Dear Barry,

Thank you for the question. In deed, it is not common to ask what would be the tendency of CO2 rate (and consequently of climat and life on earth) without the input of fossil carbon. But i cannot find any data that shows that "CO2 had dropped to dangerously low levels" There is, in deed, a drop following the Holocene optimum but the values are far from the typical values of ice-age. Moreover it seems that this drop is much smoother than the increase connected to industrial activities from 20th century.

In an other hand we cannot deny that a cooling of climate "even very smooth" instead of warming would have different consequences (posistive or negative ?) for some ecosystems (or part of ecosystems) . What is stressed by many scientists is the speed of warming which is drastic and does not allow many ecosystems to adapt.

Hope it helps in the debat

Best regards

Damien

No, it did not. The magnitudes and the lengths are entirely different.

For Dr. Kenneth, the well-being can be even better without using fossil energy on the current level. There are other important factors improved life, for example, the incredible development of medicine.

Humanity exploited all the oil arose in millions of years within two centuries. This is (was) a one time opportunity for undeserved wealth and prosperity. We should use it wisely for future generations. The fossil era is over, not because of global warming but because of the cheaper renewables. It means that replacement of fossils could happen earlier, before global warming or run out of cheap oil happens.

CO2 levels were indeed much higher in the Eocene and throughout Earth's history the composition of the atmosphere has fluctuated constantly.  One of the reasons for this is the planet is tectonically active.  Life (other than human) on the planet also causes significant alterations to both oxygen and CO2 levels.

We, as a species have been adding CO2 to the atmosphere for more than 1500 years because of human industry, which was underway centuries before what we commonly describe as the Industrial Revolution.  Human populations had deforested huge swathes of Europe by 1200 CE and burned the wood in charcoal furnaces or iron smelting.  During the last 1000 years the climate fluctuations have in the main however been caused by tectonic events or a change in solar activity.

Some of the climate fluctuations in the last 1000 years have been far more pronounced than the one we are currently witnessing and they caused quite severe problems in agriculture and freak weather.  None however threatened mass extinction or total collape of civilisation as that predicted by some of the more fanatic climate change advocates.

It is quite fascinating that in spite of the proportionately large increase in CO2 in the last century that the effect on climate and sea level has been modest.  Local fluctuations may indeed have been more pronounced but globally the effects are very small.

Returning to the Eocene (interesting prospect that it is)  Had humans evolved during that period the biosphere would have been quite capable of supporting a population and an industrial output the equivalent of that of today.  The very much higher levels of CO2 did not cause runaway greenhouse gas accumulation leading to a Venus like planet because on a tectonically active planet that is not possible. 

CO2 has promoted living conditions for hundreds of millions of years. What then went wrong? The concentration of CO2 in the atmosphere has already reached 410 parts per million (ppm), compared to the 280 of the pre-industrial era, but the most significant figure is that over the last 50 years the increase was equal to that in the previous geological epochs required 5000 years! This shrinkage of one-hundredth factor measures the intensity of the forcing action, the global warming, which has caused the shift from stability to climate instability (see, eg, Abrupt Climate Change, NRC Report, 2002 , The National Academies Press, Washington, DC). With all the global consequences we are experiencing, that are negative and will not change in positive. In fact, the lasting of CO2 in the atmosphere for centuries and other phenomena that increase global warming - CFCs that will be circulating into the atmosphere for many decades, the dreaded melting of permafrost, the reduction of reflecting power of earth surface due to the diminution of the extension of glacier masses - imply as highly unlikely the return of a colder age.

Therefore, thanks to the old positive effects of natural greenhouse gases, but now, since just a few days ago Antarctica left a colossal iceberg over 5000 square kilometers (as large as an Italian region, Liguria), it seems evident to me that the problem we face is to implement definitely the Paris Accords.

I also think that the horse has run away from the stable, but it is not a good reason not to engage himself in the actions of mitigation, mainly those that are possible by every citizen of the planet

Massimo

The Paris accords are implemented (agreed) but it is unlikley we will see any immediate practical interventions because lowering our emissions to zero will take decades.  

Reducing the level of CO2 currently in our atmosphere is at present little more than science fiction.  It would be geo-engineering on a colossal scale and no one, not even the 'consensus' of scientists has any idea of what possible disasters attempting this could cause.

It makes sense to transition to non-fossil fuels but the only viable option for producing the electricity on the scale humanity needs is a gigantic nuclear programme.  Sadly the environmentalists have spent many decades opposing this forcing us to consume ever more coal, oil and gas.

We will some time in the future be able to transition to renewables but not yet, or any time soon.  No renewable energy system comes anywhere near to producing sufficient energy to meet our needs and even if it did renewables are neither risk free nor totally environment friendly.  I doubt we would want to see an area the size of Liguria covered in windmills or solar cells. 

There is one other option, we can turn off the lights, the air conditioning the refrigeration and the heating.  The problem is that will also cause massive problems as crime increases, food spoils by the millions of tons and millions freeze to death.  

I do have one suggestion for the environmentalists, if they cancel their multiple conferences for a couple of years and use Skype just think of the reduction in CO2 we could make there.  

Kenneth.. I have outlined that the increase of CO2 is the forcing action that has dramatically pushed climate from stability to instability and I wrote above: “the horse has run away from the stable”. Now, what do I have to do with the figures that you are proposing and I know well? Weep, pour some tears.. It’s completely evident that the struggle is very difficult, but just as I never joined  the celebration of the triumphs of science and technology, so it would seem me an opposite excess to sustain now that science, technology and, mainly, governments and citizens can’t act.

Only one example from the recent report of the researchers of the UNEP International Resource Panel: among other interesting data it is provided an estimation of cutting 25 BILLION metric tons within 2050 (http://www.resourcepanel.org/reports/green-technology-choices). Those 100 BILLION have been cumulated in more than fifty years; there is somebody who thinks that the needed lowering can be achieved in few years? Anyway, I am in favor of the troubled road of mitigation, also for limiting as much as possible the problems of adaptation. What are your suggestions?   

Adaptation to climate change makes far more sense that attempting to somehow manipulate it.  Humans have in fact adapted very successfully in the the last 100,000 years or so which is why we are not extinct.

In the next few decades there will be major priorities that are far more urgent than climate variation.  There is already a shortage of drinkable water which will need more immediate attention than what are largely fantasies about carbon capture.  We do have the technology to provide sufficient water but sadly not the political will at present.

The absurd geo-political posturing currently engaged in by the major powers represents a threat to stability in many regions of the world and is also a far more immediate threat than climate change.  It needs prioritising over the Paris Accords.

Mass migration from the poorer parts of the world to the richer is similarly a real threat to stability of both the recipient nations and those haemorrhaging people.  It is odd that a 'tipping point' is never predicted there, in spite of uncontrolled mass migration being genuinely unsustainable.  The Paris Accords, if taken to their conclusion deny the poorer countries the ability to expand their economies (which requires energy consumption) 

We do need to drop the climate change doomsday hype and address the immediate problems the world faces rather than ones that we perpetually conjecturalise on.  Even if climate change is a future problem for humanity we need to deal with the present problems first.

The modern soothsayer:

https://www.researchgate.net/post/Are_Computer_Models_nothing_more_than_a_modern_day_Soothsayer

Climatologists are used not to give a relevant weight to the fluctuations of ENSO, NAO, or to the volcanic “extremes” and so on, because, mainly on the base of what happened in the Recent Dryas, they are accustomed to individuate, beyond the fluctuations, the two major factors of climate change in the dynamics of glacier masses and of salinity of oceanic currents; no significant role to the atmosphere, that is, to all the phenomena that take place there. Due to this latter belief many of them up to now exclude greenhouse gases, that just in the atmosphere circulate, as actors of climate change. Even though Climatology, Volcanology, Seismology and other disciplines are not able to make predictions I don’t think that for this reason they are not as pertaining to science. The possibility of quantify an evolution of a system, of knowing at any time its state is achievable only to some branches of Physics, to a lesser extent of Chemistry and even less of Biology.

A such kind of debate has animated those three years, at the end of which the Academies of Sciences of the G8 countries, plus those of China, India, Brazil and South Africa, addressed two statements to the G8 summits, in 2005 (Gleaneagles) and in 2006 (S. Peterburg): "There will always be uncertainty in understanding a system as complex as the world’s climate. However there is now strong evidence that significant global warming is occurring… It is likely that most of the warming in recent decades can be attributed to human activities.…The scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action…” (http://nationalacademies.org/onpi/06072005.pdf)

A reason why a so wide and important part of the scientific community pronounced in such peremptory terms was, surely, to have taken into account the results presented in the NRC report of three years before (2002), that I have quoted in a previous answer. When it is not possible to predict, to quantify future behaviors of phenomena that we are observing, we can resort to the powerful tool of the qualitative analysis, that is, the theory of stability founded by Henry Poincaré and Aleksandr Lyapunov at the turn of Nineteenth century.

The most significant climate changes are characterized as threshold effects due to the achievement of a threshold value of some control parameter. If the effects to remove are so huge, as  suggests the figure  regard to 100 billion metric tons of CO2, and they are so, it's very difficult not to interpret the climate change as a transition from stability to instability. Over the last century, in fact,  among the most important parameters that regulate such a complex reality as climate, what has changed with the greatest intensity and in the shortest time was precisely the concentration of CO2 in the atmosphere; it is with respect to that parameter that the climate has been stable till when the forcing action has reached its threshold value.

Comparing Earth's atmosphere with that of Venus is pointless, apart from a similar size Venus has nothing in common with Earth.

In the last 4 billion years the Earth has seen wild variations in climate while Venus has not. The reason is simple.  Earth is tectonically active Venus is not.

It is precisely because Earth is not 'stable' that we are here to discuss these issues.  

Venus is far closer to the Sun than is the Earth (67 million miles as opposed to 93 million) 

Venus does not have a moon

Venus is not tectonically active.  Having an active geology is not the same as being tectonically active 

The planet makes only one rotation every 243 days dramatically affecting its ability to create a planetary magnetic field

Venus has little variation in planetary relief having only two small areas of its surface elevated above a almost uniform flat plain.

We can be reasonably sure that Venus has been stable since not long after its formation.  The very limited planetary dynamics have left it with a uniform surface temperature far higher than any that has ever occured on Earth since the Hadean.  Without a moon or close proximity to a large planet tectonic activity could not be sustained.  Without a strong planetary magnetic field its surface will have been bombarded with very high levels of ionising radiation, especially with its close proximity to the Sun.  

There is really little point in making reference to Venus in a debate about climate on Earth.  Venus never had an Earth like climate and could not have had.  To refer to ‘runaway greenhouse effects’ on Venus is entirely misleading, somehow suggesting that Venus was once habitable (before this ‘runaway’) by DNA based life forms.  It was not.

If we are to use 'models' to analyse climate variation on Earth the only one we have is the Earth itself.  We may look at climate events in Earth's history as comparators but even there we need to exercise caution.  A great deal of the climate variation on Earth is caused by its position vis-a-vis the Sun and the rest of the Galaxy.   It is not all about CO2.

Aleš, if you say “Lyapunov’s exponents” you are talking about a model. I have studied several models and the ones I found less unsatisfactory – those of the “Dutch school” of a some years ago – I have proposed them as the basis for a pair of PHD theses. I would never ask that a climate model be able to produce a quantification as it is possible to obtain, in some cases, when studying a fluid-dynamics problem by means of the Navier-Stokes equation with rigorous numerical methods, but I don’t know any climate model that can represent in a complete way all the more important climate phenomena when interfering, and their feedbacks. This is the reason why I prefer the “simple” model proposed by “Abrupt Climate Change” in terms of a general behavior; not so simple if gives count, in the phase portrait, of possible chaotic character of climate evolution.

Kenneth, “(a) ‘However there is now strong evidence that significant global warming is occurring.’  What is that evidence?” This was an assessment of the Academies of Sciences that I have quoted; I don’t say “ask them” because I agreed with those statements – I think that also Katrina and the breaking of Arctic polar cap have had an influence – but now, when the maxima of temperature are cumulating in the last twenty years, a very bizarre statistic!, the drought is expanding, the increasing of extreme events characterizes the climate and an iceberg as great as Liguria has detached itself from Antarctica your request about “evidence” recalls me that nothing can be seen by those who do not want to see.

Larsen C ice shelf & Iceberg A-68

“Glaciologists are not alarmed about most of these processes; they are examples of Antarctica simply doing what we know Antarctica has done for thousands of years”.

https://www.theguardian.com/science/2017/jun/23/melting-and-cracking-is-antarctica-falling-apart-climate-change

A few points from Dr Judith Curry:

Global Climate Models have not been subject to the rigorous verification and validation that is the norm for engineering and regulatory science.

There are valid concerns about a fundamental lack of predictability in the complex nonlinear climate system.

There are numerous arguments supporting the conclusion that climate models are not fit for the purpose of identifying with high confidence the proportion of the 20th century warming that was human-caused as opposed to natural.

There is growing evidence that climate models predict too much warming from increased atmospheric carbon dioxide.

The climate model simulation results for the 21st century reported by the Inter governmental Panel on Climate Change (IPCC) do not include key elements of climate variability, and hence are not useful as projections for how the 21st century climate will actually evolve.

Professor Judith A. Curry.  President of Climate Forecast Applications Network. Henry G. Houghton Research Award from the American Meteorological Society1992.  Recently retired from the Georgia Institute of Technology, Former Professor and Chair of the School of Earth and Atmospheric Sciences.

Freak weather is so common in the US that it is 'normal'.  Nothing that has happened in the latter part of the 20th century or in the last two decades of this one is new and none of it 'predicts' any future patterns.   All we know is it will keep happening.

"The Great White Hurricane," was a major storm that hit the North Eastern United States in March 1888 from the Chesapeake Bay to Maine.  The storm caused 400 deaths and $25m worth of property damage ($630,000,000)

There are many more examples going back beyond European colonisation of America and certainly before the industrialisation of the continent.  Freak weather is therefore not a reliable indicator of climate change/variation. 

Should Climate Interactive perhaps explain in more detail the huge uncertainty range in its predictions for the rise in temperature by 2100? 

We would certainly want 'error bars' of this magnitude explained in my school!

I think the industrial revolution set us up for extinction. 

We were already set up for extinction, its a consequence of evolution

The extinction of the megafauna is often cited as being a consequence of climate change.  What is notable about this series of extinction is that they took place over thousands of years and not within a couple of centuries.  That would indicate that the extinctions were the result of multiple causes, not simply a variation in climate.

Not all megafauna died out at the end of the Ice Age.  Significant numbers of species survived challenging the notion that animals with a large body mass could not cope with variations in temperature.  

See attached, rather long winded report.  Note the confounders mentioned at para19.

19. Major uncertainties

The rate of observed expansion of tropics is uncertain and depends on the metrics used.

Uncertainties also result from the utilizing of reanalysis to determine trends and limited observational records. There are major uncertainty in the estimates of the relative contribution of anthropogenic factors and internal variability to recent trends. Uncertainties in modeling future

Changes in global circulation arises from the presentation of stratosphere as well as simulated Arctic amplification.

I have just bought the most curious book on evolution.  It is called Improbable Destinies: How Predicatable is Evolution? by Jonathan Losos.  The author seems almost obsessed with debunking the work of Simon Conway Morris and while some good points are made within the book it comes across as a polemic. To be fair Conway Morris' book Life's Solution: Inevitable Humans in a lonely Universe can also at times be polemical  

If anyone gets the chance to read this I would love to hear their views.  

I agree entirely that the evolution of life on Earth cannot be predicted and that we are likely to be lonely in the universe, although not alone.  

The number of coincidences that would need to be duplicated is huge since they all need to result in a sentient species capable of introspection and simultaneously construction of highly complex tools.   While I would never give up hope that 'out there' is a species of sentient animals evolved over billions of years who are asking the same questions we are the chances of us ever encountering one are statistically slim.   

I am interested to know what coincidences everyone has in mind.  I agree that collagen is a necessity and that it acts as one of the first constraints in terms of the evolution of complex life.

• Astronomically we need to be in the goldilocks zone. ( it may also need to be orbitting a main sequence star for sufficient evolutionary time to have occurred for sentient life to have evolved)
• We need a planet of approximately Earth size with the same chemical configuration (including surface water covering more than 50% of the planet)
• It needs a moon within an orbit capable of facilitating tectonic activity and tides. (That moon cannot be too massive or the tectonic activity will be enormous)
• It needs an iron core of sufficient size to create a magnetosphere without which life will not be able to evolve on its surface.
• It will need atmospheric gasses that can block significant wavelengths of the electromagnetic spectrum
• It needs a sidereal period and an axial tilt sufficient to create seasons, essential for evolution.
• It needs to be protected by gas giant outer planets to have permitted the evolution of complex life during the evolutionary period (too many Chixculubs otherwise)*

And thats just the easy bits!  Then we come on to the biochemistry & biology.    

If the planet is too small it will have difficulties maintaining a suitable atmosphere and surface water (Mars for instance)

If it is too large the increased gravitational effects would be detrimental to the formation of cells.

Then there's the psychology!

If 'out there' there is such a place and if on it a sentient species did evolve it will have to have gone through not only the biological evolution that we have but the social evolution too.  Surving that is almost as fraught as the million and one natural events that could have seen us off.  A sentient species that is like us and that has evolved the science we have will have weapons of mass destruction.  

SETI has been a disappointment to date.  We have not heard from anyone in our immediate vicinity but we have found lots and lots of exoplanets.  If there is anyone else 'out there' they are a long way away.  It could of course be that we are in the lead and that thousands of civilisations are indeed close to us living in their Middle Ages.   

* A bolide impact of 1km diameter or more takes place every on Jupiter every 500–1000 yr, but on Earth these impact only every 2–4 Myr.

Kenneth

Jonathan Losos says that had the Chixculub event not happened dinosaurs (their evolutionary descendants that is) would (likely) still be roaming the Earth as the dominant species..  I would be interested in your view on that. 

I think SETI may be a futile exercise but I guess it is one we feel the need to do.

The biggest problem is that not only does sentient (self-introspective) life have to be out there it needs to have a set of equipment broadcasting on the EMS that we can detect the signals from.  We have only been doing that for just over 100 years out of 100,000 years of evolution.

The Ancient Greeks were very introspective but none of that ever got broadcast off the planet in their day.  

It is interesting to see what turn the discussion took. Did the Inustrial Revolution save us from an Ice Age? Of course such question makes sense only, if we see climate change as an process caused by humans. However, climate changes long before humans walked on this planet and I argue that it would be illogical that the causes for these changes would no suddenly be no more at place. At the same time new causes, like human impact to the equation, are added. One awpect from the initial question I do not fully agree to: that humans have used fossil fuel for the past 1,000 years. Of course coal and even oil, e.g. were used long before the IR (small scale coal mining already during Roman times and oil in China thousands of years ago), but large scale mining an duse started with the Industrial Revolution, first coal and later oil. Only then consumption became so huge that the burning of the stored carbon could led to huge increase in concenrtation in the atmopshere. Whether this has prevented us from an ice age is difficult to say.

Planet Earth is about 4.5 billion years old and in this long time there had been periods that were much, much warmer than it is today (e.g. during the time dinosaurs lived on our planet) and also periods that were far colder (ice ages). In other words: it would be strange when the climate would be the same indefinately. This never has been the case. There were also periods when CO2 concnetration was much higher than today. Indeed there was a time when no O2 was in the atmosphere...

Climate change is something that bothers us, because we are effected, because we are there to be bothered. It does not effect Planet Earth in any meaningful way as the planet will be there even if Human aren't anymore (although also Planet Earth won't be eternal). Among many other challenges the scientific mainstream believes that the generation of special gases through the burning of fossil fuels is the driving force for climate change. A few, however, see human contribution little in global warming and some even talk of global cooling.

In RG there have been many contributions that put global warming and global cooling as two different processes. What is different is the outcome of very complex processes. The outcome is either warming or cooling, and to make it even more complex both can happen - in different places.... or at differnt times (a specific place can have warmer summers and colder winters as a resukt of change of the climate....,). How much of this change is contributed by human activies we can discuss and do research about, but it would be strange if only humans have contributed to these changes, or if they would be entirely caused by natural processes - both is very unlikely the case.

Sometimes people think that IPCC does investigate into global warming, but indeed it looks into climate change. The expression global warming is out since many years as it is acknowldeged that it is much more than around temperature change. Global cooling, if it exists is also climate change.

In Germany we can have temperatures in winter of minus 20 degrees Celsius. That is winter and we call this winter weather. Some years winters are mild, other years very harsh, long and very cold. Weather and climate are different things, and the weather is never the same. It changes and also if the sun energy received on January 1 at a particular place would be the same every year (which is not the case as the sender (sun) sends not always the same) it still would result in different weather as the energy received is only one from many, many factors that makes the weather.

In the discussion often people speak of a food crisis because of global warming. I doubt that this is the only possible interpretation. Today we produce considerable more food per capita than a few decades ago. When people are starving then it is usual because of the impacts of wars, civil wars, ethnic tensions, or just because of poverty, but not necessarily because of climate change, at least not so directly as often assumed. Here in the Pacific Island countries the talk of climate change and its impact on food security has been rather dominant, despite this part of the world does not know widespread undernutrition and when we look at malnutrition than we discover that the biggest concern is obesity, and when we would anlyze the causes then we would not find climate change, but MacDonalds and other fast food outlets.

I think that a cooling effect (if it exists) due to reduced sun activity moderates anthropogenic warming impacts, the same other natural impacts on the climate would such as volcanic eruptions etc. We should realise that something as complex as climate has many contributing factors that lead to change.

To assume that everything is caused by humans or everything by natural causes is far too simplistic. For that reason it is rather difficult to make any precise predictions of the future. So both (processes that contribute to warming and such contributing to cooling) not only can happen, but they do, and they always did. What now is sold as new ideas and change to previous scientific knowledge is actually nothing really new other than that one aspect from an extremely complex process is taken out and displayed as the whole truth.

Interesting, following.