As is so often the case these days, the “discussion” about climate change has devolved into nothing but name-calling, ranting and pesonal dispersions. On the one side, there are people who claim that humans have caused global warming and radical steps are needed to curtail the trend. On the other side, there are people who claim the whole thing is a left-wing government conspiracy; not only is global warming not human-caused but it may not even be a real thing…in fact, some say, the earth might be in a cooling period.
To be honest, my primary interest in this series isn’t whether or not global warming is happening. What I’m really interested in are the Christian-living aspects of this debate. See, for some reason, there seem to be an awfully lot of conservative Christians in the “it’s all a hoax” camp. Some of the most aggressive anti-global warming rhetoric has come from the Christian community and this concerns me. I’m not concerned because I’m sure global warming is happening (I honestly don’t know what I think at this point…stick around!). No, I’m concerned because I don’t know why so many Christians are anti-global warming and I suspect that most of them don’t know either.
What I afraid is happening is that, for too many of Christians, our political affiliations have dictated our beliefs on the global warming issue before we even look at the facts. I think this is true primarily among Repbulican Christians, but I think it is also true to a lesser degree for Christians who consider themselves Democrats. Both parties have a dog in this fight and prolific propaganda machines that make it very hard to see what’s actually going on in the ring.
Let me be clear: I’m a theologically conservative Christian, a political conservative (in most ways) and a Republican. So Republicans, be assured: I have no anti-Republican axe to grind. On the contrary, my tendency is to want the Republicans to be right. But wanting them to be right doesn’t necessarily mean that they are right that global warming isn’t happening. And yes, I know I’m oversimplifying…there are certainly Republicans who believe in global warming, but the polls say this is a minority belief among Republicans.
Beyond maybe being able to decide for myself, on the basis of the evidence, if global warming is actually happening, I’d really like to help the average Christian who is just trying to figure out what to think about this stuff. Is global warming happening? Are we at fault or is it a natural cycle? Is it anti-Christian to believe that humans have caused global warming (assuming there really is such a thing)? What should we do?
Anyway, recently, I decided that I’ve had enough of all the hype on both sides of this issue and I’m done listening to anybody on this subject. Instead, I decided I am going to see what I can do to get to the bottom of this. If you’d like to come along on my little armchair investigation, then this article series is for you.
Part 1 – Is the U.S. Getting Warmer? (with some important realizations about this debate that became evident during my research)
In this installment, I’m going to tell you about my investigation into whether or not the temperature is actually rising in the United States. Why the U.S.? No, it’s not because I think the U.S. is all that matters. I’m starting here primarily because I found out that you can get a lot of unfiltered data about temperatures in the U.S. from the National Oceanic and Atmospheric Administration. These measurements are available at http://www.ncdc.noaa.gov/oa/climate/research/cag3/cag3.html. These are temperature readings taken at observational stations around the U.S. dating back to 1895. Anybody can get them and they haven’t been spun one way or the other..exactly what I was looking for.
Of course, the U.S. only accounts for about 1.9% of the earth’s surface, so trends in the U.S. don’t necessarily indicate global trends, but it’s a great place to start working with actual data rather than with someone else’s interpretation of it.
Let’s start with a general trend calculation. When we take all the temperatures recorded in the U.S. since 1895 and use them to calculate an average annual temperature for the whole country, then compare each annual average to all the others, we get the following chart:
According to this, the U.S. is getting warmer, but only at the rate of .14 degrees (Farenheit) per decade. That’s not a lot, since at that rate it would take 71 years to see a full 1 degree increase in average annual temperatures. However, you can see from the chart above that, starting about 1980 or so, we’ve had far more annual averages above the historical average than below it (27 above vs. 7 below), whereas before 1980, most of the annual temps fell below the average. So what? Well, if things aren’t changing discernably over time, then your above-average and below-average measurements shouldn’t be clumped together like that. They should be spread out so that any given period has roughly the same number of above-average and below-average measurements.
But that’s not what we’re seeing here. In fact, what we’re seeing here is that the historical annual temperature average (the black line) has been strongly affected by the last 30 years. If we look at temperatures in the U.S. up to 1979 they average out to 51.9 degrees but when we include 1980-2012 in our data pool, the average jumps to 52.18 degrees. From 1980 to 2012, the average temperature in the U.S. averages to 52.92 degrees. Since 2000, the average U.S. temperature has been 53.41. That’s a definite – and I think significant - warming trend. Things get a little clearer when we look at the average temperature of whole decades:
The U.S. has definately gotten warmer in the last three decades. So much warmer, in fact, that the last three decades have significantly skewed estimates of the strength of this warming trend. If we take the last three decades out of the pool, the U.S. appears to be heating up at a rate of only .04 degrees per decade, virtually insignificant. Add the last thirty years into the mix and the U.S. appears to be heating up at a rate of .14 degrees per decade. Consider only the last three decades and suddenly we’re heating up at .48 degrees per decade, a 1,200% increase over the .04 degree per decade trend! One of the important things to note here is that the significance of these “trends” depends largely on where you decide to start and stop including data.
Now, so far it looks like our investigation vindicates the global warming folks, at least with respect to the U.S. But, hold on. as you can see from this chart, there was a relatively similar increase in average temperatures from roughly 1920 to 1940. In fact, during those years the warming trend was .41 degrees per decade, quite close to the .48 degrees per decade warming trend we’ve seen in the U.S. over the last 30 years. But of course, that warming trend was reversed from roughly 1940 to 1980 and things cooled back down.
What does that mean? Well, it means that warming trends (in the U.S.) don’t necessarily continue indefinately. We’ve had three decades of warming recently, but there’s no particular reason to think this represents a trend that will continue into the future. In fact, there are some indications that we may be entering just such a cooling period. If we look at average U.S. temperatures from 1998 to 2011, we’re seeing a -.81 degree per decade cooling trend.
This has been seized upon by some anti-global warming folks to say that global warming is a farce. But, hang on, did you notice that I used 1998 to 2011? I chose those dates because they give the greatest cooling trend. If we include a year on either side (1997-2012) this -.81 deg/decade cooling trend turns into a .13 deg/decade warming trend! Again, and I can’t stress this enough: calculation of warming and cooling trends are profoundly affected by where you choose to start and end your data set. This practice is consistently used by both global warming advocates and by anti-global warming doubters.
Is the U.S. cooling down? Well, on the one hand, we’ve seen consistently (but not uniformly) lower annual averages since 1998. On the other hand, even the lowest of these annual averages in 2008 (52.3) was higher than the 1895-1979 average, so “cooler” is only relative to the recent years of unusually high temperatures. And it should be pointed out that 2012 was the hottest year on record with a whopping average annual U.S. temperature of 55.32 degrees which not only bucks the trend but also means that rest of the decade will have to be much, much cooler to offset this anomaly and continue to show a cooling trend in here in the U.S.
So what have we learned so far? Here’s my list:
1. This is complicated stuff!
2. Trends can be easily skewed by the simple act of beginning and ending your data collection at slightly different points. Yet we can’t just look at all the data lumped together because long-term averages can hide significant short-term trends. Ultimately its probably impossible to remove all bias from analysis of the data.
3. We don’t have enough data from the NOAA tables to say with any confidence that the U.S. is experiencing a long-term warming trend…or that it’s not. In the last 100 years we’ve seen two periods of warming and two periods of cooling. The last cooling trend (1940-1980) didn’t go all the way back down to pre 1920 levels which might suggest a broader trend towards warming, but you cannot support that claim by looking at only one period. Since we haven’t yet cooled down from the most recent warming trend (1980-1997) we don’t know how far down the average temperatures might go, assuming they go down at all. More than 100 years of consistent temperature measurments is helpful, but it doesn’t actually provide a big enough data pool.
It’s important realize that a) we haven’t looked at all the evidence for and against global warming b) we have only looked at data from the United States and c) we haven’t asked if any of the data can be linked to human or non-human causes. We’ll turn to some of those in the next installement. Stay tuned!
In the meantime, I’d love to hear your feedback: