Also, holes in the ozone. Solar flare.
Nice try buddy, but you'll have to try a little harder. First of all the article you linked mentioned nothing about ozone, so I had to go find the connection myself. And surprise surprise, look what I found!
So yes, a massive solar flare 150 years ago temporarily reduced the amount of atmospheric ozone by ~5%, and the effect lasted for about 4 years. Then the ozone levels recovered as the nitrogen oxides responsible for it rained out of the sky. But 70 years later, the human race started pouring CFCs and other chemicals into the atmosphere (chemicals which have lifetimes between 50-1170 years). The result? A long-term 3% depletion of atmospheric ozone levels, 100% caused by yours truly - people. So here you have an example where the human effort managed to achieve over half the magnitude of ozone depletion lasting for a vastly longer period of time as a major natural event thought to happen once in 500 years managed.
In other words: obviously natural cycles and events have major effects on the atmosphere. But in the last century, humanity has started to become a real contender.
At the risk of redundancy I'm going to repeat some of what TheBigOne, dmantione and Mumblefratz have already said. It's important, and you have categorically ignored it so far. People have changed the rules of the game. According to ice core data, the concentration of CO2 in the atmosphere has never risen above 300 ppmv in the last 400,000 years. If you go back millions, tens of millions of years you can find periods with higher CO2 levels - and lo and behold, there were also significantly higher temperatures! However, the current levels of CO2 are up to 380 ppmv, and it is accruing faster than expected based on historical data. Today's situation has never before been observed in nature, so we cannot use historical data alone to predict the results.
I'll give you a simple example. Take a simple string pendulum. It's just a weight tied to a rod that's fixed at the other end. If you study the motion of the pendulum weight that results from minor displacements from the equilibrium position, you'll find that it's just simple harmonic motion. You might expect that your findings will still apply for large displacements, as well, but you would be wrong. In fact, the general equation of motion for a pendulum are non-linear, and don't have a closed-form solution - all we can do is find approximate solutions, whether analytically or numerically.
To deny that humans have dramatically altered the natural levels of CO2 is denial at its worst. I have no patience for it. For the past century humanity has spewed a constant, thick stream of the stuff into the atmosphere - where do you think it all went, outer space?! Arguing that increased levels of CO2 isn't affecting, or isn't going to affect the earth's climate, on the other hand, is perfectly fine. Nobody knows for sure what will happen, that is the nature of science and its predictions. On the other hand, if you argue that current levels of CO2, and even higher future levels will have no impact on the climate based solely on observing historical data that contain no analogous situation, then you are being dishonest - intentionally or not.
We have one and only one way of really predicting large-scale atmospheric and climate changes based on an atmospheric state that has never before been observed. Computer models. The atmosphere and climate are extraordinarily complex, non-linear systems, meaning that analytical comparative methods are individually worthless. The non-linearity of the systems has one extraordinarily important consequence: minute variances in the initial state can result in completely different results (this is called the butterfly effect, and it is relevant in all non-linear systems). Intuitive predictions based on past data of incomparable solutions are only going to get us so far. We need to run (and we are, and have run) thorough simulations that take into account as many factors as we can. Not all simulations that have been run so far have predicted doom and gloom scenarios, but most have predicted some pretty bad effects - effects that don't occur if you run the same simulations with normal CO2 levels. The only reasonable conclusion to make, then, is that there is a chance that human activity has effected a chain of events that will end badly. It is not a foregone conclusion; it is a risk.
And in my opinion, anyone who understands the risk but prefers to do nothing about it has got to be selfish and somewhere in the middle of your life or beyond, or dangerously short-sighted.
What do I care about their prediction? You do see the temperatures right?
Do you mean that you don't care about their predictions because some of their short-term predictions haven't held up? That's somewhat sensible, but also somewhat unreasonable. Global climate change is a long-term prediction. There can be large statistical varations along the way, things can even seemingly going in the opposite direction of the prediction at times, but still end up right where they're expected to. That's how pretty much every evolutionary theory works (and I'm not talking about the evolution of life). For example, we've got lots of theories that accurately describe the long-term evolution of stars, but they don't tell us what to expect on a year-by-year basis, and thus yearly events are irrelevent - only the cummulation of thousands, millions, even billions of years are relevant for those theories. To compliment them, we have separate theories that describe smaller timescales fairly well, too - but they require more detailed information than long-term theories do in order to be useful. This is because stars, like the atmosphere and climate, are non-linear.
In other words, it isn't surprising that short-term predictions made using the theory of global climate change are often incorrect. Climate change has a relevant time-scale - on the order of a decade - and any predictions that are made using a shorter time scale than that should be taken with a large grain of salt. And more importantly, anybody who makes such a prediction with any sort of confidence is either ignorant or irresponsible. From my reading, I get the distinct impression that most of the confidence behind these types of predictions is instilled by the media, not the scientists who make them; and the media is a dangerous mix of both ignorance and irresponsibility, so that isn't surprising.
It would be like saying I'm about to die because I feel tired. Of course I feel tired, normal people are asleep right now. I could be about to die, but looking at the last few hours of my life and measuring my energy as it runs down is irrelevant. It ignores that I did the exact same thing yesterday, and damn near every day of my life outside of a few exceptions that either included Claritin(really good shit, the first time I took it I couldn't sleep for three days) or massive sugar doses.
No. Here's a much closer analogy. Every night you take a sleeping pill before going to bed (maybe you have insomnia or something). But tonight, you take two sleeping pills, and you get tired much faster than normal. That's not necessarily bad, it makes sense. But recently, a pharmacologist researching the sleeping pills you take has just done a new study that suggests that the dosage of two pills might be dangerous in a fairly high percentage of cases. The company issues a warning. Before retiring to bed, you happen upon that warning (maybe you get a newsletter). The warning says that taking two pills will make you tired much quicker, but that in 15% of people it can induce a coma once asleep. Do you go to sleep hoping everything will be alright and you'll wake up in the morning? Or do you call the doctor or an ambulance?
The ice core data, that's relevant. The last seventy years of incorrect data? Not so relevant. Yes, it's incorrect, the monitoring stations are severely abused, we know jack shit before the satellites, and they even adjusted the satellites numbers to fit the ground stations for a while, go figure.
Yeah, I pretty much agree with you there. Nonetheless, measurements today
indicate levels of CO2 and other pollutants are significantly higher than what we've seen in ice cores - except if you go back so far that there are other very major differences as well, and simulations indicate that such high levels could mean bad things for our future.
The ice core data does say that for the last 400k years the CO2 has been really low, but what else does it say? Along with saying that CO2 has been at record low levels recently, it says the Earth has been a walk in freezer for most of that time as well. It also says that CO2 has dick to do with the rising temperatures between the ice ages, and that desertification occurs not when the Earth warms up, but when it cools.
I'll say it again. Due to the non-linearity of the system, historical data alone isn't going to give us an accurate picture of what will occur in the future based on the current atmospheric state, considering that we've never observed a situation like it. Analysis for historical analysis must be combined with simulations, mostly by helping us to determine relevant factors and interaction mechanisms to put into the simulations. It's not flawless, but it's the only method we have.
And nobody is suggesting that we reduce CO2 levels to ice age levels. That would not only be retarded, but also close to impossible unless you're talking about centuries of effort.
If we actually look just a wee bit further back in time, cutting CO2 production is more likely somewhere between suicide and comedy than saving the planet. The next ice age isn't something to work toward.
Yeah, if we halve the CO2 levels from current levels that would probably not be so good. Extremes are never good ideas.
But, this quote of yours is extremely telling. You're willing to accept that small CO2 levels might bring along an ice age, but you're unwilling to accept that extraordinarily high CO2 levels like what we see now (let alone what it'll be in a few decades) are capable of changing anything. I really don't see the logic.
Besides, the only thing more dishonest than a politician or trial lawyer is a scientist being paid by one
To go into technicalities I'd argue that scientists being paid by politicians or lawyers are only as dishonest as their funders. Thankfully, there are plenty of scientists out there who are not in the employ of either.
If you're so worried about the integrity of a couple bible thumpers giving weather forecasts, I don't know how you can even bother reading anything the UN puts out.
While I think the UN is largely obsolete in its current implementation and wholely ineffectual, I'm more inclined to put some trust into a team of scientists put together by them than into a guy who uses the bible to predict the weather and is looking forward to the Tribulation period and the extreme period of global warming it will bring with it...