Questioning the Global Warming Science II:
An Updated bibliography (June 2006-May 2008)
Prepared by
Madhav L Khandekar
Climate Consultant Markham Ontario Canada
mkhandekar@rogers.com
Prepared For
Friends of Science (FOS)
Calgary Alberta Canada
31 May 2008
Introduction
In an earlier FOS Document (www.friendsofsciece.org) a list of
about 70 peer-reviewed papers was prepared which were published
since about 2000 and which have questioned one or more aspects
of the present view of the global warming science. Since the
publication of that Document in February 2007, a number of
additional papers have appeared in well-known international
Journals covering a wide range of issues which are being debated
in the scientific community as well as in the media. The
publication of more papers questioning the GW science is now
casting a serious doubt on many of the IPCC (Intergovernmental
Panel on Climate Change) assumptions about human-induced
climate change.
Besides peer-reviewed publications, recent satellite data do not
show any warming of the troposphere since the 1998 peak which
was associated with the 1997/98 El Nino. The best available
satellite data show the tropospheric temperature trend over the NH
(Northern Hemisphere) essentially same for the last ten years while
over the southern hemisphere, the temperature shows a slight
decline for the last few years (see Figure 1). Also on a yearly time
scale, a yardstick introduced by the IPCC, the year 2007 has turned
out to be seventh warmest (1998,2005,2003,2002,2004 and 2006
being warmer than 2007) since the 1990s. Although the IPCC
continues to claim 2007 as one of the warmest years, it is apparent
that the mean temperature of the earth has not increased since
1998, the hottest year and in reality the mean temperature appears
to be slightly declining at present. This observational evidence
contradicts the AGW (Anthropogenic Global warming) hypothesis
and there is now a growing conviction among many scientists that
the present climate change is a consequence of natural climate
variability and NOT a result of human activity.
This document lists about 35 key papers that have appeared in the
peer-reviewed Journals during the past two years. Once again, the
papers cover a wide range of topics and this document presents a
listing of these papers using a similar format as used in the earlier
Document. Following are the subheadings under which the recent
papers are listed:
1.
2.
3.
4.
5.
6.
7.
8.
Temperature reconstructions using proxy data
solar variability and sun’s role in the earth’s climate
Land-use change and urbanization impact
Arctic & Antarctic warming/cooling
Large-scale atmosphere/ocean circulation changes
Climate sensitivity and related issues
Climate model forecasts, uncertainties and discrepancies
Miscellaneous topics (hurricanes, sea level rise, CO2 growth,
IPCC processes etc.)
9. Summary and the emerging view of present climate change
1. Temperature Reconstruction using proxy data
The famous Hockey-stick representation of the earth’s mean
temperature history over the past two millennia has received
widespread attention in the last five years. Papers by McIntyre &
Mckitrick among others have now demolished the Hockey Stick
which was used as an icon of human-induced global warming by
the IPCC 2001 Documents. The interest in reconstructing the
mean temperature using tree ring data seems to continue among the
purists and two recent papers have reinforced the claim that the
Mann et al analysis (1998 Nature) was essentially correct.
However an excellent paper by Loehle(2007) using non-tree ring
proxies shows conclusively that the MWP (Medieval warm Period
~ 8-12 century ) was indeed as warm or warmer than present. The
following is the list of new papers since January 2007:
a. “The ‘hockey-stick’ and the 1990s: a statistical
perspective on reconstructing hemispheric
temperatures” Bo Li, D W Nychka & C M Ammann.
Tellus (2007)59A p.591-598.
b. “Robustness of the Mann, Bradley, Hughes
reconstruction of northern hemisphere surface
temperatures: examination of criticisms based on the
nature and processing of proxy climate evidence” E R
Wahl & C M Ammann. Climatic Change (2007) 85
p.33-69
c. “Bias and concealment in the IPCC process: The
“Hockey-Stick” affair and its implications” David
Holland Energy & Environment (2007)18 p.951-983
d. “A 2000-year global temperature reconstruction based
on non-treering proxies” Craig Loehle Energy &
Environment (2007) 18 p.1049-1058
The first two papers listed above strongly defend the original
Hockey-Stick (Nature 1998 Volume 398) reconstruction of Mann
et al by dissecting McIntyre/McKitrick papers which lead
eventually to a hearing at the US Congress in 2006. The last two
papers appear in the Sp Issue of Energy & Environment (2007)
devoted to the IPCC structure, processes and politics. In the paper
by Holland the author exposes several weaknesses in the IPCC
2001 documents and also identifies errors in the Mann et al paper.
The last paper by Craig Loehle uses 18 series of proxies other than
tree rings like borehole temperatures, Conroy Lake pollen,
Chesapeake Bay Mg/Ca etc with each series having at least 20
dates over the 2000-year period. Loehle also points out several
problems with tree –ring data like ring width enrichment due to
increased CO2 and obtains the reconstruction using the 18 series of
non tree ring proxies to clearly documents that the MWP
(Medieval warm Period from 8th thru 12th century) was warmer
than the present by about 0.3C at least.
In summary, the hockey-stick saga should be considered as over
now with a definitive conclusion that the MWP was at least as
warm as the late 20th century temperatures and probably warmer
than the present. The recent papers by Li, Wahl and Amman
(Tellus & Climatic Change) appear to be nothing more than an
academic exercise and do not add any new information re: global
cooling or other current issues.
2. Solar variability and sun’s role in the earth’s
climate
More and more peer-reviewed papers keep appearing pointing the
dominant role of the sun and its variable output as measured by the
TSI (Total solar irradiance) and also by the complex mechanism
via the sun’s energy in the ultraviolet fields and plasmas. Some of
key papers on solar influence are listed below:
a. “Linkage between solar activity, climate predictability
and water resources development” W J R Alexander
et al J of the South African Institution of Civil
Engineering (June 2007) 49 p.32-44
b. “Has solar variability caused climate change that
affected human culture?” Joan Feynmann Advances in
Space Research (2007)40 p.1173-1180
c. ‘Effect of solar variability on the earth’s climate
patterns” Alexander Ruzmaikin Advances in Space
Research (2007) 40 p. 1146-1151
d. “Implications of the secondary role of carbon dioxide
and methane forcing in climate change: past present &
future” Willie Soon Physical Geography (2007) 28 p.
97-125
e. “Phenomenological reconstruction of the solar
signature in the northern hemisphere surface
temperature records since 1600” N Scafetta & B West J
of Geophysical Research (2007) 112 D24S03
doi:10.1029/2007JD008437
f. “Is climate sensitive to solar variability?” N Scafetta &
B West Physics Today (March 2008) 61 p.50-51
g. “Cosmoclimtology” H Svensmark Astronomical
Geophysics(2007)48 p.18-24
The papers listed above represent the ongoing research interest re:
sun’s role of earth’s climate as well as on human culture. The
paper by Alexander et al clearly document strong link between
rainfall variability and solar cycles in South Africa and vicinity
based on more than 100 years of data. Researchers Scafetta &
West continue to document strong links between TSI and earth’s
mean temperature. The comprehensive paper by Willie Soon
shows how the solar forcing at climatic sensitive latitudes has been
stronger than carbon dioxide and methane forcing over the past
650k years. Finally the recent book by H Svensmark & N Calder
“The chilling Stars: a new theory of climate change” (Icon Books
Ltd Cambridge UK) which has become one of the best sellers of
the year 2007 is sparking considerable debate among the scientific
community re: the role of sun as the possible primary driver of the
earth’s climate in geological as well as historical times. Also the
NASA in USA has announced its long-term plans to investigate the
sun’s role in earth’s climate. The sun’s role in the earth’s climate is
receiving more attention with many solar scientists pointing to the
current Solar Cycle 24 which is very quiet at this time with very
few sunspots so far. Further, there is mounting speculation about
the current solar cycle and the next two solar cycles (see Figure 2)
becoming weaker and this could lead to global cooling and a mini
ice-age similar to the Little Ice Age during the period 1650-1850.
3. Urbanization & Land-use Change
The issue of urbanization and land-use change impact on
temperature trends continues to attract researchers and has
led to publication of several papers on regional and global
impact. Following key papers have appeared on urban
impact and related areas in the last two years:
a. “Methodology and results of calculating central
California surface temperature trends: evidence
of human-induced climate change?” J Christy et
al (2006) J of Climate 19 p. 548-563
b. “Interpreting recent temperature trends in
California” P B Duffy, C Bonfils & D Lobell
(2007) EOS Transactions AGU 88 9 October
2007 p.409-410
c. “Recent California climate variability: spatial and
temporal patterns in temperature trends” S
Ladochy S Medina & W Patzert Climate
Research (2007) 33 p.159-169
d. “land use/land cover change and its impact on
climate” R Mahmood, R A Pielke sr & K G
Hubbard (2006) Global & Planetary Change
Editorial, Volume 54 vii
e. “Quantifying the influence of anthropogenic
surface processes and inhomogeneities on
gridded climate data” R McKitrick & P Michaels
(2007) j of Geophysical Research 112 D24S09
doi:10.1029/2007JD008465
In the above list, the first three papers relate to recent
surface temperature trends in California and their
interpretation. The main conclusion seems to be the impact
of massive growth in irrigated agriculture in the central
California valley on the winter and spring temperature
trends. Other external influences such as aerosols and GHG
warming may be operating, but the main forcing (Christy et
al 2006) seems to be impact of irrigation and land-use
change. The paper by Ladochy et al documents a
significant local heat island created by urbanization over
urban centres in California. The short editorial of the Sp
issue of Global & Planetary Change(2006) emphasizes the
impact of land-use/land-cover change on regional and
global climate. Several papers in this Sp Issue demonstrate
the land-use change impact on precipitation, temperature
and near-surface atmospheric moisture content. The last
paper (e) makes a careful evaluation of gridded temperature
data used in climate models and concludes that the
anthropogenic surface processes (urbanization etc) can
account for up to 50% of recent temperature increase which
has been attributed to GHG-induced temperature increase.
In summary, the urbanization and land-use change impacts
are important contributors to surface temperature trends
and must be taken into account while discussing GHGinduced climate change. As discusses in the earlier
bibliography document, there is a need to determine the
warming due only to human-added carbon dioxide.
4. Arctic & Antarctic warming/Cooling:
Recent observational studies now show that the Arctic seaice cover has depleted significantly while in the Antarctic,
the sea-ice concentration has increased. Also the Antarctic
has experienced increased snow accumulation in recent
years. Some of the key papers on Arctic/Antarctic
temperatures and other parameters are listed below:
a. “Do changes in the mid-latitude circulation have
any impact on the Arctic surface temperature
trend?” R G Graversen (2006) J of Climate 19
p.5422-5438
b. “Vertical structure of recent Arctic warming” R
G Graversen et al (January 2008) Nature 541
p.53-56
c. “A doubling of snow accumulation in the western
Antarctic Peninsula since 1850” E R Thomas, G J
Marshall & J R McConnell (2008) Geophysical
Research Letters 35 L01706
doi:10.1029/2007GL032529
The first two papers (by Rune Graversen & coworkers)
document how the surface air temperature in the Arctic is
sensitive to the mid-latitude circulation and to the
atmospheric northward energy transport which also
influences the vertical structure of the Arctic. Other
processes like cloud cover and atmospheric water vapour
content also contribute to the warming of the Arctic
troposphere up to 400 hPa level. The third paper documents
a doubling of snow accumulation on the southwestern
Antarctic Peninsula during the decade 1997-2006. This
doubling of the snow accumulation is inferred from the ice
core records and further a strong relationship between the
snow accumulation and the SAM (Southern Annular Mode,
an atmospheric circulation feature of southern hemisphere)
is shown to exist.
These and other papers listed in the earlier document now
strongly suggest the role of large-scale circulation patterns
on the warming in the Arctic. The question whether this
change in the circulation pattern is due to increased
concentration of GHGs or is part of natural climate
variability remains to be answered, but more evidence now
suggests that these atmospheric circulation changes are part
of natural climate variability which may be linked to
changes in solar variability.
5. Large-scale atmosphere/ocean circulation
changes
Large-scale atmospheric and oceanic circulation patterns
are being analyzed in greater details in recent papers. These
studies provide an improved understanding of how these
circulations have changed in recent years and whether these
changes are related to GHG forcing or otherwise.
Following key papers on atmosphere/ocean circulation
changes are listed.
a. “Temporal variability of the Atlantic meridional
overturning circulation at 26.50 N” S A Cunningham et
al (August 2007) Science 317 p.935-938
b. “Cloud and radiation budget changes associated with
tropical intraseasonal oscillation” R W Spencer et al
(2007) Geophysical Research Letters 34
L15707doi:10.1029/2007GL029698
c. “Monsoon mysteries” J Shukla (October 2007)
Science 318 p. 204-205
d. “Ocean circulation in a warming climate” J R
Toggweiler & J Russell (January 2008) Nature 451 p.
286-288
e. “A new dynamical mechanism for major climate
shifts” A T Tsonis, K Swanson & S Kravtsov (2007)
Geophysical Research Letters 34 L13705
doi:10.1029/2007GL030288
The above papers provide a broad spectrum of topics of
present research interest. In paper (a) the authors analyze
data from rapid climate change array of moored
instruments along 26.50 N and conclude that the available
data (from March 2004 to May 2005) is too short to
identify changes in meridional overturning due to global
warming. In paper (b) satellite data on clouds associated
with tropical intra-seasonal oscillations are analyzed to
support the iris hypothesis first suggested by Prof Lindzen
and coworkers a few years ago. In paper (c) Prof Shukla
points out to the present climate models’ inability to
simulate Asian summer Monsoon (Shukla echoes the
sentiments expressed by Prof S Gadgil –see earlier
bibliography- that after fifty years of research &
development most climate models fail to adequately
simulate Indian/Asian Monsoons). The paper by
Toggweiler & Russell analyze climate models’ prediction
of weaker ocean circulation in response to global warming.
Their analysis using past evidence suggests that the future
circulation could be stronger, thus casting doubt about
present climate models and their ability for future
projection. Finally the paper by Tsonis et al uses a novel
approach to demonstrate the climate shift that occurred
around 1976 using large-scale atmosphere/ocean indices.
The paper speculates how this climate shift may have
augmented the GHG-induced warming of the recent years.
6. Climate sensitivity and related issues
The debate about climate sensitivity (increase in the mean
temperature with doubling of the CO2 concentration)
continues and three key papers are listed below:
a. “Aerosol radiative forcing and climate sensitivity
deduced from the last glacial maximum to Holocene
transition” P Chylek & U Lohmann Geophysical
Research Letters (2007) 35 L04804
doi:10.1029/GL032759
b. “Taking greenhouse warming seriously” R Lindzen
Energy & Environment (2007) 18 p.937-950
c. “Heat capacity, time constant and sensitivity of earth’s
climate system” S Schwartz J of Geophy. Research
(2007)112 D24S05 doi:10.1029/2007JD008746
The papers (a) and (c) use different techniques and obtain
climate sensitivity to be between 1.2 to 2C for a doubling
of CO2.The paper by Prof Lindzen obtains upper limit to
the present warming by greenhouse forcing as no more than
about 33% of the recent warming (which amounts to just
about .2C), thus implying a small climate sensitivity. These
and other estimates now suggest the climate sensitivity to
be no more than about 1 to 1.5C, which is not of great
concern.
7. Climate model forecasts, uncertainties and
discrepancies
a. “A comparison of tropical temperature trends
with model predictions” D H Douglas et al Int’l
J of Climatology (2007) DOI:10.1002/joc.1651
b. “Advancing decadal-scale climate prediction in the
north Atlantic sector” N S Keenlyside et al Nature (May
2008)453 p.84-88
c.“How nature foiled the 2006 hurricane forecasts” W K
M Lau & K –M Kim EOS Transactions AGU 88 27
February 2007
d. “Improved surface temperature prediction for the
coming decade from a global climate model” D Smith
et al Science 317 (August 2007) p.796-799
The paper (a) shows how the observed tropical tropospheric
temperature trends from satellite data are significantly
lower than most model-generated trends. The papers (b)
and (d) include multi-decadal variability in the Atlantic as
well as in the Pacific (associated with the PDO & ENSO)
and predict cooling of the earth’s climate over the next few
years as the natural variability dominates GHG forcing. In
paper (c), the authors document how the forecasts for
hurricane season of 2006 which was issued before the
beginning of the hurricane season (~ by May 2006) was
foiled due to spreading of a large amount of dust from the
Sahara Desert over the north Atlantic in summer of 2006
and this led to significant cooling of the Atlantic SSTs.
This unexpected cooling led to a considerably weaker
hurricane season of 2006 than what was forecast at the
beginning of the season.
These papers highlight several uncertainties in climate
models and their future projections. The projected cooling
of the earth’s mean temperature over the next few years
indicates how natural variability can dominate GHGinduced warming and this creates considerable uncertainty
in projections of future warming. Perhaps the most telling
discrepancy is between satellite-derived temperature trend
vs model-generated trends for the tropical troposphere. The
models use the GHG forcing to produce temperature trends
which simply do not match with the reality.
8. Miscellaneous topics (hurricanes, sea-level
rise, CO2 growth, IPCC processes etc)
a. “The IPCC: structure, processes and politics climate
change-the failure of science” W J R Alexander
Energy & Environment (2007) 18 p. 1073-1077
b. “180 years of atmospheric CO2 gas analysis by
chemical methods’ Ernst-Georg Beck Energy &
Environment (2007) 18 p. 259-282
c. “Decadal variations of intense typhoon occurrence in
the western Pacific” Johnny C L Chan Proc. Of the
Royal Society A 464 (2008) p. 249-272
d. “Has the IPCC exaggerated adverse impact of global
warming on human societies?” M L Khandekar
Energy & Environment (2008) 19 p. 713-719
e. “Environmental effects of increased atmospheric
carbon dioxide” A Robinson N Robinson & W Soon J
of American Physicians and Surgeons(2007)12 p.7990.
f. “Decadal trends in sea level patterns: 1993-2004” Carl
Wunsch, R M Ponte & P Heimbach J of Climate
(2007) 20 p.5889-5911
Prof. (emeritus) Alexander criticizes the IPCC as well as
the Royal Society in UK for ignoring well documented
evidence of solar variability and its linkage to various
weather elements and to climate variability while pushing
for human influence on climate. In (b) the author analyzes
over 90,000 pieces of data on chemical analysis of
atmospheric CO2 (mostly over Europe) to document much
higher values of CO2 being present in the 1800s which the
IPCC did not take into account. The paper by Chan
documents decadal variations in intense typhoons over the
western Pacific and discounts any suggestion of a linear
relationship between typhoon/hurricane intensity and SST
increase. In (d) Khandekar examines and rejects IPCC
exaggerated claims of adverse global warming impacts on
human societies while citing beneficial impacts like lower
house-heating cost and longer agricultural season for highlatitude countries. Robinson and coworkers document
beneficial impacts of increased carbon dioxide like
enrichment of forestry while refuting IPCC claims of
deleterious impacts. Finally, Prof (emeritus) Carl Wunsch
and coauthors carefully analyze a large amount of sea level
data over the period 1993-2004. Allowing for thermal,
salinity and mass redistribution contribution in regional
patterns, Wunsch et al obtain a value for the sea level rise
as 1.6 mm/year, this value being about 60% of the pure
altimetric estimate. The authors (Wunsch et al) further
conclude that the database is insufficient to compute mean
sea level trends with accuracy necessary to discuss the
impact of global warming.
9. Summary & the emerging view of present
climate change
This document has examined about 35 key papers
appearing in the peer-reviewed literature in the last two
years or so. Many more papers have been published which
have questioned one or more assumptions re: the present
global warming & climate changes issue. Based on these
and other papers examined in the earlier document, the
emerging view of present climate change can be
summarized as follows:
1. The recent warming of the earth’s surface (~ 0.55C
since 1980) is primarily due to natural climate
variability exhibited through changes in large scale
atmosphere/ocean circulation patterns. These
circulation changes are linked to changes in solar
variability through complex mechanism, not fully
understood at this time.
2. Human activity on ground (urbanization, land-use
change) has also significantly contributed to the resent
warming of the earth’s surface.
3. The warming due solely to human-added CO2 appears
to be small, no more than about 30% of the recent
warming.
4. Future warming of the earth’s surface due to a
doubling of CO2 is now estimated to be between 1 to
1.5C
5. Excellent satellite data of the last 29 years show very
little additional warming since 1997. For southern
hemisphere, there is a slight cooling revealed for the
past few years.
6. Solar variability and in particular the solar ‘downturn’
during the next two solar cycles ( 24 & 25) is now
considered to be exerting a definite impact on the
earth’s climate at present and for the next two or more
decades. According to some solar scientists, there
exists a definite possibility of a significant global
cooling leading to a mini ice age in the next 25 to 30
years.
7. Despite significant advances, climate models still do
not provide any usable skill in predicting climate
events like El Nino and La Nina or important regional
features like Indian & Asian Monsoon which affects
about 60% of the world’s humanity at present.
8. There is no evidence of escalating sea level rise at
present. The best estimate of future sea level rise is
now about 2.0 mm/year or about 20 cm for the next
100 years.
9. The excessive Arctic warming is due to an increase of
the atmospheric northward transport of heat and
moisture.
10. There are beneficial impacts of global warming,
especially for high-latitude countries in terms of milder
winters and longer agriculture season.
-Author information: Dr M L Khandekar is a former
research scientist from Environment Canada and is
presently on the editorial board of the Journal Natural
Hazards (Kluwer Netherlands). Khandekar has been in
the fields of weather & climate for over fifty years and
has published more than 125 papers, reports, book
reviews etc. While at Environment Canada, Khandekar
wrote a monograph operational analysis and prediction
of ocean wind waves which was published by SpringerVeralg in 1989. Khandekar is an expert reviewer for the
IPCC 2007 climate change documents.
Figure 1: Global temperature anomalies over the lower
troposphere based on MSU (Microwave Sounding Unit)
measurements aboard polar orbiting satellites (1979-2007)
Figure 2: Sunspot Cycles 1700-2030