A "not bad" article, although I did wonder how the Mediaeval Warm Period (also called a "Maunder Maximum" I believe) could end in 1300 yet the Little Ice Age started in 1280. Seems odd two diametrically opposed climate regimes could overlap...

One aspect of climate change Monika noted was that accurate climate records go back only a century or so. She made no mention though about the Weather Bureau and its efforts in climate monitoring, in a political climate where funding is effectively being reduced so that climate monitoring abilities are lessened, not increased.

Cathy,

Thank you for providing some useful info. I do take exception to one statement though: 'Four of these datasets show year-2005 to be about the same as or cooler than years-2001-03, and a full 0.4-deg-C-cooler than 1998'.

Non of the graphs i have researched show such a huge difference in any year from that of it's close neighbours. A global temp diff of 0.4 represents roughly 60 years of consecutive warming in our current 130+ year trend and has not been realised from 1998 levels since more than 30 years previous? Did you mean 0.04 deg perhaps?

Could you possibly give me your personal hypothesis of what our current rate of increase in levels of atmospheric CO2 and Methane mean in relation to GW in light of the long term information shown in the last graph on this page?

http://www.pbs.org/wgbh/nova/warnings/stories/nojs.html

The relationship between greehouse gases and global temperature is undeniable and our curent levels of these gases are significantly higher (and still growing) now than at any time in the last 160,000 years. Global darkening is one possible explanation as to why temperatures are currently not where these levels would predict but certainly human pollution is a balancing act that needs very careful observation and adjustment. Agreed?

BrainDrain,

The temperature records that I describe are not plotted in terms of absolute (averaged) measured temperature. Rather they are plotted as excursions ("anomalies") from the average temperature over an agreed preceding, 30-yr-long ("climate normal") period, either 1950-1980 or 1960-1990. Therefore, the magnitudes of the relative peaks that I cite are correct. See, for example:

<http://data.giss.nasa.gov/gistemp/graphs/>

Regarding the CO2 and T figures from the ice cores over the last full glacial/interglacial cycle, two things. First, there is a general correlation between them. Second, close analysis shows that the changes in temperature PRECEDE by many hundred to a couple of thousand years the parallel changes in CO2; therefore CO2 cannot be the primary cause of the temperature changes at the scale of these climate cycles. (The same is true, incidentally, at the annual scale today: seasonal changes in temperature precede the parallel changes in CO2 by about 6 months).

And third, relating to your other question, because the samples come from a thickness of ice deposited over many years to decades, the figures represent averages, and do not capture annual peaks and lows. Therefore it is not true that the highest interglacial CO2 figure over the last several hundred thousand years is 280 ppm. Rather, the 280 ppm measurements in the ice cores each represents an average of numbers both above and below this level. Studies of plant stomata, an alternative way of measuring ancient CO2 but with higher temporal resolution, suggest that the peaks during recent interglacial intervals attained at least 380 ppm, i.e. the same as today.

None of this is to gainsay that atmospheric CO2 today is high and steadily increasing at least in part because of human additions. But any further warming that this may cause is likely to be minor, and more likely beneficial than harmful.

Cathy

Cathy,

Having not done the research myself, I won't engage with the statistical aspects of your arguments - in fact, I will grant that it sounds for the most part like you are making a reasonable, scientific argument. Which is why the mind boggles that you would finish it with such an unscientific claim as, "any further warming that this may cause is likely to be minor, <i>and more likely beneficial than harmful</i>."

This claim seems to be based on the idea that we are about to go into a significant cooling phase, and yet the evidence for this seems far less than overwhelming.

Even if we accept that the scientific community is strongly divided on this subject (a claim that i do not accept other than for the sake of this argument), the fact that the most knowledgeable people cannot agree would surely indicate a general lack of knowledge - and if we don't know what effect our CO2 emissions are having on the planet, then let's do what we can to stop it, eh?

Chris_b,

You worry about my opinion that "any further warming than this is likely to be minor, and more likely beneficial than harmful", and infer that "This claim seems to be based on the idea that we are about to go into a significant cooling phase, and yet the evidence for this seems far less than overwhelming".

Actually, that is not my reasoning, though the empirical evidence that the earth will next enter a cooling cycle is certainly stronger than the evidence for further warming (alarmist public claims about warming this effect are largely not based on evidence, but on unvalidated computer models).

Two reasons why increased CO2 will be beneficial are (i) should cooling occur, as is likely, then a small amount of it (a few tenths of a degree) will be offset by CO2-induced warming; and (ii) increased CO2 acts as an aerial plant fertilizer, increasing most cereal crop yields and also improving plant evaporo-transpiration efficiency, i.e. saving water.

A third, socio-economic, reason is, now that I think about it, that lifting the underprivileged of the world out of poverty requires cheap energy, which at the moment is best generated from hydrocarbon or nuclear sources.

This argument may make you feel uncomfortable, but then again neither you nor I belong to a malnourished peasant family living in a mud hut somewhere. We therefore have to be very careful not to allow indulge our guilt complexes in a way that will restrict the opportunities of other needy persons to lead a more comfortable life.

Cathy

Shame on you Monika

You well know the impact that your industry has on the health of citizens and the environment as a result of governments' vested interest in refusing to regulate the capping of emissions.

I really don't intend to debate the science of climate change or global warming or whatever. The facts are very clear indeed - pollutant industries are emitting uncontrolled greenhouse gases and carcinogenic chemicals.

One needs to consider the impact of the enormous emissions of ozone damaging CFC's which emit from nuclear reactors; the equally enormous emissions of polycyclic aromatic hydrocarbons from uranium mining and the emissions of CO which elevates methane and ozone before oxidising to CO2. I would require much more space to mention all the other health and environmentally damaging, catalytic chemicals emitted by industry which is not even required to monitor for some of the extremely dangerous chemicals emanating from its operations.

And for the many "armchair critics" I advise that in recent years, the Minister for the Environment upheld part of my appeal against a pollutant company which was making life unbearable for citizens living in close proximity.

The Minister instructed the company to reduce its particulates. Generally an emission was around 700mg/m3. The resultant emissions came down to around 8mg/m3. Simple as that! And the company continued to operate profitably with the exception of a relatively small expense on pollutant prevention control.

As for other carbon based chemicals where the Minister approved a request for reductions, well the Department of Environment simply ignored that instruction and allowed the company to continue with excessive emissions!

So you can bang on all you like about future scientific measures to reduce CO2, Monika, but NOW is the time for your industry and it's bedfellows to take some responsibility for the health of citizens and the extremely damaging impact it is having on OUR environment. I have become exceedingly irritated by all the inane flyers spewed out by your industry assuring communities of its good corporate governance whilst privatising and polluting our fresh air!