Global Warming - Why Should We Worry?

The reading is from an editorial in the June Science, the monthly journal of the American Association for the Advancement of Science.

Climate Change and Climate Science.
By Donald Kennedy

The results are everywhere, except in popular accounts of what's going on. Those, unfortunately, often emphasize distant possibilities rather than probable outcomes. A recent Pentagon scenario-building exercise suggested a sudden breakdown in the North Atlantic circulation, producing a dramatic regional cooling. A disaster film called "The Day After Tomorrow", released a couple of weeks ago, suggests an apocalyptic future not foreseen by most serious climatologists. In fact, we do not know whether global warming will continue to increase on a steady ramp or possibly cross the threshold of some nonlinear process. We're in the middle of a large uncontrolled experiment on the only planet we have.

The view of the Earth from space as we have seen from satellite pictures is one of a beautiful blue ball with white swirling splotches. That blue comes from the oceans, which cover 71% of the surface of the Earth while the white comes from surface ice, snow and clouds. All that water provided the womb and nursery, as it were, from which life on this planet has been nurtured. That same water has also provided the thermal ballast that maintains the environmental conditions that allow life to continue to flourish on this planet. We all at some level of our beings understand that this water planet is our only home and that we must nurture it if our kind is to survive. I suspect that, that understanding leads to some esthetic sense that the Earth with all that water in those photographs is so beautiful.

We seem to have arrived in my life-time at a political consensus in much of the first world that human activities have lead to a despoiling of the environment and that we should do something to deal with things like poisoned rivers and lakes. This was started by Rachel Carson with her book, "Silent Spring", about 50 years ago. We see the pollution in the air and hear on the news about air quality. 50 years ago nobody had heard of an air quality index. We read about the increased incidence of lung problems in the young. We develop a personalized understand that particulates and acids in the air are bad for lungs and we now believe the acid rain kills forests and chokes streams. Chemical effluents in the Susquehanna River nearly killed the Chesapeake Bay in Maryland, which was one of the great producers of seafood for the East Coast of the US. Today the Chesapeake has returned as a great producer of safe seafood because enough of the up-river and down-river people of Maryland, Delaware, Virginia and Pennsylvania realized what a disaster it was. The body politic can be moved to save our environment even when there is perceived adverse economic impact. Some people will always shake their heads and fight it and many will argue that we are going too far, but the majority have gotten on board because they can experience the problems directly or they see a personal advantage (as with urban dwellers in favor of preserving old growth forests to visit on vacation).

For many reasons Global Warming, which I prefer to call Global Climate Change, has not achieved that consensus view in the public mind of Americans, as have other environmental problems. Many highly knowledgeable atmospheric scientists claim that the consequences of global climate change are potentially as serious or more dangerous to human civilization than unsightly landscapes and polluted air and water. The consensus of the publics of much of Europe, Japan and elsewhere other than the United States is that this is a serious enough problem that we should do something about it. They are willing to pledge themselves to holding or even decreasing carbon emissions from their factories, power plants and automobiles. Why is the United States not on board with the rest of the world? We might argue that it is simply the self-interested ignorance of the Bush administration, which pushes for consumerism and personal wealth above and beyond all other human concerns! But it really is not that simple.

It is true that the Clinton administration did agree to the Kyoto, treaty which set limits on carbon dioxide emissions, but it was not because they had a clear public consensus. They believed that that they had a clear consensus in the scientific community and that was sufficient to move them. It did not, however, move the Congress, which did not ratify the Kyoto treaty. Business did not like it and there were and there are scientists telling the public a different story than that of catastrophic climate change. Like so many other complex issues, ethical, economic, technical and political in nature, there are people across the spectrum of belief. There always are, and of course there always will be. Some times talking to people about this and listening to it in the media it doesn't sound much different than the way people talk about the existence of God or the ethics of stem cell research. I speak to people at work about it, who are used to the complexity of scientific arguments, and I hear positions which pretty much divide along political lines rather than scientific lines. Oh, they make scientific sounding arguments but the bottom line comes down to the liberal / conservative political divide and statements of faith and belief. Only people working day-to-day in the field have a real appreciation of the facts and even they cannot see through the problem without the help of computer simulations.

Global Warming is like so many of the complex problems we face today. It is truly beyond the ability of any of us to actually determine the truth by ourselves. In some sense none of us can defend having an opinion on the basis of first hand personal knowledge, experience or observation. We have no choice but to delegate the truth gathering to others. We have to give it to a committee and have them report back to us what their findings are. And as so often happens with committees when the answer is not one that everybody likes they tell the committee to go back and look again. The governments of the world have actually appointed a committee to look at global warming. It is called the Intergovernmental Panel on Climate Change, or IPCC. Its members are, in general, very well respected climate scientists from all over the world and while they disagree on some details they have a developed a very solid international consensus. You can look at their recommendations yourself by going to their web site, www.ipcc.ch which I found by going to Google and searching on IPCC. Their third report, "Climate Change 2001", has been available for sometime now.

I am a believer, and I, of course, want you to be a believer that Climate Change is a serious threat to humanity. Am I a believer because I am a scientist and can actually understand all the complex intricacies of the physics and chemistry? Well yes AND no. I think I understand enough to know what I can't know but I am principally a believer because I have been interested in this problem for about twenty years now. I have watched professionals far more knowledgeable than I struggle with it and watched a solid consensus emerge over that time as more and more good data has become available.

Scientists at Los Alamos were writing what are called general circulation computer models twenty years ago. They understood then that the computers were not large enough to perform first principle calculations. Today with computers literally trillions of times faster and larger we still can NOT perform first principals calculations of the global climate system. We do have much better data about the climate of the world and over the past twenty years scientist have figured out how to read the world's past climate from ice cores taken from the Greenland and Antarctic ice caps. There is an entirely new scientific specialty of paleo-climatology. Given this new data climate scientists can now test their computer models against 400 thousand years of climate data. So while they still today cannot perform a computer simulation from first principles physics they can adjust the parameters in such a way that the computer codes do a very good job on predicting the past 400 thousand years. Given that, they feel confident with the future extrapolations that the Climate Models make. There is still a very large amount of the important details that have to be left out of these models.

So I am a believer that the large amounts of CO2 we are pouring into to the atmosphere will change the climate of the earth in a potentially catastrophic manner for humanity. I believe this because there is a solid worldwide consensus among climate scientists as to what could be the result of climate change. There is also a solid consensus that climate change will happen as a result of changing CO2 levels in the atmosphere. You have all heard or read about the sea level change as the Greenland and Antarctic ice caps melt. I have not seen the movie "The Day After Tomorrow", which came out this summer. I really wanted to see it before I presented this talk today but Grace and I have been so busy over the past two months that we actually could not get around to seeing it, so I can't tell you how over-blown it is or isn't. There is a litany of problems that rapid climate change could bring about. One problem with the computer climate models is that they primarily deal with the temperature of the atmosphere and major atmospheric circulation. They can tell us gross things about the extent of the Ice Caps and sea ice but they cannot get into details about storms and storm tracks. Climate models do not yet deal well with the interaction of the atmosphere and the ocean currents like the Gulf Stream. Predictions about increasingly strong storm activity are based on reasonable physics arguments and extrapolating from the temperature increase of the atmosphere predicted by the climate models.

I am sure you understand or have heard that the major oceans currents like the Gulf Stream and the Japanese current hugely affect temperature in both the North Atlantic and the North Pacific. The El Nino and La Nina warmings and cooling in the pacific control the weather across the entire western hemisphere. Canada and Europe are essentially at the same latitude. That means they get the same heat input from sunlight and yet Canada only feeds 40 million people, because the vast majority of its land is frozen tundra. Europe on the other hand supports nearly 300 million people. The difference is that nearly one third of all the heat energy input to Europe arrives not in the form of sunlight directly from the sun but rather carried in by warm air coming on the Gulf Stream from the Caribbean.

Image what would happen if the Gulf Stream were to stop. Is that possible from Global Warming? Well, yes, it is actually quite within the realm of reason. The Gulf Stream is partly driven by the concentration of salt which makes the cooling waters sink off the coast of Norway. That sinking water spills over a natural deep canyon at the bottom of the ocean and returns to the equator trapped in a cold dense steam. If the salt concentration were to dilute too quickly that water would not sink as it cooled. The Greenland Ice cap is all fresh water. As it melts, a lot of that water will pour into the North Atlantic, diluting the salt in the Gulf Stream. That could turn off the heat conveyor belt that has kept Europe moderate for that past 100,000 years. The average temperature of the Earth's atmosphere might still be increasing but Europe's temperatures would plummet. We would have a tough time figuring out how to get all those people fed.

It has been my belief for many years that the number and severity of large atmospheric storms would increase along with the increasing greenhouse gases. I haven't actually explained to you how the Greenhouse effect actually works and why increasing CO2 leads to increased temperature of the earth's atmosphere. I had originally planned to explain that in some detail and then I was going to explain how that would lead to increased violent storm activities. I don't have enough time to really do that but I am particularly fond of this idea because I believe I was the first scientist to point out this problem back in 1984, when I did so in a proposal to the Department of Energy.

In its most basic form the argument goes like this: the sun heats the earth with sunlight. Because the earth gets hot it shines, in infrared light, the same radiant heat you feel when you sit in front of a fire. That radiant heat escapes into space cooling the earth. When the incoming sunlight energy is exactly balanced by the outgoing infrared energy the earth's temperature reaches a constant. Energy IN equals energy OUT. A lot of people don't understand that fact. The earth must all the time give as much energy back to space as it takes in from the sun or else it would keep getting hotter and hotter. So the earth will get just hot enough so that the flow out equals the flow in. When we calculate that temperature for "just hot enough" it is minus 19 degrees centigrade. [3 degrees Fahrenheit.] The reason the earth is warmer (33 degrees centigrade [60 degrees Fahrenheit] warmer, on the average) is due to the ability of certain gases in the atmosphere to absorb infrared light (the other name for radiant energy). Infrared Light that goes up from the earth's surface is absorbed by these gases and then sent out in all directions so that in the atmosphere, just a little above the ground, the IR radiation coming from the ground is going in all directions equally. On average then half the IR is returned to the ground. Instead of flowing freely into space from the ground, the radiant energy has to diffuse up to a high altitude, where it does finally get above enough of the gases to flow freely into space. The IR absorbing gases act like a blanket around the earth, trapping some of the heat. This is what is called the Greenhouse effect.

The most important greenhouse gases are water vapor, Carbon dioxide and methane. Water vapor contributes about 65% of the absorption, Carbon dioxide 25% and methane less than 10%. Important for understanding the generation of storms and the importance of Carbon dioxide in the process is that a very small increase in temperature at the surface of the oceans leads to an increase in the amount of water vapor in the air. This in turn increases the trapping of infrared light, which now acts to increase the temperature and so on. We call this positive feedback. This increase in water vapor also gives us more seeding of clouds, which has at least three important effects. More clouds mean more atmospheric water to bring about storms. The water vapor also serves to carry heat energy from the surface to high altitude. In fact the cycle of evaporation at the surface with condensation at high altitude and then raining out of the water is just like the cycle that is used in your refrigerator.

It is perfectly reasonable to describe storms as refrigerators. Heat is picked up at the ocean surface and delivered to high altitude with cold water returned to the ground to be heated again. The more water vapor present at high altitude once the storm starts the faster the upward convection in the heated air in the storm. It is the heat from the condensing water that makes the air more buoyant causing it to rise. This is the reason that thunderheads tower high in the sky above other clouds. The more water vapor the more rising air and the more violent the storm. The more the energy in the storm, the higher the likelihood of tornadoes. This is similar for hurricanes. It is the condensing water vapor near the center of hurricanes that heats the air. The warmer the air, the lower the pressure and the more clouds that are swept into the hurricane. The lower the pressure the tighter the circle of wind and the more violent the winds. The storms and the clouds also provide other feedback to the heat balance of the atmosphere, which has always appealed to me. I said there are at least three effects from the increasing water vapor and two of them are ameliorative. The violent storms help bring the trapped heat from the surface up to the high atmosphere where it can be carried away into space more readily. This helps balance that flow of heat back to space that is blocked by the greenhouse gases. These very violent storms are pumping dry air up above the cloud tops because the storm dumps the water vapor as snow and rain. That dry air dilutes the higher altitude water vapor decreasing the high altitude contribution to greenhouse trapping and these storm clouds reflect more sunlight back into space so it never reaches the ground in the first place. This is an important moderating effect on the earth's temperature. The temperature doesn't rise as much but instead we get ever more violent and destructive weather. So with the examples about the Gulf Stream and violent storms you understand why I like to speak of Global Climate Change rather than Global Warming. The temperature may not go up very much but we will not like the results any better.

I have told you that there is a consensus among scientists that we are going to see increasing manifestations of rapid climate change; this change is due principally to the increasing amounts of CO2 in the atmosphere; and that we do not understand the detailed dynamics of the system well enough under rapid change that we can rule out things like turning off the Gulf Stream. I also should tell you that in the last 20 years we have achieved a significant understanding of the causes of Ice Ages and we can rule out with this understanding that we are just experiencing a natural interglacial warming. All the measurements of today's temperature and CO2 are far off the scale of anything that has happened in the past 400,000 years. To put that in perspective for you, modern Homo sapiens are thought to have appeared a little over 150,000 years ago.

Do I believe and do knowledgeable scientist believe we can do anything to save ourselves from disaster? Let's add a little to the litany of disaster even though I assume that you have read about many of these things. There is the effect of increasing temperature on habitat for plants and animals with escalating species decline and die off. There have been articles in the popular press this year, including National Geographic and Newsweek, reporting on the current bleaching and death of coral formations worldwide. Glaciers are retreating throughout the world. Your grandchildren will probably know of glaciers only through pictures and they may have to search very far and wide to find a living coral reef. Increasing sea levels will inundate countries like Bangladesh and some small island nations will simply disappear. The Climate system takes a while to respond to increasing heat input, and current models suggest that even if we freeze CO2 output from fossil fuel use well below today's level we still face continuing warming.

There are things that we can and should do both individually and as a nation but the current direction of the world is very problematic. The United States, with 5% of the world population, produces over 25% of the world CO2 output (5.5 billion metric tones annually!). The US production of CO2 comes 40% from making electricity, 33% from transportation and 16% from industrial activity. Getting cars off the road helps. Current gas mileage is around 24 miles/gallon; if we got the average to 40 miles/gallon it would be equivalent to getting 44 million cars off of the road. Smaller, lighter cars use less fuel and small hybrids are claiming 52 mpg. What about electricity production? Well, getting non-fossil fuel based systems like solar electric and wind will help. I have read claims that we could get 20% of our electricity from non-fossil fuel by 2020. Any of us could put a solar electric system on our roofs and that would help some. I happen to believe that nuclear power is a better option than our current fossil fuel based systems. Nuclear power plants produce no CO2. If we are willing to pay the price even fossil fuel based electric generation is possible with something like a 60% decrease in emissions. With the appropriate incentive we could force power companies to adopt the appropriate technology. Energy efficiency is also a way to help. We must be ever more efficient and sensible in the way we use electricity in our homes and factories. I have seen studies that claim that increasing energy efficiency over the past twenty years has reduced CO2 output in the US by over 53 million tons. Deforestation is another serious problem. Forests suck up carbon dioxide and store it as vegetable matter. Growing and keeping large forests actually helps clean the atmosphere of CO2. Tropical deforestation now accounts for over 20% of CO2 production. We must find way to help countries hold on to their forest.

We must invest research money in searching for technical solutions across the board. Our current farming practices, while producing large amounts of food, use lots of energy and release significant CO2 as well as nitrous oxide, another greenhouse gas, to the atmosphere. Soils that store organic matter are storing carbon that comes from atmospheric CO2. Can we find efficient ways to increase the humus content of our soils for long-term storage of carbon? We need to increase research on this topic. Finding productive farming techniques that use less fertilizer and increase humus production will matter particularly when applied nationwide or even worldwide. Some of this you and I can do by just paying attention and suggesting to other people that every little thing they do will matter. I am certain that some of you do think about these things all the time. Multiply individual actions by millions and they add up. Your political involvement also matters. The United States must support the Kyoto treaty and put in place economic incentives that will make our industry do its share to reduce CO2. My position is that this will buy us a little time but it is only a little bit of time - maybe twenty years if we can improve energy efficiency by an overall twenty five per cent across the board. Why only twenty years?

Because the real problem with all of this is that we have an ever-increasing population around the world. With the world population increasing by 1.5 % per year, which it is doing currently, it will only take about 14 years to increase the population by 25%. So a 25% decrease in CO2 production achieved by efficiency and other method is completely eaten up by world population growth in 14 years. On top of that the people in Indian and China don't drive as many cars as we do and they don't have much in the way of electrical appliances, but in twenty years they plan to. So not only will the population increase eat up the gain it will be worse because the new population in those countries will be producing more CO2 than they do today. I believe that the world is over populated as it is and we are already eating up energy resources faster than nature can provide new energy to the globe. We are producing disastrous amounts of CO2 and the best we can do is buy a little time for our children until we can create the political will to curb population growth and maybe find technological solutions to the problems. We see that in Europe and Japan the public knows about and is worried about this problem. While I am somewhat pessimistic we have evidence that the American public responds when given the opportunity to engage.

It is true that in a democracy all discussions are essentially political discussions, and I think I hear in today's political debates that when things become political all points of view are equally valid. Many people in the scientific community claim that the current White House tries to alter the outcome of scientific studies to match up with their political agenda. The Republican controlled Congress is, for the first time, asking for peoples' political affiliation when they set up expert panels. The religious right claims that Universities are packed with Liberal scientists and they can and will get different answers from science if they just put more people with their point of view into Universities. Does this mean that Conservatives don't care about truth or they believe that essentially there is no truth? My bias would be to say yes to that except that I understand that human beings, including liberals, are so emotionally committed to their preconceptions that they will refuse any information which doesn't agree with those preconceptions. If you tell them things they don't agree with you must have a bias. I simply do not accept that you can shape nature to your political agenda. It is true that decisions that gravely affect our way of life have to be decided in the political arena but there are truths and in the case of Global Climate change the physical system will come out the way natural law makes it and our political agenda be damned. This means that you cannot afford to be disengaged from this discussion because the outcome really matters. It also means that as a society we have to find a way that gets us beyond political obfuscation when discussing issues of this magnitude. This week millions of dollars of destruction occurred in Florida. Many people were seriously injured and a goodly number killed. At this point can I tell you that global warming had anything to do with this? After all, there have always been hurricanes. The predictions are that hurricanes will increase in frequency and in deadliness. Do we have the attention span to figure it out in time? Humanity has muddled through in the past when things got very bad. We can pay attention when people are forced by circumstances to finally accept problems as real. I am hoping that when the problems become more obviously manifested we will find the will to act to save the world for our children. Given the uncertainties in our understanding of the climate system we might just luck out and nothing totally cataclysmic will happen before we find a way, and the will, to reverse the damage.

[David Simons is a member of the Unitarian Universalist Fellowship of Stanislaus County. He earned his Ph.D. in physics from the University of Maryland in 1974. His doctoral thesis concerned the energization mechanisms of electrons in the Aurora Borealis. He lead the atmospheric sciences group at Los Alamos National Laboratory in the 1980's, working on a diverse set of physics and chemistry problems related to nuclear explosions, radio propagation, radiations transport, lightning physics, near earth space plasma dynamics and complex terrain atmospheric circulation. He has worked at the Lawrence Livermore National Laboratory since 2001.]

This is a Guest Sermon from our collection. Our Minister's Sermons are in a separate section.