Dear Oyedemi S. Oyekola,

In practical terms knowledge of past climate allows modellers to calibrate their climate models. If the models work fine for past climate they should also work for future climate and hence we can have a rough idea of how future climate looks like based on the output from calibrated climate models. On the other hand past climate is used as input to these models, it is the so-called starting conditions.

Regards,

Augusto

Hi Augusto,

Great answer!

Regards

Dear Kenneth,

Thanks for your contribution. There are so many parameters to incorporate as feedback.

Past climate change data/events or palaeoclimate data offers a range of tools that can reduce uncertainty on future predictions. Reconstruction of the climate system in periods prior to instrumental records is possible using chemical, biological, and physical proxies that respond to environmental conditions. These proxies can provide information on climate variability that cannot be provided by direct observation of the modern climate. They can, for instance, show us how ‘slow’ components of the climate system such as ice sheets and the terrestrial biosphere respond to change on timescales longer than we have been measuring. And they can demonstrate behavior in the climate system that has not been observed during short instrumental record.

Few examples are

· Palaeoclimate archives show coherent regional changes in precipitation in different climate boundary conditions, including many regions where models disagree widely about precipitation change.

· Tree-ring records extend regional drought records through the last millenium and beyond allowing assessment of the pattern and frequency of drought events

· Comparisons of palaeoclimate data for the Little Ice Age with models driven by solar, volcanic and anthropogenic inputs have assessed the role of these forcings during this event and to climate more generally

In this way, with the present need to better predict future climate, palaeoclimate also has an important applied-science aspect.

Hello Kundan,

Thank you for connecting past climate events with future prediction models.

Hubert Lamb was interested in your question. He impressed Margaret Thatcher so much that the UK Government provided funds for him to establish the Climate Research Unit at the University of East Anglia and still supports the Unit.

Climate, History and the Modern World, 2nd Ed. Hubert H Lamb, 1995

http://ens9004.mza.infd.edu.ar/sitio/upload/08-%20LAMB,%20H.H.%20-%20LIBRO%20-%20Climate,%20History%20and%20the.pdf

Just came across a book I had forgotten I have, Climate Change in Prehistory by William J. Burroughs, Cambridge, 2005.

Burroughs covers part of the Pleistocene (since 100 KBP) and the entire Holocene, prehistory, recorded history and prospects for the future. Longer period and broader coverage than H H Lamb.

This is a good survey. that aims for a balanced view of climate history. I have a quibble or two about facts about the human genome, but not about how he uses genome research to show that our ancient ancestors adapted to extreme environments. Many details in all surveys are superseded by new research. so I tend to ignore them so long as the big picture is sound.

Burroughs takes a realistic view of climate risks arising from natural variability, which has been downplayed during the last 25 years or so. This survey is a good antidote to the view that Nature is benign and human activities are evil.

Dear Frederick,

Thank you for bringing in the policy makers views and their perspectives about dreadful climate change and global warming. They world leaders can relate with the reality of the warming now. Evidences are everywhere that humans are "friendly" with nature.

It is important to emphasis that events in nature is cyclic and kind (as you rightly put it).

Dear Kenneth,

Thanks

Dear Oyedemi

Yes, both H H Lamb and William Burroughs make the point that climate has changed naturally over all time scales in ways that both harmed and benefited mankind. Both identify the cold periods as having been harmful and the warm periods as being beneficial.

Rather than being alarmed by the current warmth relative to the Little Ice Age, we should take note that in most regions of the world people are better fed and have better heath than ever before in human history, thanks mostly to fossil fuels.

I say this having worked in both urban and rural development in more than 15 developing counties since 1970 on every inhabited continent except Australia.

What should concern us is the possibility that natural variability will return us to the temperature level prevailing during a cold period. Let us hope that we have produced enough Greenhouse gases to overcome the next drop in global temperature similar to the Dalton Minimum.

Dear Frederick,

Thanks for your thoughtful contributions. We are still fast approaching the global temperature minimum from solar activity point of view. Bearing it in mind that Sun is vital in climate elements composition.

The solar activity has been decreasing in the last four solar cycles. The average sunspot number is 76.6 (Solar Cycle 21: 1976-1986), 72.2 (Solar Cycle 22: 1986-1996), 59.1 (Solar Cycle 23: 1996-2008), and 41.3 (Solar Cycle 24: 2008-2017). This corresponds to about 5.74% decrease from solar cycle 21 to solar cycle 22, 18.14% from solar cycle 22 to 23, and a whooping 30% decrease from solar cycle 21 to solar cycle 24. This is the state of solar activity using sunspot number as proxy.

Dear Oyedemi

"We are still fast approaching the global temperature minimum from solar activity point of view. "

The current generation will not live long enough to witness the possible impact of solar cycles as the de Vries / Suess cycle is about 208 years and the Gleissberg cycle about half of that.

We can expect gradual progress in our knowledge of oceanic oscillations as the Argo program accumulates data and possibly refine out knowledge of linkages with solar cycles.

The leading general circulation models (GCMs) have not converged for decades, which meansthe role of water vapour is still not well constrained. The water-vapour feedback parameter is similarly uncertain and the role of cosmic particles in cloud formation is still uncertain.

Hubert Lamb was very much concerned that public policy was being determined before the science was settled. So we have been subjected to the claim that the science is settled and at the same time assured that more funds are needed for studying climate.

I do agree that more funding is needed, but the reason is that we need to resolve uncertainties in the science. In my opinion, the policymakers have jumped the gun. We have expensive solutions to control climate before we know whether adaptation would be better.

In the worst case, if we opted for adaptation, we could then have expensive solutions to adaptation when climate change cannot be predicted, either the amplitude or direction of either temperature or precipitation or both. For example, in regard to Cambodia, the World Bank has advised that future water levels cannot be prediction because regional precipitation cannot be predicted.

Perhaps the best approach would be to pursue the policy of "watchful waiting" that Hubert Lamb advocated. Spend the money on research both on natural and human drivers of climate change, but do nothing for 60 years or so, the period of some oceanic oscillations.

If policymakers must do something, let them focus on problems such as pollution, soil degradation, land use, building codes that would reduce settlement in flood plains of rivers, prevention of landslides.

Once we know more about the natural factors that are potential drivers of climate, we may be able to define more precisely and accurately the role of Greenhouse gases compared to natural drivers.

I expect that the so-called Greenhouse gases, such as water vapour and CO2 do have a role in climate change.

But I deprecate the political ploy that has defined carbon dioxide as a pollutant.because there is no scientific basis for such a determination. Defining CO2 as a pollutant strikes me as Orwellian. The shade (ghost) of Lysenko haunts governments worldwide and the scientists are silent.

Dear Frederick,

Thank you so much for your elaboration on climate change concern. If carbon dioxide is a pollutant, which greenhouse gas will be the main driving force of climate change? It has be proven right and left with avalanche of facts that CO2 plays a significant role as a forcing agent of climate change.

Regards

Dear Oyedemi

""...which greenhouse gas will be the main driving force of climate change "

Water vapour is the most prevalent greenhouse gas (35,000 parts per million) and clouds are the most sensitive climate feature because of their impact on albedo. Failure of climate model projections to converge for decades is a warning that the science is not settled.

According to the IPCC, CO2 accounts for slightly over 1 degree Celsius for doubling of CO2. The water vapour feedback parameter multiplies this value of climate sensitivity by various factors, depending on the modeling group. It is the effect of this parameter that is the source of alarm.

The political difficulty is that there is no way to demonize water vapour in the way that CO2 has been demonized. In fact, it is so difficult to demonize CO2 because even children know that CO2 is the basis for all life on Earth. And high school children learn that without the "Greenhouse Effect". the Earth would be too cold to support plant and animal life as we know it. So instead we are told that it is "carbon" that is the evil.

The reason that I object so much to such "doublespeak" is that I see politicization of science as it applies to our environment. I see also deification of the Earth, as in the Gaia Hypothesis. (Gaia, the Greek Earth Goddess). Now we even have a movement where people are encouraged to relate to trees as people.

Such people are so removed from nature that they do not see that they live in "social cocoons" protected from nature in tooth and claw. They attribute to the Earth Goddess their comfortable homes, secure jobs and full stomachs all of which are products of their advanced technological, economic and political systems.

That's why your question about ""...knowledge of the past climate change events" is so important. Stephen King got it right when he said, "“The world has teeth and it can bite you with them any time it wants.” (The Girl Who Loved Tom Gordon). That is also a personification of nature, but as both Hubert Lamb and William Burroughs show, Stephen King's view is closer to reality than the view that nature was a safe place to live until humans messed it up.

As for the degree to which CO2 affects global climate, the IPCC does not present settled science. For all the IPCC reports up to AR4 the IPCC gave a central value for climate sensitivity. but not for AR5. The reason was that the modeling groups cannot agree on the value, specifically upon the impact of water vapour and clouds. For AR5 the IPCC had either to reduce the central estimate of climate sensitivity or leave it out. They left it out.

The disagreement about climate sensitivity (or the methodology to estimate sensitivity) extended to the IPCC meeting in Stockholm where at least three governments would not agree to the draft announcement at the conclusion of the meeting. The lack of agreement was smoothed over by adding a footnote.

Most people read only the IPCC Summary for Policymakers because it is too much work to read the science volumes. And few people realize that the science volumes are revised after the member countries agree on the policy. Fewer still know about the threatened law suits and resignations by science contributors in protest against the editing of their contributions. The science volumes of the IPCC are still worth reading even though the IPCC itself is a political organization whose terms of reference direct it to find that humans cause climate change.