Looking at the financial interests of the plays is definitely a good way to judge whether or not you need to be skeptical.

There is certainly a lot of money involved in avoiding global warming. Many new technologies are needed and a lot of new infrastructure.

However, the actual scientists who are studying global warming have no financial motive that I can see. They are not collecting the money from cap and trade or even from the new technologies. Their direct financial interest is actually in controversy. If global warming might be a big deal, more research is needed. This is great for the researchers. Actually saying that there is enough data to reach a sound conclusion could hurt the researchers. Now we can put the money into researching technology rather than climate. I don't think many of the scientist involved will collect much money from that.

On the other hand, you have players, such as oil and gas companies and the scientists from countries that are major producers of these resources who predominate the critical scientists. It is easy to see how these countries and companies would like to provide money to anyone who can cast doubt on the issue.

It must be quite a far sited policy (not something the US specializes in) to pay researchers to come up with conclusions that might allow them to raise taxes through a back door (cap and trade). It is either that, or companies (most of which don't exist yet), who are funding research into climate change, just so that the governments of various nations will all get together and end up in creating business for these companies. None of these options seems plausible to me. This is especially unlikely since the Bush administration was in power for most of the period when the current consensus was developed.

A more likely conclusion is: The same thing is happening with global warming as with smoking. You have lots of companies, countries, and individuals who benefit from burning fossil fuels. You also have a lot of people who enjoy the way that they live right now and do not want to be told that they are doing something that is bad (for themselves with smoking or for other people). It is easy to have those who stand to be hurt by any changes in the current system pore a lot of resources into fighting change.

The article notes that the ratio of the nitrogen isotopes matches what is in the earths atmosphere. It seems to me, that just makes it possible that the comets are a significant source of the nitrogen on Earth. It is also possible that the nitrogen in the comets and in the atmosphere came from a common source.

If we are looking for a tax to pay for the roads, the real cost is based on both the vehicle weight and the distance traveled. A fair way of paying for the roads is to take both of these into account. In the modern world, the gas tax does that fairly well, since gas usage is based on both factors. In the short run, the gas tax is also a great way to encourage "greener" cars. The article is talking about 2020. The GPS is only really useful to make all roads into toll roads. You can charge people for exactly the roads they drive on and even add congestion charges to encourage driving at off peak hours. However, if the objective is just to pay for the roads that we have and replace the gas tax, using the odometer and the size of the car, people could pay for the use of their car periodically. If people want to be able to charge by state, then license plate recognition technology can already be used to do that. The states can track which cars enter the state and charge them something for the privilege of driving on the roads. That sort of approach seems to be a lot less prone to privacy concerns than tracking the actual roads driven and the actual times the roads are driven on. It also works fine for older cars. odometer readings can be collected in a lot of states when the car is inspected or when it changes hands and is re-registered. It makes it so people are paying a big lump sum periodically rather than a smaller monthly bill. However, there are plenty of ways to spread out the payments so that people do not get hit will too big of a charge up front.

In order for us to be in a void that affected how distant supernovas appear, it seems the void would need to be large enough to encompass many galaxies. Otherwise, we would see all supernovas as uniformly more distant. If the gravitational effect is primarily an edge effect, then we do not need to be in the exact center to see a uniform effect. However, if someone is looking for the effect, it seems that they should be able to find where the boundary is with enough data.