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 Twitter, my 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…]

[ …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 allmodelsarewrong.com: 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.