I keep hearing from people who don’t believe in global warming that the last decade saw a cooling. I’ve been running a bunch of ten year trend lines and I must be doing it wrong, since I cannot find a recent ten year trend line that points down. Am I looking in the wrong place for temperature data?
Thanks in advance.
Ten years is not much of a sample. Pick up a copy of “Global Warming and Climate Change Demystified” by Jerry Silver. It’s a great little book that explains the science behind global warming in a simplified layman’s way. It’s quite obvious that the world is warming.
Oh I understand that. I’ve just read or heard so many times from certain political sources that we’ve been cooling for the last decade. I’m just looking for any source of data that backs that up.
Why don’t you contact George Will? I’m sure he’s got the references.
I think the 10 year trend line is going up. I also do believe the last 3-4 years have been “Cooler”. Also someone posted an article, could have been you, that had 3-4 factors to adjust for. Things like Solar activity etc and once you adjust for those we are still “Warmer” over the last 3-4 years.
Pulling up the graphs at NASA http://data.giss.nasa.gov/gistemp/graphs/ it would appear that several show a “Downturn” over the last 5 years in the 5year mean. Again these are not adjusted for the above factors and actually “look”, in my uneducated opinion, to follow the cycle with a “longer term” upward trend.
I probably shouldn’t even answer this question because I’m not and expert with proper accreditation 
~Matt
This is the most up to date graph I have seen–although I believe you can get Jan 09 data now. If you look at the 4 major data sets it’s clear that the trend when drawn from the peak of 1998 is downward. If you draw the line from 1999 to now it 's slightly upwards. The question really is are we on a blue or a red line trajectory?As for 1998 isn’t that supposed to be the super El Nino effect? Around the time we reached the -.2 level in 2008 was when you started seeing the panic calls by global warming supporters/scientists that we were now actually entering a perdiod of cooling BEFORE global warming returns. And some scientists are predicting a new “ice age” is upon us.
Not sure who drew those lines in but I’m guessing true trend lines wouldn’t be even close to those.
Just a visual on that would appear that the trend for the entire graph is up. The only down trend would be 2005-2009.
~Matt
I won’t pretend to be all that knowledgable about graphs and statistics and all, but it kinda looks like 1998 is a total anomaly. I wonder what the trends would be if that year was excluded. Looks like 2008 would pretty much be in line with 1980, 1981, 1987, 1988, 1996, 1997, 1999, 2000, 2001.
To me, it sure looks like the trend would be more accurately depicted if the anomaly year was excluded from the calculation of the trends.
Not sure who drew those lines in but I’m guessing true trend lines wouldn’t be even close to those.
Just a visual on that would appear that the trend for the entire graph is up. The only down trend would be 2005-2009.
~Matt
I simply put those lines in to illustrate the trend in the peaks–over the entire graph(red line) and the last decade (blue line). It’s as good of a eyeball method as any. You can also add in trend lines at the trough points for each time period to get a channel. Obviously the trend using regression or some other technique will look different. Perhaps Fatmouse can put up his graphs showing us what he’s seeing via his method.
A few more–taking out the peaks–and a blank one so you can play along at home.
It’s as good of a eyeball method as any
Not really because the “Peaks” aren’t what matters it’s the “Average” or “Mean”. If for some reason we had a REALLY hot month or two right now that was higher than back in 1998 that would not change the fact that the “Trend” for the last 4-5 years is down despite the fact that the “Peak to peak” would be up.
Perhaps Fatmouse can put up his graphs showing us what he’s seeing via his metho
Someone on this forum already did and the the trend was up thru the entire graph. I would like to see a trend for just the last 5 years, I’m guessing that trend would be down.
~Matt
It’s as good of a eyeball method as any
Not really because the “Peaks” aren’t what matters it’s the “Average” or “Mean”. If for some reason we had a REALLY hot month or two right now that was higher than back in 1998 that would not change the fact that the “Trend” for the last 4-5 years is down despite the fact that the “Peak to peak” would be up.
Perhaps Fatmouse can put up his graphs showing us what he’s seeing via his metho
Someone on this forum already did and the the trend was up thru the entire graph. I would like to see a trend for just the last 5 years, I’m guessing that trend would be down.
~Matt
But what if that new peak represented a change in the trend? : )
Here’s some based on the average of the years differences off the date from the NASA site.
Temps from 1800-2008
Temps 1980-2008
Temps 1998-2008
Temps 2004-2008
Only one that shows a significant “Downward trend” would be if you looked at just the last 5 years. Sorry the one is not rotated
~Matt
Looks like you guys have done a good job in my absence. The use of peaks, as matt pointed out, is not how normal trend lines are made. Perhaps that’s where some of the confusion lies.
The site I’ve been using to generate charts can look at a variety of start dates.
Thanks for the data charts guys. That was helpful.
Using that site, which is kinda nifty other than it only does linear, you are at a downward slope at anything after 2001.
Assuming similar “Cool” years we will have a downward 10 year progression by 2011.
~Matt
Edit to add that I’m not sure why that matters considering we’ve had 110+ years of upward pressure and that adjusted for other factors we are still seeing upward movement. Also considering 10 years is not much time I’d hate to base my “Anti global warming” argument on a 10 year trend of just the last 10 years.
the raw data is available as graphs or tabular data here:
http://data.giss.nasa.gov/gistemp/graphs/
It doesn’t have that spike in 1998ish like the graph posted above does, not sure what that is about
How someone looks at the data and concludes a cooling trend recently, I do not know
perhaps they are stupid, or lying?
That’s were I got my points from.
**t doesn’t have that spike in 1998ish like the graph posted above does, not sure what that is about **
Actually it does it’s just not as visible on that graph. The one that Chainpin posted goes from 1979-2009 with a higher resolution of points. Look at your graph right around 1998 and you’ll see a high point and then an ensuing drop. That’s the “point”.
The one posted by Chainpin also shows several different series some of which my be higher than just the temps that are in the land temp tables.
**How someone looks at the data and concludes a cooling trend recently, I do not know **
All depends on where you draw your trend line. If you draw it from 2001-2008 you’ll see an almost flat line. If you draw it from 2004-2008 you’ll see a definite “cooling trend”.
As I posted drawing any “Conclusion” from that to “Dispute” global warming, all other things equal, seems far shakier than claiming global warming due to 110+ years of warming.
~Matt