Thank you very much for your applause and Sherry (Sherwood Rowland) is a very difficult act to follow
because what you will notice is that I have some of the same sorts of slides,
although they are much better quality when Sherry reads them.
The title may surprise you, something called anthropocene, it’s a term I launched some 5 or 10 years ago maybe,
indicating that I think we are geologically seen in a new era.
And where mankind influences the environment to major degree and I can only see that this,
at least for the foreseeable future will be increasingly the case.
So if I don’t make a mistake now.
So since the beginning of the 19th century mankind due to its growing activities opened a new geological era, the anthropocene.
Anthro means man.
For instance, we are clearly effecting climate and can deliberately do so and we call that geo-engineering,
to which I will come back a little later in the talk.
You can almost read it for yourself but maybe in the back of the hall even these slides are difficult to read.
During the past 3 centuries human population has increased 10 fold to more than 6 thousand million or 6 billion in American units.
And which 4 fold in the 20th century.
Cattle population increased to 14 hundred million, that’s by a factor of 4 during the past century.
And cattle produces methane among other sources of methane, cattle is an important one.
So the cattle, there is basically one cow in the world which supplies a family of 4 with milk and cheese and steaks.
But they produce methane and effect climate and chemistry of the atmosphere.
Industrial urbanisation grew more than 10 fold in the past century, almost half of the people now live in cities
and even more in mega cities.
Especially the latter is happening in the developing world, I’ve no good explanation for that.
Why people in the developing world want to live in mega cities.
Industrial output increased 40 times during the past century.
And energy use 16 times.
50% of the land surface has been transformed by human activity and water use increased 9 fold during the past century
to about 800 cubic metre per capita per year.
65% of that is used for irrigation, 25% for industry and 10% for households.
It takes about 20,000 litres of water to grow one kilo of coffee.
11,000 litres of water to make a quarter pounder and 5,000 litres of water to make 1 kilo of cheese.
So in the rich countries we have an oversupply of water and over use of water, in developing countries this is not the case.
Human appropriation of terrestrial net primary productivity is on the average 30% but with large uncertainty.
So the real number is somewhere in the range 10 to 55%.
Fish catch increased 40 times, the release of SO2 sulphur dioxide to the atmosphere,
currently about 130 million tonnes per year, by coal and oil burning is at least twice the sum of all natural emissions.
Over land the increase has been 7 fold causing acid rain, health effects,
poor visibility and climate change due to sulphate aerosols.
Releases of NO to the atmosphere has also increased very much,
this is about 25 million ton of nitrogen hitting the atmosphere due to human activities.
And that gives rise, and this I talk about the NO in the troposphere, that gives rise to the ozone mountain,
the ozone which you see in summer time, the summer smoke ozone.
Several climatically important gases have substantially increased and the numbers are 30% for CO2 and more than 100% for methane.
That was of course shown by Sherry, we see here why we definitely can talk about anthropocene, what is shown in these new graphs.
You see over the last 10,000 years the amount of CO2 in the atmosphere didn’t increase or decrease much, maybe a slight increase.
But you see this jump here, and that’s about, that started about 200 years ago and is accelerating.
And we see here the last few hundred years depicted in the inset here, you see especially the rise in CO2 especially
and I’ll come back to that happening after the Second World War.
The same with methane, same sort of picture, the same for N2O
and there are many other gases if you would have measurements of them, definitely would show the same features.
And of course that means that we get warming and warming units are given in watts per square metre and I will come back to that.
And most of that was happening after the Second World War.
Typical pictures, if you will consider the activities, the economic activities, the damming of rivers,
the use of fertiliser, consumption of water etc, this could be a very long list, I just give you a very short indication,
really a lot happened over the last 60 years, 50 years since the Second World War.
Humanity is also responsible for the presence of many toxic substances in the environment
and even such which are not toxic at all but which nevertheless have appeared in the ozone hole.
And I go to the next slide because Sherry has talked about this,
of course ozone is important to trapping or filtering out radiation from the sun.
Species extinction.
Under natural circumstances species extinction was about 1 species per million per year, it’s now 100 to 10,000 times larger.
So if you take the middle of this wide range it would say that the risk for depletion,
of extinction is about 1 species per 1,000 per year.
So if that number is correct then that’s major influence on the environment.
Erosion is much due to human activities, the human made natural erosion is about 15 times larger,
the human made erosion, soil erosion is about 15 times larger than the erosion coming from natural processes.
We can look at the use of nitrogen fertiliser, we see one line, that is the natural nitrogen fixation rate over land
and of course that doesn’t show much of a change over time, it’s a natural phenomenon.
And the units are given here in teragram, in million tonne per year.
The anthropogenic nitrogen fixation, that’s synthetic fertiliser use, grew especially strongly after the Second World War,
you have the same feature here.
And it surpassed the natural nitrogen fixation by, basically this is down to using agriculture to produce food.
And one of the by-products of that is N2O which was also mentioned by Sherry
and plays a large role in the chemistry of the stratosphere.
It’s also a greenhouse gas.
Something about the composition of the atmosphere can be rather quick, Sherry showed this,
almost all air is contained in nitrogen, oxygen and argon.
We cannot influence their concentrations in the atmosphere to any degrees but the little bit of trace gases which,
gas which is left, they are gases which can be influenced by human activities, methane, ozone, N2O, CFC gases,
all of this was shown by Sherry in some way and I don’t think I need to repeat this.
We see a strong rise of the concentrations of these trace gases.
We had one success story, the chlorofluorocarbons are no longer increasing in the atmosphere.
These are the most impressive curves of human activities in the atmosphere, we see the growth of carbon dioxide,
also shown by Sherry and the ozone hole.
Something which surprised everybody of us, spring time ozone hole which shows a steady decline
by altogether a factor of 3 in the atmospheric concentrations of Antarctica.
And where is this ozone depletion happening, it’s just happening exactly in the height region
where normally you have a maximum in ozone, you're going down to zero in very short time.
Now when this data became available they were not accepted very easily because this is so surprising,
so especially our British colleagues analysed the data over and over again but they got the same answer,
so this was really happening and it shows you that in the atmosphere strange things can happen
because of human activities or any other activities but in this case human activities.
Something about the greenhouse effect, the earth receives about 300 watt per square metre of energy from the sun.
If we call that 100 units then what comes down to the earth surface is about 47 units because of absorption of radiation,
short wave radiation in the atmosphere, reflection to space what is left is 47.
This 47 units at earth surface, the earth has to get rid of and it does that in the first place by the release of,
by the evaporation of water at the earth surface which is cooling and also by heat convection.
That’s about 18 units or, so the earth still has to get rid of about 16 units or 18 units of radiation.
But it’s just not shooting up 18 units, what's happening is that there is a trapping of the radiation
by the greenhouse gases in the atmosphere.
So you have tremendous recycling which is taking place here of heat radiation in the atmosphere,
that’s the heating of the atmosphere by human activities.
This is the result; you get a temperature increase, especially of the last 50 years,
about 20 centimetres sea level rise and more to come in the future.
And also reduction of snow-covered areas.
That’s coming from the IPCC analysis of 2007.
Here we show the heat balance of the atmosphere in the orange colour, you see the greenhouse warming explained by Sherry
so I won’t deal with it, would explain much of it, you know about it also, what is interesting is
and what is very uncertain is what is happening with regard to the reflection of solar radiation by particles in the atmosphere.
Most of these particles which are listed here, sulphide particles, organic particles, all of those are basically air pollutants.
And you want to take out these from the atmosphere,
but if you do that then the cooling effect supplied by the particles in the atmosphere will disappear so it will get warmer.
So we have a choice here and a dilemma for policy makers which one can foresee.
There is also the uncertainties are tremendous of course, this slide goes back to the IPCC 2001,
the numbers are better known and Sherry explained this.
But these particles also affect cloudiness because clouds are formed on aerosol particles.
So with more particles in the atmosphere the more droplets of water in the clouds
and that means that the surface to volume ratio of clouds become bigger and you get more reflection
and that’s a very important term about which we are struggling to put estimates, make estimates of.
So the IPCC in 2001 made the following statement, warming of the climate system is obvious,
comes from increase in global temperatures, ocean temperatures, sea level rise.
It’s of the order, for doubling of CO2 in the atmosphere, we know by the end of this century the heating
which is expected or projected by the IPCC is between 2 and 4.5 degrees Celsius.
The sea level rise is projected to be between 20 and 58 centimetres by the end of this century.
However Stefan Rahmstorf and quite a few more claim that these are severely underestimated,
we are really talking about 0.5 and 1.4 metres by the end of this century.
For doubling of CO2 of course we don’t know whether CO2 is going to double, that depends on the behaviour of human beings.
Other effects and hence redistribution of precipitation and hence risk for extreme weather,
increase in heat waves in Europe as in the summer of 2003 and too rapid climate change so that eco systems cannot adapt.
What is needed to do about this is we have to reduce the emissions of CO2 in the first place
and methane second place maybe, nitric oxide in the atmosphere.
To stabilise the amount of CO2 in the atmosphere the required reduction in emissions is more than 60%.
When you realise how difficult it will be, in reality we don’t have a reduction in the amount of CO2 in the atmosphere
but we still have year by year an increase by 2 to 3% of the emissions.
So we are on the wrong track.
The same in methane we have almost constant levels, Sherry showed that and we should be happy
but maybe this is just an interim phase because if for instance the tundra
and artic regions are going to warm then the permafrost we talk about,
then that will release CO2 to the atmosphere and probably also methane.
So we shouldn’t be happy that we have solved the problem.
Nitric oxide comes from agricultural activities and needs a reduction of 80% to stabilise.
So really we cannot expect that to happen.
But we have also the greenhouse, the CFC’s which makes us a little happier because they are banned from use.
And here we see the emissions in metric tons of CO2 per capita per year
and you see that our American friends are taking a big share but Europe and Oceania also add their contribution.
And you see the poor countries which are not part of the game yet and they definitely will become,
that makes it even more difficult to stabilise or decrease the amount of CO2 in the atmosphere.
Also shown by Sherry, any time in the past when temperatures went up or down due to Milankovitch cycle, climate cycle,
any time temperatures reached a maximum, also carbon dioxide and the greenhouse gases went up,
so they didn’t help much in combating the climate impact.
They in fact strengthen the impact of the Milankovitch cycle.
And very sensitive are the high latitude regions.
The global average we will come back to but in this particular model doubling of CO2
gave increase in temperatures in the tropics of the order of 2 degrees but you see at high latitudes,
especially in the northern hemisphere bigger, much bigger increases.
And that’s reflected in reports.
New studies indicate that the artic oceans, ice cover is about 40% thinner than 20 to 40 years ago.
There is dramatic climate change happening in the artic, about 2 to 3 times faster than that for the whole globe.
And then that brings me in addition to the melting of permafrost and possible release of CO2 and methane.
Can we do something against greenhouse gas emissions, well in the first place what is required
is that we reduce the emissions of CO2 and also methane but in the first place CO2 to the atmosphere, that’s absolutely needed.
That can be done by energy savings, renewable energy, nuclear energy, winds and solar energy and sequestration of CO2.
But that is not what we see is happening very much, the increased amount of CO2 in the atmosphere is worrisome.
And one can ask oneself what would it take if one would increase the reflectivity of solar radiation to cool the atmosphere,
the earth and the atmosphere.
What would be the effect of 1 to 2 million tons of sulphur emissions in the stratosphere,
in the stratosphere where things stay around for a long time, so you don’t need so much materials,
still 1 to 2 million tons is still a lot but if you would put in so much in the troposphere it would go much worse.
And we would have an enhanced greenhouse acid rain effect.
What would happen if we supply sulphur to the stratosphere in this amount.
You do that by balloons or aircraft, you bring H2S for instance in the stratosphere and then the stratosphere,
in the stratosphere the H2S is converted into sulphate particles by many reactions and they reflect solar radiation.
Here is a picture of how it looks like, this is the stratosphere, starts with higher altitudes over the equator
and then in the troposphere you can put in the sulphur here, preferred air motions will come down into the troposphere.
So we, together with some scientists, Phil Rasch and Danielle Coleman, we did some model calculations
with some of the most advanced models we have and we supplied this model with sulphur and look what's happening.
The concept is not new, it’s not mine, it goes back originally to Bodyko a Russian scientist, 1977,
there has been reports on this by the US national academy of sciences and also some more recent studies.
And our study is the newest one.
What do we do, we fix aerosol and greenhouse forcing at present level, present day levels over the earth,
that's what we call the control case.
Then we do a calculation in which we add CO2, then that would heat the atmosphere and the earth surface.
Alternatively we inject 1 teragram of sulphur per year as SO2 at 20 kilometres, between about 10 degrees north
and 10 degrees south, we call that geo-sulphate, that should cool the earth and the atmosphere.
And then you do both and if you do both that may indicate that we could do something about the heating of the atmosphere,
even if we don’t like to do that.
And here are the results of the calculations.
If you take the global annual average surface temperatures, you see here the control case,
here you see the increase of temperatures because of the increase, the doubling of CO2
and here we get the decrease of temperatures for 1 teragram of sulphur input into the atmosphere.
And if you do both you come down to this curve which is not far away from the control case.
So in the computer it works.
With precipitation basically the same results.
Control case just shown here a little bit, then the increase precipitation, you expect from a warm earth
and the decrease precipitation you expect from the sulphate injections.
And then you get the average is head on.
If we look at the earth surface we double times, 2 times CO2 case, you see the heating of the polar regions,
if you put sulphur in the stratosphere the whole area has become more or less white,
that means we are in the temperatures between 0 and around plus or minus 0.5 degrees Celsius.
There is some radiation coming, some effects still warming, still some warming at higher latitudes
and that is due to the fact that in winter time the radiation cannot come down here,
it’s dark and so the greenhouse effect is doing its work here.
So any time in the past when volcanic eruptions happened, model calculations have been conducted,
comparing the observations, the observations and model calculations and this is a model by Soden et al
and their conclusion is that models can reasonable simulate response to substantial aerosol lowering in the stratosphere.
So it looks good but there are problems.
I come back to that, some closing thoughts.
We propose to study, not do it yet, certainly not do it yet.
The albedo scheme only to be used if climatic changes are drastic, say of the order of 2 degrees Celsius globally averaged
and if there are no serious side effects.
And there can be serious side effects.
Maybe we have modelled the hydrological cycle very well.
Things depend also on particle size and chemistry, ozone, the ozone hole may be more long living
because at the moment it’s returning to normal but it will take 50 to 100 years,
if you put sulphur in the stratosphere it would take longer time because more chlorine will be activated.
Then we have the question do the particles, do they effect cirrus clouds in the upper troposphere and local stratosphere,
that could be a very important effect which we should be very careful about modelling.
And we have maybe the main shock is that the oceans are going to be acidified.
And if that is the case then certainly will have an impact on the ecology of the oceans.
So on paper things look good, but in reality we should be very careful not to do such an experiment
but I have shown these calculations to give you and others an idea
about what we have already done to the atmosphere because of the emissions of CO2.
And to counteract that we would have to put 1 to 2 million tons of sulphur each year for many years in the stratosphere
and that looks very ridiculous but it is as ridiculous as what we do with regard to the emissions of CO2 to the atmosphere.
And I thank you here for your attention.