(1) I think it is likely that the climate system has warmed, but the data do not allow us to say accurately by how much, let alone whether or not the warming is harmful to humans or 'the eco-system'. Some of the consequences of the warming since 1979 seem to have been beneficial. There seems to have been no warming of any significance in the last decade or so.

The claim by the IPCC is for warming since the 1950s. What has happened in the last decade does not contradict this. “but the data do not allow us to say accurately by how much” is merely an attempt to obfuscate. The warming might be 0.67 C or 0.68 C. The fact that the figure is not absolutely accurate does not mean there has been no warming going on. http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.gif

(2) The palaeo data do not allow us to say whether or not observed recent changes are unprecedented, though they can be suggestive. Palaeo data come with their own errors, and a broad-scale — our recent changes are measured in years, but that is too fine a scale for ice-cores.

Ice cores have annual rings, so why are yearly changes not able to be measured? Because they are yearly, there is plenty of data to estimate rates of warming. http://www.iceandclimate.nbi.ku.dk/research/strat_dating/

(3) These changes are not linear. Some glaciers are advancing, and the amount of ice does not seem to have changed much (Antarctic sea-ice is at record levels, and Antarctica contains about 90 per cent of the world's ice).

Total ice has decreased. You are obfuscating again. http://nsidc.org/cryosphere/sotc/ice_sheets.html http://nsidc.org/cryosphere/sotc/sea_ice.html

(4) Sea levels have been rising slowly and steadily for a long time, according to tide gauges. Current levels at 3mm per year, do not suggest anything dramatic.

Um No http://www.cmar.csiro.au/sealevel/images/CSIRO_GMSL_figure.jpg

(5) Greenhouse gas emissions have been rising while temperature seems not to have done, something that is hidden in AR5.

Temperatures have risen since the 1950s which is the claim. http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.gif

Would you like to have another go Don?

Don, excellent answer to Agronomist.

But you didn't explain what is far more important. That is, even if correct, all his points are irrelevant. They are not relevant unless the impacts of human caused warming are stated and the uncertainties are stated.

I’ll add my responses to Agronomist’s questions as you numbered them:
“Don, excellent answer to Agronomist.

“Agronomist,

You cite the AR5 SPM as follows:
(1) Warming of the climate system is unequivocal, and
(2) since the 1950s, many of the observed changes are unprecedented over decades to millennia.
(3) The atmosphere and ocean have warmed, the amounts of snow and ice have diminished,
(4) sea level has risen, and
(5) the concentrations of greenhouse gases have increased.'”

My responses:
1. Yes, the climate has warmed, just as it has done many times in the past. The changes have no been attributed to human causes; or more correctly the uncertainties are so large as to make the studies that have attempted to attribute cause to human effects make such attribution meaningless
2. Disingenuous and probably wrong. The evidence is not available. But what paleo-evidence is available demonstrates the have been much larger and much faster warming and cooling events in the past.
3. So what? And anyway, this says nothing about attribution.
4. Yes, sea level has risen and fallen in the past too. No evidence to attribute it to human causes
5. Yes. The evidence is that has don’t a lot more good than harm so far, and is likely to continue to do so for most of this century.

To Don, some corrections.
1. Yes some glaciers are advancing - they happen to be sited above the freezing layer. Because of higher sea surface warmth, more evaporation, so such glaciers receive more precipitation. Such advance is in agreement with a warming world.
2. Global Warming data shows that the rate of that warming has decreased - but is still happening. The term “Global Warming” applies JUST to that very small segment of our atmosphere that is in contact with earth's land and water surface. It is not measuring what is happening in the broader atmosphere, nor the ocean below sea level. Much of the world's warming is now occurring in the oceans down to 1km under the surface. Just GOOGLE ARGO buoys for precise information - over 3000 of them.
3. Antarctic sea ice is expanding because of global warming - causing stronger polar winds which tend to push ice away from the continent, and the resultant gaps refreezing. Also unprecedented melting around the west Antarctic ice sheet is releasing more fresh water which is easier to freeze that normal salty ocean water
4. See page 1139 in IPCC WG1AR5 document on the Physical Science to get a correct view of sea level rise. The rate of sea level rise has been increasing over recent decades.
5. Page 37 of that document refutes Don's comment on temperature increase - it has continued, and is continuing to rise, along with CO2 concentration.
6. It is disappointing that Don does not reference any research that supports his assertions.
7. When corroborating evidence is not supplied, anyone can question anything, but don’t expect such views to be respected.

To Leo:
1. Unfortunately your comments continue to reflect lack of knowledge. For the record, I have a PhD in Atmospheric Science, have worked with the Bureau of Meteorology for over 12 years and spent a year in the Antarctic. BUT I am not a research scientist.

To Peter Lang,
1. Are you familiar with isotopes - that is, elements, such as uranium, that have different numbers of neutrons in their nucleus?
2. Carbon dioxide in the atmosphere is bombarded by high energy cosmic rays (as are all other components of the atmosphere). A certain proportion of these carbon atoms are converted into different isotopes - still carbon, but with differnt numbers of neutrons
3. Carbon that has been buried for millions of years do not have such isotopes. Such isotopes that may have been there when forests were first burried have long since passed many lifetimes, and reverted to normal carbon
4. It is relatively easy to determine the amount of CO2 in the atmosphere that has come from fossil fuels - burnt by us - and adding to the thickness of the CO2 blanket which, incidentally, has prevented our planet from turning into a snow ball for millennia.
5. What has been keeping us warm on this world, keeps us warmer if it gets thicker - which it is and warmer we are getting.

Thanks for the background, Tony, it helps me understand why you are a fraud-backer, and post such tripe.
I suppose if you spent time in Antarctica, you would have struck someone like Chris Turney to develop your ideas, which would be worse for you than developing them in the playground.
You should have known better from your experience than to recommend BOM as a reliable source of information

Don,

"Yes, green house gases have been increasing while temperatures have not..."

To be precise: "air surface temperature" has plateaued at record levels.

Oceans are still warming.

"....and the amount of ice does not seem to have changed much (Antarctic sea-ice is at record levels, and Antarctica contains about 90 per cent of the world's ice)."

So this kind of report from NASA means nothing to you?

http://www.nasa.gov/jpl/news/antarctic-ice-sheet-20140512/

"The pace and magnitude of the changes observed in this region match the expectation that Amundsen Sea embayment glaciers should be less stable than others. In some cases, the changes have outstripped expectations."

It's the sheer pace of warming that matters....the speed of human release of CO2 is, in paleo terms, a sudden outgassing.

Our civilisation has developed in a human-friendly climate niche - the planet seldom produces epochs like ours.

We're messing with it....