Global Warming Objections, Part VI: Climate Modeling

by Chuck Hall

One of the most useful aspects of science is that data can be used to make predictions. By collecting data and studying how systems interact, it is possible to extrapolate further using the data, and to thereby make predictions as to the outcome of future events. One of the tests of the accuracy of a theory is the accuracy of the predictions it makes.
Climate science uses mathematical modeling, based on climate models. In the early days, numbers had to be crunched by hand, using slide rules and pencils. Nowadays we have supercomputers capable of making millions or billions of calculations per second. The more calculations that can be made, the more accurate the model will be.
Scientists working in the field of climatology have been making predictions about global warming since as early as 1896. Back then, the calculations were slow because computers didn’t exist. Even so, they were able to make certain predictions about carbon dioxide and its relationship to global temperature. Svante Arrhenius was a Swedish scientist who predicted, in 1896, that carbon dioxide emissions due to human activities would raise global temperatures. Even though he was working with very primitive equipment by today’s standards, he attained some degree of success with his predictions.
Since Arrhenius’s time, science has progressed quite a bit. Climatologists have made a number of predictions based on climate data. The ‘proof of the pudding’ that their models are accurate lies in the accuracy of the predictions those models reveal. Some of the many predictions made by climate models include:
NASA scientist James Hansen, in 1988, predicted that temperatures would climb over the next twelve years. His predictions were remarkably accurate.
Models have predicted that increase in surface temperatures would be accompanied by a cooling of the stratosphere. This prediction has been confirmed by satellite data.
Models have predicted that a brief, but short-lived, cooling period would occur in the event of a large volcanic eruption. The eruption of Mount Pinatubo in 1994 has confirmed this prediction.
Models predicted that global warming effects would be accelerated in the Arctic regions as snow melted. Snow reflects sunlight, but the earth underneath absorbs it. This prediction has been confirmed by observation.
Finally, models predict an accelerating increase in surface temperature, correlating to the amount of carbon dioxide in the atmosphere. This has been amply demonstrated to be so.
In almost every instance, computer models of climate change have made accurate predictions.
Another way to test the validity of the computer models is a technique called ‘hindsighting.’ In hindsighting, the computer models are started from a known period in history, using atmospheric data available for that time period. They are then run forward to a later time. The results are then compared to the climate data for that later time period for accuracy. For example, using data from the 1880s, the computer model is set to run from 1880 to the present. The computer results are then compared to the actual observed data from the present time. The results reveal that the climate model is accurate, because the data from the computer model matches what is actually observed in real life.
A true test of a scientific theory is its power to predict future events. Climate models for global warming have demonstrated such predictability. Dissenters are stuck with the problem of coming up with an alternate theory that explains the data. To date, no such alternate theory exists.