But is it really happening? Whom should you trust?

For anyone who is not a climate scientist and lacks the necessary advanced scientific expertise, trying to get a handle on the truth here can be devastatingly difficult. With claims and counterclaims being thrown around by politicians, reporters, pundits of all kinds and scientists (some more suitably qualified than others), it can be very difficult to know who to believe.

As far as all climate scientists are concerned, there is absolutely no question whatsoever that global warming is happening. There are temperature-measuring centers around the globe that demonstrate without a doubt that the global mean temperature is in fact rising. But what about the anthropogenic part? Are we the primary cause?

Although there isn’t universal agreement on this question, the level of agreement that we are the primary cause is so high among active, bonafide climate scientists, that this is considered the scientific consensus view and has been for several decades. For nearly all climate scientists, AGW is real and happening, and is a great source of concern.

So who is in the consensus?

The scientists in question are those who publish climate science papers in peer-reviewed journals and are currently active researchers in the field.

What is a peer-reviewed journal?

For a scientific paper of any kind to be treated as serious science, it must pass a rigorous process known as peer-review. This means that the paper has been submitted to several other scientists, who have recognized expertise in the field, for review. They submit comments and criticisms (which have a reputation for commonly being quite harsh) to which the author must respond, either by defending their work or making necessary changes to the satisfaction of the reviewers. This process might go through a few iterations before the reviewers are all satisfied and the journal is ready to publish the paper.

Journals are considered reputable in the scientific community if they are committed to only publishing peer-reviewed papers.

Note:  It is widely acknowledged that the peer-review process is far from perfect. Deciding who may review papers and how reviewing is done is not sufficiently standardized. At times, poor science has been allowed to slip through the system, only being caught out later. Some argue that peer-review has led to the reinforcement of biases within the scientific community. Much effort has been made to improve the process, with mixed success. In climate science in particular, much effort is made to ensure that the process is undertaken in a particularly rigorous way in order to address these issues. Despite its weaknesses, it is broadly acknowledged that this is the best system that we have in ensuring that scientific research meets a minimum qualitative standard.

The bottom line

According to a number of studies, between 90% and 100% of such scientists were in agreement that Anthropogenic Global Warming was real. (I did find someone who argued that the true figure is somewhere between 80% and 90%.)

This included scientists from the leading scientific organizations, like NASA, NOAA and the top universities around the world. This finding was also endorsed by the more-than-one-hundred major scientific organizations worldwide, including the US National Academy of Sciences, the Royal Society of the United Kingdom and the Russian Academy of Sciences, to name just a few.

What to make of the scientific consensus

Normally-speaking, accepting the scientific consensus should be the default position. We rely upon scientific opinion every day in thousands of ways, even though we don’t have the expertise to evaluate it. We don’t question the fundamentals of aeronautics before we get on a plane. We acknowledge that it’s too complex for us to understand, but we see that it works and we trust the experts.

In order to dispute the scientific consensus, and one as strong as this, one would need to offer a particularly strong argument.

A conspiracy theory?

One possible response is to suggest that the scientific consensus is driven by some sort of left-wing, environmentalist conspiracy. Climate scientists are probably environmentalists at heart, concerned about the possible dangers of greenhouse gases and perhaps they are making a bigger deal about it than they really have evidence for.

So, for example, some might point to dire predictions made by environmentalists, such as Al Gore, which many argue were shown to be way-overstated. Others might point to claims that various climate-related organizations played with their figures to support the conclusion of Climate Change.

I’m not really a big fan of conspiracy theories myself, and the specific conspiracy claims that I’ve come across have not usually stood up to any scrutiny. But beyond that, think about the size of the conspiracy we’d be talking about. All the aforementioned organizations (NASA, National Academy of Sciences, etc) would have to be in on it. What’s more, there are highly-regarded climate scientists who are conservatives, such as Richard Alley, a member of the Republican party, who are also endorsing this position.

Who else? Well, there’s also Shell, the leading fossil-fuel producing company in the world, completely in support of this conclusion and working to redefine its business in order to end up on the right side of history.

So, realistically, I think we can close the door on this possibility.

Groupthink?

Maybe we could suggest something more nuanced; not that there is a conspiracy, but that the field of climate science is like an echo chamber, where the climate change hypothesis has become so widely accepted, that no one can think outside the box anymore.

Anyone who is over 30 will remember that cholesterol used to be the big dietary “no-no”. This was the accepted wisdom which no one in the medical field questioned. Then, one day, the medical profession announced that there’s “good cholesterol” and “bad cholesterol”. And then, that cholesterol isn’t really the problem; it’s actually carbs.

The philosopher of science, Thomas Kuhn, argued that this is part of the nature of scientific development. Once a paradigm takes hold for explaining the data, it will often continue to prevail, even in the face of contradictory data. Only after a massive amount of contradictory data has accumulated does a paradigm shift happen and a new paradigm emerges to explain all the data.

On the other hand, in the case of climate change there would be a tremendously strong incentive to debunk the consensus if such a thing were considered possible. Think about it. Climate change has become a huge source of concern internationally with worrying implications for our future. The financial demands it makes of the world are immense. Those who could conclusively demonstrate a weak link in the argument and show the world that there really is nothing to worry about would be viewed as nothing short of the greatest heroes internationally, celebrated on a par with Einstein. It is no secret that every scientist enters their field with a drive to discover something that no one else knows. They are not there simply to affirm known truths. The fact that there isn’t one peak scientific body to challenge the consensus is very telling. (See this relevant comment from climate scientist, Richard Alley*.)

* He also happens to be a member of the Republican party.

So could the climate change hypothesis be a false paradigm that is waiting to ultimately be debunked? Although unlikely, we probably can’t rule out that possibility altogether. But even if that were to ultimately happen, it would be extremely difficult to justify dismissing the current scientific consensus on the basis of such a mere future possibility. As the Talmud says, “A judge only has what his eyes can see” (Bava Batra 131a). If we can’t rely on the scientific thinking of the day, there’s no point engaging in scientific research at all. If it wasn’t an urgent problem perhaps one could justify waiting it out, but we don’t really have the luxury of doing that here. A strong majority of climate scientists tell us that this is real and of immediate concern.

Conclusions

So let us answer the questions raised at the beginning of this piece:

• Do we really know that the climate is warming and will continue to warm?

• Even if we do know that, can we really be sure that humans are the primary cause?

There is no dispute at all that the climate is warming. There is also a very broad consensus among active and reputable climate scientists that humanly-generated greenhouse gas emissions are the primary cause of global warming. Given that CO2 emissions are increasing, we can expect this warming to continue.

The question is no longer whether we should be concerned, but rather, how concerned we should be.