Global Warming or Global Cooling:
Does Air Temperature Really Matter?
by William DiPuccio
Despite a consensus among scientists on the use of ocean heat as a robust measure for anthropogenic global
warming (AGW), air temperature continues to be employed as the icon of global climate projections. In a
recent AP article by Seth Borenstein, “Statisticians reject global cooling”, the Associated Press “gave
temperature data to four independent statisticians and asked them to look for trends, without telling them
what the numbers represented. The experts found no true temperature declines over time.”
A lot of mercury and red alcohol has been spilled over the last several years dissecting the reliability of nearsurface temperature measurements. The controversy has spawned high profile blogs dedicated to the
scrutiny of surface station reliability (www.surfacestations.org) and the analysis of climate statistics
(www.climateaudit.org). The exercise has proven to be fruitful in many cases, discovering systemic
weaknesses in the network of surface stations, exposing sloppy calculations, and raising legitimate questions
about the algorithms used to adjust raw data. Though satellite air temperature measurements do not suffer
from these limitations, our observations extend back only 30 years.
The use of air temperature as an index of global warmth has weak scientific support, except, perhaps, on a
multi-decadal or century time-scale. Climate scientists agree that 80% - 90% of the heat in earth’s climate
system is stored in the oceans. For any given area on the ocean’s surface, the upper 2.6 meters of water has
the same heat capacity as the entire atmosphere above it! Air temperature may not register accumulated
ocean heat from year to year. Since this heat is not always at the ocean’s surface, there may be long lags in
air temperature response time. But eventually, as the ocean heats or cools, air temperature is sure to follow.
Accordingly, the findings represented in Borenstein’s article are no surprise and do little to support or
damage the case for AGW.
Hype generated by scientists and activists over short-term changes in global air temperature (up or down) has
diverted us from the real question: Is heat accumulating in the world’s oceans? Many climate scientists,
including those at NASA’s Goddard Institute for Space Studies (GISS) and the British Met Office Hadley
Centre for Climate Change, are being rather disingenuous in their use of air temperature. They advocate
ocean heat as a climate metric in research articles (including AR4—the most recent IPCC report), but then
use air temperature as a metric when discussing AGW with the public. Presumably, from a marketing
perspective, the man on the street cannot connect with “Joules of accumulated heat” absorbed by the ocean.
So what does ocean heat tell us about the progress of global warming? That’s the elephant in the living room
that proponents of AGW aren’t talking about—at least not lately. Writing in 2005, NASA scientists James
Hansen, Josh Willis, Gavin Schmidt, et. al. suggested that their model projections of global warming had
been verified by a solid decade of increasing ocean heat (1993 to 2003). This was regarded as confirmation
of the AGW hypothesis (see “Earth’s Energy Imbalance: Confirmation and Implications”, Science, 3 June
2005, 1431-35).
But by mid-2003 warming ceased rather abruptly and, by all appearances, not one Joule of energy has been
added to the ocean for over 6 years. According to some analysts there has been a slight cooling, even as
CO2 levels continue to rise. Advocates of AGW have dismissed this as natural variability. But the
implications are clear. If the climate system is not accumulating heat, the hypothesis may be false.
Changes in ocean heat content calculated from bathymetric temperature profiles at various locations across
the earth Heat content has been nearly flat since mid-2003. Accuracy has improved dramatically with the
deployment of ARGO floats in 2003—a system of over 3200 automated buoys. The sharp, uncharacteristic
step that year may be an artifact caused by the transition from older bathythermograph observations.
Courtesy of Bob Tisdale, “Climate Observations” (bobtisdale.blogspot.com/2009/10/nodc-corrections-toocean-heat-content_16.html).
The current trend also raises some pointed questions. If climate change is now dominated by CO2 induced
warming, what mechanism is responsible for the current cessation of warming? The immediate cause is well
known: The periodic cooling and warming of ocean waters called the Pacific Decadal Oscillation (PDO).
But the underlying causes of the PDO itself are not well understood, which is also true for much of the
variability in our climate system.
If we cannot explain the causes behind natural variability, then how can we project future climate trends?
Moreover, how can we be sure that the prior warming trend was anthropogenic rather than natural? After all,
we cannot eliminate from consideration causes we do not understand. Borenstein’s article proceeds on the
assumption that if there is warming, it must be anthropogenic, and it must be from CO2. The question of
attribution—the most difficult scientific question of all—is never raised.
At the very least, the flattening of ocean heat over the last 6 years should raise cautionary flags and provoke
a re-examination of climate model projections. If CO2 induced warming is so easily overwhelmed by
natural variability, then perhaps the threat of “runaway warming” and climate “tipping points” has been
overstated. Despite the sophistication of our efforts, perhaps our ignorance exceeds our knowledge.
Unfortunately, climate scientists who continue to hide behind the metric of air temperature are dodging the
hard questions. Repeated efforts to confront them on the issue of ocean heat have met with silence (see
Roger Pielke’s article cited below). Now that heat accumulation has stopped (and maybe even reversed), the
tables have turned. The same criterion used to confirm Anthropogenic Global Warming, is now challenging
its legitimacy.
Bill DiPuccio was a weather forecaster and instructor for the U.S. Navy, and a Meteorological/Radiosonde
Technician for the National Weather Service. More recently, he served as head of the science department for St.
Nicholas Orthodox School in Akron, Ohio (closed in 2006). He continues to write science curriculum, publish
articles, and conduct science camps.
References
Seth Borenstein, “Statisticians reject global cooling” www.comcast.net/articles/newsgeneral/20091026/US.SCI.Global.Cooling_/
William DiPuccio, “Have Changes in Ocean Heat Falsified the Global Warming Hypothesis?”
http://pielkeclimatesci.wordpress.com/2009/05/05/have-changes-in-ocean-heat-falsified-the-global-warminghypothesis-a-guest-weblog-by-william-dipuccio/
William DiPuccio, “A Glimpse Inside the Global Warming Controversy: Why You Need to Consider Both
Sides”
http://scienceandpublicpolicy.org/images/stories/papers/originals/A_Glimpse_Inside_the_Global_Warming_
Controversey.pdf
Roger Pielke, “Comments On AP Story “Statistics Experts Reject Global Cooling Claims”
pielkeclimatesci.wordpress.com/2009/10/26/comments-on-ap-story-statistics-experts-reject-global-coolingclaims/
Bob Tisdale, “Why Are OHC Observations (0-700m) Diverging From GISS Projections?”
bobtisdale.blogspot.com/2009/10/why-are-ohc-observations-0-700m.html