I was inspired to write this article after reading the community post Geologists at Daily Kos that encouraged geologists who read DK to give a geologic perspective on current issues. For some background, I have degrees in both Geology and Geophysics and worked as a Geophysicist in the Oil industry for 35 years. I am not an expert on climate change but feel a geologic perspective could be valuable when thinking about climate and carbon emissions. I will also state upfront that although I worked in the oil extraction business I believe it is in man’s best interest to reduce carbon emissions.
A Geologic Perspective of Temperature Changes on Earth
Figure 1 is a common graph showing the correlation between Global Temperature and Atmospheric CO2 in the post-industrial age. There is consensus in the scientific community that the relationship is causal but how should we think about this in a geologic perspective?
It’s hard to conceive on a geologic scale what an extremely minute period of time is represented in Figure 1, the 140 years since the industrial revolution. If the 3.7 billion years that life has been on earth is represented by a year, then the 140 years displayed in Figure 1 would be the last 1.2 seconds of the year. For a geologic perspective of climate change on earth consider Figures 2 and 3. Figure 2 displays the earth’s major temperature changes over the last 2.4 billion years.
There have been 5 major ice ages in the last 2.5 billion years. Believe it or not we are currently still in an ice age. Figure 3 is more relevant to today as it shows in more detail the time period that man has thrived on earth, the last 450,000 years (less than the last 1% of Figure 2).
Figure 3 shows the glacial and interglacial stages of the current ice age. We are in a relatively warm interglacial period that has had stable temperatures for the last 10,000 years (the short plateau on the last 3% of Figure 3). A couple of interesting points to note. First: Changes of 20 degrees Fahrenheit (8 to 9 deg. C) are common and have occurred at least 8 to 10 times since man has been on earth. This makes the 1 deg. C change of figure 1 (or the 1.5 deg. C Paris goals) seem small, but this doesn’t mean it won’t create catastrophic problems for man. Second: the period of time that man’s population has exploded to fill nearly every inhabitable corner of the earth has occurred in the last 10,000 years during a period when the climate has been stable.
Man has thrived in a period of stable climate
In our short-sighted view, we believe that the climate should stay the same as we have experienced the last 10,00 years but the history of the earth shows that climate has always changed and it will continue to change. The question for man, if we hope to have a long successful run on this planet, is how do we best deal with this inevitable change? Unfortunately, we have created a couple of problems for ourselves. One is that we have been so successful as a species that there is not enough open land to just migrate when climate change happens. This is what we did during the previous ice ages. As hunter gatherer societies we naturally followed the food sources as the climate changed. Secondly, our population has become so large, dense and dependent on technology that the earth cannot support the current population on the naturally occurring energy budget. Over the last 150 years we have relied on fossil fuels fill this energy gap which has caused the current CO2 related climate change.
Terraforming the Earth
What humankind needs to avoid catastrophic problems is to freeze the earth’s climate in the state it has been the last 10,000 years. To do this we must be able to override the natural (and manmade) drivers of climate change. In essence we must attempt to terraform the earth to best support human life. Is it even possible to override the large-scale climate cycles of the earth? The causes of the glacial and interglacial cycles over the last 500,000 years are thought to be caused by predictable orbital variations called Milankovitch cycles. Some have predicted that the current warm period would end in 20,000 to 50,000 years (again, a very short time in a geologic perspective) plunging us into another ice age. Others have argued that we will avoid the next ice age due to our carbon emissions. The fact our carbon emissions over the last 150 years seem to be causing significant climate change implies that the earth’s climate is at a delicate balance that can swing dramatically with small changes in the system. This gives hope that we can manipulate the system and keep the climate near its current state and minimize catastrophic problems for man. This brings us to the obvious question: What actions should we take to best manipulate climate for mankind’s benefit. It appears that to avoid climate changes that cause catastrophic problems for mankind we must maintain the current balance of the climate system by reducing carbon emissions while creating enough energy to support the current human population. Creating enough energy for a growing population while reducing carbon emissions will be very difficult but I believe it is possible. If we believe climate change is real we don’t have a choice but to try. I have some opinions on the best way forward but will leave this for another post.