

Climate change: A cooling consensus - shawndumas
http://www.economist.com/blogs/democracyinamerica/2013/06/climate-change/

======
asynchronous13
> Since 1998, the warmest year of the twentieth century

Clever. "the warmest year of the twentieth century" is completely true. But it
seems a little misleading, since there's been a few years even warmer in the
21st century.

Whenever I see the year 1998 mentioned in a discussion about climate, I am
immediately suspicious. The temperature recorded in 1998 was a serious
outlier.

Let's pretend the datapoint from 1998 did not exist. Then we could accurately
say, "The last decade has been hotter than any previous year on record!". But
with 1998, you could accurately say, "Most of the last decade has been cooler
than it was in 1998!"

It's always nice to look directly at the data.
[http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A.gif](http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A.gif)

It's true, if you take the past 10 years only, the trend is pretty flat. But
if you look at a 10 year running average we're in the middle of an upslope. We
can even make it look like we're in a cooling period if we pick 1998 as the
first year! Fun with data.

~~~
glenra
> It's always nice to look directly at the data.

It is, but you should keep in mind there isn't just one "the data" and in this
case, what data source you pick affects what answer you get. The people you're
arguing with might be looking at something other than GISS. For instance,
here's the WoodForTrees index:

[http://www.woodfortrees.org/plot/wti](http://www.woodfortrees.org/plot/wti)

the WoodForTrees Index is an average of four popular temperature series. This
index was created specifically in order to reduce the need for arguing about
which series to use. I believe the current formula is:

WTI = mean(GISTEMP-0.35, HADCRUT3VGL-0.26, RSS-0.10, UAH)

Playing around with the data sources, it seems like 1998 was an all-time high
within the period of the satellite record - _not_ surpassed by "a few years
even warmer in the 21st century" \- according to three out of four of those.
Specifically, UAH, HADCRU3, and RSS. It _was_ surpassed according to GISS or
HADCRU4.

So not only is it _not_ inaccurate to say "Since 1998, the warmest year of the
twentieth century", it also would not be inaccurate to say "Since 1998, the
warmest year for which we have satellite records."

~~~
asynchronous13
Wood for Trees is great! I didn't know about that before. (you say it's an
average, but then use mean in the equation, that's a significant distinction)

UAH and RSS measure lower troposphere, while GISS and HADCRUT measure surface
temperatures. I'm usually more interested in the temperatures in the first 10
feet of atmosphere rather than the first 10 miles of atmosphere (of course, I
don't make climate models). HADCRUT4 is a different model of the same source
data that HADCRUT3 uses and in theory should be more accurate.

In any case, you've got the hang of it now. By selecting a convenient data
source, one can make many creative and not inaccurate statements.

~~~
glenra
By the way, when skeptics say there's been "no warming for the last decade",
they often mean this:

[http://www.woodfortrees.org/plot/wti/last:120/plot/wti/last:...](http://www.woodfortrees.org/plot/wti/last:120/plot/wti/last:120/trend)

That one works even if you use GISS - the trend for the last ten years is
cooling. (The trend over several other recent periods is "warming, but not
very much".)

Note: the way I plotted "the last ten years" was to plot the last 120 monthly
samples. The WRONG way to do that is to specify a "From" year and plot to the
current day, because the resulting chart wouldn't start and end on the same
month.

------
vijayboyapati
The main problem with "climate science" is epistemological. It does not hold
up to the foundational standards of the natural science which rely on
falsification. With a system as complex as the earth's environment,
falsification is essentially impossible. You cannot rewind the clock back 50
years, change a variable and play out what the temperature would be now. In a
way, this makes climate science similar to economics. Yet climate "scientists"
continue to act as if their work is as repeatable and falsifiable as a
highschool lab experiment.

~~~
_delirium
If you take a very narrow view of falsification, then evolution is
unfalsifiable too, and therefore not science (this is actually a common
argument made by anti-evolution people).

~~~
jeltz
That is untrue since evolution has indeed been studied in falsifiable
experiments.

[https://en.wikipedia.org/wiki/Experimental_evolution](https://en.wikipedia.org/wiki/Experimental_evolution)

On the other hand studying how exactly the current specieses evolved is more
like history.

~~~
_delirium
There are certainly specific experiments that have been carried out w.r.t.
mechanisms (also true with climate science, fwiw). It's more the overall "big"
conclusions that are a bit difficult to replicate in a laboratory, e.g. "the
earth is warming as a result of human-caused greenhouse-gas emissions" and
"humans descended from other animals through a process of evolution driven by
natural selection".

~~~
jeltz
Any examples of such experiments for climate science? Other than actually
predicting climate change and then waiting 30 years I have trouble imagining
falsifiable experiments. For evolution you can isolate a couple of populations
with short generations in the lab and study them.

------
LordHumungous
For a system as complex as Earth's climate, it should come as no surprise that
computer models are inaccurate. I think scientists do themselves a disservice
when they point to these models as the best evidence for global warming. The
really important datapoints are temperature and ice core measurements, as well
as the melting of the ice caps, all of which show that the earth is warming at
an alarming rate.

~~~
soperj
So far this year, there has been more sea ice worldwide than average.
([http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/global.daily....](http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/global.daily.ice.area.withtrend.jpg))
Mostly on account of there being more than average in the Antarctic, and a
little less than average in the arctic. Antarctic has been setting
records(maximums, not minimums) in the last few years in terms of sea ice
extent.

~~~
asynchronous13
Ok, i did a bit of googling to try and understand this. It turns out that the
extent of sea ice in Antarctica _has_ been expanding! though calling it record
setting is misleading.

The fresh water from the massive melt-off of land ice creates an insulation
layer when it meets the sea water that prevents the sea ice from melting. One
article [1] called it a "small but statistically significant sea-ice
expansion". Another data point says there is more sea ice in antarctica today
than 30 years ago. Put those two points together, and "small but statistically
significant" becomes "RECORD SETTING!"

[1] [http://www.nature.com/news/global-warming-expands-
antarctic-...](http://www.nature.com/news/global-warming-expands-antarctic-
sea-ice-1.12709)

~~~
soperj
Record setting, as in, It's the largest extent on record.

~~~
asynchronous13
misleading, as in, the minor increase in sea ice is insignificant compared to
the massive amount of land ice that has melted.

------
lotharbot
Key quote:

 _" This isn't a crisis for climate science. This is just the way science
goes. But it is a crisis for climate-policy advocates who based their
arguments on the authority of scientific consensus."_

~~~
rpgmaker
That's not the key quote: that's the quote that reassures you. I've never
taken global warming as gospel. I often read people making fun of the right
for dismissing it but I never did, because even if they were against global
warming because of their anti-intellectuality they might still be right in the
end. The evidence of global warming, at least in the apocalyptic way that's
been portrayed by some, has always seemed shaky to me.

------
vannevar
The title is inaccurate. From the first paragraph of the article:

 _There is no serious doubt that our planet continues to heat, but it has
heated less than most climate scientists had predicted._ The consensus is that
the planet continues to warm, not cool.

~~~
shawndumas
the title is _very_ accurate; the consensus on how much it was supposed to
heat up is eroding (the use of the word 'cooling' is a play on words). FTA "In
the end, the so-called scientific consensus on global warming doesn’t look
like much like consensus when scientists are struggling to explain the
intricacies of the earth’s climate system, or uttering the word “uncertainty”
with striking regularity."

and

"The moralising stridency of so many arguments for cap-and-trade, carbon
taxes, and global emissions treaties was founded on the idea that there is a
consensus about how much warming there would be if carbon emissions continue
on trend. The rather heated debates we have had about the likely economic and
social damage of carbon emissions have been based on that idea that there is
something like a scientific consensus about the range of warming we can
expect. If that consensus is now falling apart, as it seems it may be, that
is, for good or ill, a very big deal."

~~~
vannevar
_the title is very accurate_

No, it's not. As the article notes up front, there is no serious doubt that
the climate is warming. So not only is the climate not cooling, neither is the
consensus.

Estimates of the long-term rate of warming have always varied, but the
consensus remains that the rate is significant and even the lower estimates
will result in environmental changes that will impact millions of people.

~~~
baak
It's a pun... cooler heads prevailing doesn't mean peoples' heads are actually
cooling down. The title was a play on words about the upset about global
warming dying down.

------
Tloewald
I've never seen such a concentration of nutball comments on an Economist
article. Hardly one sane comment in the lot. A bit alarming to see such an
article from The Economist.

------
warfangle
But have the icecaps slowed in melting? Their contribution to ocean currents
has a wide effect on surface temperature.

------
wikiburner
Previous discussion:
[https://news.ycombinator.com/item?id=5796539](https://news.ycombinator.com/item?id=5796539)

and some previous articles:

[http://www.bbc.co.uk/news/science-
environment-22567023](http://www.bbc.co.uk/news/science-environment-22567023)

[http://www.nytimes.com/2013/06/11/science/earth/what-to-
make...](http://www.nytimes.com/2013/06/11/science/earth/what-to-make-of-a-
climate-change-plateau.html)

