On 3 Sep, 22:47, "nightjar" .me.uk>
wrote:
>> On 2 Sep, 19:10, "nightjar" .me.uk>
> ...
>>> The IPCC does not take measurements, but takes its figures from the
>>> several
>>> sources I gave.
>
>> But it does give opinions.
>
> Which are then misreported. For example, many newspapers claimed that the
> IPCC report had concluded that it was highly likely that humans had caused
> global warming. In fact, the report only said it was highly likely
> (probability >96%%) Â that global warming had occurred and that it was likely
> (probability >66%% - i.e up to 1 in 3 experts disagreed) that there had been
> some human involvement in it, which is far short of saying it caused it.
>
Still a majority.
What the IPCC actually says is:
http://ipcc-wg1.ucar.edu/wg1/docs/WG1AR4_SPM_Approved_05Feb.pdf
"Global atmospheric concentrations of carbon dioxide, methane and
nitrous oxide have increased
markedly as a result of human activities since 1750 and now far exceed
pre-industrial values
determined from ice cores spanning many thousands of years (see Figure
SPM-1). The global increases
in carbon dioxide concentration are due primarily to fossil fuel use
and land-use change, while those of
methane and nitrous oxide are primarily due to agriculture. {2.3, 6.4,
7.3}
• Carbon dioxide is the most important anthropogenic greenhouse gas
(see Figure SPM-2). The global
atmospheric concentration of carbon dioxide has increased from a pre-
industrial value of about 280 ppm to
379 ppm3 in 2005. The atmospheric concentration of carbon dioxide in
2005 exceeds by far the natural range
over the last 650,000 years (180 to 300 ppm) as determined from ice
cores. The annual carbon dioxide
concentration growth-rate was larger during the last 10 years (1995 –
2005 average: 1.9 ppm per year), than it
has been since the beginning of continuous direct atmospheric
measurements (1960 – 2005 average: 1.4 ppm
per year) although there is year-to-year variability in growth rates.
{2.3, 7.3}
• The primary source of the increased atmospheric concentration of
carbon dioxide since the pre-industrial
period results from fossil fuel use, with land use change providing
another significant but smaller
contribution. Annual fossil carbon dioxide emissions4 increased from
an average of 6.4 [6.0 to 6.8] 5 GtC"
>
>
>>> The advantage of the UAH and RSS (both just as much
>>> specialists as the Met Office) figures over any other is that they are
>>> taken
>>> across the whole globe, irrespective of whether that is jungle, ocean,
>>> desert or settled land, while the NASA and Met Office figures are taken
>>> from
>>> a relatively limited number of fixed points, many of which are near
>>> centres
>>> of population, which can affect the figures.
>
>> But not a continuing upward trend all things being equal.
>
> Unfortunately, all things are not equal. The surface temperatures in places
> that do not have measuring stations have to be guessed and are only as good
> as the maths being used to make that guess. If city temperatures have been
> steadily getting higher than the surrounding countryside, as is likely,
> stations in urban areas are likely to be showing an trend that does not
> reflect the global trend, although they are used to calculate it.
>
Measuring stations are widely scattered across the globe.
> ...
>
>> And the ice cores?
>
> Very useful for some purposes, like plotting sun spot cycles.
>
Most useful for plotting pre-industrial CO2 concentrations which have
been much lower than at present.
> ...
>
>>> The start of the industrial revolution coincided with a relatively cold
>>> period in recent earth history (I assume a few thousand years is an
>>> acceptable timescale?),
>
>> The significant upward trend is only over the last 100 years,
>> corresponding with a rapid rise in CO2 levels, the start of which was
>> not significantly cold. See the 1850-2007 graph in:
>
>
> The industrial revolution was over before that graph even starts and the end
> of the 18th century, when it started, was the end of a mini ice age. As most
> natural systems exhibit hysteresis, there is nothing to stop the most, if
> not all, of rise during the 20th century being part of the natural recovery
> from that. The fact that temperatures rise while CO2 increases aslo does not
> give us any information about which causes the other.
>
What about the ice cores?
Again, directly from the IPCC:
"The atmospheric concentration of carbon dioxide in 2005 exceeds by
far the natural range
over the last 650,000 years (180 to 300 ppm) as determined from ice
cores."
>
>>> so a subsequent warming is to be expected. The
>>> debate is entirely about whether that is only due to natural forces,
>>> whether
>>> there was any human element in it and, if so, how much.
>
>> No the rise is much greater than would be otherwise expected.
>
> It is greater, which is why the contributors to the IPCC report tend to the
> view that there has been some human contribution, but not so much greater
> that they are willing to say so with any certainty.
>
Quote and source please?
> ...
>
>> Deep ice cores are up to 400,000 years old.
>
> But those cannot exist in either the North East or North West passages, so
> are merely a red herring you have introduced.
>
What? They are a measure of GLOBAL CO2?
> ....
>
>>> I accept that global warming has happened and I have do not have any
>>> interest, vested or otherwise, in denying it. I merely question the
>>> mechanism that caused it.
>
>> Which is the whole point.
>
> The point being you hold rigidly to one view, while I have serious doubts
> about that view and am prepared to consider alternatives.
>
I am holding to the most widely accepted view, which is better than
you keeping your head in the sand and just hoping that millions of
lives will not be lost as a result of anthropogenic climate
intervention.
>
>>> In any case, I believe that the money being spent
>>> on CO2 reduction, whether it is justified or not, would be much better
>>> spent
>>> on preparing the world for future climate change, whichever way it goes.
>
>> But the continued release of CO2 and other greenhouse gases carries
>> the danger of uncontrollable positive feedback and is therefore best
>> avoided.
>
> While you may not think a decade is a long time in terms of global
> temperature change, a decade and a half is a very long time in terms of the
> theories about it. If there were any basis for the uncontrolled positive
> feedback scenario, which dates back to 1992, we should already have seen hot
> spots in the troposphere, which we hve not. For anyone with any
> understanding of control theory, that is not particularly surprising.
>
Again, a decade and a half is well within normal variability.
>
>> I agree that we should prepare for climate change, which will
>> mean moving many millions of people away from low lying areas, such as
>> Central London for example, and modifications to farming and disease
>> control, to mention a few. A massive undertaking.
>
> Again, only if you adhere to the more outdated theories and their
> sensationlist predictions. The sea is currently rising about 3mm per annum,
> mainly due to thermal expansion. The worst case is now thought to be about
> 9mm per annum, which would lead to large areas, mainly in Asia, having to be
> evacuated over the next century. However, even without that rate, London is
> at risk because SE England is sinking and the Environment Agency is already
> taking steps to deal with the fact that the existing flood defences are only
> going to protect it until 2030.
>
I fail to see your point. London is at risk of flooding, partly due to
climate change, so why continue risking contributing to that change,
with its likely to effect on future generations, instead of your plan
of doing nothing?
>
>> Alternatively, we
>> could just try not bunging so much CO2 and methane into the atmosphere
>> and wait for that predicted cooling, starting in 2012 was it?
>
> As Britain only produces 2%% of the world's CO2, no realistic target for CO2
> reduction in the UK is going to make any significant difference, even if you
> think that CO2 is important.
>
By setting an example to other countries, instead of continuing with
the many bad examples we have set in the past, we could make a much
greater contribution to future well-being.
