The below referenced graph shows the monthly global temperature variance from January 1998 through March 2006. (References are provided on the graph.) This is consistent with the data of the East Anglia Climate unit. The maximum variance was +0.773 C in April 1998, now in March 2006 it was +0.192 C, about 1F lower.
CO2 has continued to rise during this period, yet the global temperature has not.
Some argue that El Nino was the cause of the high temperature in April 1998 adding 0.2 C to the global temperature. (Which makes little sense, where did that energy come from?) The graph shows this adjustment, still there was no increase in the global temperature.
What is the argument that we are still undergoing global warming after 8 years of no global warming?
First of all, what is that measuring? Air temperature? Certainly from an energy in/energy out perspective, anomalous weather patterns could cause air temperatures to increase by changing the amount of energy transferred to/from water, even given the same amount of energy inputted to the system.
Conversely, even if the Earth were a net absorber of energy, it wouldn’t necessarily lead to increased air temperature. The energy could be absorbed by the water, for instance in increased tropical water temperatures. Which might lead to — devastating hurricanes. Or it could be absorbed by melting water. Which might lead to — rising water levels.
Eventually, yes, but the total amount of heat energy in the oceans dwarfs that in the troposphere.
To use an analogy, it took ice in abandoned icehouses years to fully melt. Imagine how long it might take for an ocean thousands of feet deep to heat up.
Yes, here is the Global Land-Ocean Temperature Index graph (References on the graph) for the period 1998 through 2006. It doesn’t appear the that there is any increase there neither, consistent with the lower troposphere air temperature.
Plus, why wasn’t the land-ocean absorbing the “heat” in 1998?
The OP’s graph was taken or derived (somehow: I haven’t found that actual graph anywhere on the website yet) from the Global Hydrology and Climate Center, “a partnership comprised of organizational elements from NASA Marshall Space Flight Center (MSFC), the State of Alabama’s Space Science and Technology Alliance (SSTA), and the Universities Space Research Association (USRA)”.
It appears to be part of the GHCC’s research into temperature trends in different parts of the atmosphere. Unfortunately, their most recently posted general description of the issue appears to be a brief article originally published in early 1997, but it should be useful at least as a basic explanation:
Oddly, this 1997 article includes a graph of “Global Tropospheric Temperature Anomalies” from 1979 to 2005, and it looks from that graph as though the post-1997 temperature anomalies are overwhelmingly positive: i.e., the troposphere has been warming since 1997. I have no idea what the relationship is between this graph and the 1997 article or the graph provided by the OP.
But the basic point the authors seemed to be making was that yes, it is possible for global temperatures on water and land to be increasing while global temperatures in the lower troposphere are not. I don’t know what developments have occurred in researching this subject since 1997, but I’ll scout around and see what I can find.
1998 was an extra hot year due to the El Nino of the century. El Nino cycles don’t invove more total energy, they are characterised by more of that energy residing at the surface rather than being spread more uniformally throughout the ocean - see the diagrams in the Wikipedia page.
Amazingly, 2005 is close to, if not hotter than, 1998 even without an El Nino, and the 4 hottest years other than 1998 were … guess what? … 2000-2004.
In any case, even if global temperatures did plateau (which they categorically are not), it’s the greenhouse gas concentration which is the big danger. No climatologist denies that if we carry on increasing the concentration at the current rate, we will reach a dangerous concentration this century.
According to the linked page, the data appears to have been drawn from some manipulation or correlation of the data on the following two pages: Globally-Averaged Atmospheric Temperatures NASA Global Hydrology and Climate Center MONTHLY MEANS OF LOWER TROPOSPHERE LT5.2 Univerity of Alabama Huntsville, National Space Science & Technology Center
Unfortunately, neither of the “source” pages actually match the linked site and I have not found an explanation of how the numbers were determined.
I do note that on the NASA site, there are two separate graphs in which the stratospheric record shows a steady decrease while the tropospheric graph shows an erratic pattern that is generally rising.
There is also an apparent flaw in the question of the OP. It is true that the numbers are lower, now, than they were in the single spike year of 1998, but unless we have identified the source of the spike, we can make no predicitions regarding where the trend will go. If the 1998 spike was due to volcanic activity, solar flares, or some other source, it may simply be a single anomalous event.
This chart uses the same raw data as your chart, except dating back to 1979. Excluding an anomalously hot 1998, the global trend is upwards, about 0.1 degrees C per decade.
[Edit on preview – SentientMeat explained 1998 using El Nino.]
Monthly graphs can be misleading - we don’t talk about global warming every summer and imminent ice ages every winter! That’s why averaging is so essential in order to make sense of overall trends. That’s also why in this graph the incline rounds of slightly towards the present: we haven’t yet got the future data to average for it. Nevertheless, you can still see a definite upward trend with the 1998 spike skewing things a little.
I think I phrased that poorly. I mean “excluding” in the sense that, if there was no El Nino in 1998, you would have seen a relatively constant upwards trend between 1990 and 2005.
As SentientMeat said, the total amount of energy is the same in an El Nino year, compared to normal years – the difference is where that energy is located.
In 1998, more of that energy stayed in the atmosphere and near the ocean surface, rather than circulating into deep ocean currents. If you measured these deep currents, you’d find that they had a lower temperature in 1998 than in other years.
Both these graphs are derived from NASA’s Goddard Institute for Space Studies Surface Temperature Analysis research (I found the page that I think Beechnut is using to generate his/her graphs, btw), but they seem to be describing somewhat different things.
The graph in scr4’s link plots “Global-Mean Surface Temperature Anomaly” (in degrees C) from 1880 to 2000, with the value for 1980 being around 0 degrees and subsequent values generally increasing, to a high of about 0.6 degrees in about 2002.
However, the graph in Beechnut’s link plots “Global Land-Ocean Temperature Index” (in degrees C) from 1998 to 2006. The big spike in 1998 may distract from the overall more gradual rise between 1999 and 2006, but the rise is still there in the graph.
I conclude that what this shows is mostly that it’s harder to spot data trends over shorter timescales than over longer ones. Depending on which set of data points you pick, the general trend can appear more or less pronounced.
Keep in mind that short term trends do not negate long term trends. See: Stock Market. January 1998 through March 2006. Stock Market. 1940 through 2006.
