Archive for December, 2015

Just how mild has this December been?

December 30, 2015
A great deal of rain has fallen on some parts of the UK this month (December 2015)

A great deal of rain has fallen on some parts of the UK this month (December 2015) (Source : BBC)

It’s been exceptionally warm this month.

We will have to wait a day or two for the various agencies to compile their annual reports, but let me précis the results for you:

  • 2015 has been ‘warm’.

And this  warmth has been evident where I live and work, in Teddington.

Analysing the data from my weather station a day early, I have compared my local results with the ‘climate normals’ for nearby Kingston upon Thames.

‘Climate Normals’ are the average values of various meteorological quantities over (typically) 30 year periods, in this case from 1981 to 2010.

Graph showing the 'Climate Normals' for the daily maximum and minimum temperatures for Kingston upon Thames. Also shown are data from my weather station for September, October, November and December.

Graph showing the ‘Climate Normals’ for the daily maximum and minimum temperatures for Kingston upon Thames. Also shown are the averaged data from my weather station for September, October, November and December. Click the graph for a larger version

My data shows that locally:

  • The average minimum temperature for December was higher than the expected average maximum temperature!
  • And the average minimum temperature is more characteristic of May or June, than December!

Averaged over the whole of the UK, the differences from the climate normals are reduced.

However the rainfall rates in particular places – thankfully not Teddington – have been shockingly extreme.

The image at the head of the article suggests that in North Wales, 50% more rain fell in December than in the previous record breaking December. FIFTY PERCENT!

It is well-understood that this extreme rainfall is linked to the general  warmth of the air. Why?

The amount of water vapour that can be held in air is much larger than one might at first imagine, and increases from around 5,000 tonnes per cubic kilometre of air at 0 °C, to nearly 18,000 tonnes per cubic kilometre of air at 20 °C (Link to Data or see the graph below).

Thousands of tonnes of water? Yes. One cubic kilometre of air has a mass of approximately 1.7 million tonnes and water vapour makes up about 1% by mass at 20 °C.

Humidity versus Temperature

The mass of water in tonnes in one cubic kilometre of saturated air is surprisingly large. Every rise of 1 °C results in an increase in ‘holding capacity’ of around 6%.

So air which is 5 °C warmer than normal can hold roughly 50% more water than normal – and hence has the potential for increased rainfall.

And if the winds bring a stream of this warm, moist air across highland regions, then extreme rainfall is inevitable. And breaking rainfall records by large amounts becomes not only possible, but likely.

I am aware that not all air is saturated, and that air temperature varies with height, and that there are complex mixing patterns in the atmosphere. And I am aware that this rate of ‘moistening’ does not apply globally.

But for air travelling over the ocean to the UK, every one degree rise in air temperature corresponds to an increase in water-holding capacity of around 6%.

At it’s heart, it actually is that simple: if the wet air striking the UK was cooler, rainfall rates would not be so extreme.


I have found it thrilling that my weather station has produced meaningful quantitative data about the local weather and climate.

Although the station is very basic, it has allowed me to go beyond qualitative comments. This is the essence of scientific observation

And in a meditative sense, the simplicity of the endeavour brings me great pleasure, especially when compared with the near impossible things I am trying to do at work at the moment!

Happy New Year and all that.

Further Reading

NOAA’s ‘State of the Global Climate’  analysis for November.

The UK monthly weather summary.

NOTE: This post was updated on January 9th 2016 to reflect the fact that I got the water holding capacity of air wrong by a factor 1000! Air holds THOUSANDS of tonnes of water per cubic kilometre

Climate Hopes and Fears.

December 14, 2015
FT Calculator for Greenhouse Gas emissions required to achieve various degrees of global warming.

FT Calculator for Greenhouse Gas emissions required to achieve various degrees of global warming. If we continue on our current path, we are headed towards – in our best estimation – 6 degrees Celsius of global warming. The calculator allows you to see the anticipated effects of the pledged emission reductions.

The Paris agreement on Climate Change is cause for hope. In honesty, I cried at the news.

But the task that the countries of the world have set for themselves is breathtakingly difficult.

And in the euphoria surrounding the Paris Accord, I am not sure the level of difficulty has been properly conveyed.

The process will involve an entire century of ever stronger commitment to meet even the most minimal of targets.

Imagine going on a long car journey full of 200 ‘children’ who will bicker and fight – some of whom are not too bright but are armed with nuclear weapons. How long will it be until we hear the first ‘Are we there yet?’ or ‘ I wanna go home now!’ or ‘ Can I have some extra oil now?’ or ‘It’s all Johnny’s fault!’ or ‘It’s not fair!’

Perhaps unsurprisingly, it is the Financial Times that has cut to the chase with an Interactive Calculator that shows the level of emission reductions required to meet various warming targets.

The calculator indicates that if we continue on our current path, we are headed (in our best estimation) towards 6 °C of global warming.

The calculator then allows you to see the anticipated effects of the pledged emission reductions.

What is shocking is that even the drastic (and barely believable) reductions pledged in Paris are not sufficient to achieve the 2 °C limit.

As quoted by the Guardian, James Hansen (whom I greatly admire) is certainly sceptical:

“It’s a fraud really, a fake. It’s just bullshit for them to say: ‘We’ll have a 2C warming target and then try to do a little better every five years.’ It’s just worthless words. There is no action, just promises. As long as fossil fuels appear to be the cheapest fuels out there, they will be continued to be burned.”

Hansen suggests all governments should institute a $15/tonne carbon tax (rising each year by $10/tonne) . He sees the price of oil (and coal and gas) as the single essential lever we need to pull to achieve our collective goals.

Personally I am with Hansen on the need for urgent action right now, but I feel more charitable towards our leaders.

I don’t know whether it is more rational to feel hopeful or fearful.

But despite myself, I do feel hopeful. I hope that maybe in my lifetime (I expect to die aged 80 in 2040) I will have seen global emissions peak and the rate of increase of atmospheric carbon dioxide begin to flatten.


The first and second laws of climo-dynamics

December 8, 2015

Amidst war, instability and terror, the most powerful people on Earth have gathered in Paris to discuss the effect human beings are having on the Climate.

In my opinion this is cause for rejoicing!

Many groups express doubts that the leaders and their teams will do ‘enough’ to stop the Earth warming by 2 °C. And I agree.

However I am not worried because I think that progress in this field is controlled by the immutable Laws of Climo-dynamics – the climate equivalent of the laws of thermo-dynamics.

The first and second laws of thermo-dynamics

The first law of thermodynamics is essentially a statement that every physical process which actually occurs must conserve energy.

This allows us to identify some processes as being impossible. For example, the amount of power that a solar panel can supply is limited by the amount of energy in the sunlight which falls upon it.

However some physical processes which are possible according to the First Law simply do not happen. For example, a cup of hot tea always cools to the temperature of its surroundings – it never spontaneously warms up to a temperature above its surroundings.

This reality is the content of the second law of thermodynamics. The second law explains that there is a quantity called entropy – and processes which occur spontaneously only ever cause an increase in entropy.

Together, the first and second laws of thermodynamics tells us which processes are energetically and entropically possible. And thus they identify processes which will occur spontaneously.

The first and second laws of climo-dynamics

To understand what will happen in the Climate Talks, we need to understand the analogous laws of Climo-dynamics

In particular we want to know whether the laws of Climo-dynamics permit a transition to an economy based on renewable energy.

For most of the 20th Century, such a transition was technologically impossible. But somewhere towards the end of the last Century, a transition to a renewable-energy economy  became technologically possible.

What changed was subtle. New materials enabled giant wind turbines, and new battery and fuel-cell technologies enabled cars that could work without hydrocarbon fuels. And solar panels enabled renewable electricity generation on a colossal scale.

So a transition to a renewable energy economy has been technologically possible for a couple of decades now. What has held up the transition has been the second law of climo-dynamics.

What is not widely understood is that the individuals and countries in this drama cannot act freely any more than the atoms and molecules in a gas.

A change – no matter how technologically favourable – can only occur when it is politically possible.

But once a change has become both technologically and politically possible, it becomes inevitable.

And this is – I believe – where we are right now. There is widespread acknowledgement of the reality of the problem, and solutions exists at prices which are on the edge of economic viability.

What will happen next?

Back in 2012 I wrote:

I do feel that people’s consciousness is changing, and it does seem inevitable that we will – eventually – begin to face up to this problem. At some point in time, the graph [of annual carbon emissions] will peak – and we will begin to move beyond the carbon age. Let’s hope it is sooner rather than later.

Friends,  Le jour de gloire est arrivé. It seems that ‘sooner’ is ‘now’. News reports indicate that annual carbon emissions may have peaked, and I look forward in my lifetime to seeing the rising trend of atmospheric CO2 concentration begin to slow.

During the Cuban  Missile Crisis, humanity stood collectively on the brink of apocalypse. But we stepped back.

I think that Climate Change represents a threat of equivalent magnitude, but I believe that we are again about to step back from the brink.

Amidst war, instability and terror, political reality changed, and we are finally facing up to the technological and political realities of climate change.




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