|The impact of the heat
island effect on ground temperatures around the world remains one of the
leading debates within the scientific community. The heat island effect is
created when ground measuring stations which used to be surrounded by grassy
fields and forests become surrounded by cities growing around them. These
cities have been shown to be as much as 12oF warmer than the
surrounding green countryside. Hence, the temperature at the recording
station has also increased as the city has grown around it. But by how
This graph represents the unmodified temperatures
summarized by NASA by rural verses urban categories. (The gray lines
represent the statistical error for the temperatures, while the red and
black lines represent a 5-year running average. Notice that the rural data
set (red, top graph) does not show much warming for the past 120 years,
while the urban data set (black, lower graph) shows a steep, continuous
increase in temperature. Over the period it increased by 2.5 degrees.
The rural data set, on the other hand, shows very little warming in the last
half of the twentieth century and has even declined slightly.
When the two data sets are combined (black, upper
graph), the entire US data set still shows a significant increase in
temperature for the period. This increase in temperature has nothing to do
with global warming and everything to do with changes in land use.
NASA's Goddard Institute for
Space Studies (GISS), led by Dr. James Hansen, has attempted to remove the
heat island effect through a series of equations. The GISS produced a graph
that looked similar to the rural (red) line above, but still showed
the late 1990s and 2000s to be the warmest in recorded history.
However, two Canadian scientists discovered an error
in the GISS adjustments. The error was small and NASA immediately corrected
it. Once corrected, the late 1990s and 2000s were no longer the warmest
period in US history. The warmest period was in the 1930s and 40s, with 1934
being the warmest year on record, and 1998 the second warmest. Six of the
ten hottest years occurred in the 1920s-50s, while only four have occurred
in the 1990s and 2000s.
Scientists are becoming increasingly alarmed over the
statistical messaging of US data by NASA's GISS led by Dr. James Hansen. The
2007 error is not the only questionable data that Hansen has released the
past few years. Each time Hansen announces that the GISS has discovered a
better way to statistically modify actual US ground temperatures, warming
becomes even more pronounced and any cooling less pronounced.
For instance, a
of the data compiled by the Historical Climatology Network (USHCN), for
Santa Rosa, California show a cooling trend since 1900, while the same data
after Hansen's GISS applies their top secret statistical adjustment shows a
warming! USHCN measures temperature by taking daily readings from an
immobile temperature station. GISS compiles its reports by collecting the
USHCN temperature readings and then subjecting them to secret adjustments,
allegedly to correct for artificial influences such as land-use changes.
Hansen is the scientist who raised the alarm about global warming in 1988
and has been an extremely outspoken proponent of man-caused global warming
every since. So much so that he has said that any company or scientist that
does not agree with him should be prosecuted for crimes against humanity.
More and more scientists are saying that this kind of demagoguery has no
place in science. Certainly not in a person who is in charge of the United
States temperature data and refuses to let any other scientist review his
data adjusting equations. It is so bad, that the
US Senate Committee on Public Works notes that Hansen's former NASA
Supervisor, Dr. John Theon that Hansen is an embarrassment to NASA.
YouTube statement by
Senator James Inholf (OK) about Hansen).
This concern lead
some scientists to actually plot the USHCN data for the entire United
States and compare it against the NOAA adjusted data. The comparison is
shocking. The unadjusted data clearly show that the warming in the last
quarter of the twentieth century in the US is substantially less than the
1930-1945 period than the NOAA adjusted data would have us believe. The NOAA
adjustments increase the temperatures of the 1975 to 2000 period and reduce
the temperatures of the 1930 to 1945 period.
Having said that, it must be clear that some data
adjustment is necessary for climate comparisons and trends. These include
"adjustments for changing equipment, and adjustments for changing site
locations and/or urbanization. However, all of these adjustments are
educated guesses. Some, like the time of observation adjustment, probably
are decent guesses. Some, like site location adjustments, are terrible as
Economist Dr. Ross McKitrick and climatologist Dr. Patrick Michaels,
clearly showed that land use still affects published temperature records.
population growth, economic development, coal consumption and other
socio-economic indicators with the temperature trends for the respective
areas. If there were no urban heat island effect, there should be no
difference between high growth and low growth areas around the world.
Instead, they found a large and significantly
correlated relationship between population growth (i.e. land use) and
temperature as measured by surface stations in the area. On the other hand,
there was no correlation when surface satellite temperatures (which is not
affected by heat island) was used for the same areas. When the surface
station data was corrected for the heat island effect they found, the
warming since 1989 would be reduced by half! (Read
article in Journal of Geophysical Research)
While this issue is not yet settled, the controversy is growing. Stay tuned.