By Roy Spencer, Ph.D., principal research scientist in the Earth System Science Center. Prior to joining The University of Alabama in Huntsville, Dr. Spencer was a senior scientist for climate studies at NASA's Marshall Space Flight Center.
Nothing helps raise public awareness like a good meme, and at least on that score, the "97 percent of scientists agree" meme has been wildly successful in convincing people that the science of global warming is settled. But as we shall see, the statistic - even if it were true - tells us nothing particularly useful regarding the global warming debate.
The 97 percent number comes from a 2013 paper that was published by John Cook in Environmental Research Letters and that claimed to review about 12,000 published scientific papers on global warming and climate change. Now, for those of us who work in climate change research, it is well known that "climate change" is widely assumed to be mostly human-caused, despite the fact that very few published studies have actually attempted to demonstrate this to be the case.
Again, it is simply assumed.
And that is one of the (many) problems with the Cook literature review study. It only established that there is widespread consensus that humans contribute to (not even dominate) global warming, a position that the vast majority of climate "skeptics" agree with - including myself. I do not know of any climate skeptic researchers who claim that humans have no influence on the climate system. The existence of trees has an influence on the climate system, and it is entirely reasonable to assume that humans do as well.
The most pertinent questions really are: just how much warming is occurring? (not as much as predicted); how much of that warming is being caused by humans? (we don't really know); is modest warming a bad thing? (maybe not); and is there anything we can do about it anyway? (not without a new energy technology).
Also, while the scientific consensus on climate change is a mile wide, it is only inches deep. Very few climate researchers can tell you what evidence points to (say) 50 percent of recent global warming being human-caused. There might be a few dozen scientists in the world who are familiar enough with the science to defend it. Instead, the vast majority of scientists simply repeat what they have heard, or are familiar within only a cursory manner. Climate change research involves so many specialties and sub-disciplines that few scientists have a knowledge base sufficiently holistic to make an informed judgment.
Regarding just how wrong scientific consensus can be, I like to use the example of peptic ulcers. With millions of sufferers being treated over the last century by doctors, you would think we would know what causes them. Until relatively recently it was assumed that eating spicy food or stress caused them. But two Australian doctors, Robin Warren and Barry Marshall, had a theory that they were caused by bacteria, a fringe idea that led to them being shunned and ridiculed at conferences.
Yet they were correct, and were awarded the 2005 Nobel Prize in medicine for their work. One can only imagine the thousands of published medical papers that simply assumed that ulcers were caused by stress or spicy food. Would it have been 97 percent? Or even more? I don't know. Yet they were all wrong.
Now, if the physical cause of millions of peptic ulcers went undiscovered for so many years, isn't it possible that there are natural causes of climate change? Climate change is a relatively young science. Computerized climate models do a reasonably good job of replicating the average behavior of the climate system, but have been almost worthless for forecasting climate change. They have not even been able to hindcast (let alone forecast) the warming rate of the past 30-50 years, generally overstating that warming by about a factor of two.
When I have discussed the evidences for natural causes of climate change with "consensus" researchers, they inevitably retreat to the position that "we need to get away from fossil fuels anyway." But there are no large-scale replacements yet available - even optimistic estimates place 80 percent of the energy generation burden on fossil fuels in the coming decades. You cannot simply legislate or regulate new forms of energy generation into existence.
We really don't understand the natural sources of climate change on decadal or centennial time scales. I liken these sources as "chaos" in the climate system, most likely tied to small changes in ocean circulation that occur naturally, just because that's what nonlinear dynamical systems (like the ocean and atmosphere) do. We have published research that suggests as much as 50 percent of global average warming over the last 50 years was due to more frequent El Nino activity, which affects the ocean circulation, global cloudiness, and global temperatures.
Yes, human greenhouse gas emissions from burning fossil fuels almost certainly play a role. How much of a role is unknown.
The extreme popularity and success of the 97 percent meme tells us something about the global warming debate and how it is received. People gravitate toward simple ways to support and defend their preconceived beliefs. Global warming is one of those issues that the believer holds onto with an almost religious fervor. As a scientist I learned long ago that there is no point wanting this or that theory to be correct. Mother Nature really doesn't care what you believe. Instead, I just follow the evidence and generally assume that whatever is developed as an explanation is most likely going to be proved wrong eventually ... as is the case with most published science.
Climate science isn't rocket science. It's actually much more difficult.Read more at Watts Up With That.