global warming

Global Warming Facts, Data & Statistics

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While many people theorize whether or not global warming exists, we here at EcoWorld believe that global warming and climate change are not only real – but they are both topics we need to understand more about. With this in mind, our editors have worked on the following list of global warming facts…
Editor’s Note: Viewing the global temperature records shown on the tables and analysis to follow, one might immediately ask: Even if recent warming may be leveling off since temperature records are arguably flat for the last ten years – what if they aren’t? That is the classic, and not cavalierly dismissed, question from the global warming alarmists. Then again, what if we successfully cool the planet, avoiding climate catastrophe by banning spurious combustion, only to regret that in the process we never developed a fleet of passenger and cargo transport aerospaceplanes, and as a result were unable to spacelift the throw-weight necessary to stop an asteroid from hitting our planet and wiping us out?
Beware of how often you play the “we-do-this-or-we-all-perish” card while relying on the precautionary principle. How often must we transform and reorganize our entire industrial base, just to avoid a plausible, but somewhat (if not extremely) low probability of leaving ourselves vulnerable to certain slaughter? And should we shift our focus away from ridding the air of really noxious pollutants; micro-particulates, sulpher dioxide, carbon monoxide, lead, ozone, just to reduce C02 emissions?
Global Warming Data
The data in the following set of tables, compiled by Dr. Richard Lindzen, an atmospheric scientist from MIT, only goes back to the mid 19th century; there are only about 150 years of data. Per-WWI data could be skewed. Depending on whether or not that is true, or even so, there is only about a 0.5 (one-half degree) centigrade change in global temperature that is clearly indicated. But what if the recent 25 year rising trend doesn’t fall? What are the 500 year trends, year by year? Do we know? What are the 10,000 year trends?
What if the earth really is warming – what if the data takes another leap, then another, instead of settling back to the 150 year mean? Do we combat this by curtailing and controlling all burning?
Why instead don’t we simply replace more of the 40% of forests that have been lost in the last 150 years, and restore to life 30% of the deserts that have marched forward over the last 150 years? We can plant trees in the cities while we’re at it, to ameliorate the hugely significant additional effect of the urban heat islands of our world’s new mega-cities. Do we strip the last forests to grow biofuel, instead of simply constructing (usually on rooftops) photovoltaic and solar-thermal arrays that consume – by well over two orders of magnitude – far less space? Wouldn’t we rather replace desert with rangeland and farms, and rangeland and farms with forest, and put canopies of green across our cities, rather than regulate all burning?
Global Warming Statistics
There is broad agreement about the behavior of the global mean temperature.
While there is agreement regarding the historical data, that does not mean that the resulting observations are very solid. The point of the following tables is simply to render transparent the global temperature records underlying most global warming observations and predictions, and comment on what they may or may not indicate.

GLOBAL MEAN ANNUAL SURFACE TEMPERATURE Per Year from 1900 through 2005

Source: UK Meteorological Office

The tables above and below this paragraph are the records commonly displayed by the IPCC. Interestingly, the record is essentially flat since 1995. The modest spike in 1998 is commonly associated with an El Nino. The temperature records reflected in these two tables are completely consistent with a rapid rise from 1976 to 1986 and a leveling off since. This would be more like what is referred to as a regime change than a response to global greenhouse warming.

GLOBAL MEAN ANNUAL SURFACE TEMPERATURE Per Year from 1995 through 2005

Source: UK Meteorological Office

When considering global temperature trends it is important to take into account uncertainty bands. When this is done, as the table below indicates, there is no basis for claiming an significant global warming trend since 1986, though there might very well be one.

GLOBAL MEAN ANNUAL SURFACE TEMPERATURE WITH UNCERTAINTY BANDS Per Year from 1855 through 2005

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It is sometimes claimed that the recent warming period involves much more rapid warming than the mean warming for the past century or so. This is, of course, true of any warming period in a record that includes periods of cooling as well as periods of relatively stationary temperature. For example, the rate of warming during 1910-1940 is somewhat more rapid than the recent rate. More over, if one looks for short periods, there is no difficulty in finding rates that are many times the rate over the last century.
There are only a few groups that compile records of the global mean temperature, and at least two of these groups are strongly committed to the popular view of global warming. On the three tables below, the planets yearly fluctuations in surface temperature are shown against the average measurements from 1961 to 1990 in the case of the first table, and 1951 to 1980 in the 2nd and 3rd tables. Each of these groups of researchers have used the same data, in a range of years which begins between 1851 and 1880, and ends in 2006.

GLOBAL ANNUAL SURFACE TEMPERATURE DEPARTURES FROM THE 1961 TO 1990 AVERAGE Per Year From 1850 through 2005

Note: The 95% confidence limits for the annual global estimate are shown (black error bars). Sources: NOAA/NCDC, HadCRUT, and NASA GISS

Of the three groups compiling each of the above graphs, at least two of these groups are strongly committed to the popular view of global warming. All the groups use the same data, but differ a bit in how they treat the data. Reassuringly, the records look pretty much the same. Two groups (Hansen’s at GISS and NOAA) claim that 2005 was a record breaker, but by a statistically insignificant amount, and clearly the difference between this result and the others is well within the uncertainty as displayed by the error bars. The table from NOAA shows a total warming of only .45C over the length of the record.
The matter of error bars is not without interest. Hansen doesn’t show any. However, the error bars in NCDC analysis are noticeably larger than those from the UK. As best I can tell, the NCDC uses stricter quality control, leading them to reject data from obviously suspect stations (like those in rapidly urbanizing regions). The UK, on the other hand, keeps these stations, and “corrects” them in a largely subjective manner. Thus, the UK has a larger number of points going into the mean, many of which have been “corrected” to look like the mean. This leads to an artificially small error bar.
In all cases, the error bar refers simply to the scatter of points going into the mean. In the next three tables, the late Stan Grotch of the Livermore Radiation Lab showed the nature and implications on the error bars of this scatter.

DEVIATIONS OF ANNUAL MEAN TEMPERATURE FROM LONG-TERM AVERAGE Per Year From 1851 to 1984

Data points averaged to obtain time record of global mean temperature. Note points range from less than -2C to more than +2C. Source: S.L. Grotch, Lawrence Livermore Laboratory)

Note that the error bars (below tables) are based solely on the scatter of the individual station data points (above table). They don’t include any information about other sources of uncertainty such as changes in land usage, changes in instrumentation, etc.

GLOBALLY AVERAGED DEVIATIONS FROM AVERAGE TEMPERATURE PLOTTED ON A SCALE RELEVANT TO THE INDIVIDUAL STATION DEVIATIONS Per Year from 1851 to 1984

Each value here is based on the average of all the points for each year in the previous figure. Source: S.L. Grotch, Lawrence Livermore Laboratory)

Another major problem in interpretation arises from the existence of natural internal variability. This is a frequently misunderstood issue. The point is that the earth’s global mean temperature varies even in the absense of any external forcing at all. This is an inevitable property of a turbulent fluid where the greenhouse effect (mostly due to water vapor and clouds) varies dramatically with location. Moreover, the ocean is continually moving in and out of equilibrium with the surface for a variety of reasons. An example of such behavior is El Nino. However, there are similar phenomena in other regions.

GLOBALLY AVERAGED DEVIATIONS FROM AVERAGE TEMPERATURE PLOTTED ON A SCALE STRETCHED TO FILL THE GRAPH Per Year from 1851 to 1984

Each value here is based on the curve in the previous figure stretched to fill the graph. Note that range is now about -0.6C to +.3C. Source: S.L. Grotch, Lawrence Livermore Laboratory

There is argument as to the significance of natural internal variability, but it is clear from the temperature record that changes of 0.5C over short periods are not particularly uncommon. Natural internal variability, or “noise” in systems such as the earth are generally reflected in temperature observations. Finally, it is characteristic of noise that it is random. Data indicates natural internal variability or “noise” should be represented by a horizontal band of width 0.4 – 0.5 centigrade. The below table shows that it is rare so far to find that the noise band and the sampling error bars don’t overlap.

OBSERVATIONS VS. INTERNAL VARIABILITY Per Year From 1851 to 2000

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We have not given much attention, so far, to systematic errors due to instrument changes. Two warrant some mention. Over much of the world, traditional thermometers have been replaced by electronic thermometers, which have much shorter response times. This appears to have contributed a bit to recent warming. Perhaps more serious are problems with pre World War I ocean measurements. Note that 70% of the earth’s surface is ocean. Crudely speaking, before WWI, temperatures were measured by collecting sea water in a canvas bucket, and measuring the temperature. After that, the temperature was taken by measuring the temperature in the engine intake.
In the late ’80’s there was a cooperative program between the late Prof. Reginald Newell at MIT and the UK Meteorological Office to intercalibrate the two methods. The resulting paper showed ocean temperatures about 0.2 centigrade warmer (for the pre WWI period) than those given in the paper that finally appeared. Professor Newell was extremely upset with the change, since he could not find out what the basis for it was. Such a change accounts for about 0.14 centigrade of the century long term trend commonly cited.
The point of all this is not to claim that there has been no warming. After all, the system’s temperature is always varying. However, when dealing with small temperature changes in a turbulent system, there is little appropriateness to dogmatism. Perhaps the most important message one gets from the data is that the change in temperature has been on the order of 0.5 centigrade, and the main question should be whether we have any solid basis for considering such a change to be large or small, serious or inconsequential.
About the Author: Richard S. Lindzen is the Alfred P. Sloan Professor of Atmospheric Science at the Massachusetts Institute of Technology.

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