The mythology of man-made global warming

Posted 3rd February 2010

No evidence of hot-spots in the troposphere:

The UK Met Office describes the Anthropogenic Global Warming (AGW) hypothesis as follows: “It is now clear that man-made greenhouse gases are causing climate change.  The rate of change began as significant, has becoming alarming and is simply unsustainable in the long term” and the greenhouse effect is depicted on their website thus:

Solar rays hit the earth and heat up the surface (as shown on the left).  The earth’s surface emits infrared radiation back in to space thereby cooling the planet (depicted by two of the red arrows in the right hand picture).  Greenhouse gases in the troposphere trap some of the infrared rays reflecting heat back down to the surface.  The AGW theory suggests that increased CO2 concentration in the atmosphere, caused by humans, is raising global temperatures.

For the theory to hold true, the observable rate of temperature increase would be higher in the troposphere than at the earth’s surface.  The rate of temperature increase would be most noticeable in the tropics because that is where the surface would be radiating the most heat.

Yet the observations, from radiosonde (weather balloons) have consistently shown that not to be the case:

The left hand picture is the climate model prediction of warming in the mid troposphere due to greenhouse gases from 1958 to 1999.  The computer models predict most warming occurs at the mid troposphere at the Equator.  The right hand picture shows actual temperatures measured over the same period by radiosonde (weather balloon).  Actual balloon measurements show no increase in the rate of warming in the mid troposphere at the Equator, ie. no evidence of hot-spots in the troposphere and what is more none of the scientific papers supporting the AGW theory have claimed to have found such evidence.

In short the AGW theory is not borne out by the evidence.  Had the AGW hypothesis been subject to the proper scientific method, the failure to substantiate this fundamental premise (of increased warming in the troposphere over the Equator) would have rendered the man-made global warming theory invalid.

Lack of fundamental evidence insufficient to stop the IPCC and the AGW lobby

However, the Intergovernmental Panel on Climate Change (IPCC), the pro-AGW paleoclimatic community, Al Gore and grandstanding politicians were undaunted by the lack of this fundamental foundation to the AGW hypothesis.  The reasons why will be addressed later but to support the man-made global warming claims, they adduced additional evidence:

1.  Since the birth of the industrial revolution in the early 1800s, temperatures had risen at an accelerating rate which by the end of the twentieth century had become “unsustainable”.  A well publicised chart showing the correlation between industrial activity and global temperatures from the mid-nineteenth century to the then present day looked, to the uninformed observer (as was this writer at that time), pretty compelling.

2. Michael E. Mann and Raymond S. Bradley (Department of Geosciences, University of Massachusetts) and Malcolm K. Hughes (Laboratory of Tree-Ring Research, University of Arizona) produced a paper MBH98 which contained the controversial hockeystick graph showing global temperatures oscillating within a narrow range for about 1000 years and then breaking out upwards in the 1990s.

3. Extreme weather events were portrayed as becoming more frequent and violent as a direct result of man-made global warming.  Many linked hurricane Katrina accordingly.

4. Extensive TV footage of melting ice sheets and dire warnings of rising sea levels seemed credible proof that we really were sowing the seeds of our own demise by overheating the planet.  Plane Stupid produced an excellent advertisement showing polar bears falling out of the sky implying that air travel is killing off our favourite “cuddly” species of the Arctic.

5. Glaciers in retreat were shown extensively as yet further proof of our collective wickedness.

What is the evidence supporting these 5 claims?

1. Are rising man-made CO2 emissions are causing global warming?

Both sides of the global warming debate agree that there is a close correlation, over the last 800,000 years, of CO2 concentrations in the atmosphere with global temperatures.  Furthermore it is generally agreed that hitherto, the rise in temperatures preceded the rise in CO2 levels by around 800 years.  However, the IPCC and the pro-global warming lobby insist that it is now CO2 which is driving the rise in temperature with no hard evidence to support this illogical premise.  On the contrary, temperatures rose fairly rapidly from about 1900 to 1940 but then declined until the late 1970s during a period when CO2 emissions were rising in the post-war industrial boom.  According to satellite data, following peak temperatures in the mid 1990s, 2008 and 2009 were significantly cooler in spite of a further increase in CO2 emissions.

95% of greenhouse gas is water vapour, CO2 is a relatively minor constituent making a marginal contribution to the greenhouse system

Some studies acknowledge that rises in CO2 concentrations have a warming influence but that it is logarithmic, ie. the first 20 parts per million have the most effect but thereafter the influence wanes to negligible by the time the current 388 parts per million are reached.  CO2 concentrations have been much higher in the past.

CO2 is beneficial for promoting plant growth which is important if we are to feed the growing global human population without destroying our environment.  Dutch growers buy CO2 to increase concentrations in their greenhouses to increase crop yields.

Finally, while acknowledging that the earth’s climate is a complex system with millions of variables, the correlation between solar activity and temperature appears much more compelling :

The advantage of using the Arctic temperature data is they are unlikely to be affected by the Urban Heating Island effect; many, once isolated, land based temperature recording stations are now within urban environments which distort the records.

2. MBH98 – the Hockeystick Graph

The scientific method requires that data, methodologies and assumptions should be available for independent peer review.  Indeed it is mandatory for work to be published in serious scientific journals.  However, numerous attempts, by interested parties to obtain the requisite information from Mann et al who produced MBH98 paper, were met with obfuscation and hostility.  The leaked documents and emails from the Climate Research Unit at the University of East Anglia, now referred to as Climategate, confirmed the lengths the authors went to, to avoid sharing how they had produced their results.

However, some persisted in trying to replicate the work of Mann et al, who produced the MBH98 paper, and eventually  Steve McIntyre, a retired geologist and mathematician, in collaboration with Ross McKitrick, an economist, exposed the flaws in the paper and the resulting hockeystick.  In 2005 US Congress appointed Edward Wegman of George Mason University, also past Chairman of the National Academy of Sciences Committee on Theoretical and Applied Statistics, to head a committee to adjudicate between Mann et al and McIntyre/McKitrick.  The Wegman Report not only fully endorsed the findings of McIntyre and McKitrick but also presented a wide-ranging critique of the insularity of the paleoclimate community, their isolation from mainstream statistics, and their hostility towards external review and replication work.
The report concluded: “Overall our committee believes that Dr Mann’s assessments that the decade of the 1990s was the hottest decade of the millennium, cannot be supported by his analysis.” Further, in reference to the supposed independent peer reviews, it said: “at least 43 authors have direct connections to Dr Mann by virtue of coauthoring papers with him.”

Temperature data, both recorded and so called proxy data (from ice cores, tree rings, coral reefs, fossil pollen etc.), are subject to interpretation and there is currently no long term reliable record of global temperatures.

Recorded temperatures at the earth’s surface are inconsistent and subject to adjustment for urban heat effects.  For example, the recorded difference in temperature between Reno and its out of town airport can be as high as 10 degrees Fahrenheit.  Inconsistencies in the data have arisen, such as in the former USSR, where cold weather subsidies created a downwards bias; when the USSR fragmented, records suffered further.  Once remote temperature recording stations are now surrounded by urban development and the adjustments applied, to rectify urban heat effects, are inevitably subjective.  Anthony Watts, a retired meteorologist, has conducted extensive study on this and other aspects of the global warming debate.

The proxy data are similarly subject to adjustment.  Tree rings in particular, on which much of MBH98 and the hockey stick depend, are only an approximate indicator of temperature.  The width and density of tree rings varies with temperature each year but other factors such as humidity also have an effect.  Furthermore, the tree ring data are derived from a limited number of locations and cannot therefore be a reliable proxy for global temperature.  It has also come to light that some tree data were discarded because they undermined the theory.  The work of McIntyre/McKitrick and Climategate exposes the degree to which the data have been manipulated to fit the hypothesis.

For the IPCC Report in 1990, the graph of temperatures during the second millennium produced by HH Lamb was used:

But a decade later, the IPCC depiction, of global temperatures during the second millennium, looked like this in its 2001 report:

This is the now discredited hockey stick graph produced as a result of MBH98.  There have been subsequent revisions by Mann et al to address the criticisms but none of the derivative versions are credible.  See “How The Trick was pulled off”

Another proxy is history.  The Norse settled in Greenland from about 980AD during the Medieval Warm Period, until circa. 1400 indicating that the climate has been significantly warmer than it is today.  The Bronze Age was even warmer still.  The onset of the Little Ice Age and the Vikings’ failure to adapt to the inhospitable climate, caused the collapse of their settlements (Jared Diamond, Collapse. ISBN-10: 0670033375).  The Little Ice Age ended at around 1800.  Further confirmation of the LIA is provided by Samuel Pepys who wrote of ice skating on the Thames with Nell Gwynne in 1683 when the river and surrounding coastline froze for two months.  That the globe has been warming since is neither surprising nor alarming.

HH Lamb’s graph in the 1990 IPCC Report seems a much more realistic depiction of temperatures over the second millennium.

3. Are extreme weather events a consequence of global warming?

Chris Landsea, of the National Oceanic and Atmospheric Administration’s (NOAA) hurricane research division in Miami, resigned from the IPCC in 2005 protest over IPCC claims that extreme weather events are a direct consequence of global warming.  His studies show improved monitoring in recent years is responsible for most, if not all, of the observed trend in increasing frequency of tropical cyclones.  A 2007 paper by Gabe Vecchi, another climate scientist at NOAA, concluded increased wind shear from rising sea surface temperatures make it more difficult for hurricanes to form and grow.

4.  Is global warming causing the polar ice caps to melt?

Footage of the ice shelf crashing into Arctic Ocean makes good television but polar ice undergoes significant expansion and contraction through winter and summer.  On the basis of satellite data, although there is some correlation of polar ice with global temperature, the data are inconclusive.  In the last couple of years the polar ice in the Arctic has expanded. In the southern hemisphere, there is evidence of Antarctic cooling from 1966­ to 2000.

5. Are glaciers disappearing?

Glacial erosion in the Himalayas has been overstated by the IPCC (as indicated by the recent reversal of the claim that Himalayan glaciers will have disappeared by 2035). The most recent studies by researchers at ETH Zurich show that in the 1940s Swiss glaciers were melting at an even ­faster pace than at present.  The rapid erosion is ascribed to solar radiation rather than man-made global warming.
http://www.agu.org/pubs/crossref/2009/2009GL040789.shtml

Is the planet getting warmer?

Radiosonde and satellite data are probably the most reliable but even satellite data require adjustment as their orbit drifts over their lifetime. John Christy and Roy Spencer at the University of Alabama in Huntsville have produced numerous papers on temperature data.  What they confirm is that the climate is always changing and will continue to do so.  On the basis of current evidence, human activity has negligible influence on global temperatures.  What Christy and Spencer do suggest is that, in the past, some changes have been quite abrupt but the ability to predict them does not yet exist.  However, serious climate science continues apace to further our understanding of the causes of change and develop ways to predict dramatic shifts.

Indications from solar science are that the sun is the more likely cause of climate change but there are many aspects to solar influence.  Solar cycles have influence by virtue of their intensity and duration.  NASA recently announced that Solar Cycle 25 peaking in 2022 could be one of the weakest in centuries.  The Maunder Minimum which occurred during the Little Ice Age was characterised by neglible sunspot activity.  The physical relationship between the sun and earth also affects temperature.  For example, Milankovitch Cycles refer to the eccentricity of the earth’s orbit, axial tilt and precession (the earth oscillates on its vertical axis).  Other factors include the magnetic influence of the sun, gallactic cosmic rays and solar wind.

The planet has been warming since the end of the last ice age approximately 18,000 years ago although there are natural fluctuations within the upward trend.  Once global warming stops we will be heading for the next ice age.  Ice ages typically last for about 100,000 years and sea levels fall dramatically.

Read the graph, of Atmospheric Temperature from ice core data,  from right to left.  It shows temperature fluctuations over the last 800,000 years.  It is clear the Earth has been warmer than today and it would appear that we are unlikely to see such temperatures again before the onset of the next ice age, if previous patterns are repeated.  Cooler temperatures are characterised by famine and higher fatalities.

What of the scientific “consensus”?

The IPCC implies that some 2,500 climate scientists support its claims.  This paper by John McLean contains analysis of the number of contributors to the AR4 (2007) report:
http://mclean.ch/climate/docs/IPCC_numbers.pdf
Just because someone’s name is on the IPCC report as a contributor or reviewer doesn’t mean they are a climate scientist nor does it mean they endorse the Summary for Policy Makers’ conclusions.  As it says in the paper: “Fifty-three authors and five reviewers are all that might generously be said to have explicitly supported the claim of a significant human influence on climate.”

In contrast, in December 2007 the US Senate Environment and Public Works Committee published a report detailing submissions from more than 400 prominent international scientists, many of whom were current and past participants in the UN IPCC, criticising the climate claims made by the IPCC and former Vice President Al Gore.  In March 2009, the report was updated to include submissions from an additional 300 international scientists bringing the total to over 700 who dissent from the man-made global warming hypothesis.

The US Senate Minority Report contains references to scientists being intimidated to discourage them from speaking out publicly.

Summary

Earth’s climate is highly complex involving millions of variables that current models cannot replicate.  Our collective knowledge of climate science is limited and it would be dangerous to introduce global policy shifts on the basis of our limited knowledge.  However the AGW hypothesis is invalid; there is no evidence of increased warming in the tropical troposphere, contrary to what the climate models predict.  This one fact is sufficient to discard the hypothesis or at least acknowledge that any influence of man-made CO2 emissions is negligible.  The temperature data for the last millennium are unreliable and do not support the AGW myth.  There is insufficient empirical data and no evidence to claim that weather, polar sea ice or glaciers are being adversely affected by man-made carbon emissions.  So why has the AGW theory gained so much traction in the face of opposition from a significant number of renowned scientists?  That question is addressed in the 21st Century Carbon Caper.