From my series of posts a little over five years ago in my original “How I Became…” series, you might have thought that I embrace change quickly. After all, I have made a lot of theological changes in my life time. In fact, while I am willing to change my mind on things, it takes years or even decades for those changes to see fruition.
Climate change is no exception.
It was back in 2007 that my son Josh introduced me to “An Inconvenient Truth”. I said back then that I was not completely convinced, and that it would probably take another 5-10 years of data, for me to really make up my mind. Well, here it is 13 years later, and I am now truly convinced. A version of the two graphs presented here are what made me initially cautious, and have now convinced me.
I should note that I was never a climate change denier. Perhaps you could have called me a skeptic, but I think even that term is too strong. Cautious is probably the best way to describe my thoughts on the matter.
I am not a climate scientist. I have no opinion on the validity of climate models. I am however a qualified economist, and have made a living working with data and statistics.
Let me first tell you what you are seeing on the top graph.
In 1998, a drilling project in East Antartica extracted the deepest ice core ever, reaching down 2.2 miles (3.6 kilometers) into the frozen ice. This ice, through its yearly layers, and the gasses trapped therein, gave us a historical record of over 400,000 years of climate at that location. Through it scientists were able to determine levels of Carbon Dioxide (CO2) and temperature at any point in time during that period.
So how did they determine the temperature?
Measuring the amount of Carbon Dioxide is easiest to understand. They simply took the amount of CO2 compared to all the gases and expressed it as parts per million (ppm). As for the temperature…
Oxygen has three naturally occurring isotopes: 16O, 17O, and 18O, where the 16, 17 and 18 refer to the atomic mass made up of 8 protons and 8 neutrons, 8 protons and 9 neutrons and 8 protons and 10 neutrons respectively. The most abundant of these isotopes is 16O, while a small percentage exist as 18O and an even smaller percentage as 17O.
Analysing the ratio between 18O and 16O can provide a way of determining [historical] temperature.
In short, the ratio of 18O and 16O in snow varies according to temperature. By examining the ratio of these gases trapped at various points in the ice core, they were able determine the temperature at the time that the snow fell.
So, as you can see from the graph above, temperatures over the past 400,000 years have varied from approximately 3 degrees above the 1961 average, to 9 degrees below. At the same time CO2 varied over the same time period from 180 parts per million (ppm) to 300 ppm.
You can see how closely the two lines are inter-related. There is a very high degree of correlation between temperature and carbon dioxide.
Then the industrial revolution happened. From 1800 to 1950 CO2 rose from 280 ppm to 310 ppm, reaching past the top of the historical band. From 1950 until now, CO2 has climbed up and up and up, so that in January it measured 413 ppm, over one hundred points higher than it had been at any time in nearly half a million years!
So why was I initially so cautious?
One of my initial thoughts was that, temperature wise, we are already close to a historical high. Perhaps adding CO2 to the atmosphere was what keeping our temperature from crashing as it had in past eras? Besides, as any statistician will tell you, correlation does not equal causation. Indeed a close look at the data will show that CO2 has historically followed temperature changes and not the other way around.
So what changed my mind?
Let’s look at the graph below and discuss further.
While I stated above that temperature has preceded CO2 changes, the high correlation and strong trends indicate that there is very likely to be a feedback mechanism. That is, while in the past an initial change in temperature led to a change in CO2, it is also very likely that change in CO2 led to a further change in temperature, and they proceeded in lock step until a minimum or maximum was reached, or until some cataclysmic event resulted in a shock to the trend.
What I see in the second graph is what troubles me most. The earth has had relatively stable temperatures for about 12,000 years. That corresponds with the timeline for the rise of agriculture among humans. The rise of civilizations only occurred about 5,000 years ago. In that entire 12,000 years the proportion of CO2 has been between 255 and 285 ppm. For 12,000 years we have had a variance of only 30 ppm. We are now 130 points higher than at any point in that 12,000 years!!!
One reason why it has taken me so long to become convinced is because temperature has been slow to respond to the carbon dioxide increases. From 1998 until 2012 there was no increasing trend in temperature, and it took until 2016 to beat the 1998 temperatures. But we are again hitting new temperature highs and I believe we will continue to do so.
As I said at the beginning of this post, I am not a climate scientist. I have no expertise in climate models. I have to trust those that are. However, I do now strongly believe that we face a very uncertain future with our current levels of CO2. Whether that involves a temperature spike, and then a temperature crash I do not know. What I do know is that civilization and the events that proceeded it have only been able to occur when CO2 was between a range of 250 and 285 ppm. With CO2 now at 413 ppm, I would argue that our entire civilization is at stake. Can any action be too drastic to return us to the safe levels of CO2?
Strong words, I realize. What do we do as Christians? As human beings? I am not going to comment further here, but will try and interact with your comments below. As always, your thoughts are welcome.
Update: I am deleting the abortion thread. It was getting way off topic and deteriorating into name calling.
Update 2: The Bernie thread is also now gone. It was irrelevant.