One of the tools I find useful in considering issues is to follow a common mathematician's approach -- called the reductio ad absurdum. That means reduction to absurdity. What you do is assume the thing at hand to be true, and then pursue it logically to see where you go -- whether it leads you to absurdity. This is also the starting point for a proof by contradiction. Again, assume the thing to be true and see if it leads logically to a conclusion that contradicts what you know to be true.
So let's assume that there is indeed a fake involved in the decline in Arctic sea ice. The people involved were a little particular -- the passive microwave sea ice record.
Some questions to pursue, then:
- How long would the conspiracy have to have lasted?
- How much data would have to be faked?
- Who all would have to be involved in the fakery?
- Are there other sources of data to confirm or refute the passive microwave observations?
* The period of the passive microwave data is 1979 (actually late October 1978) to the present. Much of the time, only a single instrument was flying (easier to fake?). SMMR from 1978 to 1987, DMSP SSMI F-8 for a few years, F-11 for some more, then F-13 1995 to 2009. As we get more recent, though, there are multiple satellites, F-14 until late 2008, F-15 until 2008/present (the different dates depending on what algorithm you're using. And a different passive microwave instrument, AMSRE from 2002 to present
So when does the fakery have to be? The trend from start passed significance in the mid-1990s, and has only gotten moreso since then. If the trend were faked, it had to start from some time around then. Since the declining trend has only gotten larger since then, the conspiracy must have been getting bolder.
Probably at least 15 years -- perhaps nature produced that marginally significant trend back then, but then the conspiracy took the chance to intervene?
Anyone familiar with scientists has already rejected the conspiracy as reductio ad absurdum. Scientists are very fond of talking about what they're up to. You may have noticed some of that here. The lifetime of a conspiracy of scientists is probably measured in seconds for that reason alone.
Let's continue, though. Maybe (chortle) there are some wily scientists who are great conspirators.
* The scale of data involved is, well, every passive microwave instrument flying since 1979. They're not terribly high-density instruments by modern standards. About 0.08 Gb/day for SMMR and SSMI. AMSRE is more demanding, but still only about 1 Gb/day. Now you wouldn't have to fake every byte. The Arctic ice pack at its maximum only covers (well, covered, wintertime maximum has also declined) about 15 million km^2 -- about 3% of the globe. But only the decrease in area itself would need to be faked, something like 2.5 million km^2. 0.5% of the data, so a mere 50 Mb/day even for AMSRE.
On the other hand, it would have to be skillful fakery. You can't just throw in random numbers. The algorithms for finding sea ice concentration and ocean wind speed, among others would go nuts -- and be detected thereby. The fake has to make sense as sea ice observations (of no ice) and as wind observations, and for each other the others as well.
But who has to be doing the faking?
* Who? The SSMI are on US Department of Defense satellites. So either the DoD are the original fakers, or somebody or some group has managed to hack the DoD satellite program. And, for some reason known only to them, they mess only with the sea ice concentration observations.
With the AMSRE, the instrument is from Japan and is flying on a NASA platform. So either the Japanese instrument makers decided to fake the observations carefully (only that 0.5% or so in the Arctic periphery), or NASA decided to fake what it relayed to ground -- and the Japanese team never noticed.
I confess that the numbers don't have to be very large here -- a handful of people in the DoD (or hacking DoD) and another handful in Japan and NASA (or hacking NASA). A single group hacking both DoD and NASA would make the smaller number. It might also make it easier to figure why the conspiracy would be faking a decline in sea ice cover. Why Japan, NASA, and the DoD would want to fake a decline in sea ice is a bit of a mystery to me even assuming that there were a conspiracy. NASA has rather different goals than DoD, and why Japan would want the same as either ...? Numbers get bigger if you consider the next point. Quite a lot larger.
* Are there other data sources? Yes. Quite a few, and this is where and why things really blow up for the conspiracy-minded folks.
- Instruments that use visible wavelengths -- MODIS, AVHRR, GOES, OLS, and so on. These instruments are on platforms from the US -- NOAA, NASA, DoD, Europe (EUMETSAT), India, China, Japan, and probably several more.
- Flight observations from the US, Canada, Russia, Norway, and others. Anybody flying a plane can see that there's no ice for hundreds of km that the conspirators are trying to lie about. Anybody
- Ship observations from the US, Canada, Russia, Norway, and, again, others. China, for instance, has started taking ships to the Arctic recently.
- Fishermen -- See The Deadliest Catch for some visuals and an appreciation of what they're doing. In any case, fishermen pursue the ice edge because the fishing, at least for some things, is best near the ice edge. If the ice edge were a lie, the fishermen would either not be catching what they need, or they'd be dead. The location of the ice edge is a matter of life and death.
- Traditional cultures in the Arctic -- many different tribes in different part of the Arctic hunt from the ice. They do use satellite information (something I know first hand). If the satellite information were a lie, the tribes would be going to the wrong place, or I'd assume that they'd notice that they hadn't fallen in to the ocean when the satellite types said they should.
* Summing up -- The idea of conspiracy is absurd. Too many different groups would have to be involved, and be involved for a long time.
Ok, you knew I was going to get to this conclusion. After all, I'm one of the people who would have to be involved in the conspiracy, or be too embarrassed to admit that I'd been duped. So the thing to do instead or in addition is to examine a point or three yourself. Whether the visible satellites observations match up with the passive microwave is something you can check out yourself fairly easily. Neven, for instance, routinely shows both types of observations.
Back in 2007, when the ice cover was behaving so strangely compared to prior years, that was one of the things I did myself. Not that I was thinking conspiracy, but that maybe the sensor was going bad. So I looked for some visible observations as a check against the passive microwave. They agreed, something amazing really was going on.