'Lethal ice age' prevented by climate change?
- 09 Jan 2012, 18:28
- Verity Payne
A Nature Geoscience paper (published
online) has found that man-made climate change might delay the
onset of the next ice age, expected to begin some 1,500 years from
now. This has caused quite a stir among climate skeptics, who have
rushed to proclaim that man-made climate change "
may save us from the next ice age".
This enthusiastic reporting neatly exposes some inconsistencies
in a few of their favourite arguments.
The Nature Geoscience paper: Man-made emissions may
delay ice age
thought that ice ages are triggered by small changes in the
Earth's orbit around the sun. The pattern of these changes indicate
that another ice age might begin in around 1,500 years.
However, scientists have now found that man-made greenhouse gas
emissions are warming the Earth enough to prevent it from
responding in the way that it has over the last million years.
Professor Jim Channell, University of Florida, one of the
"We know from past records that Earth's
orbital characteristics during our present interglacial period are
a dead ringer for orbital characteristics in an interglacial period
780,000 years ago."
Scientists would expect the Earth to behave in a similar way to
that period, but human greenhouse gas emissions may have disrupted
the normal glaciation cycle. As Channell puts it:
"The problem is that now we have added
to the total amount of CO2 cycling through the system by burning
fossil fuels, the cooling forces can't keep up."
Skeptics struggle to get their story
This finding has prompted an excited response from climate
skeptic lobbyists and certain newspapers, who are claiming that
man-made global warming will '
thwart' the next ice age and is therefore a good thing.
There are three reasons why this is an odd argument. First, it
is a tacit admission that man-made climate change is happening,
will alter temperatures significantly, and has far-reaching
consequences for human society. This might seem like a surprising
thing for climate skeptics to admit. It's hardly news however that
climate skeptic arguments are often selective and incoherent - as
following the publication of the BEST study results.
Secondly, on at least two occasions last year (see
here for examples), skeptics were claiming that the Earth was
poised to enter a new 'mini ice age'. To subsequently trade on the
idea that climate change is good because it will prevent ice ages
does look suspiciously like having it both ways at once.
But the biggest problem for the skeptics is that being pleased
about a (potential) lack of climate disruption occurring 1,500
years into the future does rather beg the question of why they
aren't worried about climate disruption occurring much sooner -
over the next century, say.
It's a basic error to sensationalise a possible event that's
more than a thousand years away while ignoring the disruption to
the climate expected in the interim - but this is exactly what the
media coverage does. The Daily Mail opt for the headline '
Human carbon emissions could put OFF a lethal new ice age, say
scientists' - parroting the skeptic blogs in claiming that "we
would be better off in a warmer world." This statement doesn't fit
with the most comprehensive assessment of the scientific literature
to date - that conducted by the IPCC in 2007 (
Telegraph turn to climate skeptic lobbyists the Global Warming
Policy Foundation (GWPF) for their information:
"The Global Warming Policy Foundation
said the study demonstrated that man-made carbon dioxide emissions
were preventing a 'global disaster'".
...in 1500 years time, surely?
"The think tank, set up by Lord Lawson,
cited a controversial theory proposed by Sir Fred Hoyle and
Professor Chandra Wickramasinghe in 1999 which said we 'must look
to a sustained greenhouse effect to maintain the present
advantageous world climate.'"
One might wonder why the GWPF are focusing on a potential
benefit which is 1,500 years away, on the basis of a single
scientific paper, when they are so vociferous in their rejection of
the consensus scientific position, which is supported by the work
of thousands of researchers.
Missing the point
Indeed, the reaction of skeptics to this study misses the point,
to co-author Dr Luke Skinner, department of Earth Sciences at
the University of Cambridge. He points out that the skeptic notion
that we are somehow 'preserving' our climate by releasing
greenhouse gases is flawed:
"Where we're going is not maintaining
our currently warm climate but heating it much further, and adding
CO2 to a warm climate is very different from adding it to a cold
"The rate of change with CO2 is basically unprecedented, and there
are huge consequences if we can't cope with that."
Skinner also comments on
BBC Radio 4's Today programme:
"If anything, the study... suggests that
the climate system is quite sensitive to quite small changes in
CO2, let alone the huge change that we've been responsible for over
the last 200 years."
In other words, what Dr Skinner is saying is that you can't have
it both ways. If human greenhouse gas emissions are capable of
preventing disruptive climate shifts in 1,500 years time, they're
capable of causing disruptive climate shifts well before then.
After all, the average global temperature difference during an
ice age can be as little as
4°C - and we might see that
by the end of the century, never mind in 1,500 years' time.