So “global surface temperature may not increase over the next decade”, Is that a reduction in the rate of change for the trend but still with a positive linear slope, or is it a reversal of the trend now sloping towards the zero baseline. Is a trendline of a yearly anomaly of +.5 that ends up at a yearly anomaly of +.1 over the baseline cooling or less warming. Or is the yearly anomaly going to be flat resulting in a flat trendline. Does the anomaly have to be on the negative side of the baseline to be cooling. How you define this is important.

As far as “the next decade” that is 2011-2020 — the next ten years is 2009-2018 — but I understand the article deals with comparisons of 1994-2004 to the time frames 2000-2010 and 2005-2015 as far as the forecasts go. As RC puts it, the first period of ten years (using decade in the sense of any ten year period) starts in November of that year, so the first period to compare is 1 Nov 1994 – 31 Oct 2004 to Nov 2000 – 31 Oct 2010 I believe RC thinks the paper’s hindcast of the first period is too low and the model off, and therefore the forecasts compared to 94-04 will be too.

The abstract — and if you don’t like the abstract, blame whomever wrote it — specifies “decades” for the predictions:

“Thus these results point towards the possibility of routine decadal climate predictions.”

And about the predictions:

“Using this method, and by considering both internal natural climate variations and projected future anthropogenic forcing, we make the following forecast”

Sounds like ‘Our guess is based off these other guesses.’? And notice the interchangeable use of prediction/forecast.

We therefore get:

“North Atlantic SST and European and North American surface temperatures will cool slightly”

Some cooling.

And we also get:

“tropical Pacific SST will remain almost unchanged.”

Some near equilibrium. (‘Almost unchanged’ which direction though?)

Then the anomaly overall for 2000-2010 or 2005-2015:

“global surface temperature may not increase over the next decade”

Which also means they may increase over “the next decade” — rather meaningless. ‘it might go up and it might go down’ is not a forecast or a prediction, it is a tautology. I think this is basically what Roger means by “everything being consistent”.

But why might it not warm? Because:

“natural climate variations in the North Atlantic and tropical Pacific temporarily offset the projected anthropogenic warming.”

As other have correctly pointed out, if we can offset “warming” naturally (temperature down), the opposite may be possible also, regarding the “projected” agw.

Now, if one group of water cools and one stays the same, and this offsets the land, the abstract at least certainly seems to be saying:

“Various components used to derive the anomaly will be some mix of warming, cooling, and equilibrium the next decade, and the anomaly will basically be flat.”

So variations in the weather can cause a mix of warming cooling and nothing. Certainly this is consistent with the models. If you put in enough models and give yourself two or three standard deviations that is.

But just wait until the warming comes back with a vengence the next decade from 2018 to 2027….

Which brings up a question — what does it mean to have a trend (+.7) that is larger than the largest yearly value (+.62)?

Does it not bother anyone that the anomaly range itself is only -.4 to +.62 in almost 13 decades with multiple types of measurement methods over the period?

The only question is would you yourself (whomever you are) bet that any yearly anomaly will go over +.8 in the next 20 years? I would not, much less try and attribute it to anything except perhaps the measurements themselves.

Mark, my prediction is a 0 rise in the anomaly between now and 2012, + or – 10. If they move the base period in 2011 to 1981-2010 I might have to revisit that.

Which brings up an interesting question; what would the anomaly have to do or for how long to flatten or reverse the trend line since 1880? Given the drastic change in the monthly anomaly numbers since 1976 it doesn’t seem possible for the linear yearly trend to do anything but experience a reduction in the rate of increase. Since in order to flatten the line, it would take a total of -15 to get it to flatten since 1880 and -4 to flatten since 1960.

John, you asked why 1960. HadCRUT base period starts in 1961. Mauna Loa data starts in 1958. Why not? Pick the last 30 years, 1978-2007 if it makes you feel better, or 1990-2007 if “17 years is long enough”. We all know things change depending on the start, but the trend being up is an obvious fact.

Of course, a model that’s been crafted to reflect an atmosphere as is becomes inconsistent if you leave off features present in the modeled atmosphere. The model relies on GHG to be consistent, so of course removing them would make it inconsistent.

What point does that prove? That if there was nothing to absorb outgoing longwave infrared thermal radiation, the atmosphere would be different. So obvious as to be uninteresting and not worth mentioning.

Just remove carbon dioxide, yes, 9% of the greenhouse effect goes away. In the model. What happens in reality? Maybe water vapor fills in for it or the lapse rate readjusts and there is no net change. But it is unphysical to remove all carbon dioxide so the thought exercise is meaningless and any answers simply conjecture.

I could observe whether or not the sun is rising earlier and setting later, and how high the sun is in the sky at midday. We have a solid scientific understanding of what really causes summer to occur. However, we do not have a solid understanding of whether or not our relatively small contribution of GHGs to earth’s system has any causal influence on the always changing climate. To me the lack of an answer to Roger’s question indicates this deficiency in scientific understanding, which naturally leads one to question the predictions of climate models.

I could observe whether or not the sun is rising earlier and setting later, and how high the sun is in the sky at midday. We have a solid scientific understanding of what really causes summer to occur. However, we do not have a solid understanding of whether or not our relatively small contribution of GHGs to earth’s system has any causal influence on the always changing climate. To me the lack of an answer to Roger’s question indicates this deficiency in scientific understanding, which naturally leads one to question the predictions of climate models.

The reason it’s disproven is because no models predicted the cooling, over exactly two solar cycles, here:
http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17257 at the *south* pole, where there *is* no black carbon. This shows that the warming is not “global” at all, ergo CO2 is not to blame (not significantly anyway).

It appears, since warming has stalled, that the tipping point may have been reached. Of course the tipping point is really that the public is realizing en masse that it’s a scam by wannabe carbon traders and their dupes, and a bunch of alarmists are about to lose their jobs, after dragging the reputation of science through the dirt.

Beside that, even if it *is* happening, how do they know it’s going to be bad? Certainly well over 50 generations reveled in the Holocene Optimum.

It’s certainly no emergency…

0.11, 0,20, 0.31, 0.43, 0.56

Heh, heh, heh! Sorry, I find it hard to take seriously anyone who makes such statements…and you make the same statement virtually all the time. My guess is I could find the phrase “50 generations” at least a score of times in your book.

So you think you can see 50 generations into the future? By most conventional usage, that 1500 years…or at least 1000 years.

Let’s hear some of your predictions for…say the next 3-5 generations.

In the year 2000, the world per-capita GDP (purchasing power parity, or PPP), year 2000 dollars was about $7200. What are your predictions for world per-capita GDP (PPP, year 2000 dollars for):

2020
2040
2060
2080
2100?

What are your 50/50 predictions for world average surface temperature anomaly and satellite lower tropospheric relative to 1990 for those years?

What are your predictions for mean world sea levels relative to 1990 for those years?

What are your predictions for world average life expectancy at birth for those years?

Here are my guesses for those years, 2020, 2040, 2080, 2100.

World GDP (PPP, year 2000 dollars): $13,000; $31,000; $130,000; $1,000,000; $10,000,000.

Lower tropospheric temperature (versus 1990): 0.27; 0.46; 0.70; 0.94; 1.20.

World average life expectancy at birth (currently 67): 75, 85, 100, 140, 200.

What are your predictions?

You write, “Imagine if I had a set of 25 weather forecasts (from various models) for temperatures tomorrow of 50 to 100 degrees. When the temperature turns out to be 63 degrees, I could say that indeed this was observed to be consistent with the models. But as a tool of decision making it is useless.”

I’m surprised you haven’t hammered this important point home more often…and specifically to policy makers and the scientific/policy press, regarding the IPCC’s projections.

For example, the IPCC Third Assessment Report contained the statement, “The globally averaged surface temperature is projected to increase by 1.4 to 5.8°C over the period 1990 to 2100.”

Don’t you agree that this is exactly like your hypothetical weather forecast of 50 to 100 degrees? Doesn’t it make a big difference if the real value is 63 degrees (as in your scenario) or 93 degrees?

Wigley and Raper at least addressed that issue in their July 2001 Science paper, in which they assumed equal probability for all scenarios, and came up with a 50% probability of warming from 1990 to 2100 of 3.06 deg C, and a 90% probability of warming between 1.68 and 4.87 deg C.

I followed that with my own predictions in 2002 and 2005. The 2005 predictions were published in full on my blog in April 2006. My predictions were for a 50% probability of warming from 1990 to 2100 of 1.2 deg C, and a 90% probability of warming between 0.02 and 2.45 deg C.

Don’t you agree that:

1) The IPCC TAR projections simply aren’t useful for policy, since, like your temperature forecast, they are very broad and contain no “most likely” value?

2) It makes a difference to policy whether the Wigley and Raper or Bahner projections are correct (i.e., whether, in the absence of government intervention, there is a 50 percent chance of warming between 1990 and 2100 of 3.06 deg C, or a 50 percent chance warming of 1.2 deg C)?

If you want to know what the paper really says, try reading:
http://climateprogress.org/2008/05/02/nature-article-on-cooling-confuses-revkin-media-deniers-next-decade-may-see-rapid-warming/

It is more accurate to say the Nature study is consistent with the following statements:

* The “coming decade” (2010 to 2020) is poised to be the warmest on record, globally.
* The coming decade is poised to see faster temperature rise than any decade since the authors’ calculations began in 1960.
* The fast warming would likely begin early in the next decade — similar to the 2007 prediction by the Hadley Center in Science (see http://climateprogress.org/2007/08/15/climate-forecast-hot-and-then-very-hot/).
* The mean North American temperature for the decade from 2005 to 2015 is projected to be slightly warmer than the actual average temperature of the decade from 1993 to 2003.

I’m not exactly what more evidence people need for human-caused global warming than the much faster than predicted loss of the Artic ice, the loss of the inland glaciers, the ice sheets shrinking “100 years ahead of schedule.”, recent sea level faster than the models predicted, and the tropics expanding faster than the models predicted.

The coming decade will with little doubt end the doubt of those who can be persuaded by the facts, but who refuse to accept a well verified theory. By then it will be all but too late to stop the catastrophe, but you can all feel good that you didn’t act precipitously to save the next 50 generations from ever worsening misery.