Archive for March, 2017

Climate Reflections

March 28, 2017

I am currently in Exeter attending the 22nd meeting of the WMO GCOS/WCRP AOPC. Let me translate:

In short, I am here to talk about monitoring the global climate with some of the best climate scientists from around the world.

The topics being discussed are diverse, and I am here to talk about one small part of the work. However, I feel honoured to take coffee with these people and to be able to legitimately call them ‘colleagues’.

My contribution is to speak on Thursday about creating a reference network of climate monitoring stations.

Historically, we have used records from normal weather stations to monitor the changing climate. But these stations have known biases that have to be detected and corrected.

It would have been really helpful if 100 years ago, scientists had thought to create a reference network where every time a new thermometer screen was installed, they recorded the fact. But they didn’t.

So the idea is to create that reference network now so that in 100 year’s time when climate scientists look back they will say:

“Thank heaven for AOPC-22: that’s when our job got easier! They created a Climate Reference Network that has allowed us to detect anomalies in the climate signal inferred from analysing regular weather stations.

But that’s not what I wanted to talk about.

The mood of the meeting

This meeting is busy. People are mindful of the ability of a roomful of scientists to chat endlessly about details. And to counter this there is a powerful focus on getting things done.

However President Trump casts a shadow over the meeting.

Trump collage

Headlines from news sites today.: BBC, Guardian and Ars Technica

And the news today is that he has signed executive orders that effectively scrap energy policies based on avoiding the worst effects of climate change.

Most people at the meeting find this depressing. And it would be an understatement to say that colleagues from the US are ‘concerned’.

Trump’s policies are ultimately based on a simple belief which is summed up in the graph below from the Gapminder foundation.

2013 data for the countries of the world showing GDP per person versus carbon dioxide emissions per person. Each bubble represents a country and the size of each bubble is proportional to its  population.

2013 data for the countries of the world showing GDP per person versus carbon dioxide emissions per person. Each bubble represents a country and the size of each bubble is proportional to its population.

The graph shows that countries that emit a lot of carbon per person are richer.

However the graph shows correlation not causation. Emitting carbon dioxide of itself does not make anyone richer.

Burning carbon produces energy, and it is access to energy that makes countries rich, and unequivocally improves the quality of people’s lives.

But emitting ~30 billion tonnes of carbon dioxide per year also has another effect which is not documented on the ‘bubble graph’. As the people at this meeting have helped make clear, it has warmed the surface of the planet and will continue to do so for centuries to come. But we no longer need to emit carbon to produce energy.

Currently renewable energy sources are (generally) more expensive than fossil fuels. But there is no reason why that will always be the case.

Indeed, if Trump’s aim is to make America independent of foreign energy sources, the best thing he could do would be to increase exploitation of renewable energy which would reduce its cost.

Personally, I think that it is already too late for coal and that Trump’s efforts to open coal mines and burn more coal will fail, just like efforts to create ‘clean coal’ have utterly failed.

 

Arctic Sea Ice update: everything is proceeding exactly as we had foreseen

March 25, 2017

Graph 2017

If you read The Guardian’s news coverage of the extent of Arctic Sea Ice, you might be forgiven for thinking that something special had happened.

Arctic ice falls to record winter low after polar ‘heatwaves’

They state that2017 is the third year in a row the Arctic’s winter ice has set a new low.“. And they quote the director of the US National Snow and Ice Data Centre (NSIDC) as saying

“I have been looking at Arctic weather patterns for 35 years and have never seen anything close to what we’ve experienced these past two winters,”. 

But the truth is simpler and can be seen and understood by a child.

The extent of Arctic Sea Ice is declining year on year.
It has been happening for a couple of decades and we have no reason to think it will stop. 

The graph at the head of the page shows the extent of Arctic Sea Ice in millions of square kilometres. This has been assessed by satellites* every day since 20th October 1978 and the data can be downloaded from here.

As the graph shows, each year the sea ice grows in the northern hemisphere winter by an astonishing 10 million square kilometres. And shrinks by a corresponding amount in the summer.

The graph shows that on average:

  • The maximum extent of the sea ice in winter has been falling by about 44,000 square kilometres every year.
  • The minimum extent of the sea ice in summer has been falling about twice as fast – by about 84,000 square kilometres every year.

So since 1979,

  • the extent of the winter sea ice maximum has fallen by about 1.6 million square kilometres  and,
  • the extent of the summer sea ice minimum has fallen by about 3.2 million square kilometres .

To put that into context, the 3.2 million square kilometres is about 12 times the land area of the UK – or roughly the land area of India.

The two graphs below show the decline in winter maxima and summer minima in more detail.

And what is clear is that the decline in Arctic Sea Ice this year is pretty much exactly what we would have anticipated.

Graph 2017-3

Graph 2017-2

What happens next?

Well, we are now talking about ‘the future’ so the answer has to be ‘nobody knows’.

But the trends look to be well-established, and in our best understanding, the ultimate cause of the decline – the warming of our planet’s surface – will not abate for many decades.

So eventually we will see the Sea Ice Extent fall to zero in the summer. Drawing a straight line through the data, one obtains an estimate of about 2065.

However many ‘so-called experts’ think that an ice-free summer will come much sooner. They argue that sea ice extent is a 2-dimensional measure of a 3-dimensional quantity – the volume of sea ice.

They argue that accompanying the decline in sea ice area, there has been a thinning of the sea ice.

Satellite measurements of sea ice thickness are relative new, and don’t yet show any clear trend. But despite that, scientists have been combining the sparse data that do exist with the data on sea ice area to produce an estimate for Sea Ice Volume . Their estimates are shown below.

Sea Ice Volume March 2017

Now we can see the true drama of the situation. While the sea ice minimum area has declined by approximately 30%, the sea ice minimum volume has declined by approximately 70%.

For this data, a linear decline no longer captures the trend of the data. Fitting a quadratic trend and extrapolating, the estimate of the date at which summer sea ice volume reaches zero moves forward from 2065 to 2021.

As I mentioned, we are discussing ‘the future’ so no-one knows what is really going happen: 2021 is probably too early, but 2065 is probably too late. This 2012 article discusses the complexities of this extrapolation in detail.

But as the trend continues, the likelihood is that the sea ice will become more fragile, and eventually it will become thin enough that even mild storms will break it up.

In our lifetimes** we will reach a condition where the sea ice in the northern hemisphere entirely melts every summer. The North Pole will have become the North Pool.

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*Reader: I had thought the measurement was made from analysing visual images, but in fact it is made using microwaves. The emission of microwaves from water and ice have different characteristic polarisations and the contrast allows the fraction of sea-ice to be estimated. Details here. Sorry for the initial mistake, and thank you to Victor Venema for spotting it.

**Reader: I hope your life is long and healthy.

How would you take a dinosaur’s temperature?

March 15, 2017
A tooth from a tyrannosaurus rex.

A tooth from a tyrannosaurus rex.

Were dinosaurs warm-blooded or cold-blooded?

That is an interesting question. And one might imagine that we could infer an answer by looking at fossil skeletons and drawing inferences from analogies with modern animals.

But with dinosaurs all being dead these last 66 million years or so, a direct temperature measurement is obviously impossible.

Or so I thought until earlier today when I visited the isotope facilities at the Scottish Universities Environmental Research Centre in East Kilbride.

There they have a plan to make direct physical measurements on dinosaur remains, and from these measurements work out the temperature of the dinosaur during its life.

Their cunning three-step plan goes like this:

  1. Find some dinosaur remains: They have chosen to study the teeth from tyrannosaurs because it transpires that there are plenty of these available and so museums will let them carry out experiments on samples.
  2. Analyse the isotopic composition of carbonate compounds in the teeth. It turns out that the detailed isotopic composition of carbonates changes systematically with the temperature at which the carbonate was formed. Studying the isotopic composition of the carbon dioxide gas given off when the teeth are dissolved reveals that subtle change in carbonate composition, and hence the temperature at which the carbonate was formed.
  3. Study the ‘formation temperature’ of the carbonate in dinosaur teeth discovered in a range of different climates. If dinosaurs were cold-blooded, (i.e. unable to control their own body temperature) then the temperature ought to vary systematically with climate. But if dinosaurs were warm-blooded, then the formation temperature should be the same no matter where they lived (in the same way that human body temperature doesn’t vary with latitude).
A 'paleo-thermometer'

A ‘paleo-thermometer’

I have written out the three step plan above, and I hope it sort of made sense.

So contrary to what I said at the start of this article, it is possible – at least in principle – to measure the temperature of a dinosaur that died at least 66 million years ago.

But in fact work like this is right on the edge of ‘the possible’. It ought to work. And the people doing the work think it will work.

But the complexities of the measurement in Step 2 appeared to me to be so many that it must be possible that it won’t work. Or not as well as hoped.

However I don’t say that as a criticism: I say it with admiration.

To be able to even imagine making such a measurement seems to me to be on a par with measuring the cosmic microwave background, or gravitational waves.

It involves stretching everything we can do to its limits and then studying the faint structures and patterns that we detect. Ghosts from the past, whispering to us through time.

I was inspired.

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Thanks to Adrian Boyce and Darren Mark for their time today, and apologies to them both if I have mangled this story!

Light Sabre Research

March 5, 2017

img_5001

Sometimes one finds oneself by chance at the cutting edge of a new field of research.

This Saturday, I found myself in a secret laboratory in the heart of England, and I was fortunate enough to try out the latest in Light Sabre technology.

It’s risky: It’s scary: but if one is guided by ‘the force’ then great things may be possible.

May the force be with you.


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