Global warming is defined as the increase in the average temperature of Earth’s near-surface air and oceans and its projected continuation. Causes include greenhouse gases, aerosols and soot trapping heat, preventing it from leading our atmosphere. There may be other short-term random or cyclic causes, such as the cyclic nature of our sun and the typical variations in weather from year to year.
To begin, let’s define a few terms. Weather refers to the instantaneous nature of our atmosphere, while climate refers to the averages – temperature, rainfall, cloud cover, ocean levels, and so on – over a period of time. Effects of climate change range from the obvious changes in temperature to the melting of polar ice, rising sea levels, increased precipitation, changes in agriculture, effects on the chemistry of our oceans, and species extinction. Several organizations have been formed to analyse and report on climate change, including the National Climatic Data Center and the Intergovernmental Panel on Climate Change, and existing organizations, including the National Oceanic and Atmospheric Administration and the National Aeronautics and Space Administration, have extended their roles to work on climate change. One such report is the Bulletin of the American Meteorological Society’s annual State of the Climate report which documents the weather and climate from the past year. I’ll be using this and other reports from some of these organizations to support the existence of climate change.
This image[1 p.25], my first piece of evidence, is a plot of the average temperature. The x-axis is time, by years on the left and averaged by decades on the right side. The y-axis is the latitude, and the color is the deviation from the average temperature for that latitude. The earliest indications of interest are around 1940. On the right-hand side, the deeper blues at the middle latitudes disappear around that time, indicating that the 1940s are the first decade where temperatures averaged no less than one quarter of a degree below average since 1850. In the 1940s, the far northern latitudes also indicate some warming relative to the previous decades. The more interesting period begins in the 1980s, where across the globe temperatures begin to exceed the 150 year average. This extends through the present. This information is taken from the Hadley Centre of the UK Meteorologic Office’s HadCRUT3 dataset, which contains temperature deviations from the average from 1850 through the present in 5 degree by 5 degree grid boxes across the entire land and marine surface of the Earth. The indication is clear – beginning around the 1930s, the average temperature of the earth has been increasing. The overall increase, globally, is about one degree Celsius.
My next graphic[1 p.27] is actually a series of eleven markers thought to correlate strongly with climate change. Surface air temperatures, over land and over sea, and sea surface temperatures are expected to increase, for obvious reasons. The sea level is also projected to increase due to melting of glacial ice, as well as due to the increased specific volume (decreased density) of water as its temperature increases. For all four of these indicators, a clear increasing trend is present for all of the datasets. Multiple datasets are displayed, using a variety of different methods of gathering data, in order to show the difference between experimental error and actual temperature variation.
The snow cover is also plotted for the northern hemisphere, although this is not my favorite graph – the decreasing trend is recent, and the average snow cover has too much variance year-to-year to show an actual trend at this point.
On the right are graphs extending back only to 1940, at the latest. This includes tropospheric temperature, which is the lowest part of our atmosphere and the part where most of our whether occurs, which is of course projected to increase with time. The stratospheric temperature reflects the area above the stratosphere, which is actually projected to decrease, due to the effects of greenhouse gases – to put it simply, greenhouse gases keep the heat in the lower part of the atmosphere, and at the surface, keeping the upper atmosphere cool. This would be a useful result, if we all lived on Star Wars‘ Cloud City, but we are stuck in the realm of the first few graphs, which sadly go up.
The next result is the ocean heat content. This was not a metric I was familiar with until today, however my thermodynamics background says that it is a measure of the total energy of the oceans down to 700 meters. I don’t know why they didn’t use average temperature, as it would give the same result. This is, however, different from the sea-surface temperature, since it essentially averages the temperature over the first few hundred meters, rather than only looking at the surface – it would be expected that this value would be less volatile than the surface temperature – that it would show less variation season-to-season and year-to-year.
The specific humidity isn’t the percent humidity you see on weather broadcasts, that’s a value adjusted for temperature. This value isn’t dependent on temperature, it’s just the amount of water in the atmosphere in grams of water per kilogram air. This value is expected to increase with global warming.
The arctic sea-ice graph shows the amount of arctic ice by surface area. It is taken at the same time every year, and is a function of the intensity of the summer, as well as how much ice was able to regenerate the previous winter. In a stable system, the amount would remain more or less constant year-to-year. The decrease indicates that our climate has not stabilized – that is, due to changes in average temperature, the ‘correct’ value of this graph – the value for which the system is ‘stable’ – has changed. The glacier mass balance is much the same, only it shows the amount of glacial ice by mass, rather than surface area.
A note on ice: Robin Bell, of Columbia University, calls the ice caps Earth’s “air conditioner”. When the climate works, the ice caps cool the Earth in their respective summers – by melting. Melting water takes a large amount of energy, more than heating water does, so we are very reliant on there being ice to melt, to take up the excess energy from the sun. Then in the winter, the ice caps refreeze. But, when the temperatures increase even a small amount, you get a problem: The ice caps melt more than they refreeze. The usual variations in temperature from year to year smooth out easily, but when the average temperature increases for a few years in a row, the planet just can’t maintain the ice caps.
Eleven graphs right there, from a total of 55 data sets. One of those markers is too recent to show a trend, the other ten markers correspond with the trend you would expect for global warming.
In the recent months there has been some controversy about hacked emails between climate scientists. Deniers say that these emails indicate that climate scientists are faking data related to tree rings. In reality, this referred to a correction being performed on ring data from certain northern trees. Data for the last fifty years from tree rings shows an anomalous decline in temperature. The data are inconsistent with temperature data from other sources, and we must assume that there is an additional variable. We have reason to believe that that variable is air pollution, but regardless, we know that tree ring data from after 1960 is unreliable, and we use other data to amend it. The writer of the email called this a trick, which deniers assumed (and continue to assume, despite correction) indicated a malicious trick. In fact, this refers to a ‘trick of the trade’, so to speak, and is not malicious.
I am now going to begin quoting a number of sources that deny global warming. I quote so many to demonstrate that I am not creating a straw man argument. A straw man argument is where a party makes their opponent appear to have no valid argument by either making up or cherry-picking flawed arguments and debunking them. By seeking the best arguments based on reason and evidence from a variety of sources, I hope to avoid doing that. This is made difficult due to the trouble of actually finding scientific arguments against global warming, however I shall try my best.
So let’s ask South Dakota’s Legislature what they think.
WHEREAS, the earth has been cooling for the last eight years despite small increases in anthropogenic carbon dioxide; and
Not true. The first image above shows that the last decade was the warmest on record (see the right-hand graph, rightmost column…look at all those orange squares…) and the Earth has been warming overall. While the average temperature over the last eight years has been decreasing, this is within the realm of random variation. Why do they choose eight years? They use eight years because that’s the longest time period where the data fit their hypothesis. If they used ten years, or twenty, the temperature would appear to be increasing. This illustrates a common tactic in the deniers’ bag of tricks – picking the data that supports their argument, and ignoring the rest without reason. Climate scientists ignore tree ring data from the past 50 years because it’s demonstrably inaccurate. Deniers ignore temperature data more then eight years old because it doesn’t support their hypothesis.
WHEREAS, there is no evidence of atmospheric warming in the troposphere where the majority of warming would be taking place; and
Also not true. See the second image above, top right graph. Before 1980, no model showed a reading above 0, after 1995, no model showed a reading below 0, and there is a clear trend upwards at least since the late 1970s.
WHEREAS, historical climatological data shows without question the earth has gone through trends where the climate was much warmer than in our present age…
It’s also gone through trends where the climate was much cooler than in our present age, such as ice ages. Those weren’t too fun either. We’ve also been hit by asteroids large enough to wipe out most life on Earth. Doesn’t make it safe. We regularly experience thunderstorms, but we shouldn’t stand out in a field during one. What happened in the past or what happens regularly is not necessarily safe, and since we now see that climate change is happening much more quickly, and can associate it with human causes, we should be concerned.
WHEREAS, the polar ice cap is subject to shifting warm water currents and the break-up of ice by high wind events. Many oceanographers believe this to be the major cause of melting polar ice, not atmospheric warming
If this was true, then it wouldn’t be a recent trend. They propose that polar ice melting is due to shifting currents and wind. Both of these have existed for a very long time. Either some recent change has caused an increase in shifting currents and wind (which is not what they propose), or some other recent mechanism is causing the melting of polar ice. Say, increased water temperatures.
WHEREAS, carbon dioxide is not a pollutant but rather a highly beneficial ingredient for all plant life on earth. Many scientists refer to carbon dioxide as “the gas of life”; and
Carbon dioxide is a greenhouse gas. So is water vapor. So is ozone. Ozone is essential to protecting us from the sun’s harmful UV radiation – preserving the ozone is the reason for the limiting of CFCs, which damage the ozone layer. Water vapor – water is certainly essential to life, and it’s a greenhouse gas. Things can have both positive and negative effects, a chemical compound isn’t confined to some sort of loyalty; only doing things useful to us, or to only doing things harmful.
By the way, carbon dioxide is interesting. On Mars, there’s a lot of carbon dioxide, all frozen in rocks. One of the theories for terraforming Mars involves kickstarting the system with a few carbon-releasing plants or factories, creating an artificial greenhouse effect, which would then begin to melt the frozen carbon dioxide – it’s a cycle that just keeps feeding back until there’s no more carbon dioxide to melt. This isn’t relevant to Earth, there’s no significant frozen carbon dioxide here, just an interesting fact. The other bonus to this plan is that once it’s nice and warm due to the artificial greenhouse effect, we drop a few plants on Mars and begin creating an oxygen atmosphere. The estimates are that it would take a century or so to warm the planet, and then millennia to create the atmosphere – but technology is always improving.
That’s not all it does. Carbon dioxide, CO2, reacts with water, H2O, to form carbonic acid, H2CO3. The decreasing pH of the seawater – it’s increasing acidity – is due to increased concentrations of carbon dioxide in the atmosphere – it’s an equilibrium thing. For a long time, the amount of carbonic acid in the oceans was constant because the concentration of carbon dioxide in the air was constant. But once you push the concentration of carbon dioxide up, the reaction produces more carbonic acid to remain in equilibrium. Based on experiments done on fossils in the sea floor, the concentration of carbonic acid is at a 65 million year maximum, according to Ken Caldeira of the Carnegie Institution for Science’s Department of Global Ecology. The last time we saw this much carbonic acid in our water was around the same time as the Cretaceous-Paleogene extinction event, one of the greatest mass extinctions in Earth’s history, caused by a massive asteroid impacting the Earth. Scientists say that the impact released compounds into the air and oceans which caused an increase in carbonic acid, which, along with decreased sunlight due to dust and sulfuric acid aerosols and likely acid rain, caused the extinction of most land life and much marine life at the time.
WHEREAS, more than 31,000 American scientists collectively signed a petition to President Obama stating: “There is no convincing scientific evidence that human release of carbon dioxide, or methane, or other greenhouse gasses is causing or will, in the foreseeable future, cause catastrophic heating of the earth’s atmosphere and disruption of the earth’s climate. Moreover, there is substantial scientific evidence that increases in atmospheric carbon dioxide will produce many beneficial effects on the natural plant and animal environments of the earth”:
Right. The petition. That petition was such a joke I don’t even know where to start. Some people who ‘signed’ it did so because they supported, as all scientists do, continuing to look for evidence of alternative viewpoints, and the petition was misrepresented to them when they signed it. Some of the scientists who signed it were in fields that have nothing to do with climatology. The largest subset of this are people with a B.S. or equivalent degree. Some of the scientists who signed it were really meteorologists. That’s right, weathermen. They’re using weathermen and biologists and chemists to try to argue with climatologists.
I shall now present an amusing fact:
(2) That there are a variety of climatological, meteorological, astrological, thermological, cosmological, and ecological dynamics that can effect world weather phenomena and that the significance and interrelativity of these factors is largely speculative; and
If you’re really sharp, you’ll have caught the word ‘astrological’ in there. Hint: astrology and astronomy aren’t the same thing.
If you’re even sharper, you’ll have caught ‘cosmological’ – yeah, the nature and evolution of the entire universe over all time somehow explains a trend that began in the past century that is confined to this one planet.
Also, I’ve never heard of thermology before, and neither has my spellcheck. Thermodynamical, yes, but thermological? Also, effect vs. affect.
I try to present the alternative arguments. I really do. The elected officials and their relative advisors, from an entire state, wrote this ‘argument’. Not many higher bodies I can find. But they’re just making this too damn easy.
No, really. I’ve looked as hard as I can. The front page articles on globalwarminghysteria.com are:
- A ‘prayer’ to carbon
- An article bashing scientists for claiming a little bit of uncertainty (it’s not enough to say that the earth is warming, or that bad things will happen, but they want us to tell them exactly when the mass extinction will happen…)
- Whining that the media is ignoring them (they also complain that the department of energy and the environmental protection agency shouldn’t exist…, and then go on to make the classic argument that cold winters disprove climate change…weather is not climate…climate is weather, averaged and analyzed over the entire earth over some period of time…climate is a far better indicator of trends than the weather at one place in one year…these trends have been apparent for over fifty years…)
In fact, the most promising Google result was one titled “the best argument against global warming” by Dr. Peter Gleick – but no luck. That article did tell me why my Google search for “climate change AND evidence” wasn’t turning up any bits of anti-climate change evidence – as the writer puts it, “Oh, right. There isn’t one.”
A blog called Pajamasmedia – truly a professional, scientific source – talks about glacial melting not being evidence of global warming. Sorry, he’s wrong. Melting ice takes energy – glaciers are a sort of buffer that takes up thermal energy – melting ice takes up far more energy than heating up the equivalent amount of water by a few degrees. This is why your iced coffee stays nice and cold for a good long time while the ice is solid, but once it’s all melted it warms up pretty quickly. This is also why we care so much about glacial melting – because if the glaciers weren’t there, the average temperature increase would probably be much more dramatic. Otherwise the article was pretty much right, but I had to point out that melting ice does in fact take energy.
Another list of the arguments against global warming includes:
It is argued that global warming is a minor issue because of which major issues like HIV/AIDS, Nuclear proliferation and poverty are not devoted their deserved time and resources.
This is silly. We can focus our considerable scientific power on more than one crisis at once.
Vested interest of scientists. It is argued that scientists exaggerate the effects of global warming because they receive funds from environmental companies.
People really like this argument. See, this is why scientists have to publish in peer-reviewed journals and submit all their evidence to the review of any interested parties. There’s far more fame and fortune in discovering that all of global warming is a conspiracy and outing every scientist as a tool of environmentalists. It hasn’t been done because there’s no evidence of that, and deniers can only spread rumors rather than provide facts.
Unreliability of computer climate models. It is argued that these models are not able to predict tomorrow’s weather. So how can they predict long-term climate change?
Climate models are not the only factor of evidence, nor even the primary evidence. We see a clear past trend of warming which is not dependent on climate models. Of all the graphs I’ve shown above, not one is a computer-based future climate model.
There are other factors involved in global warming. It is argued that human activities are not the only cause of global warming.
Not the only cause, but certainly a cause. CO2 is rising, and it is our fault. Regardless of the cause, it’s our problem, so this argument is meaningless.
Newspapers sensationalize global warming in order to sell. It is argued that newspapers distort the picture of global warming when actually that is not the case.
So don’t read newspapers. Read journals and reports and evidence. That’s what this is about, anyway, the evidence, not what some writer at some paper thinks.
Scientists have made wrong predictions before. It is argued that science and scientists are not always right. Perhaps they have made an error in their calculations or drawn incorrect conclusions on available evidence.
“Scientists have made wrong predictions before” is not a premise that leads to the conclusion “all predictions made by scientists are wrong”. Even if there was a chance that scientists are wrong, the significance of the evidence and the severity of the predictions must be taken seriously. In addition, this is why the peer-review process works. Every scientific work on climate change is published with full methodologies, and all data is freely available. It is highly improbable, though not impossible, that the conclusion is entirely false, given that no actual evidentiary counterargument can be produced.
The science of global warming is not proved. It is argued that we don’t have long term historical records of weather.
Our first-hand records are sufficiently long term to show not only increasing temperatures, but also the beginning of that trend. We can see that temperatures were fairly steady, and then began to increase. Data further back is available from tree rings, ice cores, and other highly reliable and self-consistent methods.
Water vapor plays a major part in global warming. It is argued that man made emissions like carbon dioxide has only minor effects.
Water vapor is indeed the primary greenhouse gas in our atmosphere, but carbon dioxide is the second, ranked by total effect, taking concentration into account, and even a small increase by percentage of carbon dioxide could produce a detectable increase in average temperatures. A scientific study (which I am unable to acquire to review firsthand, states that carbon dioxide has between 9% and 24% of the total impact on the greenhouse effect (that’s not a 15% margin of error, the high number is assuming no interactions with other gases, the low number is assuming complete interactions with other gases, the actual number is somewhere in between).
The global warming is a natural phenomenon. Man has no role to play in it. Only our environment is responsible.
Proof? Or just plugging your ears and closing your eyes?
The temperature increase is very small especially when it is spread over a century.
But it’s very great when compared to historical data, where the rate of change is less that one part in a hundred the rate we see today, and if the increase continues we’ll see even larger increases in the future.
The earth was warmer before. That did not have harmful consequences on humans.
It certainly did. The effects of global temperature change are significant, and here we are pushing it much faster than it would ever go on its own. When the temperature changes slowly, the ecosystem and living species have time to adapt slowly to the change. When the temperature changes in only a few generations, the system can’t stabilize, and life can’t adapt quickly enough. We see effects.
The increase in temperature will help plants grow in currently cold and uninhabitable areas.
A small bonus, compared to a very large price.
The increase in the level of carbon dioxide will stimulate plant growth.
Again true. Also stimulate the acidification of the oceans and the greenhouse effect.
Steps to limit global warming will decrease economic growth and hurt the poor.
That’s hardly sufficient reason. Ignorance of the issue will cause sharp economic decline, due mostly to a major extinction.
People in fossil fuel industries will lose their jobs.
A small price to pay for our planet. Why do people insist on using their personal preferences to try to counter science? The universe doesn’t care what you believe. 
Climate change has been more rapid in the past.
Proof? This is perhaps the strongest argument they have, apart from successfully proving that our evidence is actually wrong, but only if they can actually demonstrate that this time is no different from the past, which is not something that they can do.
Rise in carbon dioxide levels has always come after a temperature change and not before.
Then that’s a sign that this time is different. Carbon dioxide can certainly cause a temperature increase, we know that for sure, and a temperature increase can also cause carbon dioxide to increase, as the analogy to Mars showed before. It probably would be less extreme here, because the only frozen carbon dioxide is at the poles. This may be the first time that the temperature increase is caused by greenhouse gases, rather than vice versa – which makes it all the more urgent.
The upsurge in solar activity in the sun has caused global warming.
Proof? We can very easily measure the exact amount of energy we absorb from the sun, and there’s nothing there that explains the warming trend.
Here, I have some proof[11 p.17].
This graph estimates the amount of increase or decrease in energy absorbed by the earth. Greenhouse gases, ozone are obvious. Surface albedo refers to the percentage of incoming light that is reflected back, here due to land use or to black carbon which covers up reflective snow and readily absorbs light – black things absorb light and heat up, white things reflect light. The solar irradiance bar refers to the increase or decrease in energy from the sun due to effects of the sun itself, such as sunspots, etc. As the chart displays, even on the low end of the error bars for the anthropogenic causes, they exceed the natural solar differences.
Once last thing before I sign off. No individual weather event has any single cause. Whether that cause is global warming, or natural weather patterns, or solar flares, any effect powerful enough to create a storm is an effect more powerful than anything we’re predicting. Global warming is adjusting the climate, not the weather, and one cold winter isn’t evidence against that, it’s evidence that weather fluctuates.
 Taken verbatim from http://en.wikipedia.org/w/index.php?title=Global_warming&oldid=383630557
 The 2009 report is the version cited, page numbers are from the PDF version which can be downloaded at http://www.ncdc.noaa.gov/bams-state-of-the-climate/
 South Dakota State Legislature 2010 House Concurrent Resolution 1009, accessed from http://legis.state.sd.us/sessions/2010/Bill.aspx?File=HCR1009P.htm
 Unfortunately, the best source I can find on this topic at the moment is a YouTube video, accessed at http://www.youtube.com/watch?v=Py2XVILHUjQ. The video begins to get into the topic in question around 4:50, but I would recommend that you review the entire video.
 I was trying to figure out where I remembered this quote from – I tried a Google search, the Wikiquotes for Carl Sagan, Albert Einstein, and a host of others – until I realized it was actually from the webcomic xkcd. I strongly recommend you have a look at http://xkcd.com/154/.
 http://www.ipcc.ch/publications_and_data/publications_ipcc_fourth_assessment_report_synthesis_report.htm page numbers from “full report” PDF
I’ve ranted a bit about the UK recently. Their National Health Service is doing some silly things, supporting homeopathy and the like, and the British Chiropractic Association (not a governmental entity) recently sued Simon Singh for libel because he dared to state scientifically that chiropody is not nearly as effective as its practitioners would like to believe. However, Richard Dawkins recently, in response to education legislation, proposed the creation of an entirely secular, skeptical (note: not atheist…teaching reason instead of indoctrination…) charter school, much like the very many religious charter schools in existence. Well, the UK Secretary of Education said to Parliament:
“One of the most striking things that I read recently was a thought from Richard Dawkins that he might want to take advantage of our education legislation to open a new school, which was set up on an explicitly atheist basis.”
Now, there are at least two points I’d like to make here.
First, it seems that the UK department of education is actually, at the very least, competent. That’s an interesting and useful change.
But think about what would have happened in a senior government official of the USA had said that? A cabinet member, almost supporting the idea of a not just neutral, but actively secular school? Think of the response to that!
The crazies are already up in arms because they don’t think Obama’s a christian, despite his claims that he is. Despite the fact that it doesn’t matter. Because he dared to invite a few atheists to a meeting at the White House called “Advancing Interfaith and Community Service on College and University Campuses”. If the Secretary of Education expressed actual interest in this idea, they’d want his head.
But think about the US and the UK a little bit. One of these countries was founded on religious grounds. One has an official state religion, named after that country. One has the head of that church as it’s leader, at least in name. The other was founded as a secular nation, by mostly people who would be today described as deists or secular humanists, rather than theists. It has a rather important law forbidding the government from supporting any religion over another. But the country religious in name is the one that seems more secular in practice, at least in this issue, and the country that is supposedly secular has a huge right-wing group that can’t seem to keep their religion out of their politics. Prayers at city council meetings, people who want religious memorials on public property, and until recently the president, legislature, and supreme court have been exclusively religious (there are a few nonreligious congressmen now).
For comparison, Britain had an atheist prime minister in 1945, forming the National Health Service and the Welfare State, things we still haven’t gotten quite right (not that they have either…), and have had at least three. Britain’s population is about 15% nonreligious, about the same as the USA, however they manage to have a generally more tolerant and more secular system.
Well, except for homeopathy. And Ireland.
Another essay I wrote for a class.
The American public widely denies the scientific theory of evolution. Only 40% of Americans know that humans developed from an earlier species of animals, despite the overwhelming scientific evidence to that point. I could go on by outlining the evidence for evolution of species, speciation, and natural selection, but that is not the subject of this essay. Rather, I shall assume that the audience is aware of the incredible amounts of evidence supporting evolution. Why is evolution so heavily ignored? Partly due to organized religion, partly due to politics, and partly due to the population not knowing or understanding the evidence.
Religion quite obviously plays a role. Religion on its own needn’t oppose evolution, and people who are ‘spiritual’ or not ‘biblical literalists’ often attest to a belief in evolution while retaining a belief in God, including many religious leaders: Roman Catholicism, for example, fully accepts modern cosmology, abiogenesis, and evolution, while building their faith on matters that are actually subject to faith. Carl Sagan noted in one of his books a discussion with the Dalai Lama, the religious leader of Tibetan Buddhists: Sagan posed the question of what would happen if some central tenet of their faith were disproved by science. The Dalai Lama allegedly responded that Tibetan Buddhism would have to change, but that religion works because those central tenets would be very hard to disprove. As long as religion stays in the realm of faith, the institution of religion is not the problem.
Religion causes problems when religious leaders teach a literal interpretation of their holy book, which teaches their flocks to ignore and shun evidence and to blindly accept the church’s teachings, and when religion ventures into the realm of science and make testable predictions. Preachers often do this unintentionally – their sermons are made to praise their deity, not to teach critical thinking. However, when the congregation is taught to follow blindly, they don’t learn to extend standards of evidence and reason to their worldview. This leads to justifications of ‘intelligent design’ using arguments from authority, where someone claims that some religious authority (or book) supporting the idea of a creator is sufficient evidence. Even shepherds with a mind of science can mislead their followers by omitting critical thinking and failing to make clear the metaphorical nature of their creation story. Pastors who wish to lead their congregations rightly must stress that ancient sources are not believed to be literally true, that we now know more about the world than they did, and that the important things are the loving nature of their chosen deity and the need for reason and critical thought throughout all matters in life. Because this weakens religion, pastors are not likely to adopt this view, and very few do. This is the reason that so many nonreligious people think that religion “hardens hearts and enslaves minds” – it is directly opposed to reason and scientific thought.
Politics is another factor. Due to the dichotomy between the two parties, the teaching of evolution in public schools has been made a major political issue, which vastly changes the argument: due to the nature of the two-party system, such issues are conflated with every other major political issue, from healthcare to the budget. Since most people affiliate with one of the major political parties, they give their vote to all of that party’s views, even though they may disagree with a minority of their positions. Thus, a small far-right republican base is able to influence the entire party to deny evolution and attack the teaching of science in our schools. This isn’t hypothetical – this is actually happening. Most recently the media ran a story on how the Texas school board was trying to deny evolution, as well as certain parts of American history and a few other points. You just can’t make this stuff up.
In the general population, the evidence isn’t very commonly known, or understood. Most people don’t think that their understanding of evolution directly affects their life, and they’re probably right. And so, they don’t seek out the evidence, and continue to perpetuate their ignorance to their children, and the cycle just continues. This is evidenced by some common claims of evolution deniers. Some say that certain structures are so complex, they must require more than one mutation to occur, where only one mutation – presumably to the halfway point – provides no evolutionary advantage. One example is the eye – what use is half an eye? Whereas the evolution of the eye probably proceeded from simpler omnidirectional light-sensing cells, to more complex structures with some directionality, and finally gaining the ability to produce a complete image. An experiment on bacteria has demonstrated the possibility of this: two independent mutations were observed, allowing a set of bacteria to use a certain type of food, where either mutation individually would have had no effect. Another common claim is that evolution is merely ‘random changes’, where anyone who had even a few minutes’ education in evolution by natural selection would know that evolution works by systematically selecting for or against different traits in a manner that is certainly nonrandom. If people were introduced to that idea and considered it with an open but critical mind, they might understand their world a little more. But if people are taught to ignore evidence and only trust their religious authorities, then they’ll never know any of that. All they can hope to do is repeat the same things as they are taught, gaining no insight into how and why we came to be.
The denial of evolution – the denial of the history of our species and of all life – is rampant in modern America, and throughout history. It’s caused by a lack of scientific understanding, but there are more specific causes. Organized religion cripples the faculties of logic and reason that are necessary for any understanding of science. Politics magnifies the issue to a national level and gives the religious majority the power to censor from our children’s classrooms the teachings of science. And the population’s lack of scientific curiosity keeps them from seeking out and analyzing the evidence.