2011-04-12 08:08:22Can anyone rebut this climate myth in a single paragraph using plain English (and preferably with a metaphor)
John Cook

I was asked to talk to a small group on Sunday and during the talk, there was the inevitable question time where they threw a quick fire succession of climate myths at me. To make the science as accessible as possible, I was a metaphor machine. When they asked about co2 being such a small % of the atmosphere, I used the metaphor of the election in a town of 1000 whe only 10 voted. When they asked about the last 2 winters being so cold, I used the metaphor of the fridge (Arctic) door left open, leaking cold. With each metaphor, I could see people nodding and the light of comprehension in their eyes.

Then they asked about past climate change. I remembered the last time I explained past climate change to an audience and all the blank stares in their eyes. This time, I was armed and ready with my pithy bushfire metaphor (past natural bush fires don't mean arsons don't exist). But I got blank eyes in response. So then I had to get more scientific. I explained that past climate change was evidence of high climate sensitivity, that positive feedbacks amplify initial warming. Those same feedbacks are now amplifying greenhouse warming. I'm not sure that it was as crystal clear as I would have liked.

So can anyone explain how past climate change is actually a source of concern, not comfort, in a single paragraph in plain English? This one comes up so often, would be good to be able to knock this out of the park. If you are going to attempt it, can I recommend you try your explanation with a layperson before posting here, to see whether you get blank stares or not. The key is not that you understand it but that the newbie layperson understands it. Thanks and good luck.

2011-04-12 08:19:08
Rob Honeycutt


How about hitting it out of the park with a baseball metaphor?  

Climate changes based on how much energy is exerted upon it.  Like a batter hitting a baseball.  Nature can swing a the bat too, and can sometimes hit the ball pretty hard.  But it's that measure of energy that tells us how hard we are swinging the CO2 bat.

Does that make sense?

2011-04-12 08:27:38
Dana Nuccitelli

Aw man, the fire analogy didn't work?  That's my favorite.  Did you say that before humans came around, bushfires were sparked by natural effects like lightning, but that doesn't mean humans can't also start them?

For sensitivity, you could stick with the fire analogy.  If nature is able to start really big fires, then humans are too.  If there had never been big fires in the past, then we wouldn't have to worry.

2011-04-12 08:45:15
Rob Honeycutt


The fire analogy is essentially the same one Richard Alley uses for that question.  

2011-04-12 08:46:29
Alex C


Well, what were they asking exactly?  If past climate swings indicate that this is nothing out of the ordinary, or if past climate swings were more intense (what have you) than now?  "Climate's changed before," or "it's not unprecedented?"  In the former case, your analogy should have sufficed (though "arson" might be too... accusing of mal-intent?).  My thoughts are that your audience was expecting more along the lines of the "it's not unprecedented" argument.

Take a beaker of water that a scientist has been heating up and cooling down.  He's been keeping records of how hot the water has gotten, and how much energy he has put in (how strong his Bunsen burner was going).  The burner is the forcer of temperature change, and the temperature responds to it.  The water, right now, is warming up, and is warm enough for a nice shower.  In the record though, it was once boiling at a couple of times a long time ago!  It had even gone from cold to boiling in a matter of minutes!

You cannot predict the future based on temperature though: you need to know how much forcing is at work.  Again, we know how much energy was put into the system at those times.  Presently, the water is nowhere near as hot as it was when it was boiling.  The burner, though, is raging.  We know what happened when the burner was as high as it is now - it soon boiled.  So past knowledge on energy balance and temperatures give us an idea of how much warming we should expect.  Due to increasing forcing, we are expecting very high temperatures that haven't been seen in the record for a very long time.

If the record showed little temperature response to a strong burner, then there's not much cause for concern.  If temperatures swung a lot though, then we should be concerned because our burner is on high.


A bit lengthy, not one paragraph, but I think that conveys the message in easy to understand terms.

2011-04-12 09:52:06
Daniel Bailey
Daniel Bailey

What about the thermostat analogy?

Imagine the world as a house with its temperature controlled by a thermostat on the wall.  Your comfort zone is between 65 and 75 degrees F.  Sometimes in the past it would get really cold outside the house and temperatures inside would dip into the 20's and 30's and the pipes would freeze and the fish in the fish tank would die.  These correspond to the ice ages. 

Then again, there occurred some times when it got really hot outside the house and the temperature insode the house would spike into the 90's.  And yet again, the fish in the fish tank would die.

Where that differs from today is that today, temperatures outside the house are in the comfortable, shortsleeve shirt range.  Yet it is getting really warm in the house, with inside temperatures in the mid-80s and climbing.  On closer inspection of the thermostat, you find that the temperature control gauge has been cranked up into the red zone (130 degrees plus)...and the control arm on the gauge has been broken off, rendering the future temperature spike unavoidable.  And more soon-to-be-dead fish blissfully unaware of their fate...

This is where today's climate change differs from that of the past.  Whereas in the past, we can tell what the external causes of ice ages and warm interglacials were and why they occurred, today's cause of climate change is completely apart from that: It is our fingerprints on the Earth's broken thermostat...

2011-04-12 11:19:53
Dan Friedman

Food:  You had a nice hot meal, but there were leftovers.  You let the food cool, then put them in the 'fridge for tomorrow.  It used to take a long time to reheat them on the stove or in the oven, but they would eventually warm back up.  So you got impatient and bought a big microwave oven; now you can reheat your food really quickly.  But if you're not careful, it gets too hot and you get a nasty burn.

2011-04-12 11:45:28


This is confusing but bare with me.

 You can use your microphone and auditory feedback. 

This might even be helpful if you actually use a microphone for talks (not sure), or explaning it will work too.  It would take practice.  You can demonstrate or discuss the natural sounds (or a finger thumping on the microphone) travelling through microphone and natural climate shifts over long time periods.  Then you can demonstrate or discuss how feedbacks work by moving (or discussing) the microphone closer to the speaker.  You can do this a few times to see how nature changes the climate on cycles.  The natural sounds can be compared to the sun and auditory feedback can be compared to the climate feedbacks increasing the volume and relate that to the intensity of climate warming.  Use or discuss different volumes (control knob) if you want to complicate it.  But the kicker is when you scream into the microphone and the feedbacks really surprise people.  The screaming is the human influence on climate.

Better with a real demonstration, but people understand microphone feedback well enough to see where humans are superimposed upon whatever is happening nature.

2011-04-12 17:32:22


In the first two cases, the issue that is being addressed is: "How can AGW be compatible with common sense: the cause is too weak, it still gets cold sometimes?"

The third case seems to be, "How do we know that this climate change is due to humans, and is not natural?" I think the reason the bush-fire explanation didn't convince is that you didn't make the case that it HAS TO BE a bush fire, just that it COULD BE a bush fire.

What I would focus on is the time scale of the change: Naturally occuring global climate changes have taken place much more slowly than the rates we are now experiencing (my memory is that the fastest natural transitions we've seen in/out of the ice ages is 7 times slower, and most of the transitional stuff is much slower than that; check the numbers). But the observed change over the last 150 years is quite in line with what we have expected on the basis of CO2 emissions. An analogy: You're sitting in a house in a neighborhood where the temperature typically changes 9 degrees over the period of 3 hours, from 9 am to noon. One day, you notice that the temperature has changed 9 degrees from 9 to 10 am: That's well outside normal range, and you would be well-advised to look for abnormal causes, like: broken thermostat, a fire-storm, a hot wind, something atypical. The fact that a 9-degree change in an hour is about what the heater would produce if turned full-on is suggestive, but you do have to eliminate the other possibilities as well. However, the extreme rate of heating eliminates "normal variation".

2011-04-12 19:53:13
Mark Richardson

I tried a murderer analogy. A bit too morbid, perhaps :p



The police come across a body. There is nothing wrong ,except for a big wound in their chest and a bullet in their heart. The 'skeptic' says it can't be murder: people have died naturally in the past, but the (America-heating, Socialist, New World Order etc) police think it's a human caused death.

Doctors have looked at lots of dead bodies and they found that if you severely damage a person's heart, they die. It doesn't matter how the heart is damaged: the police realise that the bullet does at least as much damage as natural causes that have killed people before. The bullet can kill, and in this case the bullet did kill: it was human caused death.




Then you can run with this a bit. Scientists find that if you damage the heart, you get 'feedbacks' to other parts of the body. Blood stops flowing, so the brain and other organs shut down. Doctors have seen this happen in loads of cases (and palaeoclimatologists have found it in loads of climate records), there's no reason to think that this body is particularly special in the context of thousands of others - the skeptic is asking you to believe that this particular body is immune to bullet wounds and heart failure when every other one hasn't been.

2011-04-12 20:51:17
Paul D


I used two pie charts for the CO2 percentage of atmosphere thing. The first showed all the gases, the second showed the ones opaque(ish) to IR.
I suppose the issue is how you explain why one gas responds differently to one sort (frequency) of light but not to another. Once you get past that, then it becomes clearer.

2011-04-12 23:44:12


The Ville,

I think the point where "common sense" takes umbrage against a tiny % of GHG molecules affecting the general temperature is that people think that the % matters. It doesn't, because the GHG molecules don't have to "convince" the other molecules to do anything, they just have to block/absorb & re-radiate the IR photons; and that is a matter of the numbers of GHG molecules, not % relative to all molecules.

I don't think people have any problem understanding that different types of gas molecules absorb different frequencies of light. After all, different types of stone have different colors because they absorb different frequencies of light.

2011-04-12 23:50:29
Daniel Bailey
Daniel Bailey

Actually, this thread sounds like one of those experiments the cognitive scientists run.



2011-04-13 01:14:09
Paul D


I think most people do have a problem understanding it Neal. That's why it is an issue.
If they understood it, they wouldn't be raising it as an issue.
The percentage thing is a contextual one, I think my pie charts highlight the different contexts (the sensitivity or lack of it to IR).

2011-04-13 04:23:49


The Ville,

I don't agree with your diagnosis. I think what people get caught up in the tiny %, not the fact that some molecules absorb frequencies that others don't.

If CO2 were 50% of the atmosphere, no one would raise the issue of %; nor would they raise a question about different frequencies.

2011-04-13 06:26:35


I like Marks analogy.

People get fevers all the time, but in this case the patients temperature rose on the day the poison was delivered to the house, blood samples show poison in the patients bloodstream, the bottle was found opened with a few drops missing, and a fingerprint is on the bottle.  Moreover, only one person was in the house at the time, the same one whose fingerprint is on the bottle and has a motive for the crime.

Multiple stands of evidence all point to the same conclusion!

2011-04-13 11:59:58


Ah, rhetoric.  You gotta love it!  But I much prefer logic. :)


Q: How can a tiny amount of CO2 make a difference?

A: Are you telling me that just one more straw never killed a camel?


Q: The climate changed in the past when there were no humans there to change it.

A: So did the moon, but it takes a human to leave a clear footprint.  ( Flashes Neil Armstrong's footprint photo. )


Q: If some places get warmer and some get colder, how is that a problem?

A: You live in Siberia and your house catches fire.


Q: It was hotter in the past.

A: Yes, I remember! - The Arctic, Novaya Zemlya, October 30 1961, about 108 degrees Kelvin!

2011-04-14 04:39:12
Peter Miesler

What about pointing out that society couldn't have survived through most of the climate changes Earth has experienced in its geologic past?

2011-04-14 04:49:21
Peter Miesler

After that you can always try developing the analogy/metaphor of our global climate as being sort of like a heat engine.

Get wild define these various valves and pistons, and manifolds, all influencing the output ~  correlate those elements to various elements of our climate/ocean's dynamic systems.

We know in the past that such and such elements had X amount of influence, however today these same elements only have 1/? the influence they had during other past time periods.  Well that missing energy input is being made up by GHGs  etc, etc,

2011-04-18 08:08:33Bart to the rescue?
Julian Brimelow


I think that Bart may have solved your analogy problem.  Some of the comments are also just too beautiful for words.

2011-04-19 07:32:33


Albatross:  you just ruined my day.  I now have to disregard all those ships logs, which means that the Arctic ice is recovering nicely.  It seems that the sailors - no doubt funded by the illuminati - have been deliberately falsifying the records.  Terms like 'speed made good' are particularly revealing: if the log showed a decline in knots, the officer of the watch would just 'make it good'. :-)

2011-04-19 18:50:40
Bart Verheggen


Before I heard of the fire analogy, I used one where John was accused of stealing something, because he had stolen something in that store numerous times before. However, John had an alibi (he was out with his friends) and Peter's fingerprints were all over the storen. The fact that John had stolen there before and Peter hadn't is by itself no evidence whatsoever of Jonn's wrongdoing or Peter's innocence.

Now admittedly, when I used this analogy with my dad a few years ago, it did result in a blank stare...

Perhaps more to the point of past climate change would be an analogy of body weight and how it responds to the energy balance of energy in (via food, drink) vs energy out (via metabolism and activity). I used such an analogy before to show that climate can't change by itself, but it can easily be adapted to show that climate had changes before:

Consider someone who has never eaten any chocolate (awful, isn't it?). His body responds like any other body though: If he eats more than his body needs, he will gain weight. Now someone shows him some delicious chocolate. The fact that he’s never had chocolate before doesn’t mean that his body wouldn’t respond to it. The knowledge that he gained weight when he ate more potatoes than he needed means that he will probably also gain weight if he eats more chocolate than his body needs. The knowledge about the effect of potatoes (past climate change) actually serves as a useful benchmark to gauge the effect of chocolate (current climate change).

2011-04-19 23:58:13
Bart Verheggen


Uhm, the names "John" and "Peter" were just chosen as translations of "Jantje en Pietje" in a typical Dutch tale. No relation to John Cook intented...

2011-05-24 22:16:36A few takes on this subject from climate scientists
John Cook


I'm on an email group where a few climate scientists are discussing how they'd answer the 'past climate change' myth and their answers are pretty kick-arse so I'm excerpting them here:

The same science that has showed us that the climate system varies naturally has shown is that the climate system will drastically change if you double atmospheric carbon dioxide.

The observations we have taken of the climate system confirm that understanding and we have certainly seen lots of evidence of the enhanced greenhouse effect over the last several decades.

You can talk about the 40% change if the audience is up to it.

Someone mentioned the bushfire metaphor, then another elaborated:

just because bush fires were caused by lightning before people settled in Australia does not deny the existence of nor urgent need to stop arsonists now.

Lastly, crunching some numbers:

First Law of Thermodynamics.  The CO2 emitted last century is trapping 700,000 GigaWatts of extra power into the planet.  You do the math.  (if he then says "but that's just according to some ... model" then you say "no--it's measured by satellites")
This may oversimplify by ignoring other forcings, feedbacks etc. but it puts the ball in the other guy's court to prove that all those factors can somehow make all that power go away (which of course they almost certainly can't).
2011-05-24 22:29:32
Paul D


Love the bush fire example. That hits home.

2011-05-24 22:33:07Bushfire metaphor
John Cook


I love it too but my search for a better explanation began when my bushfire metaphor fell flat on an audience (see start of thread). Maybe I just didn't say it right :-)

2011-05-24 22:55:09


Rivers naturally flow and form lakes. But if we build a dam the lake isn't natural.
The good side of this analogy is that it's also valid for the GHG effect, we're buiding a dam for the IR radiation.