Has global warming stopped?
Posted by Ari Jokimäki on January 28, 2013
For a long time there has been claims about global warming having stopped, and that there hasn’t been warming in N years or since year X. Current fashion is to claim that there hasn’t been any warming in 16 years. All of this is of course irrelevant to the anthropogenic global warming, which according to Easterling & Wehner (2009) “can and likely will produce periods of a decade or two where the globally averaged surface air temperature shows no trend or even slight cooling in the presence of longer‐term warming”.
Standard time-period of significance to climate is 30 years. Below global surface temperature anomalies are presented as running 30-year mean.
Do you see any signs of global warming stopping?
AGW Observer 
Annabelle said
The 30-year running mean is now what is takes to disguise the levelling off in temperatures.
Ari Jokimäki said
It seems that you missed the whole point of the post above. Climate-wise there are no signs of global warming levelling off. On shorter periods of time, read Easterling & Wehner. By the way, if you wish to continue making bad-spirited suggestions that someone is here trying to disguise something, I suggest that you read the rules of discussion here.
sailrick said
I don’t know about you, but the following does not look like warming has stopped.
Every year starting with 2001 and through 2012, has been warmer than any year in the 20th century, before 1997
Hottest 16 years on record in order of warmest first
2010
2005
1998
2003
2006
2009
2002
2007
2004
2001
2011
1997
2008
1995
1999
2000
2010 was warmer than 1998 in GISTEMP, NCDC and in HadCRUT4
—–
This one includes 2012
Ten warmest years – NOAA
2010
2005
1998
2003
2002
2006*
2009*
2007*
2004
2012
*tied for 6th
2012 ranked as the warmest “La Niña year”, surpassing the previous record set in 2011
————-
State of the Climate Global Analysis Annual 2012
National Oceanic and Atmospheric Administration National Climatic Data Center
“…all 12 years to date in the 21st century (2001–2012) rank among the 14 warmest in the 133-year period of record. Only one year during the 20th century—1998—was warmer than 2012.
The global annual temperature has increased at an average rate of 0.06°C (0.11°F) per decade since 1880 and at an average rate of 0.16°C (0.28°F) per decade since 1970.”
Jens Christian Heuer (@Wetterplaneten) said
The graph in combination with the question “Do you see any signs of global warming stopping?” is suggestive because all the years after 2000 are absent!
A graph with this years included the subject looks different. Even famous climate scientist James Hansen who is really not a climate sceptics narrates: “The 5-year mean global temperature has been flat for a decade, which we interpret as a combination of natural variability and a slowdown in the growth rate of the net climate forcing.” (Source: http://www.nasa.gov/pdf/719139main_2012_GISTEMP_summary.pdf)!
Something similar happened once before for more than 3 decades yet (1940-1970th)! But this stop of global warming was of a temporary nature! How come? The answer: A long term trend of global warming is superimposed by natural variability! Natural variability means solar irridiance and ocean currents among others. Maybe the impact of changing solar irridiance was underestimated yet!? There is a positive feedback loop: Lower solar irridiance in cloud-poor subtropics leads to decreased evaporation and thus fewer latent heat transported to Innertropical Convergence Zone (ITCZ) by tradewinds. Less latent heat means weaker convection and therefore less of high thunderclouds injecting water vapor in stratosphere. Note: Water vapor is a greenhouse gas much more potent than CO2!
Described mechanism is self-amplifying because a weaker convection in ITCZ also means weaker tradewinds and in turn less latent heat fueling convection.
Best
Jens Christian Heuer
Ari Jokimäki said
You can’t get more recent years using 30 year means. A 30 year mean is calculated so that a place in time is selected and then mean value of all values +/- 15 years from that point is calculated. As the last year in the data is 2012, the latest point from where we can calculate 30 year mean is 2012 – 15 = 1997.
cjshaker said
I don’t know about 16 years, but there seems to be evidence for a plateau in temperatures lately while CO2 continues to climb
It appears that Climate Scientists Professor Phil Jones and Professor Judith Curry both are verifying a plateau in temperatures
http://reason.com/blog/2012/10/15/a-16-year-pause-in-global-warming
Climate Scientist Judith Curry writes about this in her Blog
http://judithcurry.com/2012/10/21/sunday-mail-again/
If you go to the CRU website, and look for Professor Phil Jones, you will find this graph which also appears to show HADCRUT 3 temperatures plateauing
http://www.cru.uea.ac.uk/cru/info/warming/
Graphs of HADCRUT temperature reconstructions on their webpage shows the same plateau
http://www.cru.uea.ac.uk/cru/data/temperature/
Chris Shaker
Ari Jokimäki said
It is clear that there is short time variablity in temperature records, but like I said above in my post, that doesn’t mean anything for anthropogenic global warming, as discussed in Easterling & Wehner (2009). My graph above shows that in climatic sense, there has been no plateau yet (or, if there has been, we only know it after 15 years). If you think that “while CO2 continues to climb” is somehow meaningless argument, go ahead and provide a source that shows this to be a problem for anthropogenic global warming. For example it would be good if you could show where IPCC states that temperatures can’t plateau for a while within anthropogenic global warming theory.
stephanie said
I don’t believe global warming has stopped and it surprises me that such a large number of people are so easily persuaded to ignore the real threat that exists. On the other hand, I’m glad that I live in a city whose inhabitants are fighting the threat of global warming by taking part in the so-called Greenest City 2020 Action Plan whose aim is to eliminate the negative impact that our actions have on the environment. And global warming is one of the key areas in which the right decisions, if put into practice, may produce the desired effect even in the short term.
Another Week of GW News, Feruary 3, 2013 – A Few Things Ill Considered said
[…] 2013/01/28: AGWObserver: Has global warming stopped? […]
toby52 said
Hansen and others are commenting on a possible temporary slowdown in the rate of warming – which would produce a fluctation in the observed temperature.
After reading Sailrick’s data above, it would be a pretty obtuse person who would sit back and say “Global warming has stopped and won’t start again.”