In a recent debate about climate change, environmentalists argued that if we reduce carbon emissions significantly, the average global temperature will stabilize. They concluded that implementing stricter regulations on industrial emissions is crucial. However, some skeptics claimed that even with reduced emissions, natural climate variability will still lead to temperature increases. Therefore, they argue, regulating emissions may not be as vital as the environmentalists suggest.
Which of the following, if true, would most effectively support the environmentalists' conclusion?