I think many people have trouble developing an accurate mental picture for climate change. Obviously some people refuse to accept it and purposely do not want to get it. But I expect that many people who do accept the scientific consensus that human activities are altering climate still do not have a good "feel" for it. Climate change is very gradual, and the effect lags the cause making them seem disconnected and possibly unrelated. There is no immediate and sudden visual impact that forces recognition and acceptance - there is no Pearl Harbor, Twin Towers, or mushroom cloud.
But I believe the Gulf oilcano can usefully serve as a sort of visual aid for description of climate change.
The video feeds of the gushing oil have captivated people. That oil pouring out of the broken well can be considered analogous to the massive amount of carbon dioxide being released from smokestacks, tail pipes, and the like. Of course we see stock photos and video of smokestacks and tilepipes, but it is really pretty much steam and soot that you can see from those sources.
Obviously the scales differ. We are looking at one spill at one point on the planet. There are about 362 billion billion (362,000,000,000,000,000,000) gallons of water in the world's oceans. Current estimates put the oil gush rate around the range of 1 million to 2 million gallons per day. (An oil barrel equals 42 gallons.) Atmospheric CO2 is increasing currently by about 2 parts per million per year. Emissions are actually enough for about double that, but the oceans at least for now are able to absorb about half of the artificial CO2 release. To match that rate of dumping and adding CO2 into the atmosphere the oil gush rate would need to be about 700 million million gallons (724,000,000,000,000) per year. That would be spread around the whole about 1 million to 2 million such oilcanos! That means one for roughly every 10 square miles of ocean area.
The timescales are also different. Disasters are almost by definition sudden. (If it was not sudden it could like be avoided, right? Well, with climate change we seem determined to show that if they are too slow disasters cannot be avoided, at least by humans.) The oilcano is on the slow and gradual side as far as disasters go. Oil has been flowing since the April 20 explosion and ultimate destruction of the Deepwater Horizon rig. Of course it takes time for the impacts of the oil as they are not immediately felt competely simply at the time of release, which is similar to how it takes time before greenhouse gas emissions really produce their impacts.
For illustrative purposes a day in the oilcano situation could be considered approximately comparable to a year when it comes to greenhouse gases and climate. It took weeks for noticeable oil to reach Gulf beaches, and it takes decades for the warming effects of greenhouse gases to be fully realized. Just like if the oil magically stopped flowing into the Gulf right now the disaster would continue for quite some time because of the oil already released, the warming trend would continue if greenhouse gases were magically no longer released from fossil fuel burning and deforestation. And in both cases as the dumping flow continues the ultimate price to be paid in impacts keeps growing.
Another parallel we can draw is between attempts to mask the most obvious effects - in the case of the oil there is the use of dispersants, and in the case of greenhouse gas emissions there are geoengineering ideas to try to offset warming. In both cases there is concern about how those things may obscur other problems and cause problems of their own. Dispersants are used because they break the oil down into smaller globs, so the potential benefit is in decreasing the choking amounts that wash ashore. First, there is concern about their toxicity and how they may directly harm sea life. Another worrying factor with them is how they may contribute to massive oceanic dead zones. The more dispersed the oil, the easier microbes that are able to digest it can get rid of it, but also the more oxygen those microbes thus use up and thus divert from other life.
Ideas involving deliberate geoengineering to try to offset global warming typically involve decreasing the amount of incoming solar energy reaching the surface, which alone could raise a red flag. One of the commonly suggested ideas is to continually inject sulfates high into the atmosphere to produce aerosols that make the earth overall reflect more sunlight than usual as volcanoes can do, such as most recently Mt. Pinatubo after the 1991 eruption. However, though that may be a relatively easy way to produce cooling (another phrase that should raise a red flag), there are numerous concerns. Sulfates lead to acid rain, they may adversely affect the ozone layer, and unexpected negative local effects such as on precipitation patterns may result from such attempted manipulation of the climate.