There’s a common trope around the blogosphere that says there’s still a lot of disagreement among scientists about whether climate change is really happening. There’s also a similar, though smaller, line of reasoning that “it’s only a theory, right? It’s not a fact.”
The second argument depends on a fundamental misunderstanding of what the word ‘theory’ means. To a scientist, a theory is what you get when you’ve formed a hypothesis, designed one or more experiments (which can be replicated by other scientists), conducted the experiments, and measured and analysed the results to see whether they support or disprove the hypothesis. Only then can a hypothesis graduate to being a theory.
Note that I say ‘support or disprove’ – a hypothesis or theory generally can’t be proved, it can only be disproved. In time, an accepted theory may be proven wrong in some way: when this happens, scientists then work to modify the theory and the process repeats. In this way, scientific knowledge is constructed and elaborated.
Now, about that disagreement between scientists. The media’s habit of presenting many issues as a balanced debate has acted to convince the public that the issue is still up in the air. But that’s not strictly accurate, or indeed accurate at all: as David McCandless puts it in a comment to this post on his website Information is Beautiful, “We’ve got some additional (better) data that suggests around 97% of publishing climatologists support the idea that human activity as a significant contributing factor in global warming. 89-90% of all publishing scientists. 77% of non-publishers, non climatologists. 55% of the public.”
That information comes from this paper by Peter Doran and Maggie Kendall Zimmerman at the University of Illinois at Chicago, which includes a simple graph that illustrates all the percentages very well. In essence, the more people know about the science of climate change, the more likely they are to believe that it’s happening.
Science, of course, doesn’t rely on consensus: it relies on replicable research, which is vetted through a system of peer review. This helps to ensure that the theory is fairly robust and credible. The existence of climate change is also reinforced by the variety of scientists who are working on it, including but not limited to:
- climatologists measuring ice cores for past temperatures
- mathematicians, computer scientists, and statisticians creating climate models and analysing trends
- oceanographers measuring sea level rise and coastal inundation
- marine biologists researching reef die-off and fish population migration
- biologists studying migration, adaptation, or extinction of reptiles, mammals, and marsupials etc.
- botanists researching migration, adaptation, or extinction of plants
- and so on.
So it’s safe to say that there are a lot of scientists in a lot of different areas questioning whether climate change is occurring and what effect it’s having.
And yes, plants can migrate, at least short-lived plants: as the environmental conditions change, a patch of ground that hosts a given species may move. This may be because wind-borne seeds that are carried to the more environmentally suitable side survive better and reproduce more than those on the less suitable side, and similarly for plants fertilised by other means. Over time, the whole patch may move, following the more suitable environment. Sadly, this is harder for long-lived plants like trees.
Migration is also more difficult for alpine species, both plant and animal. Since higher altitudes generally have cooler temperatures, species can migrate up the sides of mountains, but only to a point (quite literally). After that, anything that can’t tolerate the heat gets shuffled out of the planetary kitchen.
So in summary, those who know best will assure anyone willing to listen that climate change is happening, and continues to exceed predictions. If you need any arguments to use when talking with someone who doubts climate change, try this lot from Information is Beautiful, or this very comprehensive list from Skeptical Science.
And if you want to start an argument, try citing this paper. The authors suggest that a belief in laissez-faire economics predicts a rejection of climate (and other) science, while belief in conspiracy theories also predicts a rejection of climate (and other) science.