1. Imo it's pretty simple: people who think there's a conspiracy just don't have a clue how difficult it is to handle real-life measurements. They think the world is perfect, measurements are perfect. Well wake up: they aren't.
There are biases and artificacts in the data. Sometimes there are trends in the data.
For example a measurement device grows older and older and as a result the data slowly change in time. What used to be 0.0 degree becomes 0.1 degree after a long time for example.
For example the environment changes and as a result the temperature measurements change a little. For example a new city block is built nearby. As a result the measured temperatures change a little.
Those are KNOWN biases and people try to correct for these as well as they can. And sometimes there are new insights or new correction methods and sure... magically the data change a little bit.
The only crime would be, to leave the data uncorrected and biased, because then you'd include those artifacts in your studies.
2. People who insist that the current flat line of global temperatures is the end to warming, simply fail to ignore a shitload of other measurements (like the ocean heat content). They also fail to take into account the mitigating mechanisms that are responsible for the flat-lining.
An El Nino that transported a good amount of heat into the deeper ocean... the heat hasn't gone, it's just moved deeper down.
A cooler sun.
A few volcanic eruptions that cooled the planet down a little.
They ignore the possiblity that, without warming, we could've had a very cool couple of years with harsh winters and cool summers, like you normally have under these circumstances. Instead, we still had hot summers.
3. People who insist that there's not enough warming considering the amount of CO2 ignore that
- it takes time to warm the planet, because the oceans take time to warm up. There are studies that it can take as much as 100 years.
- or they look at regions and sure, some regions respond differently. Like the Antarctic ice sheet, which magically expands. But that's a result of melt from the Antarctic glaciers and it's only a natural consequence of the warming.
- or they look at their own backyard and sure, they don't notice anything. But I look at my own backyard and I do notice that we've had really hot summers in the last 10 years, and I notice that I cannot skate anymore because the winters are rarely cold enough anymore.
- mitigation effect of massive smog clouds.
- a slow buildup of ozone in the upper ozone layer.
4. deniers haven't read this:
5. Deniers have not read about what the Triassic and Jurassic eras were like.
I think those are awesome stories and very informative about what we're heading for.
But for some reason they ignore this. It's a conveniently ignored massive set of data... like this article, deniers never mention it because such a thing cannot be denied:
6. Although to be fair, occasionally they have a point.
But not enough to support their point.
For example to state that cloud cover is an unknown and would mitigate future warming... well it's an interesting viewpoint, but you cannot rely on such a hope that clouds will save us. It could just as well be that there'll be fewer clouds in a warming world.
7. And finally, they don't understand that we have to work with what we know, not with what we don't know.
Alarmists say: we know that we're heading for a warming earth. We don't know exactly how much and how fast, but it has lots of nasty consequences.
Deniers say: we don't know exactly what will happen, let's wait until we know exactly what.
Well... they are just hoping that magically somehow our predictions turn out to be 100% off. Or they hope that magically somehow there'll be a very cheap technological development that will allow us to reshape our CO2 based economy to a zero-emission economy instantly and at almost no cost.
I think that's just hopeful dreaming.
No one person, no group of people, not all the world's scientists combined have the first clue what can be done about it, reasonably or otherwise.
There are several alternatives for sure: nuclear fission energy, geothermal energy, solar energy, wind energy, wave energy. These are available NOW.
The only thing in the way are scared politicians who don't want to spend a single penny on such things. And of course their voters who don't want to spend more money on electricity...
In the future, hopefully maybe even nuclear fusion energy, but when and whether it'll be affordable... we'll have to see.