Archive for December, 2017

Extreme weather more frequent in first than in second half of last century

December 26, 2017

Ocean storm. Credit: Shutterstock

There is an interesting and very easy to read paper by MJ. KELLY (University of Cambridge, Department of Engineering) titled “Trends in Extreme Weather Events since 1990“, published in Feb.2016 in the Journal of Geography & Natural Disasters.

The essence of this study is the following: “A survey of official weather sites and the scientific literature provides strong evidence that the first half of the 20th century had more extreme weather than the second half, when anthropogenic global warming is claimed to have been mainly responsible for observed climate change”. This is a big problem for all those who tirelessly write about increasing extreme weather events and promote immediate decarbonization of our societies to avoid the impending climate disasters. It also is a stumbling block for the poor structural engineer who plans dams, dikes, bridges and other big constructions: should he  device stronger (and much more expensive) structures, as suggested by the climate alarmist community, or should he rely on the lessons of past history?

Kelly politely writes about “the disconnect between real-world historical data on the 100 years’ time scale and the current predictions”, when in effect the disconnect shows that the numerous mentions of “more extreme weather” caused by global warming correspond perhaps to some wishful thinking, but are not grounded in reality.

Very telling is the next figure (taken from a I. Goklany paper) which gives the deaths and the death-rate (in millions per year) from extreme weather events:

Clearly, if one would plan a trip back in the past, the period 1950 to 2000 would be much less dangerous! Kelly adds more graphs (all taken from official data sources) which confirm this situation.

He than reflects on a problem that is continuously debated in the climate realists circles: We should not naively trust the official data series, as many have been “doctored” and “re-doctored” over the time (the scientific correct expression is “homogenized”), practically always in a way that inflates the current warming. A very good illustration is a graph from a paper by Hansen (1984) and from a modern global temperature series (Nasa-GISS, the employer of Hansen) :

Where in the first paper 1980 was colder than 1940, the situation has flipped to the opposite!


The conclusion is best given by the words of the author: “The lack of clarity about future extreme weather, after 20 years of intensive analysis of future climates is deeply worrying. There is nothing that emerges from references [1,2] that would require a significant refinement of the margins that have applied over the last half-century, and hyperbole is no substitute for hard facts in the engineering of the physical infrastructure.”

Air pollution: numbers and doubt

December 20, 2017


Much has been written on air pollution and its health impacts, especially following the Volkswagen Diesel scandal and the new trendy enviro fashion of Diesel bashing. In this blog, I will make a few comments on the contribution of household wood burning, on the fluency of reference values and the extraordinary statistics of air pollution caused mortality. As a long time asthma sufferer I appreciate clean air above all; this does not give me license to take the hysteria train and to throw away all principles of scientific thinking.

  1. The climate-friendly wood burning

In a previous comment I showed that residential wood burning is a big contributor to PMx fine dust particles (PM10 and PM2.5) pollution. The 2016 air quality report of the EEA confirms this with the following picture:


Clearly the contribution of road transport is minuscule compared to that from wood burning; curiously it is the former that you find mentioned as a culprit in nearly all media articles, and the latter that is most often conveniently ignored. The percentage of 56% may well be too low as the EEA report mentions a new study that finds that “the residential wood combustion emissions (are) higher than those in previous inventories by a factor of two to three…”

Residential wood burning has been pushed by the “climate-friendly” agenda without any pause for clear thinking. As so oft when feelings dominate over intellect, the unintended consequences are spectacular!

2. The crux of the reference values

When you qualify a gas as a pollutant, it is important to know what the natural background values are. These values haven been christened “counterfactual concentrations C0” in the new EEA report. Curiously, this natural background has often been ignored, so that health related effects start with an impossible 0 concentration. This was the case for PM2.5, until the 2017 (preliminary) air quality report conceded that nothing (or not much) is known about the danger of levels lower than 2.5 ug/m3, so that this new level diminished the attributed mortality by a whooping 18%.
The same problem exists for many other pollutants: natural ozone concentrations may locally be much higher, and introducing a unique EU-wide lower threshold automatically pushes meridional sunny countries into the club of the sinners. The report candidly acknowledges this by ” O3 concentrations show a clear increase as one moves from the northern parts to the southern parts of Europe, with the highest concentrations in some Mediterranean counties and in summer time”.

3. The extravagant mortality numbers

400000 people killed by air pollution in Europe, 40000 deaths in the UK…. These are numbers repeated at nauseam by the copy/paste media without any clear reflection on their validity.

By digging deep, one nevertheless can find some clearer thinking. Let us start by a “factcheck” article by Greenpeace (yes!) titled “Are there really 40000 air pollution deaths a year?“. For instance the article recalls that in the cities where studies have been made on the danger of PM’s, values were never lower than 7 ug/m3 and the data do not show any danger coming from values below. Antony Frew, professor in respiratory medicine says that “the basic data does not say that 40,000 people have died”.

Another comment comes from the Winston Centre for Risk and Evidence Communication “Does air pollution kill 40000 people each year in the UK?“. Here we find the mind blowing statement that “COMEAP point out, for example, that 60% of the estimated harm in the UK is estimated to occur at levels less than 7 ug/m3 PM, and yet the US data provide no direct evidence of harm at this level”. (COMEAP = Committee on the Medical Effects of Air Pollution). The report shows this table from COMEAP:


Note the huge plausible interval for the life-years lost: the interval is abyssal, so that an estimate of 340000 borders on the nonsensical. The Winston comment concludes wisely by “There are huge uncertainties surrounding all the measures of impacts of air pollution, with inadequate knowledge replaced by substantial doses of expert judgement. These uncertainties should be better reflected in the public debates. In addition, the situation in the UK is not what we would usually think of as a ‘crisis’.”

4. What a change in a year!

As a last reflection I suggest the very good article by “NO2 – not as bad as we thought?” The article discusses a new technical report concerning the planned Clean Air Zones in the UK. This report finds that the damages caused by NO2 to the public health is 80% lower than the estimate in a previous report. This previous report assumed that for every 10 ug/m3 PM the mortality risk would increase by 2.5%; now this risk factor is down to 0.92%. When a new report changes the danger level given in a previous one by such an enormous percentage, our politicians would be well advised not to rush into hasty actions, and would wisely wait for things to settle down.

The dubious 2°C limit

December 16, 2017

No comment on the Paris (and newest Bonn) climate meetings are written without raising the warning finger that everything should be done to limit global warming at +°2C “above pre-industrial levels“. Sebastian Lüning and Fritz Vahrenholt have published a new paper in “Frontiers in Earth Science” that tries to find the origin of the number, and how scientifically correct is the baseline yielding this maximum permitted warming.

This paper is very readable; they are not the first to point to the astounding vagueness of the foundations of this internationally agreed limit, but their paper has the big merit of being short and easy to understand. I will discuss just some major findings, and suggest a careful lecture of the full paper.

  1. The sea surface temperatures (SST) of the last 10000 years.

The last 10k years correspond to the ongoing interglacial period. The (annotated) figure shows how the SST changed during that period:

If we take as a baseline the average SST temperature of the last 10k years (up to 1850, the year that is commonly taken as the start of the industrialization), we see that the current global temperature is just +0.4°C higher. The blue box shows that the baseline period for the Paris aim is about 0.35° lower that this average (which corresponds to a period with only natural climate changes).

Taking the Holocene average SST as a baseline, +2°C would allow a supplementary warming (compared to today) by about 1.6 °C !

2. The land + sea global temperatures of the last 2000 years.

The next figure uses both land and sea temperature reconstructions:

It is obvious that taking 1850 as a baseline is extremely dishonest, even silly: the end of the Litte Ice Age corresponds to the coldest period during the last 10000 years. How could any intelligent person choose a baseline that corresponds to an extreme value, and scientifically speaking is at least 0.6°C too low?

3. Conclusions

1. The Paris convention suggests that the pre-industrial climate was more or less constant, and that it is mostly human activity which caused the observed warming since 1850. This is blatantly false, as during the Holocene the climate was highly variable, and has reached or even exceeded the actual global temperatures.
The following pictures shows how the Greenland temperature changed during that period:


2. A big chunk of the observed +0.8°C warming (w.r. to the 1850-1900 period) is of natural origin.
3. Using a 2°C target could be valid, but choosing and imposing the coldest period of the last 10000 years as a baseline is silly, dishonest and unscientific.




  • added Greenland graph (16Dec2017, 15:26 UTC