I know it’s heretical to suggest that we aren’t completely responsible for global warming but I’m going to make that suggestion. It would be happening to a substantial degree in our absence. I believe the relationship between CO2 and temperature is more complex.
Part of the problem is that we simply do not have good data. Look at the following graph (from Wikipedia):
I would like to bring your attention to several features of these plots. The first calls into question the reliability of the data, particularly when it comes to temperature determination.
There are two different sets of ice core data used, they overlap at 400,000 years ago. You will notice that the CO2 data between them agrees at least at that 400,000 year overlap.
Temperature determination is more problematic, I would suggest to the point of being essentially worthless except on a relative scale. Temperature determination is based upon deuterium concentration, but the deuterium concentration is nearly twice as high in the EPICA ice cores relative to that of the Vostok ice cores. At 400,000 years where these overlap, even on the adjusted scales, the levels are radically different. Perhaps it’s just me but this makes it difficult for me to trust the data.
The second thing I’d like to point out is that rising temperatures, as interpreted from deuterium concentrations, often proceed rising carbon dioxide levels and falling temperatures nearly always proceed, sometimes by a substantial time frame, the falling of carbon dioxide levels. My interpretation of this is that carbon dioxide levels are not the major determiner of global temperatures. If they were, rising and falling carbon dioxide levels would reliably proceed global temperature changes.
Global temperatures on Pluto are on the rise. Scientists in the linked article attribute this to lag, just as on earth where solar irradiation is highest at noon, but temperatures are highest at 3pm. I am skeptical of this explanation because Pluto lacks a thick atmosphere or oceans to retain heat, and certainly not for the fourteen years that it has been moving away from the Sun and simultaneously getting warmer.
Neptune, or at least it’s moon, Triton, is warming. Neptune itself also is warming. They blame seasonal changes, Triton they say is entering into it’s southern summertime which it does every several hundred years and it’s spring-time on Neptune. Uranus is also experience global warming. This two is ascribed to spring time on Uranus. Saturn is warming, so is Jupiter and Mars.
Alas, I can’t find any temperature trend data on Venus and Mercury, but if the seven planets (and various moons) for which data is available all show positive temperature trends, I think it’s a safe bet something more than carbon dioxide levels is responsible. That’s not to say that carbon dioxide levels have no effect, but it’s important to note that the carbon dioxide levels on Venus are around 300,000 times greater than Earths, so the effect on Earth from carbon dioxide levels probably is not that pronounced.
I think it’s far more likely that the bulk of global warming is due to increased solar activity. Please note that this does not necessarily equate to visible or infrared light. I believe there are other phenomena which are significant. The Sun’s magnetic interaction with the Earth is one of those factors. How is it that the Sun’s corona is millions of degrees when it’s surface temperature is only around 5600°K? Magnetic heating is how this is possible. Those magnetic field lines don’t end at corona, they continue out into space, interwoven into flows of particles, the solar wind, interacting with our planet and heating it. During periods of high solar activity, UV light output increases. UV is mostly absorbed in our atmosphere driving some chemical reactions but also producing heat.
Does this mean we should just relax and keep combusting hydrocarbons to provide for our energy needs? No, it does not, for several very good reasons. While there is no shortage of hydrocarbons, most of those that remain are inconvenient. They are either difficult to get at, requiring deep drilling, drilling in deep water, or complicated extraction, or they are contaminated with sulfur, or of an inconvenient molecular size, too large, viscous, and carbon rich, or gaseous. Yes, we do have technology for liquifying natural gas. We have technology for turning coal into gasoline or diesel. We have technology for cracking long chain hydrocarbons. All of these technologies are expensive but at the current price of oil not prohibitively so, but all of them are also polluting.
At current carbon dioxide levels of 380 ppm, we are also approaching the point where carbon dioxide levels are going to start causing substantial health problems. 500 ppm is considered the maximum safe occupational level. We’ve gone from 250 ppm to 380 ppm in the last century and the rate of increase is logarithmic so it will not take another century to reach 500 ppm. At 500 ppm, some people begin to experience discomfort, headaches and drowsiness. At 1000 ppm, many people are affected.
Carbon dioxide reduces the capacity for hemoglobin in the blood to carry oxygen. It also affects the acidity of the blood which has many health ramifications, most of which are unpleasant. For people who already have marginal capacity to oxygenate their tissues, this is literally a life or death issue.
The use of hydrocarbons for fuel also has scaling issues. It takes so much human energy and effort to generate energy in this manner that it limits economic growth and consigning many people to unavoidable poverty.
The changing climate will require even more energy consumption to adapt, we will have to irrigate regions that are dry to sustain food production. Water tables are already depleting faster than nature can replenish them so we will have to desalinate and pump water. This takes energy on a large scale.
Continuing to rely on hydrocarbons will result in more and more human labor going towards energy production, more health problems from pollution, and the hydrocarbons will become increasingly difficult to get at. Yes, we can drill to the mantel and extract more hydrocarbons, but doing so is expensive.
We should shift our energy needs preferably towards totally renewable sources like solar, wind, tidal energy, hydro, but also to long-term sustainable sources like geo-thermal, fission (if properly managed), and fusion. Fusion really is the holy grail of energy production since it can provide clean energy without substantial radioactive waste at a high density indefinitely. The Sun is a giant fusion reactor, it’s been providing energy for the last 4.5 billion years or so.
Nuclear fission is a dirty word, but our bad experience with it is largely the result of an industry managed by greed, doing things the least expensive way possible. If we move from one-pass U-235 fuel cycle to an integral reprocessing fast-flux actinide burning plants, we can have a supply of energy that can last millions of years and generate only short-term radioactive waste. Not as clean as solar or wind or fusion, but much better than current fission power plants.
Of the renewables I think wind is actually the most promising. It’s cheap, coming in at around 4.6¢/KWh, less even than coal, and much less than natural gas. The chief criticism of wind power, that it is an intermittent power source, has not stopped it from contributing substantially to Germany’s energy mix, and I think it could contribute to an even larger share here in the United States.
There are several reasons wind can make a larger contribution to our energy needs. First, geographical diversity. The United States is larger therefore when the wind isn’t blowing in one area, it’s blowing somewhere else. To fully take advantage of this we should build a new superconducting national super grid. The grid can be cooled to cryogenic temperatures by liquid hydrogen and serve simultaneously to transmit hydrogen and electricity.
We can take advantage of intermittent wind power by producing hydrogen during those times when the generation capacity exceeds our needs. We could also modify existing hydro projects by placing another dam downstream of the existing dam, creating a secondary reservoir, and during times of surplus generation, pump that water back from the lower reservoir to the upper reservoir to be used again to generate power when demand exceeds supply.
We could build desalinization plants to take advantage of times when production exceeds supply, and the same is true for water pumping stations. Smart metering in residential, business, and industrial settings could allow people to adjust their usage to target heavy usages to times when excess capacity exists.
In Germany, government subsidies have increased wind power usage somewhat, but really not a lot considering the costs. I think there are other things in the US that could be done to encourage wind farms. In Washington State for example, the best land for wind production is on the ridge southeast of Yakima, but that is at present part of an Army firing range. Surely, they could blow stuff up somewhere else.
I don’t know what the trick is but a better world for us and our children requires that we somehow get the political will to do this and wrestle control from the oil companies.