
On Hansen et al: Critical response to recent sea level rise publication - crygin
http://icarus-maynooth.blogspot.com/2016/03/on-hansen-et-al.html?m=1
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themgt
I have a lot of sympathy for what Hansen is doing. He absolutely is going out
on a limb, scientifically speaking, and using PR tactics to generate
mainstream media coverage for his research.

At the same time, nearly all the critical responses here acknowledge what he
is saying is within the realm of possibility. They mainly argue it's not a
proven or likely outcome. Which may be true.

But I think climate science, maybe science more generally, needs to ask itself
some existential questions here. We're not talking about the need for 5-sigma
confidence before announcing the Higgs Boson here. We're talking about the
future of the planet and human civilization. So to what extent should climate
scientists do their best to really hammer home to the public the range of
possible outcomes, and specifically how bad things conceivably could go, how
much we can't say for sure?

In part I think climate scientists specifically have learned to be extremely
cautious in what's stated publicly, because of the amount of firepower
directed towards discrediting them.

But what Hansen himself stresses is that "the major scientific issue that
exists is how rapidly ice sheets can respond to the unprecedented human-made
climate forcing, not whether they will respond. In our present paper we
present substantial, compelling evidence that the ice sheet response will be
non-linear and more rapid than has generally been acknowledged."

This statement I think is much harder to argue, and almost certainly most
climate scientists who have studied the issue would agree, if only in private,
that the IPCC predictions for sea-level rise are likely to be far more
conservative and linear than what emerging science regarding paleoclimate, ice
sheet dynamics like hydrofracturing, the geomorphology of Greenland and WAIS
especially, ocean circulation, etc are indicating will actually happen.

The ice sheet melt rate was predicted to be relatively linear prior to
detailed modeling of the specific dynamics in play. The more we understand
about the details, the worse the situation looks, and Hansen is one of the
first to try to pull those threads together and look anew at the big picture.

~~~
reitanqild
The piece linked to seems to tear apart the paper based on specific
assumptions Hansen et al took to arrive at what seems to be the preferred
result.

> So to what extent should climate scientists do their best to really hammer
> home to the public the range of possible outcomes, and specifically how bad
> things conceivably could go, how much we can't say for sure?

To take this to its logicl conclusion: feel free to lie as long as it is for
the greater good...

Not sure I want to follow you there. Scientists, engineers and a few others
are supposed to tell the truth, not just what "management" or the public wants
to hear.

~~~
themgt
Did you read his actual reviews? It's not exactly "tear apart":

[http://www.atmos-chem-phys-
discuss.net/15/20059/2015/acpd-15...](http://www.atmos-chem-phys-
discuss.net/15/20059/2015/acpd-15-20059-2015-RR1.pdf)

[http://www.atmos-chem-phys-
discuss.net/15/20059/2015/acpd-15...](http://www.atmos-chem-phys-
discuss.net/15/20059/2015/acpd-15-20059-2015-RR1.pdf)

------
themgt
I would also highly recommend reading through some of Thorne's detailed review
comments[1]

It's clear he thinks the paper is extreme but nowhere near ridiculous, perhaps
except regarding the "boulder" issue (which seems his best argument, but
tangential). Specifically the Eemian, the IPCC/AR5 defenses, the non-
linearity. A lot of it is disagreement over tone and maybe Hansen dialing
things to 11 instead of an 8 or 9.

I sort of agree with both of them, but the larger issue is the public sees
this whole thing as maybe a -3 to 2 level of severity and they're arguing over
9 or 11.

[1] [http://www.atmos-chem-phys-
discuss.net/15/20059/2015/acpd-15...](http://www.atmos-chem-phys-
discuss.net/15/20059/2015/acpd-15-20059-2015-RR1.pdf)

~~~
manachar
The public seeing something as a -3 to 2 level of severity while scientists
seeing something as a 9 or 11 seems to be the standard way science and public
policy interact.

1\. Scientists potentially find $somethingBad in the world.

2\. The world mostly doesn't pay attention, especially if the $somethingBad
makes someone money.

3\. More scientists investigate and start fleshing out the $somethingBad as a
genuine concern.

4\. Industry related to $somethingBad dumps money into science that refutes
$somethingBad. Such science seems to be unable to refute $somethingBad
completely, so it start nit-picking and fostering doubt.

5\. $somethingBad becomes a political issue, with industry calling for more
study and focusing on doubting the severity of $somethingBad.

6\. Hollywood makes a movie about $somethingBad. It wins an award despite
taking creative liberties in describing $somethingBad. Those creative
liberties are lampooned by those who don't think $somethingBad is real.

7\. Politics either continues at step 5 or finally manages to pass some laws.

We've seen this with leaded gasoline, clean air/water, endangered species,
tobacco, marijuana prohibition, asbestos, seatbelts, etc.

Maybe it's just the way democracy handles it. The downside is that scientists
who overstate the case with conviction tend to garner more of the headlines.

The probabilistic truths of science just don't survive the onslaught of
criticism from entrenched interests.

------
semi-extrinsic
TL;DR:

This blog post gives a review of the many good scientific criticisms of the
Hansen paper, and also highlights the poor responses of Hansen et al.

Basically, the paper starts with the assumption of exponentially increasing
melting from Greenland and Antarctica, modelled simply as C _e^(a_ t) liters
of fresh water added to the ocean per year. The weird thing IMO is that this
(liquid) fresh water is injected at -18 C (weird model), so they've
effectively removed the latent heat but not the sensible heat, for some
reason; the latent heat is 10x the sensible heat here, so why neglect the big
one and include the small one? They conclude that dramatic sea rise occurs
(duh). Perhaps the most important takeaway from the critique in this blog
post:

""" [The paper predicts that] basically many areas, in Europe in particular,
enter a period at least as cold if not colder than the little ice age. The
associated rainfall changes are equally as impressive. This would lead to
large-scale challenges around provision of food, services etc. for global
society and large-scale disruption of ecosystems. It is also entirely opposite
to the direction of climate change that policy makers are currently planning
for on this timescale. """

So, if the paper's conclusions are correct (and the blog post author and many
others apparently think it's not), we're basically doing everything wrong in
preparing for the consequences of climate change.

