What evidence do some scientists have for not believing in global warming?

Answer 1

Few research scientists would say that global warming is not taking place, because they would be disputing the temperature records. One leading scientist who was prepared to dispute the temperature records was the physics professor Richard Muller, who has been a longtime critic of climate studies. He knew he had the scientific expertise to investigate the studies that have been carried out and thereby to address what he called "the legitimate concerns" of sceptics who believe global warming is exaggerated. The Berkeley Earth Surface Temperature project at the University of California, Berkeley, was launched with a team of physicists and statisticians who set out to challenge the scientific consensus on global warming. Professor Muller unexpectedly found that the work of the three principal groups that have analysed the temperature trends underlying climate science is "excellent ... We see a global warming trend that is very similar to that previously reported by the other groups."

Some scientists either do not believe that changes in greenhouse gas levels are a principal cause of global warming, or believe that predictions of future warming can not be made with certainty. These cases of caution or doubt are not so much based on concrete evidence negating mainstream scientific opinion, but rather a view that the evidence is not yet so absolute that these conclusions and predictions can be made with certainty.

In 2001, Richard Lindzen agreed that global warming is occurring and could be caused by increased carbon dioxide (CO2) levels but was one who believed that scientists were not in a position to prove the connection. He said, "We are quite confident (1) that global mean temperature is about 0.5 °C higher than it was a century ago; (2) that atmospheric levels of CO2 have risen over the past two centuries; and (3) that CO2 is a greenhouse gas whose increase is likely to warm the earth (one of many, the most important being water vapor and clouds). But - and I cannot stress this enough - we are not in a position to confidently attribute past climate change to CO2 or to forecast what the climate will be in the future."

Other scientists were unconvinced that human activities are a significant cause of rising greenhouse gas levels, but recent biometric studies using C12 and C13 ratios have now proven that link.

Answer 2

Some scientists may question the evidence for global warming due to uncertainties in climate models, natural climate variability, or the complexities involved in attributing specific weather events to long-term climate trends. Additionally, disagreements may arise from differing interpretations of data or the emphasis placed on certain factors over others in climate science.