Global Warning(s)

Twenty minutes before midnight on April 14, 1912, the alarm “Iceberg right ahead!” echoed across the Titanic. The view from the bridge must have been terrifying, along with the sickening realization that a ship the size of the Titanic could not maneuver quickly or nimbly enough to avoid collision.

Less than one minute after the alarm sounded, the collision occurred. Within three hours one of the most iconic of naval disasters was complete. The tragedy was made even more poignant by the fact that the most important warning, a message from another ship that there were icebergs in Titanic’s path, was never relayed to the bridge.

Acting on these warnings may well be one of the most faith-full acts we can perform as God’s people.

Could the Titanic serve as a metaphor for Earth and Earth’s climate? I would like to argue that, unlike the crew of the Titanic, we’ve been receiving warnings from many quarters that we sail on troubled waters. Warnings have trickled into the “bridge” of our understanding for more than a century, but the most alarming warnings have come in the past 20 years. Is the message getting through, or are we too headed for disaster?

The warnings about Earth’s climate come from a rich diversity of research fields. We’ve received warnings that tell us about carbon dioxide in the atmosphere, changes in global temperature, mass extinctions of critical species, sea-level rise, and changes in ocean chemistry. Acting on these warnings may well be one of the most faith-full acts we can perform as God’s people.

Weather and Climate

It’s easy to scoff at claims about future climate change with dismissive comments about not being able to predict the weather tomorrow. Weather refers to the short-term behavior of air temperature, humidity, and pressure. This is inherently difficult—if not impossible—to predict over long periods of time.

Climate,on the other hand, is the long-term average of weather in which all of the chaotic and unpredicable bits are smoothed out. Farmers and gardeners understand climate very well. It is important to keep this distinction in mind when talking about climate change. Said differently, “Climate is what you expect. Weather is what you get!”

Our Fragile Atmosphere

It may seem odd to describe the atmosphere as “fragile.” Indeed, when you see the destructive potential of weather, it’s easy to doubt that humans can have any influence on weather and climate. Understanding the fragility of our atmosphere is one of the first steps needed to understand how we can and have influenced Earth’s climate.

Our weather and climate originate, for the most part, in the layer of the atmosphere called the troposphere. When flying across the continent you are at the top of the troposphere. Think of this 10-mile-thick layer of air as equivalent to a glossy layer of shellac on a schoolroom globe—that’s about the right proportion between the thickness of the atmosphere and the size of the Earth.

Seen that way, it becomes less surprising that we might affect Earth’s atmosphere. We are completely dependent on this fragile layer for all complex life on the planet, and it’s easy to quantify both the mass of the atmosphere and how much stuff we put into it each year. This is where we encounter our first “global warning.”

What Carbon Dioxide Tells Us

The graph shown in Figure 1 is one of the most significant graphs ever produced. It is the Keeling Curve (named after Charles Keeling) and shows the atmospheric concentration of carbon dioxide (CO2) in the air from 1957 (when the first measurements were made) to the spring of 2011.

The graph’s gentle up-and-down wiggles provide a wonderful “picture” of our planet breathing. Each spring as the Northern Hemisphere greens up, plants absorb carbon dioxide, and the concentration of the gas drops in the atmosphere. As we enter winter, plants die and CO2 is returned to the atmosphere. Such wondrous balance in creation!

Yet there is an ominous side to this diagram. The steady growth in the concentration of CO2 is alarming. Why?

Figure 1: The Keeling curve, showing CO2 concentration in Earth's atmosphere

Even in small amounts of parts per million (or ppm), CO2 plays an essential role in our atmosphere. CO2 is called a “greenhouse gas” (or GHG) because of its important warming function in the atmosphere.

The Earth receives energy from the sun in the form of light. The Earth warms and achieves a balance with its cosmic environment by emitting energy back to space. This is a basic fact of physics: the net energy in must balance the net energy out. The energy leaving Earth emits not as visible light but as long wavelength infrared (heat) waves. Greenhouse gases (which include water vapor, methane, nitrous oxide, and others) are able to trap some of this outgoing heat energy. Without the benefit of greenhouse gases, our atmosphere and Earth would be much colder!

The rise in CO2 levels from 1750 to the present matches very closely our use of fossil fuels.

BUT if we have too much CO2 in the atmosphere, then we have a different problem: the atmosphere warms up too much.

For most of human history the concentration of CO2 in the atmosphere has been around 270 ppm. Beginning with the industrial revolution (roughly around the year 1750) there has been an accelerating rise in CO2 levels, which has resulted in serious changes in global temperature.

We can take this just a bit further. The rise in CO2 levels from 1750 to the present matches very closely our use of fossil fuels. It is a simple calculation to show that the amount of extra CO2 in the atmosphere is almost entirely due to the release of CO2 from fossil fuel combustion. The first alarm has sounded: we need to change course with respect to greenhouse gas emissions!

Warning from the Past

Tree rings, coral reefs, and ice cores allow us to peer back in time to understand what Earth’s climate was like hundreds of thousands of years ago. The current level of CO2 in our atmosphere (about 390 ppm) is much higher than at any time in the past million years of Earth’s climate. In this lies a warning. We understand how CO2 and temperature are related—it’s a subtle feedback effect with CO2 playing the role of the atmosphere’s “thermostat.” By increasing the levels of CO2 and other greenhouse gases, we’re setting the Earth’s atmospheric thermostat higher. The danger is that by doing this we’re in effect running an experiment that we poorly understand.

Figure 2 shows us what may be at stake. This graph shows 100,000 years of Earth’s climate history, a history marked by large-scale changes in temperature. The exception to this is what has happened over the past 10,000 years. This is the Holocene Era (circled on the graph) and is the time in which Earth’s climate has been remarkably stable. This has permitted the development of agriculture and flourishing civilizations.

The warning from the past is this: Earth’s climate tends to be much less constant than it has been for the past 10,000 years and we, by affecting climate, may well be heading back to “climate chaos.”

Figure 2: The past 100,000 years of Earth's temperature history

What Our Thermometers Tell Us

The once majestic ice fields of Glacier National Park and other regions of the Rockies are melting. I first visited the Columbia Ice Fields more than 50 years ago. Today, this once vast glacier has retreated and is only a fraction of its former self. The lovely Angel Glacier (Figure 3) in Jasper is all but gone. In Africa the fabled “Snows of Kilimanjaro” will disappear by 2030.

Glacier retreat is a worldwide phenomenon that has accelerated noticeably over the past century. Temperature change in the Arctic is even more extreme. Polar ice is thinning rapidly, and it is almost certain that by the end of this century the northern polar cap will disappear in the late summer months.

Figure 3: Angel Glacier in Jasper National Park—just one of Earth's endangered glaciers.

Angel Glacier http://en.wikipedia.org/wiki/File:Angel_glacier.jpg

Understanding temperature data over the past 1,000 years is challenging. Daily variations in temperature (weather) can easily hide the much smaller, gradual shifts in average temperature (climate). Despite this, numerous techniques tell us that from about A.D. 1000 to  A.D. 1500, Earth was in the “Medieval Warm” period, with a gradual decline in global temperature that bottomed-out in the “Little Ice Age” of the 1600s. Since then, global temperature has started to rise. The current rate of temperature change is almost 10 times the rate observed in the past, and it provides a graphic illustration of what is now a virtual certainty: Earth is heating up, and the rise in temperature cannot be explained completely by natural phenomena. Sea-level rise and an increase in frequency of extreme weather events (including tornados and hurricanes) appear to be a consequence of the increase in global temperature.

Human-caused temperature change over the past 50 years is approximately 0.9 degrees F, with a possible total increase of between 3.5 to 9 F by the year 2100.

A 1-degree shift may not sound like much, but that is believed to be about the size of the temperature shift that occurred during the Medieval Warming. It is also believed to be a major cause of the collapse of the Mayan civilization and that of the mysterious Anasazi of Arizona.

A temperature change of 9 degrees would be about the magnitude that took Earth from the last ice age to present global temperatures. We don’t know where we are headed here, except that global mean temperature increase will, by 2100, be somewhere in the 3.5 to 9 F range. A change of 2 degrees F would be significant; a change of 9 degrees F would be catastrophic.

What the Oceans Tell Us

“Because of this the land mourns, and all who live in it waste away; the beasts of the field and the birds of the air and the fish of the sea are dying”(Hosea 4:3).

Our oceans are ill. Atmospheric carbon dioxide is absorbed (and regulated) by the oceans. When CO2 dissolves in water, a mild acid (carbonic acid) forms. Eventually CO2 is sequestered in the shells and bodies of aquatic life. However, as the amount of CO2 increases in the atmosphere and more is absorbed into the oceans, the oceans become increasingly acidic.

It’s not too late for us to change course.

The oceans are more acidic today than they have been in the past 20 million years. The change in ocean acidity correlates directly with increased CO2 concentration in the atmosphere. It is becoming clear: the oceans are providing an urgent warning that we must change our CO2 habits. Put simply, the minute organisms that are the base of the aquatic food chain and produce 70 percent of Earth’s oxygen (our planet’s “lungs”) are in grave jeopardy.

Heeding the Warnings

We are stewards of a wonderful creation. As a scientist I am humbled that God has given us the insight, intellect, and tools to understand, in part, this subtle and ever-surprising planet. What we know clearly is that we are having a profound and potentially catastrophic effect on the climate of Earth.

What can we do about that? Perhaps the first thing is to become knowledgeable about climate change. We need to get past the rhetoric and emotional language and learn some of the fundamental science behind it. It’s not too late for us to change course, but to do so we all must understand the basic causes of human-induced climate change.

Second, we can encourage our political leaders to work with us to find ways to reduce our CO2 “footprint.” Yes, we can do our part as individuals, but we must also act as nations. Write to your political representatives and encourage them to “do the right thing.”

Third, act in faith that we are called to be stewards and that we can make a difference.

To learn more about climate change and to access online resources including those created by The King’s Centre for Visualization in Science, please see explainingclimatechange.ca.

For Discussion

  1. What personal experience have you had with the effects of climate change? How does this affect you?
  2. What’s the difference between weather and climate?
  3. Why is the steady growth in the concentration of COâ‚‚ alarming?
  4. Do you agree that the growth of COâ‚‚ is a result of fossil fuels? Why or why not?
  5. How does COâ‚‚ affect the oceans?
  6. What does God require of us to help heal the land and all living things?

About the Author

An astrophysicist by training, Dr. Brian Martin is professor of physics and astronomy at The King’s University College in Edmonton, Alberta. He also codirects the King’s Centre for Visualization in Science and, with colleague Peter Mahaffy and a team of gifted undergraduate students, produces web-based resources to help students, teachers, and the general public understand the complex science of global climate change as well as other areas in science. He is a member of Fellowship CRC in Edmonton.
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