The Pure Science of the Greenhouse Effect

When Baha’is encounter opposition to something they say, do, or believe, the Baha’i teachings offer a gentle prescription for how to respond:

The heaven of divine wisdom is illumined with the two luminaries of consultation and compassion. Take ye counsel together in all matters, inasmuch as consultation is the lamp of guidance which leadeth the way, and is the bestower of understanding. – Baha’u’llah, Tablets of Baha’u’llah, p. 168.

Compassion, of course, means treating others, even those who disagree with you, in a kind, empathic and considerate way. Consultation, for Baha’is, means hearing each other’s opinions without judgment or prejudice, and then examining those opinions and the relevant facts together in a collaborative spirit of seeking the truth:

… consultation must have for its object the investigation of truth. He who expresses an opinion should not voice it as correct and right but set it forth as a contribution to the consensus of opinion, for the light of reality becomes apparent when two opinions coincide. A spark is produced when flint and steel come together. – Abdu’l-Baha, The Promulgation of Universal Peace, p. 73.

In that spirit, then, let’s examine the two specific claims a commenter made in response to a recent BahaiTeachings.org article on climate change: (1) “The purported CO2 greenhouse effect has been vastly overestimated and (2) actually climate change has failed to produce the catastrophic warming predicted by climate models.”

First, let’s evaluate the language of the claim. Many so-called “climate skeptics” or “climate deniers” use this kind of language to cast doubt, especially by utilizing dismissive adjectives like “purported” to describe the greenhouse effect. So: is the greenhouse effect “purported” or real? Here’s the definition of the greenhouse effect from Webster’s Dictionary: “The warming of the earth and its lower atmosphere caused by trapped solar radiation.”

Scientists refer to the exchange of incoming and outgoing radiation that naturally warms the Earth as the greenhouse effect, because a greenhouse works in much the same way. Incoming ultraviolet (UV) radiation easily passes through the glass walls of a greenhouse and is then absorbed by the plants and hard surfaces inside. Weaker infrared (IR) radiation, which produces heat, gets trapped inside, thus warming the greenhouse. This effect lets tropical plants thrive inside a greenhouse, even during a cold winter – and it lets human beings survive on Earth, by dint of the atmosphere keeping just enough warmth near the surface to sustain life. If you’ve ever entered a greenhouse and felt the heat inside, or gotten into a car parked in the sun for a while, you already understand the basic principle.

Of course, the Earth’s atmosphere organically fulfills the same function, letting the sun’s radiation in but not letting quite as much of it out. That’s why the planet maintains a baseline average temperature of 59 degrees, which allows human life to exist. However, when human activity unnaturally loads the Earth’s atmosphere with excessive greenhouse gases, including methane, CO2 and chlorofluorocarbons (CFCs), those gases trap more heat. That’s just pure science, with no “purported” about it.

Perhaps, as the writings of Baha’u’llah may have suggested during the 19th century, humanity could succeed in poisoning our entire atmosphere with enough of these greenhouse gases to endanger our entire species:

Strange and astonishing things exist in the earth but they are hidden from the minds and the understanding of men. These things are capable of changing the whole atmosphere of the earth and their contamination would prove lethal. – Baha’u’llah, Tablets of Baha’u’llah, p. 69.

So, has the greenhouse effect been “vastly overestimated,” as our friend the commenter suggests?

Like many of the points climate skeptics attempt to make, this one does contain some truth – but not the complete truth. During the 20th century, for example, with the study of climate science still in its relative infancy, some scientific studies projected and modeled future estimates of greenhouse gas concentrations that haven’t panned out in the real world. So yes, some studies did overestimate the future impact of climate change – but not “vastly.” 

However, that fact exemplifies the problem with accepting broad, sweeping statements couched in passive voice like this one. Why? Because in the early days of modern climate science many other scientists did project future estimates that have proven factual and accurate in hindsight. As in all scientific exploration, some estimates proved accurate and others did not. 

This reveals a standard argumentative tactic of people and groups who reject the preponderance of the scientific evidence. Those who don’t accept the current state of climate science often “cherry-pick” such overestimates, and then use those individual instances to condemn all of the science. “If one study is proven wrong,” the faulty reasoning goes, “then you can’t trust any study.”

Which leads us to the inevitable conclusion that not all science works equally well. No surprise there. Every human enterprise has its faults and foibles. However, many of the past estimates of greenhouse gas concentrations have now come to pass with remarkable accuracy. If you’d like to scan a compendium of these estimates, and judge their relative accuracy for yourself, this helpful website records and evaluates the accuracy of those past estimates and conducts a robust, ongoing scientific discussion about them.

If you examine the science of climate change carefully, and educate yourself about the various views expressed on the subject, you may come to the same conclusion that 97% of the world’s climate scientists now agree upon – that global warming is real, and that addressing it effectively will require a significant change in the way the world now works. (If you’d like to know more about that 97% consensus, visit this site.

Despite the evidence, though, many economic, political and social forces fear and therefore resist the kind of significant change that these serious scientific findings necessitate. Typically, these forces represent the status quo, and those who prosper under that current system. The science tells us, however, that the status quo cannot continue, or it will imperil the existence of the human race. We have a stark choice: either humanity changes, or the climate does. 

So from a Baha’i perspective, anthropogenic global warming (AGW) represents an opportunity for a profound, transformative change in the direction humanity has taken:

The Intergovernmental Panel on Climate Change noted that setting humanity on a sustainable path would require “rapid, far-reaching, and unprecedented changes in all aspects of society.” This includes transformations to technological, industrial, agricultural, and scientific systems, which in turn require unprecedented change in values, assumptions, standards, and patterns of thought and behavior. …

The climate crisis – one of the most pronounced symptoms of our ailing global order – requires genuine transformative change. Its various physical manifestations are an expression of the inaccuracy and insufficiency of our views of ourselves and the world. – “To Address Climate Change, Ensure Coherence Between Principle and Action,” Statement of the Baha’i International Community, 20 September 2019.

In the next essay in this series, we’ll examine the commenter’s other main contention, that: “climate change has failed to produce the catastrophic warming predicted by climate models.”