New Scientist - USA (2019-08-31)

26 | New Scientist | 31 August 2019

Editor’s pick

Using biomass to make

fuel is a criminal waste

27 July, p 23

From Fred White,

Nottingham, UK

Michael Le Page’s article barely

scratches the surface of the

problems with biofuel policy.

Solar energy conversion involving

wheat is around 0.06 per cent

efficient. That is 1/250th the

efficiency of the solar cells that we

now see covering agricultural land.

This idea takes no account of the

energy cost of planting, cultivation,

fertilisers, pest and disease control,

harvesting, processing and

distribution of biofuel. Cover roofs

in solar cells and leave the good

earth for food and nature reserves.

From Maarten van der Burgt,

Akersloot, the Netherlands

Having worked for many years in

the biomass field, I was delighted

to read Le Page’s article. Using

biomass to produce power or fuel,

when it has much more important

uses, should be a crime.

Politicians seem to believe that

because biomass is mostly green

it fits into a green future. Of course,

it is our only source of renewable

carbon. But the waste from sugar,

paper and wood processing is more

than sufficient to supply carbon-

based feedstock for the chemical

and plastics industry as well as for

some very special fuels.

Are ‘septic foci’ returning

to haunt and hurt us?

10 August, p 42

From Hazel Russman,

London, UK

Debora MacKenzie reports work

suggesting that the gum disease

bacterium Porphyromonas

gingivalis is behind a range

of diseases.

When I was growing up in the

1950s, many believed that decayed

teeth served as “septic foci”,

spreading disease throughout

the body. I remember several

advertisements for toothpastes

and mouthwashes that played on

this fear. Dentists usually removed

decaying teeth as a precautionary

measure instead of trying to

conserve them.

Then it was declared that bad

teeth were just bad teeth and

there was no such thing as a

septic focus. The idea dwindled

into pseudoscience. Is it back?

I was a climate change

denier but I got better

Letters, 13 July

From Bruce Denness,

Whitwell, Isle of Wight, UK

Lucia Singer refers to her teenage

concerns about global warming in

the 1980s and the existence even

then of deniers, who nowadays

attribute the undeniable warming

to natural fluctuations.

Sadly, I was at the time one of

those instinctive deniers. Being

professor of ocean engineering at

Newcastle University and a reader

of voluminous reports on deep-

sea drilling projects that referred

to past climate variability, instead

of just ignorantly sniping from the

bushes, I set about trying to prove

my point. This is how I failed.

Among those reports, one

interpreted global temperature

changes over the past 7 million

years from cores taken from the

Atlantic seabed. A diagram in it

seemed to show a sinusoidal

variation with a period of

4.8 million years, and variations

with successively smaller

amplitudes and periods of 2.4 and

1.2 million years. I was hooked.

I discovered hundreds of

references to proxy-temperature

variations, ranging from billions

of years down to the most recent

hundred or so years. All showed

the same summation of

sinusoidal curves with halving

period and reducing amplitude.

I built a simple model based on

those sinusoidal curves (see bit.ly/

Denness). Then I compared it with

the temperatures measured since

instruments were available.

This showed global temperature

consistently increasing above the

model’s forecast. I could explain

the difference only by adding

human-made heating – of about

3°C for every doubling of carbon

dioxide equivalent. I ate humble

pie in 1984 and have remained a

convert ever since.

In 2009, after several years of

global cooling, my model forecast

the precise scale of warming in

the middle of this decade – and

the pause in warming since.

It forecasts this to continue until

about 2030 with accelerating and

unstoppable temperature rise

after that. I would be delighted

to have my model proved wrong.

I don’t want to fry.

Looking on the bright side

of a large seaweed patch

13 July, p 17

From Paul Whiteley,

Bittaford, Devon, UK

You report the detection by

satellites of a giant seaweed patch

stretching from West Africa to

the Gulf of Mexico. This should

be seen as good news. It is taking

up nutrients and fertiliser run-off

from the land and turning them,

with minerals that are dissolved

in seawater, into the best compost

and soil conditioner I know of.

Farmers in Malta and elsewhere

have collected seaweed for

centuries in order to create new

soil and replenish the old. Farming

practices throughout the world

tend to result in increased erosion

and loss of soil quality. There

should be ships gathering up

this bounty to replace the tired,

mineral-deficient soils being

washed into the sea.

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