This debate is getting old, but the Trump presidency policies have compelled me to write this post. Yes, the debate is corrupted by competing special interests, but let’s focus on the science because the question of global warming is a question of science.
Before I continue, I would like to note that 21st century society has venerated science as a superior source of knowledge. I will point out here and now that science is only one of many ways to obtain knowledge. Also, I have heard some of my colleagues praise science as an “objective” discipline, but science is largely based on empiricism, the philosophy that all knowledge is derived from sense-experience. Thus, science is limited by the threshold of human or instrumental observation and measurement.
Now that I have established the role of science, we must turn to the definition of global warming. Merriam-Webster defines global warming as
an increase in the earth’s atmospheric and oceanic temperatures widely predicted to occur due to an increase in the greenhouse effect resulting especially from pollution
Using this definition, let’s pick apart global warming.
An Increase in Earth’s Temperatures
According to the National Oceanic and Atmospheric Administration (NOAA), ice core data from Antarctica indicates that large-scale climate changes form an example of Earth’s natural variability. Figure 3b in the article, [Petit, J.R., et al. 1999. Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature 399: 429-436], indicates the temperature fluctuations (from -8°C to 4°C) in Antarctica for the last 420,000 years before 1999.
So, is the observed 1.5°F (~0.8°C) global temperature increase since 1880 (Source: EPA) caused by just natural fluctuations? Honestly, without the specific data points, it’s hard to tell. Based on the data from the Petit, et al. paper, the Earth should be entering a cooling phase based on previous cycles, and it clearly isn’t. Moreover, a 0.8°C increase in 137 years is a fast rate compared to “historical” rates. I place quotation marks because ice core data, reliable as it may be, isn’t historical data.
An Increase in the Greenhouse Effect
Like large-scale climate changes, the greenhouse effect is also a natural phenomenon. The greenhouse effect is when greenhouse gases (e.g. water vapor, carbon dioxide, methane, nitrous oxide, ozone, chlorofluorocarbons, etc.) absorbs infrared radiation (aka heat) radiated from the Earth’s surface and emits it back into the atmosphere.
Although the greenhouse effect is natural, the industrial revolution (which started in roughly 1750) exponentially increased greenhouse gas levels through emissions. Moreover, ice core data indicates that the highest historical carbon dioxide level is around 300 ppm. The CO2 level exceeded 300 ppm after 1950. Human impact is likely responsible for this sudden increase in carbon dioxide levels.
Some greenhouse gases are products of natural processes: water vapor from the water cycle, carbon dioxide from respiration, methane from methanogenesis, and nitrous oxide from nitrification and denitrification.
CO2, CH4, and N2O are also emitted through industrial processes. Tropospheric ozone (O3) is another industrial pollutant. While ozone is natural in the stratosphere, where the ozone layer can block UV rays from Earth’s troposphere, tropospheric ozone is unnatural and a dangerous pollutant. Another prominent green house gas, chlorofluorocarbons (CFCs) were widely used refrigerants, propellants, and solvents until they were phased out in the 1990’s.
So, here’s what we have so far: temperature fluctuations are normal, but the observed recent temperature increase is irregular; the greenhouse effect is natural, but there is a much higher level of greenhouse gases than ever before; new sources of greenhouse gases are from human industry. Based on this data, the logical conclusion is that global warming is real, as in the average global temperature is increasing due to the increase of the greenhouse effect caused by pollution.
But what does this all mean? Obviously global warming means melting ice caps in both poles, which changes water levels, which changes maritime activity and salinity, the former of which impacts the climate/weather and the latter impacts sea life. However, that doesn’t mean that global warming is going to lead to a doomsday catastrophe. In the end, global warming is going to help some species and societies and harm other species and societies. So, yes, letting global warming continue at its current rate could put New York City under water by 2100. But hey another U.S. city can take its place, right?
We must not underestimate the impact of human activity on the environment. Although we are animals, we have the gift of invention and industry. When we start messing with nature without considering the eventual consequences, the grander machine of nature will overpower any machine of our making.
Also, as usual, if you wish to debate this post, feel free to write a comment! Just remember that comments are moderated by me, so keep it civil.