Once again there is a lot of misinformation and incorrect assumptions regarding global warming and agriculture in the news. Much of the narrative blames agriculture for contributing to global warming by being a major producer of so-called greenhouse gasses, particularly carbon dioxide and methane, usually lumped under the general category of “carbon.”
A common claim is that agriculture is the producer of 12 percent of man-made greenhouse gas production.
Before we delve more deeply into greenhouse gases, lets first put that number in perspective. All greenhouse gases, including the most abundant, water vapor, make up 2 percent of the Earth’s atmosphere. The rest is nitrogen, oxygen and trace gases. Carbon dioxide and methane combined make up a bit more than 3.62 percent of all greenhouse gases. According to the narrative, then, agriculture accounts for 12 percent of this total, or about 0.000086921 percent of the atmosphere – round it up and make it nine one-hundred-thousandths of one percent of the atmosphere, or about 90 parts per million.
This is a small number. But small numbers can be important, so let’s look at the argument about the significance of man made greenhouse gases.
Greenhouse gases trap heat in the atmosphere, helping to keep the surface and the troposphere, the lowest level of the atmosphere, at an overall average temperature of about 59 F. As the popular argument goes, the atmosphere was in a delicate balance before man started producing greenhouse gases during the industrial revolution by burning first coal, then oil. These added gases will reach a “tipping” point when the carbon dioxide level reaches about 400 parts per million (ppm). Once the tipping point is reached, the atmosphere could become a runaway greenhouse, sending temperatures soaring out of control, melting the ice caps, raising the sea level and boiling the seas. All life on the planet would come to an end. With today’s atmosphere essentially at or slightly above the tipping point, and agriculture already producing 90 parts per million of carbon dioxide, how much longer can man continue to grow food for a growing population before man-made global warming destroys life?
This was a good question and one worth studying in the late 1980’s and into the early 2000’s. Unfortunately, most of the studies went badly wrong when a large group of scientists began falsifying data and producing computer models designed to show catastrophic warming.
Based on these dishonest studies, governments around the globe began spending billions of dollars to reduce man-made CO2 emissions. The U.S. Environmental Protection Agency labeled CO2 as a pollutant, and there was a decade-long flirtation with carbon sequestration and carbon credit trading on the Chicago Climate Exchange.
But there were a couple of problems with story, regardless of how popular it was. And, unfortunately, it remains popular to this day.
When leading paleoclimatologists (scientists who study past climate) began fiddling with the data they used in their climate models, discarding some data which countered their carbon-driven warming hypothesis, and then emphasizing or adding weight to data which supported their hypothesis, they produced a now-famous “hockey stick” graph which showed two things: global temperatures began rising rapidly with the onset of the industrial revolution in the 18th Century while CO2 levels were also rising. The researchers asserted that the correlation of warming and elevated CO2 proved causation; that is, carbon was driving warming.
Also, the Earth began cooling in about 1998, despite the fact that man-made greenhouse gas emissions were increasing. Though some countries, like those in North America and Europe were attempting to curtail their emissions, other countries like China and India were producing much more as they grew increasingly industrialized. Rather than decreasing man made greenhouse emissions, there was a small but significant net increase. At the same time, geological and biological processes continued to add carbon dioxide, methane and other greenhouse gases to the atmosphere at a faster rate than humans possibly could.
When the planet began to cool, and greenhouse gases continued to increase, the core group of paleoclimatologists, along with many politicians and the major media, did what Professor Ian Plimer, Australia’s best-known geologist and climatologist, called “moving the goalposts.” Instead of global warming, the threat was now climate change, but the culprit was still man made carbon.
Proponents of the catastrophic anthropogenic climate change theory hold that an ill defined “something bad” is going to happen if carbon levels keep rising. Many in the major media and famous folks from all walks of life (including a former vice president) now claim that increased atmospheric carbon is to blame for hurricanes, tornadoes, heat waves, cold snaps, sea-level rise and fall, earthquakes, tsunamis, floods, droughts and all manner of weather related and non-weather related
As things stand today, there’s no evidence to bear this out and plenty of evidence to refute it.
Although science has a very long way to go in understanding climate, the main climate drivers are well known. They include the sun, perturbations in the Earth’s orbit around the sun, cyclical changes in the Earth’s axial tilt, cosmic rays, geological processes here on Earth such as plate tectonics, volcanoes and earthquakes, cloud cover, and cloud formation.
In general, the sun heats the planet to an average of about 59F. Part of the sunshine which strikes the Earth is immediately reflected back to space by clouds, ice and, to a lesser extent, land and water. Part of the energy warms the land and the oceans. And some of this is radiated back toward space as infrared radiation.
Temperature differentials in the oceans cause currents which move warm water from the equator toward the high latitudes, where it cools and flows back toward the equator. The warming land and oceans also transfer heat to the air, causing air currents to do essentially the same thing.
Critically, though, carbon dioxide and methane are able to hold and slowly re-radiate only a fraction of the planet’s overall heat. This small bit is important, though, for without it the planet’s average temperature would be about 26.6 F., colder than the freezing point of water.
All greenhouse gases reradiate infrared radiation toward the surface, which serves to hold, but not increase, heat. They also reradiate much more heat away from the surface and toward space. The narrow wavelength band captured and reradiated by carbon dioxide and methane is only a fraction of the heat radiated from surface, however. Much more heat is radiated and transported by atmospheric convection high into the atmosphere where it is radiated to space.
Far from acting as atmospheric warming agents, greenhouse gases are actually part of a planetary cooling system. If the Earth had no water, which provides a feedback loop in the warming/cooling cycle and atmospheric turnover, there would indeed be runaway warming on Earth, just as there is on Venus, which does lack water.
Leaving aside the effect carbon dioxide has on the atmosphere, which is indeed important but certainly not a climate driver, it’s vital for life as we know it to exist on this planet. All plants need carbon dioxide for photosynthesis, the process in which plants take energy from the sun and combine carbon dioxide, water and nutrients to grow. If plants had no carbon dioxide to “breathe,” they would fare no better than an animal without oxygen. In fact, the oxygen we animals cannot do without is released by plants as a waste product of photosynthesis, and plants use the carbon dioxide we release as metabolic waste when we exhale.
Carbon is absolutely essential to life as we know it. Carbon is the scaffolding for the other molecules that make up living organisms. Carbon is the backbone of life, providing the critical linkages in cells, tissues, proteins, amino acids, sugars, starch – and the list goes on.
There’s nothing wrong, and everything right, with being concerned about the ecology of our planet. Earth is the only home we have. Unfortunately, a lot of people have seen fit to play fast and loose with the rules of science and journalism and to gain in money or prestige while preying on the fears of their fellow human beings. And, while doing so, make a mockery of the fascinating and wonderful world we inhabit.
So the next time someone tells you that you, or someone else are destroying the planet with carbon, be a little skeptical and look at the world the way it really is.