Global Warming and Climategate: ‘Hide the Decline’ Explained

December 7, 2009

The Climategate email that has been featured as most damaging refers to “Mike’s nature trick” to “hide the decline.” It was written by Climate Research Unit (CRU) director Phil Jones who was forced to step down from his position pending an investigation. This email is indeed damaging to the argument that the earth is experiencing an unprecedented level of global warming, but the specifics on why this is the case have not been reported accurately.

It has been widely misreported that the decline refers to the decade-long drop in global temperatures since 1998. The fact that Jones wrote the email in November, 1999, should make it apparent that this interpretation is incorrect.

The American Thinker provides a detailed explanation of how the email refers to the decline in temperatures from the Medieval Warm Period. (The quotes in this post are from the American Thinker’s article. I have left out technical details to make this more accessible to the general reader.)

The problem for advocates of extraordinary global warming over the past century is that the earth was warmer during this Medieval Warm Period which extended from approximately 900 A.D. to 1300 A.D.

We have temperature records only for about 150 years which is why temperature charts based on actual temperatures start around 1850. To get indications of earlier temperatures, scientist have studied lake sediments, boreholes, ice cores, and tree rings.

They then employ complex computer programs to combine such “proxy” data sampled throughout a region to plot that area’s annual relative changes in temperature hundreds or even thousands of years prior. By then combining the datasets, they believe they can accurately reproduce hemispheric and global temperature trends of the previous millennia.

And while reconstructions — as past temperature interpretations from proxy data are called — can differ greatly from one source to another, those generated by the CRU have often been accepted as the de facto temperatures of the past.

Largely because the UN’s Intergovernmental Panel on Climate Change (IPCC) proclaims them to be.

It’s important to understand that early analyses of these “proxies” clearly demonstrated that three radical temperature shifts occurred within the past millennium, as do many contemporary studies. Indeed, the years 900-1300 AD were labeled the Medieval Warming Period (MWP), as global temperatures rose precipitously from the bitter cold of the previous Dark Ages to levels several degrees warmer than today. The Little Ice Age, a sudden period of cooling, then followed and lasted until the year 1850. And then began the modern warming period, which was by no means unique and appears to have ended with the millennium itself.

In 1990, the initial IPPC report showed these dramatic temperature swings:


“But this image of a fluid climate system subject to abrupt and natural up-and-downturns made unprecedented 20th century warming about as marketable as Florida swampland. And opportunists who depended on the aberrance of post-industrial revolution warming in order to condemn and control mankind’s CO2 emissions” recognized that this data presented a problem for their agenda.

By 2001 in its Third Assessment Report (TAR) the offending data had been eliminated to show the following graph of temperatures in the northern hemisphere:


This is Professor Michael Mann’s famous “hockey stick” graph that the CRU and the IPCC have used to sound the alarm on impending climate catastrophe.

Compare the “hockey stick” graph to a reconstruction of temperatures, “such as this one from, adapted from a 2005 Moberg et al. temperature history derived from tree-rings and lake and ocean sediments:”


As you can see, the post-LIA warming that began around 1850 is neither unprecedented nor spectacular. And certainly not worth rewiring the economic circuitry of the planet over.

And the CRU/IPCC reconstructions have been counterfeited for the express purpose of hiding that very fact.

After all, the stakes are enormous – perhaps trillions of dollars and unquestionably every American’s personal liberties. Tomorrow, over 20,000 delegates from 193 nations will gather in Copenhagen to craft an agreement which would not only force American power consumption to levels equal to those of about 1910, but would also have us pay reparations for an imaginary “climate debt” we’ve accumulated by building the world’s greatest economy of all time. That debt is based on the amount of CO2 our financial growth has purportedly pumped into the atmosphere, which, according to the conclusions of the IPCC, based largely upon reports from the CRU, has selfishly imperiled the planet by inducing climate change.

The hysteria of Copenhagen is based on data manipulated to advance an agenda of imposing unprecedented global controls on freedom. Climategate has provided a timely window into the corrupt science that has led to the Copenhagen summit.

Read previous coverage on global warming and Copenhagen on Florida Pundit here

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