Climate change: A cooling consensus | Hacker News Reader

Climate change: A cooling consensus

economist.com

37 pointsshawndumas57 comments

> 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

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.

Depends on the record you're looking at. If you look at the temperature records from ice cores you can see that the entire 21st century has so far been within the historical range at this point in the cycle.

http://www.wmich.edu/corekids/images/icecoredatahistorical02...

However the 21st century has been an outlier in that temperatures have suddenly (for some reason :) failed to correlate with the amount of CO2 in the atmosphere.

> 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

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."

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.

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:...

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.

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.

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).

I agree with that argument.

It's history. If not for the whole religion dust-up we'd probably call it natural history.

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

https://en.wikipedia.org/wiki/Experimental_evolution

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

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".

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.

Which scientists are you referring to? There are thousands and thousands out there and I find your sweeping generalisation a little unlikely to say the least. I don't usually see hard short term predictions, it's more often presented as ranges of temperature averaged over significant periods of time.

I'm curious. Do you also consider astronomy, cosmology, paleontology, ecology, and geology to be "science" rather than science?

Natural history.

There is no magical standard for falsification. If we want to be 100% rigorous, then to have an experiment for any law of gravitation we would need to test every pair of bodies at every possible distance.

No, the main problem with "climate science" is that it's impossible to take the political (and nearly religious to some on the left) aspects out of it.

Only then, can there be a serious discussion about "global warming".

"Nearly religious to some on the left" — um, I have no problem with describing some of the left's view of climate change as "nearly religious" if you accept that many on the right take a completely and utterly religious view.

You mean, literally religious. They do. On the contrary, calling the "global warming" belief a religion is metaphorical. However, I think it is a very good metaphor, as it immediately brings a certain enlightenment to the whole argument.

It is very unfortunate, in my opinion. As unfortunate as the politization of science.

Climate "scientists" make a big deal of pointing out that their work is simply a "best guess", and also trying to quantify the uncertainty. We know the greenhouse effect is real. We don't know how much damage (if any) it will do, but in order to make decisions about what to do, we need some kind of model.

It's not the lack of falsifiability that's bad - hard science can only answer some kinds of questions - it's the pretense of falsifiability that's a problem. Granted, you basically acknowledge this in your last sentence.

I'm not sure which problem is the "main" one, but this is certainly in the top three.

While "falsification" is impossible for complex models, the predictive power of a model can be shown to be inadequate. It takes years for it all to play out, but it's still science.

Economics is far worse since we have such a poor understanding of psychology.

Pretty much all science lies on a spectrum from, say Math on one end, thru physics and biology and eventually psychology (say) on the other. You take the view that some sciences are OK and others not, but it's more nuanced.

The greenhouse effect is solid physics and experimentally falsifiable and verified. We can measure fluctuations in solar output. But sure, the system as a whole is horribly complex and we can't make precise predictions.

Just as a matter of common sense we know that pumping crap into the atmosphere is probably a bad thing -- we shouldn't need a rapidly impending crisis to persuade us to try to avoid doing it, but getting people to do or stop doing anything is politics, not science.

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.

So far this year, there has been more sea ice worldwide than average. (http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/global.daily....) 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.

Um, did you look at the graph you linked to? They grey line is the mean for 1979-2008. The last two years, the blue line is distinctly below the mean. I don't know much about sea ice, but this graph isn't supporting your claims.

My "claim" was so far this year. It's not a claim, it's data. The red line down the bottom is the sea ice anomaly, and as you can see it's been above average for most of the year.

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-...

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

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

So what? When it comes to global climate trends, a single year is one insignificant datapoint.

Isn't the more important point not the rate of increase, but the effect current temperatures are having on the ice caps?

For example, I can sit a turkey in my oven at 20 degrees (c) and raise the temperature 20% per minute, but that rate of increase doesn't actually cook the bird. Once the temperature gets above 140 degrees, then cooking starts to take place (I'm not completely sure of the temps, but go with me). The temperature doesn't have to continue rising, every minute that the bird is held over a certain temperature, that bird will continue to cook. May be slow, may be long, but the damage is being done.

Same with your reference to ice core measurements and melting ice caps. It doesn't matter if the temperture continues to increase at the current rate, or the rate slows. As long as the average temperature is kept above 0, the ice will continue to melt. And the article doesn't say temps are decreasing, just that the rate of increase is less than expected.

for science? maybe; for pushing policy? nope -- it's very important that the numbers be the same (have a consensus) and that they be higher.

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."

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.

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.

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."

If you are a scientist, especially one who deals with statistics, and you don't utter the word "uncertainty" on a daily basis then you don't deserve to be a scientist.

Using that as a criticism, especially given the word has very technical meanings in terms of distributions and fits, is silly.

the argument that that word is aimed at is not a scientific argument but a political argument. FTA : "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."

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.

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.

but the consensus on how much it is heating up is 'cooling'.

Nope it is inaccurate. There never was a consensus about exactly how much the earth would warm up in the future. Scientists always had different models showing different projections.

The consensus was that (1) the earth is warming (2) if not stopped this will have catastrophic effects on the human race soon. Both of those things are still true and there is still the same consensus about them.

wow, guys, the argument that the article is aimed at is not a scientific argument but a political argument.

FTA : "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."

The title sounds like it's saying that the consensus is cooling, not that there's a consensus that the planet is cooling.

exactly; it's a play on words

It's wrong either way.

No, it's not wrong. You are reading it at its simplest level. Further, you have 3 replies saying the exact same thing. The quantity of saying something by the same person does not increase its quality.

As of right now, you have 30% of the comments in this submission. It really seems like you have a strange bias here to argue over something so trivial.

vannevar, could you take a moment to explain why you are so intent on understanding this article as an attack on science instead of what it really is (namely, an attack on politics)?

Because the article's premise is based on the author's skewed interpretation of the science. Ironically, if you look at the article they site for the claim that warming has slowed[1], you'll see that the rate of warming is still within the margin of error for the estimates. If anything, it should reinforce our confidence in the models that the actual curve matches so well with the prediction. And that's just surface temperature, ignoring ocean temperature and the simple fact that during this supposed 'hiatus' there has been a massive net ice melt[2].

1. http://www.economist.com/news/science-and-technology/2157446...

2. http://www.nature.com/nature/journal/v482/n7386/full/nature1...

so there is still a consensus on how much it's going to heat up?

As much as there ever was, yes. Look at the range of estimates in the chart your article cites. There's never been a consensus on the actual number, only that it's going to be significant. And so far, that consensus has been correct, as the chart shows.

so a consensus of the models predicted that warming was going to nearly plateau?

Note that this was published in the Economist, which has a reputation for overusing puns. This edition also has articles titled "T Time" and [amyloid] "Beta testing" .

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.

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

Previous discussion: https://news.ycombinator.com/item?id=5796539

and some previous articles:

http://www.bbc.co.uk/news/science-environment-22567023

http://www.nytimes.com/2013/06/11/science/earth/what-to-make...

Reply on news.ycombinator.com