Is Global Warming Real
First, let us make sure that global warming is a real phenomenon. Let us say we did not have an atmosphere that caused global warming. That is a fairly simple calculation to do, it involves many things, but the calculation itself could easily be done by an Algebra I or II student. Also, the calculation does not involve assumptions; it is based on First Principles, Laws of physics, and experimental data that are not disputed by the scientific community.
Calculating Global Warming
There are many things that factor into the calculation of the temperature of the Earth absent an atmosphere, among them the energy emitted from the Sun (luminosity), the distance of the Earth from the Sun, and the albedo of the Earth. The amount of radiation the Earth receives from the Sun is effectively constant, there are small changes but they are very minor. Nor is the distance between the Earth to the Sun a constant since the Earth follows an elliptical orbit, but we do know the distance at a given point in time, and the distance can be taken into account when making the calculation. Look in the Appendix for the exact calculation.
Since the Temperature of the Earth is warmer than the calculated -25 ?C, there must be something that is globally increasing the temperature of the Earth. That phenomenon is called global warming.
Albedo
One of the most difficult things is to figure out the albedo of the Earth. Albedo is the ratio of energy that is reflected by a surface divided by the total amount of energy that hits that surface. A perfect mirror has an Albedo of 1, and a perfect black body, something that absorbs all energy, has an albedo of 0. Albedo is the main reason why you feel warmer on the beach when you're wearing darker colors compared to wearing lighter colors. The albedo of the Earth is constantly changing, the clouds shifting; the amount of glaciers and many other things affect the albedo. By doing many calculations we are able to determine that the average albedo of the Earth in 1990 was 0.39. This means that 39% of the energy that hits the Earth from the Sun is instantly bounced back into space. The rest is absorbed, and then re-emitted. If the energy were never re-emitted, then the temperature would just keep increasing until the Earth was as hot as the Sun. Taking into account the amount of energy absorbed by the Earth before it is re-emitted, the Earth would be approximately negative 25 +/-2?C. Of course this is not an exact number, it is possible that the Earth could be as hot as -23 ?C, but that is unlikely. The more likely case is that the low temperature would cause all the water and some other things to freeze increasing the ice cover. Ice, being reflective, would increase the albedo of the Earth causing more energy to be reflected, causing the Earth to plunge deeper into the cold. If all of the Earth's water froze and covered as much of the planet as is currently covered by water or ice today, the Albedo could go as high as .6 or .7, making the temperature of the Earth somewhere between -49 and -65 ?C. These temperatures obviously do not allow life which needs liquid water to exist.
One of the things that is only recently being taken into account at the level it needs to be is how the melting of ice is changing the albedo of the Earth. Ice has an albedo of 0.9. Ocean water has an albedo of 0.08. As ice melts and is replaced with water, the albedo of the Earth is reduced. This causes an even larger increase in the Earth's temperature causing even more ice to melt causing the temperature to rise even more. This vicious cycle is causing the temperatures to rise even more than the direst predictions. As Stephen Colbert said, enjoy any jokes about glaciers while you can because our grandkids may not know what glaciers are.
Cloud Effects and Venus
Clouds also reflect the rays of the Sun, but depending on their composition and where they are they also capture heat. The physics of clouds is not completely understood, so we do not know the exact effect they will have on the temperature of the Earth. What we do know however, is that Venus which is completely covered in clouds (albedo = 0.76) has an average surface temperature of 400 ?C. Doing the same energy calculation for Venus that we did for Earth, Venus should have a temperature near 20 ?C (calculation in appendix). What is different? There are many things that led to Venus being so warm, but the largest is that at 20 ?C CO 2 could not be completely sequestered by the soil. We know all of the previous for fact. But what conclusions can we make? Well, the increased cloud cover did less to reflect the energy than the CO 2 did to trap any energy that did make it in. The CO 2 eventually won out over the cloud cover. We cannot be certain that the exact same thing on Earth would occur (this is one area where there is a minimal amount of scientific debate) as we increase the amount of clouds (by melting ice and increasing water vapor as well as emitting smoke), but it is fair to say that we are making the Earth more like Venus.
C O 2 in the Environment
One of the most alarming things is the rising CO 2 levels. 1958 is when atmospheric CO 2 levels were around 278 parts per million (ppm). Currently the atmospheric CO 2 level is 381 ppm. We know that humans are the cause of that increase. All of the evidence points out that when CO 2 levels rise the temperature rises (see Figure 1). What we do know is that the last time CO 2 was at this level was 3.5 million years ago and the last time it was higher was 50 million years ago. The temperature of the Earth 3.5 million years ago was about 3 ?C warmer, and 50 million years ago the Earth was about 5?C warmer. There is a lag however; it takes a little bit for the Earth's temperature to catch up with the level of CO 2. The CO 2 does not directly heat the Earth, it just causes more of the Sun's heat to be trapped, so it takes a while (10+ years) for the temperature to equilibrate to the new atmosphere.(9)
Occasionally people are audacious enough to say that there is no link between the rise in CO 2 and the rise in temperatures. They even make scientific/philosophic arguments for this, that there is not a causal relationship between the rise in CO 2 and the rise in temperature. One can also make an argument that is not technically incorrect that if you hit a pool ball with a cue stick and the ball moves that the cue stick was not necessarily the cause of the ball moving; after all causality is still only a theory. There are billions of pieces of anecdotal evidence that point out that hitting a pool ball with a cue stick will make the ball move, but there is no proof. Well, you know what, even though there's no proof that hitting a pool ball with a cue stick the ball to move, and there's no proof that rising CO 2 levels are the cause of the Earth's temperature rising, I'll put my money on the fact that the pool ball will move when I hit it with the stick.
Natural C O 2
Another effect of the melting ice is an increase in natural CO 2 emissions. Our emissions of CO 2 are causing natural sources to emit more. This is because there is a lot of biomass frozen in the ice. As this ice melts the biomass will be able to decay, releasing CO 2 into the air. Even though this CO 2 is coming from natural sources, it is man's intervention that is causing this release of CO 2.
Sea animals also store CO 2 for us. Coral reefs and the shells of creatures have a lot of CO 2 stored in them. Unfortunately the gases we are releasing into the air are changing the pH of the oceans such that coral reefs are being killed en masse. If coral reefs do not continue to grow, a lot of CO 2 will no longer be able to be trapped causing an even bigger increase in atmospheric CO 2. Also at low enough pH's shellfish can not make their shells. This means that if we do not stop emitting certain gases all shellfish could conceivably be killed. It is calculated that if the CO 2 levels in the atmosphere quadruple (which could happen in less than a century at the current rate we are increasing our emissions) the pH of the ocean could drop to levels where unless the shellfish and coral evolve, they will all die. Preliminary evidence suggests that they will not survive as most coral reefs are dying or dead already. Yes, shellfish did not die when CO 2 levels were this high millions of years before, but the rise of CO 2 was much slower then, the animals had a chance to adapt. The calculations of pH and the extinction of the shellfish and coral are not 100% guaranteed, they are the most likely scenario, but not guaranteed.(1)
Another sink of CO 2 that will become less effective is the oceans. Water can trap gas. As it warms it traps less gas (imagine a carbonized beverage, while cold it keeps it's bubbles, but the gas fizzes out as the liquid warms). As we heat our oceans the gas that was previously trapped is being emitted. The amount of CO 2 humans produce is nothing compared to the amount of CO 2 trapped in the oceans. If we keep messing around with the environment the ocean could start giving off that trapped CO 2 in larger quantities. This large dump of CO 2 into the environment would be catastrophic. There is more CO 2 in the oceans than in the atmosphere. This is likely to be the obvious sign that we're past the point of no return, the canary in the coal mine died, if the oceans dump a significant amount of the CO 2 they're trapping into the atmosphere it will likely take centuries to reverse the damage we've done to the Earth.
The rocks of the planet similarly have a lot of trapped CO 2; in fact there are orders of magnitude more CO 2 in the rocks compared to the oceans and atmosphere combined. The release (or capture) of CO 2 by rocks is a very slow process, thousands of years could pass before the amount trapped would naturally change.
There are other greenhouse gases, methane most notably, but even though 1 mol of methane traps a lot more heat than 1 mol of CO 2, since there's hundreds of times more CO 2 than methane (~370 ppm vs. 1.7 ppm), it is on CO 2 that we most heavily concentrate. Also, most measures that reduce CO 2 also reduce methane.(17)
Temperature Variance and Water
Even a low-ball 2?C change could be disastrous. 2?C would be enough to melt most of the glaciers and ice caps. There is enough water trapped on Greenland alone to raise the ocean water 6 meters, not to mention the Antarctic ice sheets. But what will be worse is the thermal expansion of water. Remember, water expands when it warms beyond 4?C . An average of 2?C may not seem like much, but warmer waters could expand as much as 0.11%. Again, this may not seem like much, but when you multiply that tenth of a percent by all of the water in the oceans you're talking about 3 million cubic kilometers added volume (calculation in appendix), a rise of 9m, and that's not including any water that's melted in the past decade. A more conservative 2m rise is expected in the immediate future, but that 9 meter rise is likely within the next century if we do not drastically cut our emissions.(16)
Weather Patterns
Another effect that the rising temperature could have is a complete change in weather patterns. Warmer water has two major weather consequences: Storms will be more severe and there will be more droughts in the interior of continents. The first, more severe storms is simple to understand, warmer water has more energy (temperature is simply a measure of thermal energy), since there's more energy to be released, the storms will be more severe. Katrina, for example, was only a level 1 hurricane when it went over Florida, but in the time it spent in the Gulf Coast it changed into a level 5 hurricane before making landfall in Louisiana and Mississippi. Historically, a storm spending that amount of time over the water at that time of year should not have become that strong, but since the water was warmer than it should have been the storm was stronger. There is also an increase in the number of severe weather incidents. For the past few decades, as long as this information has reliably been kept, the warmest years have had the most severe weather events (hurricanes, tornadoes, etc…). So the increasing temperature is not only making the serious weather events more severe, they're also happening more frequently. So if there are more hurricanes and the like, then how are there more droughts? Well, since there is more energy in storms and other weather events when they hit land, they hit the critical point that allows them to precipitate quicker. The severe droughts currently being experienced by inland Africa and the central United States are most likely linked to this phenomenon. Additionally the increased temperature would cause more water to evaporate from the ground, resulting in an expected 60% increase in desert area.(9)
It is slightly counter-intuitive, but just as global warming causes warmer summers, it also causes colder winters. This is because there is more energy in the environment, the increased energy causes the extremes (both hot and cold) to be more extreme.(9)
Another potentially catastrophic occurrence is the stopping of the Gulf Stream. The Gulf Stream is the current that pulls warm water from the Gulf of Mexico around the Western edge of Europe and distributes waters around the world. The Gulf Stream is driven by the temperature gradient created by the warm waters near the equator and the glaciers in the North Pole and on Greenland. If they melt too much, the Gulf Stream could stop. Millions of years ago this happened when the Glaciers on North America melted at the end of an ice age, and it took thousands of years for the Gulf Stream to restart. The Gulf Stream is already slowing! In the past 12 years the Gulf Stream has weakened by 30%.(7) The most apparent issue with this is that the Gulf Stream is what keeps Western Europe at the climate it is. Rome is roughly the same latitude as Boston, but it is much warmer. London's latitude is pretty far into Canada, yet is relatively warm. A lot of Europe will end up frozen even as the rest of the world is melting. The results of this are not fully known. We know that the Gulf Stream shutting down (as it is likely, but not definite to do) would plunge Europe into an ice age, but the shutting down of the Gulf Stream could also allow the poles to cool again. The streams are a major contributor for the poles to warm more than the equator, so if they shut down maybe the poles will cool a little bit (with the equator staying even hotter). Perhaps the poles will re-freeze, and the additional deserts the extra heat at the equator would cause together will start reflecting more energy allowing the Earth to cool a little bit. We do not know, but it is likely that if these events do happen it will be centuries before the environment we have thrived on could be restored despite these mitigating effects.
Biomes
Already as the planet is warming many animals are changing where they live. In the case of butterflies moving further north this may seem harmless, but there are issues with other animals. Mosquitoes, for example, will pose a serious issue. Many cities in Africa were placed at certain latitudes or elevations in part to avoid mosquitoes and their diseases. As things get warmer mosquitoes travel further from the equator and also to higher elevations. This is a relatively new phenomenon that people are not ready for. Incidences of malaria have increased roughly 30% in the past few years. People are not protecting themselves from malaria because malaria was previously unknown where they live. Other diseases (both animal borne and bacterial and viral) are expanding the areas they affect as their biome is expanded. (9)
Official Response
Unfortunately when the White House says things to the effect that global warming could even be good, they do not take most known information into account. The only thing they look at (to date) is how the average temperatures are affected. Since it will be warmer, land farther north could be used for farming. They don't consider the other effects like the rising seas (which IS what happens when the temperatures increase) and changing climate patterns and changing biomes. All of these events have been recorded, now it's just a matter of people outside the scientific community taking notice of the data and the trends it shows.
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