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We have nothing to fear

I’m scared.

I must be, because I’ve been avoiding writing this post for some time, when previously I’ve been so excited to blog I’ve written until the early hours of the morning.

I’m a climate scientist in the UK. I’m quite early in my career: I’ve worked in climate science for six and a half years since finishing my PhD in physics. I’m not a lecturer or a professor, I’m a researcher with time-limited funding. And in the past year or so I’ve spent a lot of time talking about climate science on Twittermy blog and in the comments sections of a climate sceptic blog.

So far I’ve been called a moron, a grant-grubber, disingenuous, and Clintonesque (they weren’t a fan: they meant hair-splitting), and I’ve had my honesty and scientific objectivity questioned. I’ve been told I’m making a serious error, a “big, big mistake”, that my words will be misunderstood and misused, and that I have been irritating in imposing my views on others. You might think these insults and criticisms were all from climate sceptics disparaging my work, but those in the second sentence are from a professor in climate change impacts and a climate activist. While dipping my toes in the waters of online climate science discussion, I seem to have been bitten by fish with, er, many different views.

I’m very grateful to PLOS for inviting me to blog about climate science, but it exposes me to a much bigger audience. Will I be attacked by big climate sceptic bloggers? Will I be deluged by insults in the comments, or unpleasant emails, from those who want me to tell a different story about climate change? More worryingly for my career, will I be seen by other climate scientists as an uppity young (ahem, youngish) thing, disrespectful or plain wrong about other people’s research? (Most worrying: will anyone return here to read my posts?)

I’m being a little melodramatic. But in the past year I’ve thought a lot about Fear. Like many, I sometimes find myself with imposter syndrome, the fear of being found out as incompetent, which is “commonly associated with academics”. But I’ve also been heartened by recent blog posts encouraging us to face fears of creating, and of being criticised, such as this by Gia Milinovich (a bit sweary):

“You have to face your fears and insecurity and doubt. […] That’s scary. That’s terrifying. But doing it will make you feel alive.”

Fear is a common reaction to climate change itself. A couple of days ago I had a message from an old friend that asked “How long until we’re all doomed then?” It was tongue-in-cheek, but there are many that are genuinely fearful. Some parts of the media emphasise worst case scenarios and catastrophic implications, whether from a desire to sell papers or out of genuine concern about the impacts of climate change. Some others emphasise the best case scenarios, reassuring us that everything will be fine, whether from a desire to sell papers or out of genuine concern and frustration about the difficulties of tackling climate change.

Never mind fear: it can all be overwhelming, confusing, repetitive. You might want to turn the page, to change the channel. Sometimes I’m the same.

I started blogging to try and find a new way of talking about climate science. The title of my blog is taken from a quote by a statistician:

“essentially, all models are wrong, but some are useful” – George E. P. Box (b 1919)

By “model” I mean any computer software that aims to simulate the Earth’s climate, or parts of the planet (such as forests and crops, or the Antarctic ice sheet), which we use to try to understand and predict climate changes and their impacts in the past and future. These models can never be perfect; we must always keep this in mind. On the other hand, these imperfections do not mean they are useless. The important thing is to understand their strengths and limitations.

I want to focus on the process, the way we make climate predictions, which can seem mysterious to many (including me, until about a month before starting my first job). I don’t want to try and convince you that all the predictions are doom and gloom, or conversely that everything is fine. Instead I want to tackle some of the tricky scientific questions head-on. How can we even try to predict the future of our planet? How confident are we about these predictions, and why? What could we do differently?

When people hear what I do, one of the first questions they ask is often this:

“How can we predict climate change in a hundred years, when we can’t even predict the weather in two weeks?”

To answer this question we need to define the difference between climate and weather. Here’s a good analogy I heard recently, from J. Marshall Shepherd

“Weather is like your mood. Climate is like your personality.”

And another from John Kennedy:

“Practically speaking: weather’s how you choose an outfit, climate’s how you choose your wardrobe.”

Climate, then, is long-term weather. More precisely, climate is the probability of different types of weather.

Why is it so different to predict those two things? I’m going to toss a coin four times in a row. Before I start, I want you to predict what the four coin tosses are going to be: something like “heads, tails, heads, tails”. If you get it right, you win the coin*. Ready?

[ four virtual coin tosses…]

50p coin on cafe table

[ …result is tails, tails, tails, heads ]

Did you get it right? I’m a nice person, so I’m going to give you another chance. I’m going to ask: how many heads in the next four?

four more virtual coin tosses… ]




…results is two heads out of four ]

The first of these is like predicting weather, and the second like climate. Weather is a sequence of day-by-day events, like the sequence of heads and tails. (In fact, predicting a short sequence of weather is a little easier than predicting coin tosses, because the weather tomorrow is often similar to today). Climate is the probability of different types of weather, like the probability of getting heads.

If everything stays the same, then the further you go into the future, the harder it is to predict an exact sequence and the easier it is to predict a probability. As I’ll talk about in later posts, everything is not staying the same… But hopefully this shows that trying to predict climate is not an entirely crazy idea in the way that the original question suggests.

My blog posts here at PLOS will be about common questions and misunderstandings in climate science, topical climate science news, and my own research. They won’t be about policy or what actions we should take. I will maintain my old blog all posts at PLOS will also be mirrored there, and some additional posts that are particularly technical or personal might only be posted there.

At my old blog we’ve had interesting discussions between people from across the spectrum of views, and I hope to continue that here. To aid this I have a firm commenting policy:

  • be civil; do not accuse; do not describe anyone as a denier (alternatives: sceptic, dissenter, contrarian), liar, fraud, or alarmist; do not generalise or make assumptions about others;
  • interpret comments in good faith; give others the benefit of the doubt; liberally sprinkle your comments with good humour, honesty, and, if you like them, cheerful emoticons, to keep the tone friendly and respectful;
  • stay on-topic.

I’m extremely happy to support PLOS in their commitments to make science accessible to all and to strengthen the scientific process by publishing repeat studies and negative results. I’m also very grateful to everyone that has supported and encouraged me over the past year: climate scientists and sceptics, bloggers and Tweeters. Thank you all.

And thank for you reading. My next post will be about another big question in climate science:

How can we do scientific experiments on our planet?

See you next time.

* You don’t, but if you were a volunteer at one of my talks you would.

  1. Hi Tamsin, wonderful to see you here on PLoS blogs!

    I have benefitted from your previous online thoughts and look forward to what you will say here. Cheers

  2. I like to think of the differences this way. I look out of the window & see weather, climate is when everyone looks out of the window. People like to extrapolate from their own beliefs or experiences, but there are a lot of us with a lot of different experiences so we have to understand that there are usually multiple possible outcomes from any one start point.

    Looking forward to your articles! …& I wish the funding were not so limited for research like yours.

  3. Hello Proffesor T.
    I like the way you write and present a subject. Keep it up, as I am interested in climate modelling and will be following your blogs, as I have already a little understanding on the difficulties of creating a good model to help predicate the outcomes depending on what is being modelled.
    Good luck davy.

  4. Hi Tamsin,

    and really glad to see you there. keep on !

    This being said, a few words perhaps on climate and weather. Of course we always speak about the same system, the “climate system”, made of the atmosphere, hydrosphere, biosphere, cryosphere, etc. The key think to remember is that this system is highly multiscale. Some processes take minutes, other take hundreds of thousand of years, and there is plenty to fill the gap. So, depending on what you want to predict, you have different predictability horizons. For example, it makes sense to speak about the predictability of ice ages (one of my favourite subjects), just as it makes sense to speak about the predictability of weather.



  5. Hi there,

    Delete this if it’s off topic. I won’t mind.

    [ I snipped your off-topic policy stuff — Tamsin ]

    One more thing: United States (I am a citizen) denies climate change with more vehemence and more ignorance than most. What are the prevailing winds here in the UK (which I have lived for more than 6 years now)? Is it more of the same? The United States is famous and “getting famousER” for hating science, which boggles the mind because of how much science plays a roll in the countries past achievements, but that’s not the case here, is it?

  6. Hmm, you entirely forgot “naive.”

    [ I agree that “naive” shouldn’t be used by either side, but I wasn’t going to give an exhaustive word list! I think people get the general gist — Tamsin ]

  7. My only information on this subject comes from the media and politicians so I look forward to reading with an open mind , being better informed , even though any technical talk may go over my head. This first blog was fine for me,

    Be brave

  8. I am a research chemist that works with several climate change type researchers, and over the past couple of decades I have been fascinated with the science of climate change: models, observations, predictions, correlations, etc. A field rich for intellectual endeavors. But on a more human, emotional level it is very terrifying. The measurable changes and their logical trajectory into the future …..

  9. Jonathon,

    There is a difference in practical circumstances, although we might be excused for not noticing.

    [ Very sorry Alex – I snipped your policy-related comment — Tamsin ]


  10. “What’s perhaps more to the point,” he wondered, “do I have anything to fear by commenting or posing questions such as …”

    Dr Edwards, are there any pdfs generally available to an interested layman, without access to a technical library, which present all the equations (leaving out any turbulence model) that would be used for the simplest possible case of a perfectly spherical planet with a smooth uniform surface and an atmosphere consisting of air, including water vapour and trace gases? What boundary conditions would be appropriate?

    For a couple of years I have been looking at climate blogs and have gradually become more and more sceptical of the incredible claims of the MET Office and others. (It would not bother me in the slightest to be branded the denier or much worse that I feel myself to have become.)

    Is there really any difficulty in understanding the difference between climate and weather? Surely weather is what the Earth is observed to give us. Climate is what we make of it.

    Climate is an artificial human construct. We simply define what we mean by climate and there is nothing permanent in the definition. Climate follows from the actual weather together with the adopted definition and therefore ‘climate’ can be given no practically useful meaning without a full knowledge of the weather.

    Are there any consequences? Yes, it is futile to talk about computing climates if you cannot compute the weather. You cannot compute the weather because you do not know what causes the weather. If you knew everything that caused the weather and could reliably compute it over an extended period you could experiment with what need not be represented accurately in detail in the long term calculation for climate.

    I should think you would need to be able to predict the weather over something like a year, successfully, getting the climate exactly right, before a credible ten year climate calculation could or should be produced. I am talking about true prediction. Running a calculation from initial conditions which pertained a year ago and showing that conditions today are faithfully reproduced – what I think is called hind-casting – is open to abuse by the ad hoc adjustment of modelling assumptions. (Unfortunately some people cannot be trusted.)

    If the response is that this would be an impossible task then it follows that there can never be reliable climate predictions one hundred years in advance.

    Even tossing a 50 pence coin can have unexpected outcomes. It might end up balanced exactly on one of the seven edge faces, as shown in the photo. Taking the seven plus two possibilities, what probability can you assign in advance to each possibility? You have arbitrarily assumed that the coin analogy has only two equally probable solutions.

  11. Thank you everyone. Sorry for the delays in replies and moderating today but I haven’t been feeling well – bad timing!

    @Jonathan Payne – I don’t know the latest survey results for concern in the UK, but certainly the discussion is much less heated and polarised than in the USA. This makes it easier for each side to really listen to each other and have respectful conversations. I’m lucky to be based there.

  12. Tamsin,

    He asked about differenses between the US and the UK, in a direct response to him, I informed him of the UK climate changes legislation, which is a huge difference.

    The irony is that I described how it was not a matter of policy.

    If that be off-limits then I dispair.


  13. My observations are not about the content but the manner of this blog. So refreshing to see honesty, humility, courtesy, scientific rigour, and an ability to pull the veils away from obscure scientific process for those less versed in the “art”. So unfortunate to hear how much of the scientific community have responded. Regardless of where we sit on the opinion spectrum about climate and human influence on it, we need more Dr. Edwards and fewer zealous advocates. I will however also state we need more and not fewer skeptics. Skepticism is a foundation of scientific endeavour.

  14. Thanks for stepping out there Dr. Edwards. Professional scientists such as yourself need to do this kind of communication. It will be expected in the future, and so you are one of the vanguards in that respect– so be brave!

    Your point about the differences between climate and weather are well made, and I hope we get a chance to speak about the other differences, such as how climate reflects dynamical regimes of weather in the Earth system. Climate change is thus a regime change in the weather. These regime changes can be from natural variability and/or from external forcings. The science is about dissecting out those various influences and their causes over time. The extent to which climate models are useful is to the extent that they have got the underlying dynamics correct, even if (as you and others point out) they won’t get the natural variability correct, except perhaps by luck.

    I look forward to reading you posts.

  15. I looke forward to reading your blog. It will be very nice and information without the constant flame wars. I may actually have the opportunity to learn.

  16. Thank you for all your kind comments.

    We’ve been discussing the word “alarmist” on Twitter. Some think it’s not disrespectful. Others have wondered what we should use instead. Suggestions are welcome!

    My main point, though, is that we should avoid generalising about groups of people (“The think about ****s is…”) and only focus on particular science questions and understanding. Any word can be given negative connotations, if someone has that intent: for example, “watermelon” by James Delingpole to mean a socialist/Marxist disguised as an environmentalist (green on the outside, red on the inside).

    People can’t usually be lumped together as easily as these terms suggest. Some people use the term “lukewarmer” to describe themselves – accepting that humans affect climate, but not accepting the consensus viewpoint – but even this encompasses a wide spectrum of views. Lukewarmers might disagree with the consensus on the scale of change, or the speed of change, or the scientific uncertainties, or the seriousness to humans, or the political implications.

    In my experience, every single individual has a different viewpoint…

  17. Alex, please don’t despair! I hate snipping, and even saved a copy of your comment for myself.

    Your comment was all about legislation and/or policies, and not at all about science or the public understanding of science. I know these distinctions can be a little murky but I really feel you focused on “what we are doing / not doing about climate change” rather than “how do we make predictions” or “what are the common misunderstandings” etc. I believe Jonathan’s question focused on differences in scientific understanding rather than action. I should have pulled him up on using “denies” though.

    Please, do come back!

  18. Dr Edwards, are there any pdfs generally available to an interested layman, without access to a technical library, which present all the equations (leaving out any turbulence model) that would be used for the simplest possible case of a perfectly spherical planet with a smooth uniform surface and an atmosphere consisting of air, including water vapour and trace gases? What boundary conditions would be appropriate?

    taid, nothing comes to mind for me right now but I hope others will leave a link here if they know of something well-explained.

    ‘climate’ can be given no practically useful meaning without a full knowledge of the weather.

    This is true, I suppose, even if we define climate as the statistical properties of weather because we often do care about the order in which different types of weather occur – i.e. their correlation in time and space. But in many cases we are interested in something more simple, such as the average (in space and time) of a period of weather, so we don’t need to know every detail such as ordering.

    There are lots of subtle discussions to be had about short-term (“decadal”) forecasting, and about the effects of chaos on climate, but I think these will have to wait for further posts and comment threads…

    I took that photo of the 50p coin, in one of my favourite cafes 🙂

  19. I would agree that generalizations about groups of people should be avoided. No two people are the same, so lumping them in a group is wrong from the very start. Stick to the facts, the data, the science, the math, the models, etc. and- you’ll stay out of the mire that way and attract a better quality of posting here.

    There is just too much interesting science to be discussed and discovered, that putting labels on individuals only interferes with the process of honest discussion and analysis. Discussing what groups of people might tend to believe can sometimes be instructive for making a general point, but this kind of discussion would be rarely needed for honest and lively scientific debate.

  20. (1) Sounds interesting Tamsin. Maybe I’m missing something obvious, but is there any way to get an e-mail alert whenever you post a new entry? (Though not every time you post a response to a comment, since that would get overwhelming.)
    (2) I realise you’re making a different point here. But whenever I hear people say things like “we should avoid generalising about groups of people”, I have to chuckle as a social scientist, since we do that all the time.

    [ Hi Malcolm! There’s an RSS feed link at the top right. You can subscribe to it with an RSS service like Google Reader or, in most email programs, subscribe to it from in there. And yes, I agree a bit of generalisation can be useful! But there has been too much of it in the climate debate, which prevents civil discussion. — Tamsin ]

  21. Fully agree. What we need is a discussion about ideas and the evidence supporting or refuting those ideas. We will find no benefit and considerable harm in labelling the person who voices an idea. We will wander further from finding truth the more we lean on the crutch of categorizing the source of information. I find in particular social/political labels especially frequent in media and blogs, and essentially useless in evaluating the message or the evidence.

  22. I have wondered about that. Did Niels say it in English or Danish? Is Danish even a language? mmmm…Danish. If it was in Danish, is the translation correct?

  23. [ Hi Colin – sorry, I snipped your link to a cartoon as I found it too snarky. I want this space to be about improving understanding of the science and uncertainties, in people across the spectrum of views, while treating each other respectfully. Cheers — Tamsin ]

  24. Hi Skiphil,

    Yes I think it’s an interesting topic – the complementary merits and disadvantages of comments on blogs, open access peer review (e.g. journals such as The Cryosphere), closed peer review, etc.

    There was a strong piece by Mike Taylor last week that demolished excuses for not publishing in open access journals: “Hiding your research behind a paywall is immoral”. Today there’s some disagreement from Chris Chambers: “Those who publish research behind paywalls are victims not perpetrators”. I love the practical tips of the first, but also recognise the career-related problems described by the second.

  25. Here another model which certainly is not 100% correct.
    But better than the K&T type of diagrams.
    It gives also an idea that the heat evacuation from the planet, starts with convection, and only the last lap is LW radiation, from the IR-sensitive trace gases to outer space.
    But interesting shows that indeed we can get rid of that back-radiation.
    It is based on the one-way heat propagation concept.
    The two-way heat propagation formulation, initiated by Prevost in 1791 gives spurious absorption.

  26. Tamsin, thanks for the comment and the links. I would argue an intermediate position, that it is highly desireable to promote open access publishing but not ‘immoral’ to publish for a variety of reasons in pay walled journals. I won’t develop the points I am perhaps OT to your post, but thanks for your consideration. I look forward to following the discussions on this blog!

  27. Well, this is certainly on topic – the public do not understand science anymore because some through the education system have deliberately changed very basic physics in order to promote the concept “AGW Greenhouse Effect”.

    To save on space.., I refer you all to three recent posts elsewhere on this, these are direct science challenges to the claim that there is such a thing as “The Greenhouse Effect” as taught at university level.

    Posts 7 and 41 here:

    The basic ‘physics’ concepts of the Greenhouse Effect on which the models are built, the KT97 and ilk “shortwave in longwave out”, are built on science manipulation of the basics, there is only one word for this.., changing the basics which are still, to some, well known in traditional physics teaching.

    I began to question the science on which the models were based when I was told, by a PhD teaching physics, that carbon dioxide was an ideal gas and would therefore diffuse spontaneously at great speed into the atmosphere to mix thoroughly and could not be unmixed, without a lot of work being done.

    This is contrary to traditional physics which teaches carbon dioxide is a real gas with real properties and processes and real mass under gravity and at one and a half times the weight of air will therefore separate out of air, to sink to the surface.

    I was a short while later told by another PhD that the ‘heat we feel from the Sun is visible light’, as in the Greenhouse Effect energy budget “shortwave in longwave out” – in the real world we cannot feel visible light as heat, it is not a thermal energy.

    The Greenhouse Effect has changed physical properties of matter and energy in order to create the illusion that its claims are real physics.

    This is not science.

  28. taid, head over to

    Unfortunately in the later stages of the calculations he fudges a little by using constants that you will not be able to calculate yourself from the given parameters.

    If your calculus is okay and you know someone who understands atmospherics then you should be able to calculate the required values.

  29. Tamsin said:

    “..climate is the probability of different types of weather.”

    I regularly forecast weather types at daily to weekly scales directly from the solar factors that drive them, and a large proportion of my forecasts are deterministic. From this viewpoint, I would definitely say that weather types dictate the climate far more than a given climate regime effects the weather types. You are welcome to inspect my forecast techniques.

  30. This is a welcome, refreshing and non-confrontational approach to the topic of climate change. I really like getting back to basics (like the coin tossing), because so often the debate in the public media and blogosphere is really people trading opinions based on partial reading and understanding of the science. To have a productive debate, surely we must all start from a common understanding of the basics as well as being open about where the problems are. Trying to end debate by being 100% certain is not helpful. Unfortunately, the media expect certainty, so we don’t get politicians saying “the economy might get better”, they say “will”, even though the economic model this statement is based on involves variables which make climate modelling seem easy by comparison.

    On getting to the basics, I think too often science journalists assumes people are stupid too understand stuff. I think that often we need to explain a little more about the nature of the climatic systems in order that people can be better able to explore their understanding, for themselves. For example, the role of the oceans is critical to understanding where the heat is going, and a lay person might ask, “is there a limit to that? Can we relax because the oceans will just keep warming the air will not (albeit adversely impacting marine life)?” … Questions like these are an opportunity to initiate useful exploratory dialogue about the climate and the models.

    I wish you well in your goal to promote civilized debate on climate change. All we need are people who are genuinely interested in exploring the topic.

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