My thanks to you both for you kind words. Thanks to all of you for coming
I must say I stand here with some considerable trepidation because
I'm a climate scientist not a historian
and I didn't know very much about John Tyndall as little as a year or two ago
when my friend, Professor Ray Bates of University College Dublin, whom I've known forever,
told me that they were thinking of having a conference in 2011
to celebrate the 150th anniversary of Tyndall's great paper - and here we all are.
Meanwhile I've been reading about Tyndall and I need to thank the EPA.
And as you may know there's a scientific conference
starting tomorrow in Dublin Castle and running through Friday
and it's cosponsored with the Royal Irish Academy
I'm grateful to the organisers and to the sponsors - that's why I'm here
and I've been steeping myself in books on Tyndall and articles on Tyndall.
There's a wonderful 30 page article by Charles Mollan that I commend to you all.
There's a book by Norman McMillan and J Meehan
and there's an edited collection of papers edited by Brock and the same McMillan and the same Mollan,
and so I was taken aback a few minutes ago when a gentleman walked up to me and said
"Hi I'm Norman McMillan" I said "Oh my God I've been reading your books!"
I've never been - in fact I've never been very much outside of Dublin in my trips to Ireland,
and I’ve certainly never been to Leighlinbridge but I’ve met some people tonight who
are very much from Leighlinbridge and so I have begged their and your forgiveness in advance
for the mistakes that I'm bound to make
I've been practising saying Leighlinbridge, which doesn't look that way when it's written, to me.
It's incidentally a great feat, a great boon, for amateur historians of Tyndall like myself
that many of his own books, he had a massive output of books especially popular books based on his lectures
and many of them are available free online
and I've been downloading them from my home in France free
and putting them on my e-book reader which is called a Kindle, I don’t know why,
but which I now call the Tyndall.
OK - With that as background.
The plan for tonight is I am going to spend the first half of the talk
discussing John Tyndall, the man and his scientific accomplishments,
and then I'm going to change gears halfway through,
and try to give you all a thumbnail sketch of the present state of climate change science
and relate it to what Tyndall has done.
It turns out that he was very much a prophet
and certainly a great, great scientist of whom Ireland should be proud.
The pictures that one sees of Tyndall tend to bear an eerie resemblance to one another
he is always looking at you and he tends to have this rather serious visage.
It turns out, I think, that you see a good deal of Tyndall the man in the portraits.
He was very much in the tradition of his time, a self-educated and self-made man.
At the beginning he had a prodigious work ethic and I'll mention some of his accomplishments as we go along
but Tyndall, when he set himself a task, threw himself into it.
Tyndall was born in 1820 in Leighlinbridge in a family that was by no means wealthy.
His ancestors had come over in the 17th century.
His father was passionate about learning - there was a lot of discourse in the family.
He was not however well paid, he was a member of the constabulary.
But Tyndall was very strongly under the influence of his father and remained so until his father's death.
His father passed away in 1847 at the peak of the famine.
I think that Tyndall in some ways modelled himself after his father.
It was thanks to him that he learned a great deal at home.
He was kept in school longer than usual for a boy at that time in those circumstances.
After finishing school,
(one could talk a great deal about his schooling which was interesting in many ways)
he joined the Irish Ordnance Survey at age 18, so that would have been in 1839
but after 3 years of, as it says here, hard work, long hours and low pay,
he transferred to the English Survey.
He didn't think he had much of a future in the Irish Survey.
In the English Survey some of what we know later to be characteristic of Tyndall came out
he didn't fancy the way the Survey was being administered,
he didn't like the way the Irish workers were treated by their English bosses
and together with quite a few others, he was dismissed
and went back to Leighlinbridge without any money and without any prospects.
Then the next year went back to England to work for a private surveyor, surveying for the railroads.
He left that job, again thinking that it didn't have much of a future, as the railroad mania died down
and took up teaching and the school that he taught at, Queenwood College in Hampshire,
was, I think, what we might call today a progressive or experimental,
certainly a highly innovative school in many ways.
There he met a person who became his fast friend and colleague.
Tyndall later in life demonstrated an enormous talent for making and keeping friends
and Edward Frankland who was the science teacher while Tyndall was the mathematics teacher
was perhaps the first of the intellectual or technical friends that Tyndall made.
They taught one another. Remember Tyndall hadn't been at university at this point
and his education was sketchy. He never, for example, learned the Classics, learned Latin,
but he was largely self taught and he told Frankland
"I'll teach you some mathematics if you teach me some chemistry", which they did.
Again very seriously; they got up early, they worked hard,
this was not an amateur or a dilettantish episode.
In 1848, although it sounds strange to today's aspiring young scientists, because these were people
without much money and without a university education they decided to go to Germany, which they did.
1848, Tyndall remember was born in 1820s, he was not yet 30. This is what he looked like at about that time.
Again I see a great similarity in the portraits that we have of Tyndall.
The university they went to was then, is still now, a first rate university in Marburg
they arrived there in the Fall of 1848,
and Tyndall at that point ran into the first of quite a few extremely famous and accomplished scientists
with whom he bonded you might say.
Bunsen is known to every school student of chemistry now because of the Bunsen burner,
the little thing that makes heat in the chemistry lab,
which Bunsen actually invented with the help of his laboratory assistant.
But Bunsen was a first class scientist at that time.
He was as you can see here not that much older than Tyndall and he was running a lab.
I don't know the details by the way of how this was arranged and financed.
I know that Tyndall took a loan for part of his expenses in Germany from a friend.
But Bunsen later became even more well known.
He discovered two chemical elements: Caesium and Rubidium.
He investigated emissions spectra, a subject very closely related to the work Tyndall did
that I am going to tell you about, that is so important to atmospheric and climate science today.
By his own admission Tyndall was ill-prepared for getting a PhD under first rate scientists.
He ended up working with other scientists, Knoblauch is one of them other than Bunsen
but Bunsen made a huge impression on Tyndall
and he said that Bunsen was an "extremely clear and dedicated lecturer"
Tyndall at one point wrote that he learned German by listening to Robert Bunsen
but when he started out he knew very little German and as I've said
he had a rather sketchy and incomplete background in mathematics and science.
He certainly didn't have a university degree in them
but once again he was a workaholic.
He got up at 5 o'clock in the morning, he hammered and by 1850
he'd completed the requirements for his PhD.
I think to someone today the idea of getting a PhD in physics,
a word that was by the way almost unknown at that time, it had been invented in 1840,
and Tyndall himself was one of the first scientists to call himself a physicist,
but to get a PhD in physics in a first rate university, under superb supervision with high standards
in only two years, coming with a rather incomplete background, is an extraordinary accomplishment.
I've looked at his PhD dissertation; I would call it rather abstractly mathematical,
and far from his later interests, but it demonstrated his capacity for work.
Tyndall kept diaries, wrote letters, had a prodigious output of words all his life
and if you read them, you can tell today that making himself at home in Calculus for example,
which is the prerequisite for all advanced mathematics, was not easy for him.
Tyndall made a lot of friends and he stayed in Germany. I'm not going to give details there isn't time.
And he met many of the leading German scientists of that time,
and also younger scientists, up and coming people, and maintained contact with them
and he made a favourable impression on many of them.
He was already interested in work - he was working on diamagnetism.
I'm not even going to define that for you but it has to do with magnetism.
He was on his way to becoming a good scientist when it was time to go back to England.
Going back to England, he learned, in the words of one of the books I've been absorbing,
that being a good scientist may have been very good for one's reputation but it didn't put food on the table
and he returned to teaching math at this school at Queenwood,
applied for and didn't get jobs at several universities, including here in Ireland.
Nevertheless and this has to do, I think, with Tyndall's ability to impress people, right away
he was elected a Fellow of the Royal Society in 1852, at a very young age of about 32.
Then, we can see it in retrospect - I'm not sure it was as clear at the time,
but then a magical day arrived in Tyndall's life which was the 11th February of 1853
where through people he had met, people who by the way in the usual way,
had known the German scientists he'd worked with, had heard good things about him,
were willing to help him advance his career and get a foot in the door in England,
he was invited to give one of the famous evening lectures at the Royal Institution
on Friday February 11th in 1853
And he worked hard, Tyndall all his life worked hard at presentation.
He was equally a fine scientist and a superb populariser and educator
and presenter of science to both technical and lay people.
He gave a lecture we can regret that there was no video camera in that day
so we can't look at it, but by all accounts it was dazzling.
And it impressed a true scientific superstar who was Michael Faraday
who was at that point superintendent and director of the Royal Institution in London.
Not all of you are scientists.
Faraday, let me say a word about him for those of you who may not know,
he has been described by knowledgeable historians of science as "the greatest experimentalist ever".
He impressed everybody and he had a lot in common with Tyndall
he wasn't very mathematical in the manner of the great 19th Century British Victorian era scientists
Rayleigh, for example, or Maxwell.
He had a rather limited mathematical toolkit as did Tyndall
but he was a gifted experimenter with profound physical insight,
and the kind of things that you can't teach, the ability to choose the right questions to work on.
Einstein, to give you a little anecdote, Einstein kept 3 portraits in his study
one of them was of Isaac Newton, one of them was Maxwell and the third one was Michael Faraday.
The unit of capacitance in the metric or System International system
the farad is named for Faraday. He made major discoveries.
He discovered mutual induction in electricity and he provided the experimental background
for much of the mathematical formulation that Maxwell is famous for.
Tyndall made a huge impression on Faraday and you couldn't ask for a better patron.
So as a result of his big success in that 1853 lecture he gave a series of lectures,
also very well received, and was offered a position at the Royal Institution
where at this very young age, he was elected Professor of Natural Philosophy
and he turned down more lucrative offers at other Institutions to stay there.
His initial salary was £200. I haven't tried to translate that into present day numbers
but it wasn't very different from what he was making as a math teacher at Queenwood.
He actually had to complain a few years later that the inducement of a later raise hadn't materialised.
The Royal Institution after a while figured out that he was good for them and they were good for him.
They made him happy and he spent his career there.
Tyndall would remain at the Royal Institution
for essentially the rest of his scientific career for 34 years.
It was an interesting place at the time, one could talk a great deal about the Institution
but it both was devoted to the development of new knowledge
and to instruction, or to spreading new knowledge, the kind of thing that Tyndall was very good at.
This is a picture of a picture of a picture of Tyndall giving a lecture.
There are wonderful stories of the things Tyndall did to make his lectures interesting
and there were series of lectures at the Royal Institution in that day
at which the cream of London's society would come, so very high ranking and distinguished people
from all walks of life, men and women both, would come to these lectures at the Royal Institution
and Tyndall worked assiduously,
you might say obsessively, preparing his lectures.
There are wonderful anecdotes, one anecdote:
a lady was visiting the Royal Institution when she saw a lithe young man
leap over a counter and catch a falling glass jar
and she was surprised when she showed up at the lecture
that the same young man was giving the lecture
and at a critical moment he leaped over this counter in front of him here and caught the jar
Tyndall had been rehearsing that little bit of stage craft.
I remember one story that says he had put a grand piano
in the basement of the Royal Institution where it couldn't be heard;
he had a pianist playing on it,
and he had a hole cut in the floor of the lecture room above
and a stick, a big wooden pole, standing mounted on the sounding board of the piano
coming up through the hole and he put the peg of a cello on the stick
and suddenly the sounds of the piano downstairs
were being heard throughout the lecture hall coming from the cello
which was picking up the vibrations.
He was masterful at creating stories about science and illustrating it vividly.
One of his accomplishments was to explain why the sky is blue
something that Rayleigh later put in mathematical form
but it has to do with the scattering of light from small particles
Tyndall's way of bringing this home to people was to talk about
the beautiful blue eyes of a beautiful woman
and that was due to the small muddy particles that were in her eyes scattering light.
He was utterly charismatic; I've said some of this here.
This was the Golden Era. Remember the people listening to the piano coming from that cello
had never heard a high fidelity stereo system, there was no radio, there was no television,
the only way to hear music was to be in the room where it was being played
so a lot of ranking scientists of that time also made an effort to be popularisers of science
Faraday was one and Huxley the supporter of Darwin in evolution was another.
It's hard to find exact modern equivalent.
The American astronomer Carl Sagan was a superstar on television
and attracted huge audiences for TV and books.
Jacques Cousteau who never called himself a scientist but was a French adventurer
and explorer and inventor and filmmaker probably is responsible for more of
what the world knows about the ocean today than any research oceanographer.
Tyndall wrote up his lectures, published them as articles, published them as books,
once again, working all the time and became very well known for them and eventually
made a good deal of money.
Tyndall was not any kind of a hermit or an inhuman geek, he was a man, he liked women
he had proposed marriage unsuccessfully but he finally married at aged 56
to a woman who was 25 years his junior.
As usual he was writing about everything he did,
he told his sister that "she was not what you would call handsome
nor was she wealthy, but we're going to be very contented together". And they were.
It was a wonderful marriage.
Tyndall by that time had fallen in love with the Alps.
He had started there just walking but after a while became mesmerised, captivated by the Alps
he had built a summer place there.
He went back there summer after summer for decades, she went with him.
Tyndall was quite a mountaineer
he was studying glaciology, that is why do glaciers move, and other questions of the time.
This was the Golden Age, you might say of individual exploration,
Tyndall was almost the first man to climb the Materhorn and he did several other first ascents.
And reading his adventures there, he was physically courageous to the point of being foolhardy.
and there are terrifying stories of Tyndall arranging the rescue of climbers and cows who had fallen into crevasses and so on.
He later in life developed ill health.
He had insomnia all his life, he then suffered indigestion, asthma, eventually gout,
and had to take a series of drugs,
and died tragically when his wife accidentally mixed up the drugs in 1893
at that point his scientific career was behind him and he was no longer a healthy man
it was a very innocent accident but a tragedy.
Again, every picture I see of Tyndall seems to be the very same Tyndall, but with a slightly different beard.
Tyndall did a lot of things scientifically. His research interests were quite broad
I think that we are going to talk tonight mainly about his work on what we call today the greenhouse effect
but he did first rate research in many other areas.
I could take all night reading you his list of honours and the scientific societies he belonged
to and he eventually succeeded Faraday as the head and the sole superstar of the Royal Institution.
I want to skip this because I want to spend sometime talking about
that other instrument that you have already seen a clue of.
I think that even those who admire Tyndall unconditionally as do I
would say that he never shirked from controversy
he was combative he was sometimes aggressive I made a mistake here
it's not a contemporary but a modern scholar I thought I had to show this for this audience
the very model of an Irishman "wild, athletic, a hard worker and a fluent talker".
Tyndall had very strong political views, he was spending his time in England,
not in Ireland of course, but he had strong views on Irish politics.
He was a strong supporter of Darwin and Evolution, which brought him into
a strong conflict with the Catholic Church of that time and its supporters.
His own views about religion were quiet he was very likely an agnostic.
Personally he was very generous I was taken by the story of a triumphant lecture tour
that Tyndall made to the United States in 1872 and 73 which was very profitable.
He ended up with a very substantial sum of money
which was wisely invested and became even more substantial, and he gave it away -
he put it in trust with some American academics to support young American scientists
he didn't like the educational system in England or Ireland or the US at that time.
He said if you wanted to learn science you ought to go to Germany
and people did and there are Nobel Laureates today
who were Tyndall scholars supported by the proceeds from that endowment.
This is the instrument I thought I would spend a little bit of time on
because I've spent a little bit of time trying to figure it out.
This one actually went on tour with him it was in the US
I'm going to try to shine my laser pointer on here on this screen over here
I hope that people can see it.
This is what you use if you were Tyndall 150 years ago
to see whether the gases carbon dioxide and water vapour which are present in small quantities in the atmosphere
as well as the gases that are present in large quantities,
the atmosphere is nearly all nitrogen and most of the rest of it is oxygen,
absorb energy in the infrared part of the spectrum.
Infrared energy, called radiant heat and other things like obscure heat by Tyndall, was a new discovery.
it had been discovered in 1800 by Herschel but was poorly understood,
and Tyndall invented this instrument and it works like this
this thing here is a brass tube, about 4ft long, it's a little longer than a metre,
in which you could either evacuate all the air or you could put in any gas that you wanted.
This tubing here is the pumps for putting the gases in and out
this is a heat source over here it's essentially a Leslie Cube which is a cube that has boiling water in it
or some other constant temperature source of heat and has different faces
typically silver, black, gold and so on so it radiates at different rates
the tube is blocked with rock salt which are plates of sodium chloride, same material that is common table salt,
which is transparent to heat but wouldn't let the gas in or out.
So you put the gas you are interested in in this tube,
you seal it off with this rock salt, you heat it and then this is essentially a collection of thermo-couples
It's a device that comes under various names
but it's a device that converts a heat differential between 2 services into a voltage.
This is wires from it to an ammeter here a galvanometer which was the ammeter of the time
in fact if you read Tyndall's classic 1861 paper which is on the Tyndall Conference website
it starts out with pages and pages of how tough it was to get the instruments to his quality
and how he had to find non-magnetic copper wire from proper sources and he basically
designed and built this from scratch and he had a very clever idea.
Over here is another heat source just like this one
and it is shining into another one of these thermopiles, collections of thermal couples,
so this one is measuring the heat that comes from the gas the heat that has passed through the gas in the tube
which is a brass tube that was arranged so that it didn't reflect or absorb any heat.
This one is absorbing this thermopile on the left side is absorbing the heat from here
and there is a screen here and by moving the screen with a clever little thumbscrew device
through very tiny dimensions as small as a thousandth of an inch Tyndall could regulate
the amount of heat going here until it exactly balanced this amount of heat.
So he had created a kind of differential thermopile
it measured not how much was being absorbed but the difference between this and that.
So he would adjust this little screen until the galvanometer read zero
the needle was right in the middle and then fill the tube with whatever gas was in question
and he could then measure the amount of the gas.
He brought this thing along he would use it in demonstrations and he would aim it at
his laboratory assistant's face and the needle would move
because you and I and everybody else are radiating in the infrared
we radiate in the infrared because of our temperature, if we were as hot as the sun
we'd radiate in the visible and other parts of the spectrum.
But the radiation depends on the temperature and the laboratory assistant's face
would radiate enough energy so that the needle would move so
that when he was doing research Tyndall had a telescope mounted
and stood across the room from this galvanometer
so he could read it at a distance without having a person there who would screw up the measurements.
without having a person there who would screw up the measurements.
He went through this kind of thing, he did years of research with this sort of instrument
and variations on it and found that indeed the hydrogen
and the oxygen and the nitrogen in the air, simple molecules, molecules of 2 atoms H2, N2, O2
didn't absorb energy in the infrared
but the more complicated atoms carbon dioxide CO2
and water H2O and so on did.
Now we know why
the answer comes from quantum mechanics
there wasn't any quantum mechanics in Tyndall's day, he was long before that
but experimentally he found out that these multi-atomic molecules, tri-atomic and larger molecules
absorbed and therefore emitted energy in the infrared.
Tyndall was no slouch, he immediately realised the implications of this
and I've written down a quote for you here, he said:
"without water vapour the Earth's surface would be held fast in the iron grip of frost".
It is important to realise what was known about infrared energy;
nobody else had made these measurements, as I said Tyndall invented the instrument.
The work that had been done was very speculative, very abstract, very theoretical.
Fourier, a first rate mathematician and physicist had theorised about this
but what Tyndall did was put the thing in the laboratory, get the measurements,
have the numbers, replicable numbers, publish in great detail so others could repeat his data.
Tyndall put the greenhouse effect on a sound laboratory empirical foundation
and he realised immediately this was important for climate so in the 1861 paper,
which is online, he wrote that
"a slight change in the amount of these gases could have important effects on climate"
then he speculated "such changes in fact may have produced all the mutations of climate
which the researches of geologists reveal".
It's amazing how prescient that statement 150 years ago is.
For example, we know today which Tyndall could never have known
that ice ages come and go because of changes in the Earth's orbit around the sun
which affect the pattern, the geographical distribution and magnitude of solar radiation, solar energy reaching the Earth
and these changes, which are predictable and hindcastable,
coincide exactly with the geological evidence for when ice ages started and ended
but the orbital variations alone aren't sufficiently large to cause an ice age
or to cause a planet in an ice age to come out of one, instead we now know
from ice-core work and so on, in which we can measure the CO2 in the atmosphere in ancient times
that as the orbital variations trigger the entering into or coming out of an ice age
they alter the CO2 amount so CO2 essentially comes out of the ocean in a warming planet
and that CO2 strengthens the natural greenhouse effect and adds to the warming
so that the CO2 lags the initial temperature change but is responsible for amplifying it.
In fact that's one of the ways we know that climate is sensitive to the carbon dioxide in the atmosphere
no computer models, no hand waving, just empirical fact.
A lot of things happened after Tyndall we don't have a lot of time but I want to mention two scientists
one is Svante Arrhenius who was no slouch. He was Swedish, he later won a Nobel Prize in chemistry
and he did laborious hand calculations and estimated that if you were to double the amount
of carbon dioxide in the atmosphere (he was interested in the ice age issue too
and he thought he would take thousands of years to do that - he was wrong)
if you double it then at equilibrium the world would warm
on average by about 6 degrees Celsius at the Earth's surface.
That's about two times larger than the number that we think is correct today.
But Arrhenius had the basic physics right
for example he understood the water vapour feedback
as you warm the atmosphere more water vapour
enters the atmosphere from the ocean, the whole hydrologic cycle amplifies,
more water is evaporated from the sea, more water is precipitated to the land,
and the water vapour itself, as Tyndall had shown, is a powerful greenhouse gas:
it too absorbs solar energy
and it too acts like a blanket and makes the planet warmer than it would otherwise have been.
He knew about that he got a lot of the physics right and his estimate with very crude
-remember, no satellite data, no super computers-
his estimate was within a factor of two of the modern answer because he was lucky,
his model, his theoretical model was too simple and that tended to move the result in one way
his spectroscopy was also wrong but that tended to move the result in the other way.
So we can look at it and say this man had huge insight also like Tyndall
he worked tirelessly, he carried out hand calculations for years, no computers at all.
Now we are going to jump to today
this is the most famous graph in Earth science; this is the Keeling Curve.
It shows the record of carbon dioxide in the atmosphere from 1958
when Keeling began the measurements 'til today
it's risen in these units which are equivalent to molecules per million molecules
from 315 to about 390 on annual average.
The oscillations that you see up and down every year are the biosphere breathing
they're photosynthesis and respiration driven by northern hemisphere plants.
The rise is entirely human caused - entirely human caused.
There is no natural factor in the rise at all, we know this. Keeling figured that out too
by isotopic analysis which can differentiate between the CO2 that comes
from burning coal and oil and natural gas and the CO2 from natural sources
like volcanoes which are much smaller than the coal and oil and natural gas.
This again is a rock solid result, nobody questions it:
mankind has changed the chemical composition of the atmosphere
in fact we know from studying CO2 trapped in ice cores
that in the 19th Century when the industrial revolution was beginning
this scale would have gone down to about 280
it's gone from 280 to 390, so better than one in four molecules of CO2
in the atmosphere today are there because you and I
and our seven billion friends and their ancestors all put them there.
Tyndall and Arrhenius who did the calculations and Keeling are three of my heroes
who belong in the Pantheon of Climate Science and to summarise their accomplishments.
It's insulting to do it in one line for each of them.
Tyndall did the experiments in the lab that showed CO2 and water absorbing infrared heat
Carbon dioxide you know is perfectly innocuous molecule, it's what's in champagne and in beer
and soda its colourless, odourless, tasteless, non toxic but it does absorb and emit infrared radiation.
Arrhenius did the first serious calculation,
his were the forerunners of the computer models we use today
and Keeling made the first measurements. Keeling and Tyndall were alike in many ways
they both observed nature, Tyndall in the laboratory Keeling in the natural environment
Keeling like Tyndall built his own instrument and designed it
just as there was no way to measure
absorption by gases in the lab until Tyndall figured it out and did it
Keeling was the same
and I'll say a few words about Charles David Keeling, whom I knew well.
He spent his entire career at Scripps Institution of Oceanography in San Diego
where I'm a professor and I knew him well for the last 25 years of his life.
He died in 2005, his work is being carried on now by many others, including his son,
who is a professor at Scripps.
Keeling was single minded, obsessive
Roger Revelle, the great director of Scripps,
said that Keeling had a gene for measuring carbon dioxide, and in fact
Revelle brought Keeling to Scripps as a post doctoral fellow in the 1950s.
Keeling was born in 1928 so he was only 30 when these measurements began
in his late 20s when came to Scripps
and Revelle, whom I also knew well, who was a towering charismatic, booming voiced figure,
magisterial in every way, terrified people just when he walked up to them,
Revelle said to Keeling "now you are here at Scripps
you're going to do what oceanographers do,
we'll put your instrument on a ship, we'll go around the world, we'll measure CO2 everywhere
and we'll come back and do it again in 10 years and see if it's changed".
And Keeling who was a post doc, the lowest life form in the academic calendar,
Keeling said to the great Revelle "that's a really stupid idea"
because Keeling had already made a lot of measurements
and knew that CO2 stayed in the atmosphere long enough for the winds to mix it around
so for climate purposes the amount of CO2 is the same everywhere
and he said "if you just let me put my instrument in one place
and measure it continuously there, we'll have a record that's good for the whole planet
and it should be a pristine atmosphere, a place remote from sources"
and the picture on the right is the observatory on Hawaii where Keeling put his instrument.
Now in fact there is a global network of these instruments but Keeling was right.
As I said like Tyndall he wasn't afraid to fight and he was single minded and devoted and incredibly skilled
I'm going to switch now and in the time I have left I'm going to
say a few words about the science since then and the graphs I'm going to show you
are taken from a book called The Copenhagen Diagnosis.
It's a hundred page book published by Elsevier, it's online,
a slightly earlier edition for free, Copenhagen Diagnosis. You can Google it and get it.
We wrote it in 2009 as a prelude to the Copenhagen UN Climate Negotiation
to bring the science up to date
We pointed out that fossil fuel emissions are growing.
This is the number that would have gone down a little bit from the left hand side in 1990 it's 41% higher
the global economic recession has put a one year hiatus in this curve but now it's started to go up again
We also mention that the temperature has been rising
now CO2 rising and the temperature rising does not mean causality
- the stock exchange was rising, hemlines were rising -
but this is the global average surface temperature record, it is rising,
and a lot of detective work has been done to establish the cause of this rise
the ups and downs are Las Niñas and El Niños mainly
This is the strongest El Niño in recent times in 1998
so if your nextdoor neighbour who is not persuaded of the tennets of modern mainstream climate science
says there hasn't been any warming since 1998
he is doing something that scientists call cherry picking
he has picked an anomalously large El Niño number
in fact in 2009 we said - the book came out in November - we said we don't have the 2009 data
but based on 11 months of data it looks like it is going to lie right about on the line
and in the revised edition which Elsevier has published it did lie on the line and 2010's a bit higher.
From the point of view of climate, this scatter year to year
is less important by far than the long-term trend
which is a little less than two tenths of a degree Celsius per decade
and which multiple data sets and a lot of analysis have confirmed.
And in fact we know now that seen in the longer time period
- this is two data sets compiled independently by two research centres -
In the longer sense there's been a rapid rise, starting in the 1970s
preceded by about 30 years of relatively flat
and some ups and downs about a nearly constant value,
stretching back into where records began.
The global network of thermometers only became good enough to make sense
to try to compile a global number in the mid 19th Century.
There's a lot of other things that are happening too.
The last report of the Intergovernmental Panel on Climate Change came out in 2007,
a new one is in the works now it'll be out in 2013,
It came out in February, we didn't know then but in September when Arctic sea ice is a minimum
that the minimum which is this white area here would be far smaller than the average minimum
for the previous years. 1979 is the beginning of the satellite era for this purpose.
We don't have good measurements of Arctic sea ice data
sea ice thickness is also falling and if you look at this as a graph versus time
this is 2007, these were the predictions of climate models on the average
and the blue area was the range of them and so the actual extent of Arctic sea ice
has fallen below the worst case scenario than any of the models.
Sea ice now, September is not quite over yet, but it's going to be close to the 2007 value.
Sea level is another indicator of climate change; every time the climate warms
sea level goes up because the oceans expand thermally ice on land melts and flows into the sea
and we now know that sea level is going up which we didn't know in 2007
because the Greenland and Antarctic ice sheets are both melting and contributing to it
The satellite data here, global altimetry data the technology is so slick now
that you can actually measure to within a centimetre or so the distance between the satellite and the ocean surface
and it falls on top of these surface based tide gauges are essentially floats on shorelines
so sea level is rising and the rate of rising is accelerating.
The IPCC which is much maligned but is a simple organisation
that convenes scientists together, it doesn't do research, but every six years
it convenes hundreds of scientists together to write an assessment
that is designed to be policy neutral and not policy prescriptive but it should be relevant to policy makers
It's a 3000 page report, there's a 30 page technical summary, and for the media there's a one sentence summary.
I was on Pat Kenny this morning and I am still smarting from that
"the balance of evidence suggests a discernible human influence"
if that looks like a lawyerly negotiated sentence it was
it was negotiated in a little mini UN General Assembly you might say
when all the nations were present and the rule was unanimity was needed
if a word wasn't accepted by every country it didn't get in there so that's what the nations agreed on
then six years later "there is new and stronger evidence that most of the warming observed" over the last half century is human caused
then in the last report I was a co-author of this report
"warming of the climate system is unequivocal" as we see from many kinds of evidence
it's not a single slender thread it's a thick rope if you like of evidence.
This is the last substantive slide I want to show (I'm getting very near the end of my time)
This is what we in the trade call detection and attribution. What you are looking at here
is for the six inhabitant continents in these six panels and for the world as a whole
all the land surfaces of the world and all the ocean surfaces
in each of these nine figures the black line is the observed average temperature near the Earth's surface
so in North America, it went up it went down in mid century has been going up steeply
in Europe similarly this is a sketch of the global pattern so the black lines on each of these show you
that the world is warming everywhere in recent decades
and they tell you a lot right away, so for example
if your sceptical next door neighbour says "well you know
this warming is just a side effect of instruments being contaminated by being in urban areas
they used to be out rural the city grew up the instruments are anomalously warm",
well there aren't any cities in the oceans but the ocean has been warming too.
The other things on each of these panels are a pink area and a blue area
and they are a collection of simulations of the climate with our best computer models
that's why it is an area and not just one line with two sets of assumptions
in the blue ones the assumption was
the factors that we'll have put into the model are the ones we know about that are natural
that we know in the past have caused climate changes: volcanic eruptions
which cause temporary coolings, variations in the sun which can cause warmings and coolings
and the blue is that in each of them the blue doesn't capture the recent warming
but the pink which are the same models used to simulate with the additional input of human effects
extra greenhouse gases in the atmosphere, extra small particles in the atmosphere, do capture it
So this is a thumbnail of a huge body of work called "Detection and Attribution".
Detection - finding out whether the signal is different from natural variability.
Attribution - finding out whether you can attribute the warming in this case to a specific cause
and that leads in fact to the second of the IPCC conclusions in 2007
which is that "most" (means more than 50%, I've been asked that by reporters)
most of the observed increase is "very likely" (that means 9 out of 10 chances)
science doesn't give you certainty
due to the observed increase in "anthropogenic" (that's jargon for human cause
greenhouse gas amounts.
So we have a statement that the world is unequivocally warming
and that with very high confidence we can say that most of the warming is human caused.
This is my last slide. This is three possible scenarios. It's from German research
analysed in the Copenhagen Diagnosis where the emissions that means
the rate at which we're putting carbon dioxide and equivalent gases into the atmosphere
in billions of tonnes, gigatonnes, of CO2 per year
as a function of time, from the present here out to mid century,
and the three lines here, green, blue and red, are three possible scenarios.
There's an infinity of scenarios; these all have the same area under the curve,
so they all give you the same total emissions of CO2.
The curves differ in that in the green one the assumption is we peak global emissions which I've shown you
are going up rapidly right now and we start to decrease them
if you do that you could decrease them gradually
with a peak decrease of less than 4% per year because you've done energy conservation and energy efficiency
and switched to renewables and nuclear and so on
and then by mid century you are still allowed to have some CO2
the thing about CO2 is it's up there forever. It lasts for centuries, some of it lasts for millennia
so the carbon dioxide your grandchildren are going to inherit the climate of
is the carbon dioxide that is essentially proportional to the total amount emitted by all of us.
If you wait until 2015 to peak and decrease the emissions you have to go down more steeply
and by 2020 you have to go down at 9% per year which economists will tell you is
difficult and maybe impossible.
I call this the ski slope diagram. (I'm learning from Tyndall and say things in a catchy way)
this is the beginners slope and this is the intermediate slope and this is the double black diamond expert slope here
so you get your choice. Now as you can see in the legend here
these are the amounts of CO2 that our best science says gives you a two out of three chance
of limiting warming to 2 degrees Celsius.
Why 2 degrees Celsius above 19th Century temperatures?
Because governments have agreed on that. That's not a science decision.
That's a decision that involves risk tolerance, priorities, how strongly you value the precautionary principle,
what your economics are and so on but the European Union has accepted that 2 degree target formally,
It's official policy of the European Union, has been for several years,
and other countries have signed on to it noncommittally and that's when science can help you
because once you've said this is the amount of warming we're willing to tolerate
then science can tell you what that means in terms of how much greenhouse gases
you are allowed to emit into the atmosphere.
That's using the modern science, a direct descendant of the pioneering work that Tyndall did
to produce results that are policy relevant
the scientists didn't choose those 2 degrees but once you've said it's like choosing your ideal weight
then your doctor and your nutritionist can help you, tell you how to reach it and maintain it.
Once you've said that's your target, I don't want to go above 2 degrees within a certain probability,
science tells you here's the options this is what the climate system tells you
so there is an urgency to this, ladies and gentlemen, that is not at all political, has nothing at all to do with ideology
but once the world has decided through its governments,
and deciding to do nothing is a decision, once the world has decided what to do,
what kind of climate change you are willing to accept then modern climate science
thanks to the work of people led by John Tyndall can help you tell what you have to do to meet that target.
Thank you very much.
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Professor Richard Somerville, Distinguished Professor Emeritus and Research Professor at Scripps Institution of Oceanography at the University of California, San Diego.
Tyndall: His Work and Scientific Heritage