
No Experimental Evidence for the Significant Anthropogenic Climate Change - ScottFree
https://arxiv.org/abs/1907.00165
======
tlb
The title seems way overblown. The actual paper observes that cloud cover went
down at the same time as temperature went up over the last few decades, and so
perhaps the temperature went up because cloud cover went down rather than
because of anything humans did. The IPCC has one correction factor for clouds,
but they argue for another.

It doesn't ask the question "why did cloud cover go down?" Perhaps they are
both anthropogenic.

~~~
topmonk
> The actual paper observes that cloud cover went down at the same time as
> temperature went up over the last few decades, and so perhaps the
> temperature went up because cloud cover went down rather than because of
> anything humans did.

It does more than that. It predicts that for every 1% decrease in low clouds,
the temperature goes up 0.11 C. They also used all available data (25 years)
of cloud cover.

The correlation is very high. Figure 3 shows this.

> It doesn't ask the question "why did cloud cover go down?" Perhaps they are
> both anthropogenic.

Perhaps, but it's entirely unproven that co2 affects low cloud generation.

I get that dumping a large amount of CO2 in the atmosphere and hoping nothing
will change seems scary. But so is converting a large portion of land into
farmland and cities, drilling into tectonic plates for geothermic energy and
oil (which seems to correlate with earthquakes forming nearby), etc. And keep
in mind it's a trace gas. We're talking about parts-per-million here.

With 8 billion people on the planet, we are going to be making changes to the
environment regardless. It's important to understand what we are doing, and
not blindly try to stop co2 production, when something else could be much more
problematic.

~~~
tlb
They only show a correlation between cloud cover and temperature. There's no
evidence for which causes which. If causation runs the other way, then that
for every 0.11C increase in temperature, clouds decrease by 1%.

The problem with this line of thinking is that, when you do something to a
system, usually lots of properties of the system change. So you can always say
"Look, properties A and B changed at the same time right after we did X! So
maybe A caused B, not X."

~~~
topmonk
> There's no evidence for which causes which. If causation runs the other way,
> then that for every 0.11C increase in temperature, clouds decrease by 1%.

What sort of evidence are we talking about? We don't have a another exact copy
of Earth so we can't perform a controlled experiment by somehow inducing low
clouds to form in one and not in the other. But if you need this sort of proof
then how can you turn around and justify the belief that CO2 is definitely
causing climate change?

Even NASA would disagree with you
([https://visibleearth.nasa.gov/view.php?id=54219](https://visibleearth.nasa.gov/view.php?id=54219)):

 _Clouds play a complex role in the Earth 's radiation budget. Low Clouds
reflect much of the sunlight that falls on them, but have little Effect on the
emitted energy. Thus, low clouds act to cool the Current climate._

(Note the paper is specifically referring to low clouds)

> The problem with this line of thinking is that, when you do something to a
> system, usually lots of properties of the system change. So you can always
> say "Look, properties A and B changed at the same time right after we did X!
> So maybe A caused B, not X."

Sure, but also, when you make changes X1, X2, X3, ... Xn, you can't just
arbitrarily say that X1 must be the cause and X2 .. Xn are not.

