Sermon: Global Warming, the Heat is On

[ previous | index | next ]

Global Warming, the Heat is On

By Charles Rush

June 12, 2005

r scripture this morning says that when God created us, we were made stewards of the earth; we are the earth's trustees. Our spiritual vocation as humans is to develop nature into a garden, to help it bloom. More than any other creatures, we shape the destiny of the world. This has become particularly acute after 10,000 of civilization. Our collective ability to impact and shape the planet is dramatic.

By the sheer force of our success, we have, in the words of St. Augustine, become a problem unto ourselves. I want to raise this today, looking at the issue of global warming, a subject about which I know very little. But there is no time like the present to get some education. I'm going to summarize the highlights of a three part series by Elizabeth Kolbert, who writes on politics for the New Yorker. [1] It is a very good read and I recommend it to you. visits a number of different frontier regions where a small temperature change has appreciable consequences.

She visits the Alaskan island of Shishmaref, that is only about 22 feet above sea level, and is inhabited by a native Inupiat tribe but it probably won't be much longer. For as long as the locals can remember the seas around the island stay pretty much permanently frozen so that their houses are actually sitting on an ice slab over the island. But for the past several years the ocean has been more like a Slurpy and this has had dramatic consequences for them, especially in the fall when the big storms come. When the sea is all frozen, the storms create a driving wind, but when the seas are liquid, the sea surge picks up and sends 12 foot waves crashing on the island, wiping out parts of the village. The tribe just recently voted to move the whole village to the mainland.

Likewise, she visited Vladimir Romanovsky in Fairbanks, Alaska where the permafrost line is in alteration. Romanovsky worked for the Russians when they were building the Gulag on the permafrost and he has been studying it ever since. Permafrost, just so you know, is ground that has been permanently frozen for two years or more. There are places in Russia where it runs a mile deep near the Artic circle and even in Alaska it ranges from a couple hundred feet to a couple thousand. What is happening in Fairbanks is that sections of the permafrost are thawing and when that happens gashes open up in the earth, sometimes rending homes and creating impassable crevasse in neighborhoods.

Romanovsky showed her some of his latest finds by comparing measurements of the ground temperature from the lower regions of the permafrost line to the surface. Usually what you find is that the bottom of the permafrost line is the warmest. There is a natural geothermal heat that radiates from the center core of the earth, and the temperatures get steadily colder as you get to the surface. However in the past few decades, he has been getting warmer temperatures on the surface which strongly suggests that the atmosphere is actually generating increasing heat.

Romanovsky explained to her that this melting may actually contain within it a multiplying effect as the thaw continues, particularly in the active layer, that region of the permafrost that has melted and refrozen annually for millennia. The active layer supports rudimentary vegetation such as shrubs, lichen, and some spruce trees. But because the temperatures are so low, when the seasons end, the dietrus doesn't actually decompose but is frozen, and it slowly gets pushed down into the permafrost. If this layer were to permanently thaw, it contains a deep sediment of material that would rot and release methane into the air in large quantities.

Methane is a greenhouse gas that is actually more powerful than CO2. This principle appears to be important in understanding climate change in our world. Because of the complex multiple factors that interact with one another, slight changes here can set in motion a chain of other resident reactions that can accelerate a trend that is already happening.

She also paid a visit to researchers on the Artic that are being sponsored by the National Science foundation. In 1979, Satellite imaging done by NASA estimated that the size of the Artic ice mass was roughly the size of the United States. At present, the perennial sea ice has shrunk approximately 250 million acres or an area the size of New York, Georgia, and Texas.

She interviewed one of the main researchers on the project, Donald Perovich who works for the Cold Regions Research and Engineering Laboratory of CCREL whose are of interest is in solar radiation and sea ice. Professor Perovich uses a device called a spectroradiameter- you don't need to know that I just like saying the name… It reminds me of the movie "Back to the Future" where the eccentric scientist invents a flux capacitor… the spectrodiameter measures incident light (directly coming from the Sun) and reflected light (bouncing back). Dividing the later by the former he factors the albedo (literally the whiteness from Latin).

Hard pack ice is intensely white. As such, the color itself tends to reflect back light keeping temperatures on the surface cooler. Conversely, ocean water is blue, a color that absorbs sunlight and thus heat. The two are nearly opposite of one another. So as the ice melts into water, you are replacing one of the best reflectors of heat with the worst.

Again, there is a compound effect to the system. As ice spreads, it reflects more and the temperatures on the surface drop adding more ice to the system. Conversely, as ice melts more heat is absorbed by the water which raises the ocean temperature and melts more ice.

You probably know that the overall temperature of the earth has varied quite a lot in our long history. I was surprised to learn that the majority of the earth's history has had no ice on either pole. However, there has been continuous ice through 4 glaciations that have lasted just over 120,000 years. We do not understand all of the factors as to why we have seen these dramatic shifts in climate, but the principal single factor is thought to be small orbital shifts in the Earths rotation around the Sun.

It was in 1859 that the concept of Global Warming was first conceptualized by John Tyndall, the British physicist. He noted that oxygen and nitrogen were transparent to radiation but that carbon dioxide, methane, and water vapor were not. These gases act like an insulating band trapping and storing heat. He, in fact, coined a term we are now quite used to hearing the "Natural Greenhouse Effect". As you know, the principal Greenhouse gas it Carbon Dioxide and Carbon Dioxide is a by-product of burning Coal and Oil, which we have increasingly done since the middle of the 18th century. Carbon Dioxide itself is a "persistent gas. It lasts for about a century."[2] That means that as it accumulates, it has effects for the future that we will not see for decades to come. The concern about the planet is that forces could be set into motion that will activate resident forces and accelerate a pattern, such that by the time we will actually see the first consequences of these change it will already be too late to do anything about it.

As you probably know, we can do some rough measurement of greenhouse gases by studying the ice cores in the poles that have small air pockets trapped that can be analyzed. When you look back over the past 5000 years you see a remarkable consistency in the concentration of greenhouse gases from the beginning of civilization to Ancient Greece to the Hapsburg empire. Then greenhouse gases begin to rise towards the end of the 18th century with the Industrial Revolution.

In 1780 CO2 was approximately 280 parts per million

By 1930 CO2 was approximately 315 parts per million

By 1970's CO2 was up to 330 parts per million

By 1990's CO2 was up to 360 parts per million.

The rise is steeper with more advanced burning of fossil fuels.

It is precisely this steep rise in Carbon dioxide and our responsibility for it that led Paul Crutzen, the Dutch Chemist and Nobel Prize winner, to write an article in Nature a few years ago suggesting a change in the name of the present era. At present, scientists refer to our era since the last glacier as the Holocene era. Crutzen says we should give a new name to the era since 1780 or so as the Anthropocene era, the Human period, because, he argued, humans became the single dominant force that shaped and influenced the total climate of the planet from then on.

As you know, there is no consensus about what happens in the future. We are simply entering unchartered territory and it is far from clear what implications actually follow. In her discussions with climatologists, Ms. Kolbert summarizes a couple areas of concern that they have identified.

One of them is our general findings from the ice corps on the polar caps. One of the things that they make clear is that our present era has been exceptional rather than normative for Earth's history. In the Holocene era, we have been blessed with exceptionally regular weather and exceptionally predictable weather patterns. Over the long term of the Earth's history, dramatic shifts in weather have been the norm and stable weather patterns the exception. Why this has taken place is a matter of speculation, but this paradigm may well be significant for our thinking on the subject of the implications of global warming.

I come back to the notion of complex interacting factors that reinforce and escalate a trend in a direction. One of the scientists that she interviewed used the analogy of a boat. It may be the case, that the total systems of the Earth's climate work like tipping a boat. You can tip it and it will swing back, tip it harder and it will swing back harder, but if you tip it beyond a certain point, it flips over. It may well be the case that in the aggregate, when enough resident changes take place, that you have a complete reconfiguration of the total weather system. The study of the ice cores suggest that such a reconfiguration is not only possible but probable.

How would this happen? No one exactly knows. But the scientist Konrad Steffen gives a simple explanation of how weather patterns presently work around Greenland and how they might be altered. As you know our Gulf stream pulls water up from the equator that eventually runs into Greenland and then pushes it down and back south again. As you also know, the weather pattern over the Eastern part of the United States is interdependent with the Gulf stream.

Professor Stefen explains that there are actually two forces that create the sea lane that is the Gulf stream. Part of it is what is happening on those major ice masses like Greenland. In the process of salt water freezing, the salt is actually pushed out of the ice towards the exterior of the ice mass. That salt is heavy and it makes the water heavier as it dissolves and this saltier water sinks to the bottom of the ocean. That is one force.

The second is related to the general drift of the warm water to cooler regions. As warm water drifts northward, it cools and evaporates, which means it becomes denser. Again, as it gets towards its northern terminus at Greenland this water too is sinking.

As it does, it creates its own pull on the warmer lighter waters in the Caribbean, so that the overall process resembles a delicate but very powerful conveyor belt of ocean currents.

Now what happens if you add heat to this system? In the first place, the oceans would warm in the south, only slightly, but as they did, this water is lighter and slightly less dense, so it sinks less.

Secondly, if the ice melts then again, only slightly, but you are dumping a large quantity of fresh water into the oceans. They become less salty. They are not as heavy and do not sink as much.

At some point, if these trends continue, it could have the effect of turning down the pump at both ends at once and the sea lanes slow. But as they do, the weather above them also changes. Theoretically, if the sea lanes actually came to a stand still, some people speculate that what would happen is a complete reconfiguration of the weather patterns… That would be something of a tipping of the boat over.

I know that for me, one of the more interesting parts of her article was the discussion of Ancient civilizations. She travels to Tell Leilan in Southern Syria where Harvey Weiss has been excavating a city that was on the edge of the Akkadian empire from 5000 b.c. until 2200 b.c... This was the cradle of civilization, the area of the world where we first cultivated wheat and other grains that made possible domestication of animals that led to the development of other technology that eventually produced our first city states.

We have many archeological examples like Tell Leilan. Professor Weiss excavated it, found that it was a small farming village that grew over the next millennia and by 2200 had walls, a developed commercial life, and probably supported 30,000 people. Then suddenly, it is abandoned. Why? There is no evidence of war. Was it disease? What?

In the past decade, we have developed the ability to analyze soil samples better and in some cases, like that of Tell Leilan, we have determined that the cause was sustained famine. Professor Weiss determined that Tell Leilan had such a sustained drought that all the earthworms died right around 2200. It turns out in the ancient world, the operative number was 5. If you had 5 years of drought, everyone fled and civilization as you knew it there came to an end.

You may know that similar speculation has attended the sudden end of the Maya civilization in South America, and there are half a dozen other examples around the world. I suspect that this explains the symbolism of Joseph's interpretation of Pharaoh's dream in Exodus. Pharaoh dreams that there will be 7 years of feast followed by 7 years of famine. He is greatly perturbed. I would assume that, based on bitter history, 7 years of famine means that God (or Nature) is going to wipe everything completely out. That is disturbing.

The point is, that even in our brief tenure as civilized people, roughly 10,000 years, we have already lived through some radical changes of weather patterns that had thorough and dramatic implications for various localities. And if we significantly alter the ecosystem, we should expect such dramatic changes ahead.

I have now exhausted my expertise on this subject but the subject is important enough to throw it open to you for response and hopefully there will be some collective insight.

In closing, what struck me about the articles, were the people that she interviewed, Academic scientists. About the fact of global warming, there seems to be nearly unanimous consensus. About the importance of greenhouse gases caused by human civilization, there seems to be very little dissent in the academic community. About what will happen, there is less consensus and less actual data to support our modeling. Finally, about our ability to actually shape anything collectively, there is less consensus still, largely because that is a social question- one as much for politicians, economists, and ethicists as it is for science.

If you have read the full series you know that Ms. Kolbert herself is more alarmist and suggests that substantial impact on our world will likely happen in the next century. I've intentionally not presented that piece, precisely because of its speculative nature. But you have thought about this subject. What is your reaction to Ms. Kolbert's interviews? What are you thinking about global warming these days?

[1] See "The Climate of Man" in the April 25th, May 2nd, and May 9th edition of The New Yorker for the year 2005.

[2] New Yorker, May 9th, 2005, p. 54.