The year 2020 will be either the hottest year on record, or just behind the hottest year, 2016. The top 10 hottest years have all been from 1998 and later, with every year starting at 2013 being in the top 10. 2020 will now knock 1998 off the list, making the 10 warmest years all since 2005. The reason 1998 stuck on the list so long is because it was an outlier El Nino year, a weather pattern that tends to produce warmer weather. Next year, 2021, is likely to be a bit cooler because it is a La Nina weather pattern, which tend to be cooler. What does all this mean for the global warming debate?

First, it’s not much of a debate, at least not scientifically. There is a solid scientific consensus that average global temperatures are increasing, and that anthropogenic factors are mostly responsible for this forcing. Don’t believe the nonsense about there not being a consensus or that it is all based on one flawed paper – in fact, there is a consensus about the consensus. The debate is entirely cultural and political, not scientific. The evidence and the consensus are strong enough that any lay person who refuses to accept this scientific consensus is reasonably called a global warming denier.

The denier position is based on a number of logical fallacies and misleading arguments. They attack the very concept of a scientific consensus, and turn the technically true into a misleading point by saying that “science is never settled”. Well…yes, science is always open to revision by new data and new interpretations and theories. But that is not the point, making their argument a straw man. No one is talking about metaphysical certitude, or not being open to revising our climate models or projections with new data. Science, however, does not just exist in the abstract, sometimes we make important decisions based upon the current state of the science. The point is whether or not climate science is confident enough in its projections of global warming to use as a basis for policy. Saying that “science is never settled” is therefore a non sequitur. It is, in fact, a bit of deliberate misdirection.

The other common logical fallacy of the global warming deniers is the Motte and Bailey fallacy. This is the strategy of retreating to a more defensible position in the face of unresistable opposition but then storming forward again whenever you think you are able. So climate deniers will often give in on the point that the Earth is warming (or at least stop challenging that point) to apparently easier to defend positions, like how do we know warming will be bad? But then when they feel they are able, they will return to the position that the Earth is, in fact, not warming.

I have been covering this topic for over two decades, long enough to see some patterns emerge in this public discussion. Again, 1998 was an outlier year. What this meant was that for about a decade following, you could argue that there was no recent warming. Deniers loved showing graphs starting with the year 1998, showing no warming trend. This is a form of cherry picking data, starting at a high point or low point in order to give whatever impression of the data that you want. This is especially easy with climate data, because the system is inherently noisy. Even ignoring the seasonal changes, there are year-to-year changes, and there are numerous natural cycles in the mix. It takes time to pull any additional signal, such as an anomalous forcing of the global average temperatures in either direction, out of this noise.

Since 2016 was another El Nino peak year, deniers might try the same thing again. We will be entering a cooler part of the 18 year cycle, but that does not alter the longer trend. However, the anthropogenic forcing factor may be so large now that it overrides even the El Nino cycle, as we are seeing with 2020 rivaling 2016 as the warmest year.

In any case, if you lived through the global warming discussing in the first decade of the 21st century, there were clearly two political (not scientific) camps making different predictions. The denier camp took the position that there is no warming trend, except for short term cycles like El Nino, and therefore there is no reason to think that the 2010-2020 decade will be any warmer than previous decades. Here’s the smoking gun – a typical article from 2012 arguing that “Global Warming Stopped 16 Year Ago…”. They then show the cherry-picked graph beginning with the 1997-8 El Nino cycle to “prove” it. The “no warming for 16 years” trope was repeated endlessly. If that argument were correct, then we would expect, if anything, a regression to the mean over the next decade.

The scientists argued that this was flawed statistics and cherry-picking. That is you properly calculate average temperature trends, subtracting out known cycles like El Nino, there is a continued anomalous increase in average temperatures. The scientists then predicted, based on their models, that the 2010-2020 decade will be the warmest on record. That is where the rubber meets the road in science – making predictions about the future. Deniers predicted no further warming, scientists predicted continued warming. We can now look back and say that the 2010-2020 decade was the warmest decade on record, with 9 of the top 10 warmest years all being in that decade.

So – can we finally say that the Earth is, in fact, warming? Will deniers finally abandon this position and retreat to other points (none of which are valid either)? To some extent, they already have. But they will never abandon a point completely just based on facts and logic. They will keep it in their back pocket and pull it out whenever they think they can. Just wait – if we have a couple of cooler La Nina years some deniers will argue the trend is reversing, or that warming has stopped. They will also move the goalpost, pick some other arbitrary time frame to make misleading points about the warming trend. Meanwhile, scientists are putting their nickel down on actual predictions. They predict the next decade will be the warmest decade on record with a 99% probability.

What I would like to see is us collectively moving on from this discussion. It’s like endlessly debating whether or not evolution happened – it did, get over it, move on. What we need to discuss is how best to mitigate climate change, to reverse the trends in CO2 release, and to stabilize the climate. If politically you don’t like the solutions being proposed by those concerned with global warming, then propose better solutions, don’t deny the science.