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Post by tacoman25 on Apr 19, 2009 3:13:59 GMT
That is incorrect GLC! Using Hadcrut:
2002-2006 was the warmest 5 years on record. 2001-2005 was the 2nd 2003-2007 was the 3rd, and 2004-2008 was the 4th by a slim margin (.016) over 2000-2004 But these are overlapping periods. If we look at distinct 5 year periods then the most recent 5-year period is the warmest. If you are convinced about the "cooling" trend then you need to wait a few more years. But your post clearly shows that all the warmest periods, whatever start/end point you use, occurred since 2000. In fact, it's quite astonishing. There have only been five 5-year periods since 2000 - yet they are the top 5 warmest periods by some distance. Even periods which include 1998 can't get close to the top 5. And do you know what? I reckon 2005-2009 will make it 6 out of 6!! And if you go by 4 year periods instead of 5, with Hadley, RSS, and UAH, 2005-2008 was cooler than 2001-2004. Look, we have either just passed the peak, or we are in the midst of a temporary pause. I agree that in about 5 years, we should have a much better idea which is the case.
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Post by neilhamp on Apr 19, 2009 9:02:48 GMT
Thank you GLC for all your comments over the past few days. I for one appreciate them. I happen to believe we are entering a cooling period associated with negative PDO and a prolonged solar minimum.
I might be wrong and we need to be reminded of the alternative arguments.
I noted that you did say "there is a continuous rise in temperature up to ~2005 at least." So I presume that you do agree that a downward trend in global tempertures may be taking place.
I quite agree with your comment that "If 2009-2013 turns out to be cooler than 2004-2008 and 1999-2003 then we can probably say a downturn is underway"
Only time will tell. The purpose of putting together the first quarter data was not so much "proof" of global cooling but simply an indication of current trends. 2000 was simply a convenient start date.
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Post by glc on Apr 19, 2009 10:47:10 GMT
NeilHamp, Tacoman25
Just be aware that short term dips have happened before - mainly due to ENSO and volcanic activity. This time it might be different but neither of you would accept (quite rightly) a similar strength case if the evidence was for warming.
However, there are small signs that AGW advocates are hedging their bets, at least. RC has recently done a few posts on aerosols which suggests they may be preparing the way in anticipation of possible cooling (or non-warming).
One of the issues I am quite definitely convinced about is that aerosols were not responsible for mid-20th century cooling.
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Post by poitsplace on Apr 19, 2009 16:30:11 GMT
NeilHamp, Tacoman25 Just be aware that short term dips have happened before - mainly due to ENSO and volcanic activity. This time it might be different but neither of you would accept (quite rightly) a similar strength case if the evidence was for warming. Yeah but eh ENSO stuff is all just a part of the overall pattern. The AMO/PDO show signs of having tipped into a negative mode. Since this pattern has been going on regularly through both warmer and cooler periods we have every reason to believe that it will continue its overall trend. We (including everyone here saying the planet will cool significantly) should also acknowledge that it's quite likely we'll see a significant El Nino within the next couple of years because...that's just the way it works. A cooling mode configuration of the ocean currents merely FAVORS La Ninas. Similarly a warming mode configuration simply favors El Ninos. Yeah, I consider this still more intellectual dishonesty on their parts FOR NOW. But just like the AGW concept, if they repeat the information long enough they'll likely become convinced that the information (this time...more balanced information) is true. I'm still quite confident that once it's realized there is no substantial warming (not much more than .5C in the next 100 years) we will find that the "scientific consensus" was simply skewed by counting those that were undecided but thought warming was a possibility among those that believed the models.
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Post by magellan on Apr 20, 2009 1:51:51 GMT
It's simple. If you start from 2000, a strong La Nina year, you will get a positive linear trend through 2009. But the 2000-2009 (up to march) starts with a La Nina year and ends with a la Nina year (2008). Late 2008 and early 2009 have been borderline La Nina. Also - it wasn't me who selected the time period. If you start with 2001, it will be nearly flat. And if you start from 2002, it will be quite negative. You'll have to take the start year up with Neilhamp and tell him in no uncertain terms that he didn't cherrypick the right year. Whatever its's too short a period. Anything less than 20 years can be disproportionatley affected by short tern 'weather' events. ENSO-wise, the most comparable year to 2009 is 2006, and we are running easily cooler than 2006 so far by every temperature source. So proof of cooling is now reliant on the fact that the first 3 months of 2009 are cooler than the first 3 months of 2006. I'd wait until the end of the year before placing too much importance on 2009. The 2007/08 La Nina meant that 2009 started from a much lower level than 2006. It's ok if you start with a La Nina year (1999) to use to show it is warming? Yet if you use 1997 as the start year, it will show Oh oh, it's not fair to include El Nino you say? It's no less logical than your misuse of linear regression to claim it is warming. Saying seven or eight years is not enough to establish a trend is arguable, but of course you say the first 3 months of 2009 is plenty of time to determine global warming is well on its way back up. Amazing.
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Post by tacoman25 on Apr 20, 2009 3:47:57 GMT
NeilHamp, Tacoman25 Just be aware that short term dips have happened before - mainly due to ENSO and volcanic activity. This time it might be different but neither of you would accept (quite rightly) a similar strength case if the evidence was for warming. However, there are small signs that AGW advocates are hedging their bets, at least. RC has recently done a few posts on aerosols which suggests they may be preparing the way in anticipation of possible cooling (or non-warming). One of the issues I am quite definitely convinced about is that aerosols were not responsible for mid-20th century cooling. Yes, I agree that short-term dips have happened before...but since the last -PDO phase, as I have pointed out many times, there has not been a non-volcanic dip or pause in warming for this long before. I would think that would cause most open-minded people to at least consider something unforseen might be happening, considering that CO2 forcing has continued to increase. And I agree that aerosols were not responsible for the mid-20th century cooling. That is an old theory created before we knew much about oceanic fluctuations like the PDO. Anyone still hanging on to that, as RC appears to be, is living in the past and ignoring relevant information.
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Post by walterdnes on Apr 20, 2009 4:21:40 GMT
BTW, I'm "chickening out" for the April projection. UAH daily and monthly seem to be all over the place relative to the other 3, What I'll do is have my numbers ready, wait for RSS monthly temps to come out, and, and adjust my projection to make RSS match. I'll extrapolate this adjustment to the other 3 sites, and that will be my "official projection".
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Post by tacoman25 on Apr 20, 2009 5:22:42 GMT
BTW, I'm "chickening out" for the April projection. UAH daily and monthly seem to be all over the place relative to the other 3, What I'll do is have my numbers ready, wait for RSS monthly temps to come out, and, and adjust my projection to make RSS match. I'll extrapolate this adjustment to the other 3 sites, and that will be my "official projection". Once all of the daily data is in, I'll make a prediction for UAH.
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Post by kiwistonewall on Apr 20, 2009 11:00:49 GMT
Warming of 0.01 degrees per decade = one tenth of one degree in a century. Time to panic "Also, the March 2009 global mean temperature differed by 0.03 °C only from the March 1981 figure - from a month when the ENSO/ONI index was pretty much equal to the current value. This cherry-picked monthly comparison would suggest that there may have been 0.03 °C of warming in 30 years." motls.blogspot.com/2009/04/giss-march-2009-coolest-march-in-this.html
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Post by socold on Apr 20, 2009 18:20:15 GMT
The March 2009 global mean temperature is 0.58C warmer than the March 1982 figure - from a month when the ENSO/ONI index was higher than the current value. This cherry-picked monthly comparison suggest that there has been over 0.2C per decade warming since 1982
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Post by gettingchilly on Apr 20, 2009 22:06:28 GMT
Mmm,
Biting my tongue. it's all good,
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Post by glc on Apr 21, 2009 9:46:04 GMT
Saying seven or eight years is not enough to establish a trend is arguable, but of course you say the first 3 months of 2009 is plenty of time to determine global warming is well on its way back up. Amazing. You ought to note more carefully who posted what. I didn't bring up the quarterly figures - I just responded to them. It's ok if you start with a La Nina year (1999) to use to show it is warming? No it's not - but it does show that short term trends are highly sensitive to the start/end period chosen. Yet if you use 1997 as the start year, it will show Oh oh, it's not fair to include El Nino you say? It's no less logical than your misuse of linear regression to claim it is warming. Again you're mssing the point. Over a short period, if you start with an El nino year and end with a La Nina year, you're almost sure to get a cooling trend. But if you start with a La Nina year you get a warming trend. Lesson 1: Ten years is too short to determine a trend because the it is too sensitive to ENSO (and other) fluctuations. If, however, you start in 1979, say, or 1980, or 1981.. or 1985...or 1988, i.e. a period of at least 20 years, you always get a warming trend. Always!!! It doesn't matter whether you start in an El Nino, La Nina, or neutral year. The trend is always up.
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Post by kiwistonewall on Apr 21, 2009 10:11:09 GMT
That begs the question.
If you start from a colder time, it will always be a warming trend, no matter how much cooling there has been in recent years.
There is no objective basis to choose any particular time.
Conclusion, it is warmer or cooler depending on your point of view.
Sums it up fairly well I think.
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Post by gridley on Apr 21, 2009 14:57:52 GMT
Again you're mssing the point. Over a short period, if you start with an El nino year and end with a La Nina year, you're almost sure to get a cooling trend. But if you start with a La Nina year you get a warming trend. Lesson 1: Ten years is too short to determine a trend because the it is too sensitive to ENSO (and other) fluctuations. If, however, you start in 1979, say, or 1980, or 1981.. or 1985...or 1988, i.e. a period of at least 20 years, you always get a warming trend. Always!!! It doesn't matter whether you start in an El Nino, La Nina, or neutral year. The trend is always up. This is a good point, glc, but it is based on a limited data set; we could take a "hot" year from the early 20th century, go forward 20 years, and show a cooling trend. The problem being that (AFAIK) we don't have PDO/ENSO data going back that far. I don't think anyone here is questioning the fact that we are still quite warm relative to the mid-20th century.
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Post by woodstove on Apr 21, 2009 15:11:07 GMT
Again you're mssing the point. Over a short period, if you start with an El nino year and end with a La Nina year, you're almost sure to get a cooling trend. But if you start with a La Nina year you get a warming trend. Lesson 1: Ten years is too short to determine a trend because the it is too sensitive to ENSO (and other) fluctuations. If, however, you start in 1979, say, or 1980, or 1981.. or 1985...or 1988, i.e. a period of at least 20 years, you always get a warming trend. Always!!! It doesn't matter whether you start in an El Nino, La Nina, or neutral year. The trend is always up. This is a good point, glc, but it is based on a limited data set; we could take a "hot" year from the early 20th century, go forward 20 years, and show a cooling trend. The problem being that (AFAIK) we don't have PDO/ENSO data going back that far. I don't think anyone here is questioning the fact that we are still quite warm relative to the mid-20th century. And since the Holocene Optimum we have been cooling (substantially):
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