When things get overwhelming, we often seek to get back to the basics and simplify. This is a particularly good idea in the midst of the current climate change/global warming debate. For most of us, it’s been a very long time since we sat in a science class. Perhaps a refresher course is in order. Our textbook for today is “A Global Warming Primer” from the National Center for Policy Analysis.
Chapter One: Just what is a greenhouse gas (GHG) anyway? Greenhouse gases partially trap solar radiation in the atmosphere. Without these gases, the earth would be an uninhabitable, frozen rock in space. Well, don’t GHGs make up most of the atmosphere? No, to the contrary. GHGs comprise no more than one to two percent of the Earth’s atmosphere. That’s a very small slice of a very big pie.
Chapter Two: OK, so just what are the GHGs in the atmosphere? Glad you asked. Water vapor makes up 95% of that tiny slice of pie from Chapter One. The other 5% is a mix of carbon dioxide (3.62%) and other trace gases (1.38%). To put it another way, carbon dioxide (CO2) accounts for 0.00072 of the atmosphere. It is neither a pollutant nor a carcinogen. Where does carbon dioxide come from? CO2 is a naturally occurring greenhouse gas. Humans and other animals emit CO2 when they exhale, and plants absorb it.
Chapter Three: So humans produce most of the CO2, right? Wrong. Humans contribute approximately 3.4% of annual CO2 emissions, while Nature accounts for 96.6%. But what about that big rise in CO2 we always hear about? Over the past 150 years or so, atmospheric CO2 concentrations have increased approximately 30%, rising from 270-280 to 360-390 parts per million (ppm). However, today’s levels are even lower than during previous periods in our Earth’s history.
Chapter Four: Just how guilty are we humans for the greenhouse effect? Back in Chapter Two we learned that greenhouses gases are 95% water vapor and 5% other gases, including CO2. These GHGs are just 1-2% of the total atmosphere. So, what’s the human share? Believe it or not, just 0.28% of the greenhouse effect is attributable to human activity. Meaning, humanity is responsible for about one-quarter of one percent of the greenhouse effect. The other 4.72% is attributable to ocean biologic activity, volcanoes, decaying plants, animal activity, etc.
Chapter Five: How do we compare today with long ago? In a nutshell: 550 million years ago CO2 levels were 18 times higher than today. When the dinosaurs roamed the Earth, CO2 levels were as much as nine times higher than today, and the average temperature was about 18º F warmer than it is today. The Earth’s average temperature has risen about 1º F since 1850.
Chapter Six: What if CO2 levels continue to rise? If that tiny fraction of the atmosphere doubled, plant productivity would improve on average 32% across species. This claim is based on nearly 800 scientific observations around the world. According to government mine safety regulations, atmospheric CO2 would have to rise as high as 5000 ppm (it’s about 390 ppm now) before it posed a direct threat to human health.
Our refresher course could go on and on, but the primary lesson to be gleaned here is this: CO2 is a miniscule fraction of the atmosphere. Man-made CO2 is an even tinier fraction. Before this nation passes laws which will not move the thermometer but would profoundly distort our economy and way of life, we would be well served to go back to the basics and get reacquainted with the facts.
Dan Juneau is President of the Louisiana Association of Business & Industry (LABI). Emily Stich, LABI’s Vice President for Research & Programs, and Environmental Quality Council Director, contributed to this column.