The topic of climate modeling is generally forward-looking. How will temperatures change over the next century? Where will sea levels rise by 2050? Who will be affected most by climate-fueled events like drought, floods, or wildfires? Scientists are attempting to answer these questions, and new data, models, and analyses continue to refine the discussion.
A different line of questions comes into view when we look backward: What did climate models of the 1980s say about now? How well did forecasts 40 years ago predict what we see today? Were any of the extreme events that happened in recent years anticipated by the experts behind these models?
As it turns out, the climate models of the 1980s worked remarkably well. Though they weren’t perfect, scientists did use them to warn us about many of the changes we see in our world today.
In 1988, Dr. James Hansen, then director of the National Aeronautics and Space Administration (NASA) Goddard Institute for Space Studies (GISS) testified before Congress. He joined other climate scientists who wanted Washington to know greenhouse gases were behind climate change. Speaking to the Senate Energy and Natural Resources Committee, Hansen laid out a stark warning: The data suggested, with 99 percent certainty, that Earth was warming due to human activity. Anthropogenic climate change had arrived, and the United States and the rest of the world would witness the consequences within decades.
This warning, and the climate forecasts that support it, are detailed in a paper published by Hansen and his colleagues the same year. The paper describes the GISS model II. Representing climate parameters in three dimensions, this model generated a 100-year control run. In the control run, the composition of atmospheric gases is fixed and unchanging. Then the model computed three scenarios varying the rate of trace gases. In scenario A (often called the “business as usual” scenario), trace gases continued to accumulate at levels typical of the 1970s and 1980s. Scenarios B and C represented a moderate decline or an abrupt halt in trace gas accumulation, respectively. In this way, the model could compare what may happen if humans do nothing—or something—to act on climate change.
- A rise in Earth’s global surface air temperature greater than 1°C above the 1951–1980 average
- Increased extreme heat days in major US cities, particularly in the South
- Steadily warming oceans, the effects of which can lead to the bleaching and death of coral reefs
More to Explore
- Learn more about the performance of past climate models in this open access paper.
- Explore trends in Arctic sea ice.
- Generate your own maps and charts, and download global temperature data from NASA GISS.
