Thursday, August 7, 2014

On Global Warming ... Interview with a Meteorologist, Part 1

Well, since the previous post got me started on the climate change kick I thought for this post I'd continue on the same theme and interview myself in Q&A style and provide some additional insight on the topic of global warming. Rather than make one really long entry, the "interview" will be broken up into several posts.

Bob, are you one of the 97%'ers?

Ha, nice question to start. No, I am not one of the 97% ... but I'm not one of the 3% either. Rather I was never asked to respond to a survey on climate change, along with thousands of other meteorologists. None of my colleagues that I know were surveyed either, a couple of whom are esteemed atmospheric scientists with an incredibly long list of publications and are nationally recognized & respected in the field (i.e., when they talk people listen). I'm not exactly sure who was polled as there are several of these surveys floating around, but you could probably classify all of them in the same category as "4 out of 5 dentists surveyed recommend sugarless gum". For one, I don't doubt that 97% or more of atmospheric scientists would agree with a simple survey question like "human activity probably caused some of the warming the last half-century". However the problem with that result is it doesn't mean those same scientists are going to share the same level of agreement on the myriad of more important hot button issues within the global warming debate (like whether the observed warming is ONLY the result of human activity, or whether additional warming will cause stronger, more destructive storms, or more wild fires, or more droughts, or cause mass extinctions, or flood cities, etc.). In other words, the survey question does NOT address the primary issues of contention that divide climate change skeptics from the supporters. Unfortunately certain media outlets, politicians (and even some scientists) will run with that 97% survey result, take it out of context, and apply it to those other contested issues regarding climate change. In some instances it's an intentional deception on their part and done solely for the pursuit of a political agenda, scoring some ratings points, or garnering more popularity which is unfortunate. Other times the mistake is completely unintentional, but either way the net result is that the public gets misled. Therein lies the main problem and is why the 97% survey result is utterly meaningless. Second, it doesn't matter whether 97% or 100% agree. What matters is if the science is right. I've already seen instances in this field which once had 100% backing but were later shown to be bunk by better science.

Can you give me an example?
Sure, my pet peeve ... positive vorticity advection (PVA). PVA is hailed in all the text books and shoved down the throat of every student taking atmospheric dynamics and synoptics classes [and that is still the case today by the way]. PVA is also mentioned in every weather map discussion in university meteorology seminars and forecast classes (often times so that the speaker would give the appearance of knowing what they were talking about, LOL). We were also taught that PVA is the #1 factor for predicting severe thunderstorms and is the leading cause of arthritis flare-ups in senior citizens (OK, just kidding about the arthritis, but you get the idea). Yet when creating models that actually forecast the weather for a given location, PVA never shows up as a meaningful contributor ... because it doesn't work! That said, I don't want to create a straw man here. To be clear, just because there have been past truths in the atmospheric sciences that were later debunked by better science doesn't mean the science behind global warming is at risk to be debunked. But I do want to point out the atmospheric sciences are young, we're learning new things all the time, and there's much we don't know. For sure, the physics are not as exact as the physics which tell us there will be an eclipse on May 20, 2055 at 9:01am. So the bottom line really it's the quality of the science, not the surveys which are important.

So who cares what you think about climate change? Are you a climate specialist? What could you possibly offer to the discussion.

I'm not a climate specialist. Climatology is one of many sub-disciplines under the atmospheric science umbrella. My area of expertise is in short-term (0-7 day) weather forecast modelling and probabilistic prediction. I'm intimately familiar with numerical weather prediction (NWP) models, like the kind climatologists use to predict future climate. So I'm fully aware of how they work, their strengths, weaknesses, capabilities and their limitations. I've also performed extensive work in the area of forecast verification which is full of land mines, and that makes it easier to sniff out weaknesses in a given study or experimental design that generates predictions.

OK, let's deal with specific questions regarding climate change. Is it even possible that humans can change the earth's climate? After all, isn't the earth just too big to be affected by mere humans?

There is absolutely no sliver of doubt that humans *can* alter the climate on our planet. Anyone can verify this for themselves. Just watch the evening news and notice how the night-time temperatures are always colder in the outlying suburbs compared to a populated city. In many cases there can be 10-15 degrees difference especially in winter. Of course this is on a small spacial scale and none of that is related to increases in carbon dioxide, but nonetheless it shows in a simple way that humans can affect the weather.

Has the earth gotten warmer in the last century?

Yes, global temperatures have risen about 1* C the last 100 years.

Has the amount of carbon dioxide increased in the period as well?

Yes, total C02 concentrations have increased over 30% in the last 100 years.

So what's the controversy? Doesn't this prove global warming is real and caused by humans?

Well, it may seem intuitive to think that at first, but I recommend some caution. First, correlation does not equal causation. Ice cream sales have also increased the last 100 years, but nobody is going to blame warmer temperatures on ice cream. Second, while there is indeed a strong physical link relating carbon dioxide and global warming (CO2 is transparent to incoming solar radiation but absorbs outgoing long-wave radiation), the ultimate relationship is not so simple. There are countless feedback mechanisms and interactions with clouds, plants, and oceans which complicate matters greatly. Here's a simple analogy of how a feedback mechanism works. Eating a sugary food causes your blood-sugar level to rise temporarily but a healthy pancreas then responds to secrete enough insulin to maintain stable blood-sugar levels. So in the end despite consuming sugar the blood-sugar level remains the same. There are a "gazillion" of these type of interactions & feedbacks that go on in the atmosphere. So the contribution of increased CO2 toward global warming can't be accurately measured unless all the interactive effects are taken into account. Third, there are instances in our past history when temperatures have risen greater than this without any human intervention, and that makes it a very difficult problem to separate natural (or random) fluctuations versus what humans have contributed.

To be continued ...

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