a wasted effort? Of course not. They may be among the best tools we have. We just need to interpret their results with an awareness of their limitations. When people sensationalize the findings by highlighting only the most unfounded alarmist projections in the upper part of the forecast range, we should resist their alarmism absent compelling evidence.
Given the relatively poor record of model predictions, we should not be frightened into adopting draconian policies that threaten our entire way of life and well-beingespecially those that would harm the world's poor. Rather, we should adapt to changes in climate, which can be done most effectively through the entrepreneurial innovations made possible through free markets.