Letters : Why no early ice ages?
Glen Waverley, Australia
Gideon Henderson examines prevailing theories about the occurrence of a
series of alternating ice ages and warmer periods that have occurred during the
last million years
(“Deep freeze”, 14 February, p 28).
Every time I see an article on this topic, I read it in the hope that it will
explain, not just why ice ages occurred during this time period, but why they
did not happen before (other than during the Permian era over 200 million years
ago).
All explanations I have seen in recent years use some version of
Milankovitch’s set of three “wobbles”, yet these imply that ice age cycles
should have been a regular feature throughout the whole of the geological
record.
Years ago, in Reader’s Digest, I encountered a theory that did
purport to explain why ice ages were a recent phenomenon. Essentially, the
theory said that there have only been ice ages since the Arctic Ocean became
almost completely land-locked at the pole (thanks to continental drift on
tectonic plates). Its only openings are the Bering Strait (very narrow) and the
shallow gap between Norway and Greenland.
The story is that evaporation from an ice-free Arctic locks up seawater as
ice and snow, causing sea levels to drop until this larger gap is exposed. Then
Arctic waters no longer mix with warmer Atlantic waters so the Arctic cools and
starts to freeze over. This reduces evaporation, so ice and snow deposits
decrease and sea level gradually rises until the gap is once again covered by
sea. In other words, the Arctic Ocean would actually be ice-free during an ice
age.
I should be delighted if anyone could answer two questions: First, how are
recent theories supposed to explain why no ice ages occurred more than a million
years ago (except the Permian)? Failure to do this is surely a fatal blow to any
proffered explanation. Second, what is fundamentally wrong with the model
described in that old Reader’s Digest?
Letters : Eyes in the skies
Harpenden, Hertfordshire
Ben Iannotta clearly describes from an American viewpoint the exciting
advantages that will come from the new hyper-spectral satellites in the next few
years
(“Blow-up”, 7 February, p 40).
For over 15 years, the Natural Environment Research Council in Britain has
supported a programme of airborne multi-spectral surveys in a wide range of
natural resource and environmental studies with the emphasis on quantitative
research, which has placed Britain in a strong position to exploit the
technology.
At the European level, the European Space Agency has been working on Envisat,
a hyper-spectral satellite due for launch in the next year or so, and there are
other projects under development elsewhere.
Finally, in Australia work has been proceeding for the past three years on a
feasibility study for a 64-channel, hyper-spectral, low-cost satellite to be
known as “ARIES-1”, due for launch in about two years’ time.
The Australian project is unique for two reasons. It was the first study that
started out by asking potential clients what their needs were; rather than
providing what the technologists and security advisers thought they should have.
Secondly, it is specifically aimed, in the first instance, at the market for
mineral exploration and geological mapping in areas where vegetation cover is
less than 50 per cent. There is more information at
http://www.aries-sat.com.au.
My big fear is that industry and government are not doing nearly enough
research and training to exploit these massive data sets.
Letters : Up with plugs
carrette@iig.com.au
I suspect that Isabelle Herbert, who wrote about instructions on how to
operate a sink plug, may never have been to the US
(Feedback, 14 February). They
don’t have such things there and that is probably why such detailed instructions
were required.
Your typical sink or bath in the US has a chrome-steel, mushroom-shaped
object hovering above the drain hole and an elegant plunger between the taps.
When you press downwards on the plunger the mushroom, via an elaborate
combination of rods, levers, water-seals and washers, descends towards the drain
hole and attempts to block it.
Your common English plug suffers from being unsophisticated and cheap. It
would also be possible for a hotel guest to steal it by using bolt-cutters. On
the plus side the plug does stop the water running away鈥攕omething the
American equivalent conspicuously fails to do despite being, say, 50 times more
expensive.
All this must be an expression of some fundamental American inferiority
complex about plumbing. Another outstanding example is the shower or bath
control. We on the other side of the Atlantic generally have a hot tap and a
cold tap. This simple and elegant system means that we can have any volume of
water delivered at any temperature.
The Americans are determined to achieve this with just the one lever. There
are scarcely two devices the same. You can twist them, pull them out and in,
left and right, up and down, but as yet they have not achieved any kind of
control over both water flow and temperature.
Letters : Be precise
Chester
Further to Sainsbury’s recipe for lentil and tomato soup
(Feedback, 7 February)
and the interesting levels of precision mentioned in it, you might be
interested to know of a hotel in Torquay (The Osbourne) which gives the depth of
its outdoor swimming pool in metres to three decimal places鈥攊n other
words, to the nearest millimetre. However, it was unclear whether they had
included the meniscus formed on the surface of the water in their
measurement.
At work, my colleague drew my attention to an advertisement for a mail-order
“bridal” doll (“Katherine, Gibson Girl” from JPT America) whose height was given
as 40.64 centimetres, obviously an item of precision casting honed to the
nearest 100 microns, with the highly accurate placing of the doll’s headgear.
The advert even claims that “no detail has been spared”.
Letters : . . . . .
Finstall, Bromsgrove
I agree that the Sainsbury recipe sounds silly, but there is an explanation
for it: 397 grammes is 14 ounces. You often see it when recipes have been
translated from one system, usually Imperial, to another, usually SI. I suspect
that Sainsbury at one time sold 14-ounce cans of tomatoes, and now they’ve
rounded up the can but not the recipe.
But you’re right not to let them get away with it. Give them 2.54 centimetres
and they’ll take 1.61 kilometres.
Letters : . . . . .
Bridge of Weir, Scotland
Your story reminds me of the civil servant who decided unilaterally to
metricate floppy disks and requested us to send data on an 88.9 millimetre
floppy. Unfortunately, the decimal point got lost in the typing.
Letters : Innocent Ni帽o
Honolulu
The letter from Paul Hatchwell contains what I consider to be misleading
information about the correlation between volcanic eruptions and El Ni帽o
events (Letters, 10 January, p 49).
In a recent article, my colleagues and I show that the suggestion of a
causative link between El Ni帽os and eruptions is not tenable (S. Self,
M.R. Rampino, J.X. Zhao, M.G. Katz, “Volcanic eruptions and ENSO: No general
correlation”, Geophysical Research Letters, vol 24, p 1247, 1997). Both
time series show a high frequency and events are bound to coincide.
The same can probably be said of earthquakes, although our study did not
cover these.
Letters : Only organic
Bristol
Kurt Kleiner reports that “even organic farmers approve of Bt crops because
the toxin is highly specific”
(This Week, 21 February p 20).
This is most emphatically not the case.
Ever since 1962, when Rachel Carson wrote about Bacillus
thuringiensis in Silent Spring, organic farmers have used Bt as a
last resort against pests. However, they have only used it occasionally in free
form, so that pest resistance could not develop. Organic farmers oppose
genetically engineering Bt into crops, as its permanent presence can rapidly
lead to insect resistance and the loss of an effective tool for organic pest
control that has been used safely for more than 30 years.
The Soil Association, as the voice of Britain’s organic farmers and
consumers, is leading the campaign against genetically engineered crops. This
unsustainable and unproven technology represents a short-sighted attempt to
prolong the market life of agrochemicals whose effectiveness has diminished due
to overuse and abuse. Organic farming is the only sustainable way to produce
agricultural crops without pollution and loss of biodiversity.
Letters : No magic bullet
London
Nell Boyce argues that DDT is a valuable tool for fighting malaria
(This Week, 7 February, p 18).
It is true that public health use of DDT is very
distinct from agricultural use. In countries still using DDT to control
mosquitoes, it is used only indoors in small quantities, not on outdoor breeding
sites. Its cheapness and persistence makes it popular not only with public
health workers, but also with householders.
However, problems remain: using DDT at all adds to its persistence in the
environment and in human bodies. DDT travels long distances on air currents,
accumulating in temperate regions. Insects develop resistance to DDT, and
availability of DDT often means it will also be used in agriculture.
Furthermore, dependence on any chemical detracts attention from non-chemical
solutions. Of central importance are educational campaigns to increase awareness
of public health issues and of the need to clean up potential mosquito breeding
sites, along with integrated solutions, such as the successful programmes which
have increased the use of bed nets.
We must all realise that phasing out DDT is part of a global problem, and the
forthcoming UN Environment Programme negotiations must include the resources to
search for a solution which focuses not on a chemical “magic bullet”, but on
community education and involvement.
Letters : Rising carbon
La Jolla, California
Vincent Gray appears to believe that the small reductions (of 5 to 8 per
cent) in carbon emissions from the combustion of fossil fuels proposed at Kyoto
will be ineffective in slowing down the rate at which atmospheric carbon dioxide
is rising at Mauna Loa
(Letters, 17 January, p 51).
While it is true that atmospheric CO2 has been rising at a roughly
constant rate for the last 25 years, contributing about 3 gigatonnes of carbon a
year, it is in fact just such reductions in emissions which have helped avoid a
continuing exponential rise in atmospheric CO2.
Both fossil fuel emissions and atmospheric CO2 did rise
exponentially from 1959 to 1973, until the first of several slowdowns in the
rate of rise of carbon emissions occurred briefly in 1974 and 1975, following
the first oil crisis. The largest was between 1980 and 1983, when there was an
actual reduction in emissions of 5.3 per cent, followed by a steady rise until a
somewhat smaller reduction in the period 1990 to 1993. Although emissions have
indeed increased since 1971 (as mentioned by Gray), the net result has been to
reduce the rate at which carbon emissions are rising from 4.5 per cent per year
prior to 1971, to an average of 1.5 per cent per year since.
The effect of this deceleration in emissions has been to slow down
significantly the rate atmospheric CO2 is rising at Mauna Loa (and
elsewhere) since 1980, so that it now appears to be rising more or less
linearly. In an article in Nature entitled “Interannual extremes in the
rate of rise of atmospheric carbon dioxide since 1980″ (vol 374, p 660), we
showed the effect of this slowing in emissions rate since 1980 as a descending
dashed curve labelled “predicted anomaly”. The figure shows that using the first
20 years as a baseline, global CO2 has slowed its rate of rise, but by
2.0 gigatonnes of carbon less over the last 20 years than the expected amount
based on the slowing of emissions.
The implication is that reductions in CO2 emissions from fossil
fuels, whether deliberately imposed or a consequence of other human factors, are
clearly necessary if the rate at which atmospheric CO2 is rising is to
slow significantly and so diminish greenhouse warming.
Letters : State action
Caldicott.Morgan@btinternet.com
Barry Fox gives the impression that we are powerless to prevent a surge in
power consumption of 325 megawatts when Britain switches to digital television
(This Week, 14 February, p 8).
However, section 140 of the Environmental Protection Act 1990 allows the
Secretary of State (John Prescott) to make regulations to prohibit the
importation, supply or use of any specified article for the purpose of
preventing pollution of the environment. If the political will exists, it would
be relatively simple to ban digital TV sets that consume more than, say, 1 watt
on standby. The onus would then be upon the manufacturers to ensure that their
products were energy efficient.
Letters : Broad badger trial
Exeter
The scientific link between bovine TB in badgers and cattle has recently been
exhaustively demonstrated, and the Krebs Report recommends a 5-year cull/
no-cull trial covering 30 sample areas totalling 3000 square kilometres.
It may not matter that it leaves the rest of the country unprotected by
culls. Nor that it will not be directly comparable with the Offaly southern
Irish badger clearance.
However, since brocks are not culled in northern Ireland, yet are associated
with 41 per cent of herd breakdowns there, might it not be a good idea to
replicate a scientific cull in Ulster?
Farmer or European Union sponsorship might be easier to obtain there.
Expanding the limited database of the British trial would bestow greater
statistical power to mathematical epidemiological modelling. And such a trial
could usefully contrast three areas with widely differing herd TB prevalences:
Britain 0.41 per cent, Ulster 2.79 per cent, Eire 3.74 per cent of herds.
Letters : Mind your teeth
brian.milner@brunel.ac.uk
Your cider bottle is labelled “open by hand” because a lot of people try to
open bottles using their teeth
(Feedback, 21 February). This occasionally
results in the bottle cap flying off under pressure from the bottle and lodging
down the user’s throat. Perhaps “Don’t open using your teeth” would be a better
warning label?
Letters : Driven by debt
Peterborough
As an unemployed geology graduate I too must voice my surprise at Neil
Harris’s article on recruitment
(Appointments, 24 January, p 52). James Thorne’s
comments in Letters
(21 February, p 53) hit the nail on the head.
I, and I imagine many others, seem to be caught in a vicious circle.
Employers ask for an unrealistic level of experience, which itself is
unattainable without employment. The only option is further study. However, when
you’re in my position (two years after graduation, and with a 拢3000 debt),
paying for further study is out of the question, unless I want to be in debt for
the rest of my life.
Despite numerous applications for low-paid science jobs, all I am left with
is the bank breathing down my neck, and the prospect of menial jobs for the
foreseeable future.
What chance do we have of gaining all this experience, and what are potential
employers doing to help us and ultimately themselves?
Letters : . . . . .
ian.patient@roke.co.uk
I remember the claims on a tube of Pritt glue in the late 1970s. After having
made fairly plausible claims such as “sticks paper, cardboard, etc”, it went on
to say: “Ideal for children”.
“Stay there, you `orrible little tyke!”
Letters : . . . . .
JReid22366@aol.com
My husband, being an avid Bolton Wanderers fan, proudly bought his team’s
football shirt. This shirt is essentially white with navy side panels and
writing.
Not trusting me with his precious purchase he decided to wash it himself.
However the instructions flummoxed him because they clearly indicated that he
should “wash dark colours separately”.
Letters : Packet puzzles
Brussels, Belgium
In response to your series on amusing notices on packaging (Feedback, every
week), I would like to share with you a translation from a French product used
for nappy rash, among other things.
On the box was written, in plain English: “For the prevention of
buttocks”.
We used it on my youngest daughter, but nothing happened.
Letters : Instant laughter
Bordon, Hampshire
I was very interested to read about the “funny spot”
(In Brief, 14 February, p 21).
Could stimulating this be another way to alleviate depression?
Letters : . . . . .
Neyland, Pembrokeshire
You may be interested to know that sound recordists sometimes cover their
microphone with a condom to protect it from the rain. This also works well if
you want to record underwater sounds.
Letters : Creative condoms
Bath
I’m sure multifunctional condom tips are pouring in, as it were
(Feedback, 14 February).
Here are mine: I fill a condom with descaler and roll it over the end of a
tap to get rid of the deposit that accumulates due to hard water. A rubber band
will hold it in place for half an hour or so.
My favourite alternative use, however, remains untested. Years ago, a
colleague who was a fellow motorcyclist told me that a condom makes a good
emergency half-gallon petrol can.
Sadly, despite keeping rubbers of the highest quality in the toolkits of
various machines over the years, I never ran out of petrol.