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Last updated on: 4/7/2015 11:22:30 AM PST

Is Human Activity Primarily Responsible for Global Climate Change?


PRO (yes) CON (no)
The Intergovernmental Panel on Climate Change (IPCC) stated the following in its Nov. 2014 "Climate Change 2014 Synthesis Report," available at ipcc.ch:

"Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems.

Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen.

Anthropogenic greenhouse gas emissions have increased since the pre-industrial era, driven largely by economic and population growth, and are now higher than ever. This has led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years. Their effects, together with those of other anthropogenic drivers, have been detected throughout the climate system and are extremely likely [95% confidence] to have been the dominant cause of the observed warming since the mid-20th century."


Nov. 2014 - Intergovernmental Panel on Climate Change (IPCC) 

James E. Hansen, PhD, former Director of the Goddard Institute for Space Studies at NASA, et al., stated the following in their Aug. 6, 2012 study "Perception of Climate Change," published in the Proceedings of the National Academy of Sciences:

"The greatest barrier to public recognition of human-made climate change is probably the natural variability of local climate…

Actions to stem emissions of the gases that cause global warming are unlikely to approach what is needed until the public recognizes that human-made climate change is underway and perceives that it will have unacceptable consequences…

Recent high profile heat waves, such as the one in Texas and Oklahoma in the summer of 2011, raise the question of whether these extreme events are related to the on-going global warming trend, which has been attributed with a high degree of confidence to human-made greenhouse gases...

The increase of these extreme anomalies, by more than an order of magnitude, implies that we can say with a high degree of confidence that events such as the extreme summer heat in the Moscow region in 2010 and Texas in 2011 were a consequence of global warming...

There are many other human-induced stresses on life… yet global warming caused by fossil fuel burning may be a unique threat because of the millennial time scale of anthropogenic carbon within surface carbon reservoirs.

It has been argued that a scenario phasing out carbon emissions fast enough to stabilize climate this century, limiting further warming to a maximum of several tenths of a degree Celsius, is still possible, but it would require a rising price on carbon emissions sufficient to spur transition to a clean energy future without burning all fossil fuels.”


Aug. 6, 2012 - James E. Hansen, PhD 

The US Global Change Research Program stated in its May 2014 "US National Climate Assessment," available at nca2014.globalchange.gov:
"Multiple lines of independent evidence confirm that human activities are the primary cause of the global warming of the past 50 years. The burning of coal, oil, and gas, and clearing of forests have increased the concentration of carbon dioxide in the atmosphere by more than 40% since the Industrial Revolution, and it has been known for almost two centuries that this carbon dioxide traps heat. Methane and nitrous oxide emissions from agriculture and other human activities add to the atmospheric burden of heat-trapping gases. Data show that natural factors like the sun and volcanoes cannot have caused the warming observed over the past 50 years. Sensors on satellites have measured the sun’s output with great accuracy and found no overall increase during the past half century. Large volcanic eruptions during this period, such as Mount Pinatubo in 1991, have exerted a short-term cooling influence. In fact, if not for human activities, global climate would actually have cooled slightly over the past 50 years."

May 2014 - US Global Change Research Program 

Richard A. Muller, PhD, Professor of Physics at the University of California at Berkeley and Faculty Senior Scientist at the Lawrence Berkeley Laboratory, stated the following in his July 28, 2012 OP-ED "The Conversion of a Climate-Change Skeptic," available at www.nytimes.com:

"Three years ago I identified problems in previous climate studies that, in my mind, threw doubt on the very existence of global warming. Last year, following an intensive research effort involving a dozen scientists, I concluded that global warming was real and that the prior estimates of the rate of warming were correct. I’m now going a step further: Humans are almost entirely the cause...

Our [Berkeley Earth Surface Temperature project] results (1.3MB)  show that the average temperature of the earth’s land has risen by two and a half degrees Fahrenheit over the past 250 years, including an increase of one and a half degrees over the most recent 50 years. Moreover, it appears likely that essentially all of this increase results from the human emission of greenhouse gases...

We carefully studied issues raised by skeptics: biases from urban heating (we duplicated our results using rural data alone), from data selection (prior groups selected fewer than 20 percent of the available temperature stations; we used virtually 100 percent), from poor station quality (we separately analyzed good stations and poor ones) and from human intervention and data adjustment (our work is completely automated and hands-off). In our papers we demonstrate that none of these potentially troublesome effects unduly biased our conclusions...

[O]ur record is long enough that we could search for the fingerprint of solar variability, based on the historical record of sunspots. That fingerprint is absent...

How definite is the attribution to humans? The carbon dioxide curve gives a better match than anything else we’ve tried. Its magnitude is consistent with the calculated greenhouse effect — extra warming from trapped heat radiation... our analysis does not depend on large, complex global climate models, the huge computer programs that are notorious for their hidden assumptions and adjustable parameters. Our result is based simply on the close agreement between the shape of the observed temperature rise and the known greenhouse gas increase."

[Editor's Note:  The Berkeley Earth Surface Temperature Project published the results of its research on Oct. 11, 2011, as four draft papers:  "Influence of Urban Heating on the Global Temperature Land Average" (361KB) "Earth Atmospheric Land Surface Temperature and Station Quality in the United States" (588KB) , "Berkeley Earth Temperature Averaging Process" (1MB) , and "Decadal Variations in the Global Atmospheric Land Temperatures" (741KB) .]


July 28, 2012 - Richard A. Muller, PhD 

Peter Gleick, PhD, CEO of the Pacific Institute, stated the following in his Jan. 16, 2012 article "Climate Change, Disbelief, and the Collision Between Human and Geologic Time," available at forbes.com:
"Climate does change naturally for reasons well understood by scientists. But it does so over thousands or tens of thousands of years – time scales so slow as to be imperceptible to humans…

Human-caused climate changes are different. As the planet’s population has grown to 7 billion people, and as we have learned how to mobilize vast quantities of carbon-based fossil fuels (ironically, created over geologic time scales) to satisfy our short-term energy demands, we have become powerful enough to overwhelm slow geological cycles. We are, for the first time in the 4+ billion year history of the Earth capable of altering the largest geophysical system on the planet – the climate – and we are doing it on a human time scale of years and decades, with consequences we are only just beginning to comprehend. And ironically, our effect on the climate is still slow enough for policy makers, climate contrarians and skeptics, and those simply not paying attention to either actively deny it or to just look the other way, committing the planet to more and more change…

[T]he inability to comprehend the planetary influence of humans isn’t based on reviewing and rejecting the scientific evidence, which is clear to 97-98% of climate scientists publishing in the field. It is based on ignoring or disbelieving it..."

Jan. 16, 2012 - Peter Gleick, PhD 

The National Academy of Sciences stated the following in the introduction to their May 19, 2010 report "Advancing the Science of Climate Change," available at www.americasclimatechoices.org:

"[H]uman activities are influencing the climate. As discussed in the following chapters, scientific evidence that the Earth is warming is now overwhelming. There is also a multitude of evidence that this warming results primarily from human activities, especially burning fossil fuels and other activities that release heat-trapping greenhouse gases (GHGs) into the atmosphere.

Projections of future climate change indicate that Earth will continue to warm unless significant and sustained actions are taken to limit emissions of GHGs. These increases in temperature and GHG concentrations are driving a multitude of related and interacting changes in the Earth system, including decreases in the amounts of ice stored in mountain glaciers and Polar Regions, increases in sea level, changes in ocean chemistry, and changes in the frequency and intensity of heat waves, precipitation events, and droughts. These changes in turn pose significant risks to both human and ecological systems."


May 19, 2010 - National Academy of Sciences 

Michael E. Mann, PhD, Professor in the Departments of Meteorology and Geosciences at Pennsylvania State University, stated the following in his Feb. 10, 2010 article "Science Supports Climate Change Claims - A Letter from Michael Mann," available at www.voicesweb.org:

"[T]he scientific case for human-caused climate change is clear.  The evidence includes independent assessments of thermometer records documenting the degree and extent of modern warming. It includes the unprecedented melting of glaciers and, as documented in more recent years, the diminution of the Greenland and Antarctic ice sheet. As a consequence of melting ice and warming oceans, the global sea level is rising and at an accelerating rate. Continental drought is becoming more pronounced in many extratropical regions, such as the deserts of the U.S. Southwest, and there is an increase in the destructive potential of Atlantic hurricanes that influence the east and Gulf coasts. Theoretical climate models predict these things to happen, but only when human influences - in particular, increasing greenhouse gas concentrations due to fossil fuel burning—are included.

Those same models project far more profound and potentially damaging impacts of climate change if action is not taken to stabilize greenhouse gas levels this next decade...

Sadly, some who are opposed to taking action to combat the potential threat have engaged in a smear campaign that appears intended to distract the public and policymakers from the reality of the threat as policymakers begin to consider taking more serious action to reduce greenhouse gas emissions."


Feb. 10, 2010 - Michael E. Mann, PhD 

The United Nations Framework Convention on Climate Change (UNFCCC) stated the following in its publication "Feeling the Heat," available at unfccc.int (accessed May 12, 2010):

"The average temperature of the earth's surface has risen by 0.74 degrees C since the late 1800s. It is expected to increase by another 1.8° C to 4° C by the year 2100 - a rapid and profound change - should the necessary action not be taken...

The principal reason for the mounting thermometer is a century and a half of industrialization: the burning of ever-greater quantities of oil, gasoline, and coal, the cutting of forests, and the practice of certain farming methods.

These activities have increased the amount of 'greenhouse gases' in the atmosphere, especially carbon dioxide, methane, and nitrous oxide. Such gases occur naturally - they are critical for life on earth, they keep some of the sun's warmth from reflecting back into space, and without them the world would be a cold and barren place. But in augmented and increasing quantities, they are pushing the global temperature to artificially high levels and altering the climate. Eleven of the last 12 years are the warmest on record...

The current warming trend is expected to cause extinctions. Numerous plant and animal species, already weakened by pollution and loss of habitat, are not expected to survive the next 100 years. Human beings, while not threatened in this way, are likely to face mounting difficulties. Recent severe storms, floods and droughts, for example, appear to show that computer models predicting more frequent 'extreme weather events' are on target."


May 12, 2010 - United Nations Framework Convention on Climate Change (UNFCCC) 

Andrew Dessler, PhD, Professor in the Department of Atmospheric Sciences at Texas A&M University, et al., stated the following in their Mar. 6, 2010 article, "On Global Warming, the Science Is Solid," published in the Houston Chronicle:

"Contrary to what one might read in newspapers, the science of climate change is strong. Our own work and the immense body of independent research conducted around the world leaves no doubt...

There is no question that natural causes, such as changes in energy from the sun, natural cycles and volcanoes, continue to affect temperature today... But despite years of intensive observations of the Earth system, no one has been able to propose a credible alternative mechanism that can explain the present-day warming without heat-trapping gases produced by human activities...

[H]umans have taken over from nature as the dominant influence on our climate."


Mar. 6, 2010 - Andrew Dessler, PhD 

Kerry Emanuel, PhD, Director of the Program in Atmospheres, Oceans, and Climate at the Massachusetts Institute of Technology (MIT), stated the following in his Feb. 15, 2010 article "Despite Uncertainties, Need to Confront Climate Change Is Clear," published in the Boston Globe:

"[C]oncentrations of the two most important long-lived greenhouse gases, carbon dioxide and methane, have been increasing since the dawn of the industrial era; carbon dioxide alone has increased by about 40 percent. These increases have been brought about by fossil fuel combustion and changes in land use...

[G]lobal temperatures have been rising for roughly the past century and have so far increased by about 1.4 F. The rate of rise of surface temperature is... larger than any natural change we have been able to discern for at least the past 1,000 years.

Disputes within climate science concern the nature and magnitude of feedback processes involving clouds and water vapor, uncertainties about the rate at which the oceans take up heat and carbon dioxide, the effects of air pollution, and the nature and importance of climate change effects such as rising sea level, increasing acidity of the ocean, and the incidence of weather hazards such as floods, droughts, storms, and heat waves. These uncertainties are reflected in divergent predictions of climate change made by computer models...

But when the dust settles, what we are left with is the evidence. And, in spite of all its complexity and uncertainties, we should not lose track of the simple fact that theory, actual observations of the planet, and complex models - however imperfect each is in isolation - all point to ongoing, potentially dangerous human alteration of climate."


Feb. 15, 2010 - Kerry Emanuel, PhD 

Al Gore, Jr., former Vice President of the United States and Chairman of the Board at the Alliance for Climate Protection, stated the following in his Feb. 27, 2010 article "We Can't Wish Away Climate Change," published in the New York Times:

"[T]he scientific enterprise will never be completely free of mistakes. What is important is that the overwhelming consensus on global warming remains unchanged...

Here is what scientists have found is happening to our climate: man-made global-warming pollution traps heat from the sun and increases atmospheric temperatures. These pollutants - especially carbon dioxide - have been increasing rapidly with the growth in the burning of coal, oil, natural gas and forests, and temperatures have increased over the same period. Almost all of the ice-covered regions of the Earth are melting - and seas are rising. Hurricanes are predicted to grow stronger and more destructive, though their number is expected to decrease. Droughts are getting longer and deeper in many mid-continent regions, even as the severity of flooding increases. The seasonal predictability of rainfall and temperatures is being disrupted, posing serious threats to agriculture. The rate of species extinction is accelerating to dangerous levels."


Feb. 27, 2010 - Al Gore, Jr. 

The US Environmental Protection Agency (EPA), stated the following in its Apr. 2009 publication "Frequently Asked Questions about Global Warming and Climate Change," available at www.epa.gov:

"The Earth's climate is changing.  In most places, average temperatures are rising... The most rapid warming has occured in recent decades.  Most of this recent warming is very likely the result of human activities.

Many human activities release 'greenhouse gases' into the atmosphere. The levels of these gases are increasing at a faster rate than at any time in hundreds of thousands of years.

We know that greenhouse gases trap heat. If human activities continue to release greenhouse gases at or above the current rate, we will continue to increase average temperatures around the globe. Increases in global temperatures will most likely change our planet’s climate in ways that will have significant long-term effects on people and the environment...

Within the past 30 years, the rate of warming across the globe has been approximately three times greater than the rate over the last 100 years. Past climate information suggests the warmth of the last half century is unusual in at least the previous 1,300 years in the Northern Hemisphere...

If humans continue to emit greenhouse gases at or above the current pace, we will probably see an average global temperature increase of 3 to 7°F by 2100, and greater warming after that."


Apr. 2009 - US Environmental Protection Agency (EPA) 

The American Geophysical Union stated the following in its Aug. 2013 position statement "Human-Induced Climate Change Requires Urgent Action," available at sciencepolicy.agu.org:
"Human activities are changing Earth’s climate. At the global level, atmospheric concentrations of carbon dioxide and other heat?trapping greenhouse gases have increased sharply since the Industrial Revolution. Fossil fuel burning dominates this increase. Human?caused increases in greenhouse gases are responsible for most of the observed global average surface warming of roughly 0.8°C (1.5°F) over the past 140 years. Because natural processes cannot quickly remove some of these gases (notably carbon dioxide) from the atmosphere, our past, present, and future emissions will influence the climate system for millennia.

Extensive, independent observations confirm the reality of global warming. These observations show large?scale increases in air and sea temperatures, sea level, and atmospheric water vapor; they document decreases in the extent of mountain glaciers, snow cover, permafrost, and Arctic sea ice. These changes are broadly consistent with long? understood physics and predictions of how the climate system is expected to respond to human?caused increases in greenhouse gases. The changes are inconsistent with explanations of climate change that rely on known natural influences."

Aug. 2013 - American Geophysical Union (AGU) 

Patrick Moore, PhD, Chair and Chief Scientist of Greenspirit Strategies Ltd. and former Director of Greenpeace International, stated the following in his Feb. 25, 2014 Senate Environment and Public Works Committee testimony "Natural Resource Adaptation: Protecting Ecosystems and Economies," available at epw.senate.gov:
"There is no scientific proof that human emissions of carbon dioxide (CO2) are the dominant cause of the minor warming of the Earth’s atmosphere over the past 100 years. If there were such a proof it would be written down for all to see. No actual proof, as it is understood in science, exists...

When modern life evolved over 500 million years ago, CO2 was more than 10 times higher than today, yet life flourished at this time. Then an Ice Age occurred 450 million years ago when CO2 was 10 times higher than today. There is some correlation, but little evidence, to support a direct causal relationship between CO2 and global temperature through the millennia. The fact that we had both higher temperatures and an ice age at a time when CO2 emissions were 10 times higher than they are today fundamentally contradicts the certainty that human-caused CO2 emissions are the main cause of global warming."

Feb. 25, 2014 - Patrick Moore, PhD 

Richard S. Lindzen, PhD, Emeritus Professor of Meteorology at the Massachusetts Institute of Technology (MIT), stated the following in his article, "Climate of Fear: Global Warming Alarmists Intimidate Dissenting Scientists into Silence," Wall Street Journal, Apr. 12, 2006:

"There have been repeated claims that this past year's hurricane activity was another sign of human-induced climate change. Everything from the heat wave in Paris to heavy snows in Buffalo has been blamed on people burning gasoline to fuel their cars, and coal and natural gas to heat, cool and electrify their homes. Yet how can a barely discernible, one-degree increase in the recorded global mean temperature since the late 19th century possibly gain public acceptance as the source of recent weather catastrophes? And how can it translate into unlikely claims about future catastrophes?...

Global temperature has risen about a degree since the late 19th century; levels of CO2 in the atmosphere have increased by about 30% over the same period; and CO2 should contribute to future warming. These claims are true. However, what the public fails to grasp is that the claims neither constitute support for alarm nor establish man's responsibility for the small amount of warming that has occurred... It isn't just that the alarmists are trumpeting model results that we know must be wrong. It is that they are trumpeting catastrophes that couldn't happen even if the models were right as justifying costly policies to try to prevent global warming."


Nov. 30, 2009 - Richard S. Lindzen, PhD 

John R. Christy, PhD, M.Div, Professor of Atmospheric Science and Director of the Earth System Science Center at the University of Alabama at Huntsville, provided the following testimony on Aug. 1, 2012 before the US Senate Environment and Public Works Committee, available at www.epw.senate.gov:

"It is popular again to claim that extreme events, such as the current central US drought, are evidence of human-caused climate change. Actually, the Earth is very large, the weather is very dynamic, and extreme events will continue to occur somewhere, every year, naturally…

New discoveries explain part of the warming found in traditional surface temperature datasets. This partial warming is unrelated to the accumulation of heat due to the extra greenhouse gases, but related to human development around the thermometer stations...

Widely publicized consensus reports by 'thousands' of scientists are misrepresentative of climate science, containing overstated confidence in their assertions of high climate sensitivity...

...[C]limate models overestimate the response of temperature to greenhouse gas increases. Also shown was a lack of evidence to blame humans for an increase in extreme events. One cannot convict CO2 of causing any of these events, because they've happened in the past before CO2 levels rose...

It is a simple fact that CO2 is plant food and the world around us evolved when levels of CO2 were five to ten times what they are today. Our green world is a consequence of atmospheric CO2. And, food for plants means food for people. The extra CO2 we are putting into the atmosphere not only invigorates the biosphere, but also enhances the yields of our food crops. This is a tremendous benefit to nature and us in my view..."


Aug. 1, 2012 - John Christy, PhD, M.Div 

Willie Soon, PhD, Physicist at the Harvard-Smithsonian Center for Astrophysics, stated the following in his Nov. 2007 article “Implications of the Secondary Role of Carbon Dioxide and Methane Forcing in Climate Change: Past, Present, and Future,” published in Physical Geography:

"There is no quantitative evidence that varying levels of minor greenhouse gases like CO2 and CH4 have accounted for even as much as half of the reconstructed glacial-interglacial temperature changes or, more importantly, for the large variations in global ice volume on both land and sea over the past 650kyr [650,000 years]. This paper shows that changes in solar insolation [amount of solar energy hitting the earth] at climatically sensitive latitudes and zones exceed the global radiative forcings [greenhouse gas accumulation in the atmosphere traping solar heat] of CO2 and CH4 by severalfold...

[T]he popular notion of CO2 and CH4 radiative forcing as the predominant amplifier of glacial-interglacial phase transitions cannot be confirmed…

Our basic hypothesis is that long-term climate change is driven by insolation changes, from both orbital variations and intrinsic solar magnetic luminosity variations. This implies natural warming and cooling variations.”


Nov. 2007 - Willie Soon, PhD 

Harrison H. Schmitt, PhD, Geologist, Honorary Associate Fellow of Engineering at the University of Wisconsin at Madison and former US Senator and NASA Astronaut, and William Happer, PhD, Professor of Physics at Princeton University, stated the following in their May 8, 2013 article "Harrison H. Schmitt and William Happer: In Defense of Carbon Dioxide," available at wsj.com:
"The cessation of observed global warming for the past decade or so has shown how exaggerated NASA's and most other computer predictions of human-caused warming have been—and how little correlation warming has with concentrations of atmospheric carbon dioxide. As many scientists have pointed out, variations in global temperature correlate much better with solar activity and with complicated cycles of the oceans and atmosphere. There isn't the slightest evidence that more carbon dioxide has caused more extreme weather...

The current levels of carbon dioxide in the earth's atmosphere, approaching 400 parts per million, are low by the standards of geological and plant evolutionary history. Levels were 3,000 ppm, or more, until the Paleogene period (beginning about 65 million years ago). For most plants, and for the animals and humans that use them, more carbon dioxide, far from being a ‘pollutant’ in need of reduction, would be a benefit…

We know that carbon dioxide has been a much larger fraction of the earth's atmosphere than it is today, and the geological record shows that life flourished on land and in the oceans during those times. The incredible list of supposed horrors that increasing carbon dioxide will bring the world is pure belief disguised as science."

May 8, 2013 - William Happer, PhD 
Harrison H. Schmitt, PhD 

The Center for the Study of Carbon Dioxide and Global Change, in a position statement written by Chairman C.D. Idso, PhD, and Vice President K.E. Idso, PhD, stated the following in its 2008 publication "Carbon Dioxide and Global Warming: Where We Stand on the Issue," available at www.co2science.org:

"There is little doubt the air's CO2  concentration has risen significantly since the inception of the Industrial Revolution; and there are few who do not attribute the CO2 increase to the increase in humanity's use of fossil fuels.  There is also little doubt the earth has warmed slightly over the same period; but there is no compelling reason to believe that the rise in temperature was caused by the rise in CO2...

Proponents of the notion that increases in the air's CO2 content lead to global warming point to the past century's weak correlation between atmospheric CO2 concentration and global air temperature as proof of their contention.  However, they typically gloss over the fact that correlation does not imply causation, and that a hundred years is not enough time to establish the validity of such a relationship when it comes to earth's temperature history...

In thus considering the seven greatest temperature transitions of the past half-million years - three glacial terminations and four glacial inceptions - we note that increases and decreases in atmospheric CO2 concentration not only did not precede the changes in air temperature, they followed them, and by hundreds to thousands of years...

Hence, the climate history of the past half-million years provides absolutely no evidence to suggest that the ongoing rise in the air's CO2 concentration will lead to significant global warming...

Proponents of the CO2-induced global warming hypothesis often predict that extreme weather events such as droughts, floods, and hurricanes will become more numerous and/or extreme in a warmer world; however, there is no evidence to support this claim.  In fact, many studies have revealed that the numbers and intensities of extreme weather events have remained relatively constant over the last century."


2008 - Center for the Study of Carbon Dioxide and Global Change 

Tim Ball, PhD, former Geography Professor at the University of Winnipeg, stated the following in his July 7, 2008 article "Alarmists Use Weather to Promote Global Warming Hoax," available at canadafreepress.com:

"Claims that recent severe weather and flooding in the US are proof of human CO2 impacts on global climate are scientific nonsense...

Those who perpetrated possibly the greatest deception in human history that CO2 is causing global warming/climate change are scared. Events are driving them to extreme, unsubstantiated and even ridiculous claims and threats.

One of these was that sea level would rise, but it foundered when the two Nobel Peace Prize winners, the Intergovernmental Panel on Climate Change (IPCC) and Al Gore were in serious disagreement. Another was Arctic sea ice except it returned to long term normal levels last winter and NASA announced the one year anomaly was due to changes in wind patterns.

So they return to their central theme of convincing you that normal weather events are abnormal...

Proponents of human caused climate change will... continue their practice of claiming natural events as unnatural. Unless people understand the basic science they will continue the fraud and pressure politicians into even more damaging energy and environmental policies."


July 7, 2008 - Tim Ball, PhD 

Don J. Easterbrook, PhD, Emeritus Professor of Geology at Western Washington University, stated the following in his June 28, 2014 article "Global Cooling Is Here," available at globalresearch.ca:
"Despite no global warming in 10 years and recording setting cold in 2007-2008, the Intergovernmental Panel on Climatic Change (IPCC) and computer modelers who believe that CO2 is the cause of global warming still predict the Earth is in store for catastrophic warming in this century…

Global warming of the past century (0.8° C) is virtually insignificant when compared to the magnitude of at least 10 global climate changes in the past 15,000 years. None of these sudden global climate changes could possibly have been caused by human CO2 input to the atmosphere because they all took place long before anthropogenic CO2 emissions began. The cause of the ten earlier 'natural' climate changes was most likely the same as the cause of global warming from 1977 to 1998...

The Pacific Ocean has a warm temperature mode and a cool temperature mode, and in the past century, has switched back forth between these two modes every 25-30 years (known as the Pacific Decadal Oscillation or PDO). In 1977 the Pacific abruptly shifted from its cool mode (where it had been since about 1945) into its warm mode, and this initiated global warming from 1977 to 1998…

Global warming (i.e, the warming since 1977) is over. The minute increase of anthropogenic CO2 in the atmosphere (0.008%) was not the cause of the warming - it was a continuation of natural cycles that occurred over the past 500 years."

June 28, 2014 - Don J. Easterbrook, PhD 

William Gray, PhD, Professor Emeritus of Atmospheric Science at Colorado State University, stated the following in his Apr. 7, 2010 article, "MIT Professor's Climate Change Op-Ed Proven False," available at www.globalwarmingheartland.org:

 "A high percentage of meteorologists and/or climate scientists do not agree that the climate changes we have seen are mostly manmade. Thousands of us think the larger part of the climate changes we have observed over the last century are of natural origin. I believe most of the changes that have been observed are due to multi-decadal and multi-century changes in deep global ocean currents. Such changes have yet to be properly incorporated into the global models or into most climate modelers’ thinking...

Many scientists believe a slightly warmer world would be, in general, more beneficial for humanity. The small changes in climate we have seen so far and the changes we will likely see in the coming decades are not potentially dangerous. It has been noted that vegetation growth is enhanced by higher CO2 levels...

[T]he global climate models will never be able to replicate the complex global atmosphere/ocean environment and its continuing changes...

We should all call out faulty science wherever we see it, including the blind belief (without any evidence beyond the faulty models) that humans are largely responsible for climate change."


Apr. 7, 2010 - William Gray, PhD 

Roy W. Spencer, PhD, Principal Research Scientist at the Earth System Science Center at the University of Alabama in Huntsville, stated the following in his Oct. 20, 2008 article "Global Warming as a Natural Response to Cloud Changes Associated with the Pacific Decadal Oscillation," available at www.drroyspencer.com:

"[W]e are finding satellite evidence that the climate system is much less sensitive to greenhouse gas emissions than the U.N.’s Intergovernmental Panel on Climate Change (IPCC, 2007) climate models suggest that it is. And if that is true, then mankind’s CO2 emissions are not strong enough to have caused the global warming we’ve seen over the last 100 years...

[M]ost of the warming could be the result of a natural cycle in cloud cover forced by a well-known mode of natural climate variability: the Pacific Decadal Oscillation (PDO). While the PDO is primarily a geographic rearrangement in atmospheric and oceanic circulation patterns in the North Pacific, it is well known that such regional changes can also influence weather patterns over much larger areas...

[R]ecent satellite measurements - even though they span only 7.5 years - support the Pacific Decadal Oscillation as a potential major player in global warming and climate change."


Oct. 20, 2008 - Roy W. Spencer, PhD 

Steven F. Hayward, PhD, FK Weyerhaeuser Fellow at the American Enterprise Instutute for Public Policy Research, stated the following in his Mar. 15, 2010 article "In Denial," available at www.aei.org:

"The models the IPCC uses for projecting a 3 to 4 degree Celsius increase in temperature all assume large positive (that is, temperature-magnifying) feedbacks from a doubling of carbon dioxide in the atmosphere...

If the climate system is less sensitive to greenhouse gases than the climate campaign believes, then what is causing plainly observable changes in the climate, such as earlier arriving springs, receding glaciers, and shrinking Arctic Ocean ice caps?...

The IPCC downplays theories of variations in solar activity, such as sunspot activity and gamma ray bursts, and although there is robust scientific literature on the issue, even the skeptic community is divided about whether solar activity is a primary cause of recent climate variation. Several studies of Arctic warming conclude that changes in ocean currents, cloud formation, and wind patterns in the upper atmosphere may explain the retreat of glaciers and sea ice better than greenhouse gases... Above all, if the medieval warm period was indeed as warm or warmer than today, we cannot rule out the possibility that the changes of recent decades are part of a natural rebound from the 'Little Ice Age' that followed the medieval warm period and ended in the 19th century."


Mar. 15, 2010 - Steven F. Hayward, PhD 

The George C. Marshall Institute, a science and public policy organization, stated the following in its July 23, 2009 publication "The Cocktail Conversation Guide to Global Warming," available at www.marshall.org:

"[G]lobal surface temperatures have not increased since about 1998. Since the late 1800s, the world’s average surface temperature is believed to have warmed about 1°F, which is, in part, a natural recovery from the 'Little Ice Age,' a period of global cooling lasting from about 1400 to the 1800s AD...

[N]atural flows of CO2 in and out of the Earth’s surface average about 20 times the human contribution...

Predictions of future climate come from computer models, which are very incomplete approximations of the behavior of the real climate system... The predictions of future climatic changes are hypotheses, not scientific facts...

Whatever the threat of climate change to humanity, it is most likely to be natural — not man-made."


July 23, 2009 - The George C. Marshall Institute 

James M. Inhofe, United States Senator (R-OK), stated the following in his Sep. 25, 2006 speech "Hot & Cold Media Spin: A Challenge to Journalists Who Cover Global Warming,” available at www.epw.senate.gov:

"I am going to speak today about the most media-hyped environmental issue of all time, global warming…

The media have missed the big pieces of the puzzle when it comes to the Earth’s temperatures and mankind’s carbon dioxide (C02) emissions. It is very simplistic to feign horror and say the one degree Fahrenheit temperature increase during the 20th century means we are all doomed. First of all, the one degree Fahrenheit rise coincided with the greatest advancement of living standards, life expectancy, food production and human health in the history of our planet. So it is hard to argue that the global warming we experienced in the 20th century was somehow negative or part of a catastrophic trend.

Second, what the climate alarmists and their advocates in the media have continued to ignore is the fact that the Little Ice Age, which resulted in harsh winters which froze New York Harbor and caused untold deaths, ended about 1850. So trying to prove man-made global warming by comparing the well-known fact that today's temperatures are warmer than during the Little Ice Age is akin to comparing summer to winter to show a catastrophic temperature trend.

In addition, something that the media almost never addresses are the holes in the theory that C02 has been the driving force in global warming. Alarmists fail to adequately explain why temperatures began warming at the end of the Little Ice Age in about 1850, long before man-made CO2 emissions could have impacted the climate. Then about 1940, just as man-made CO2 emissions rose sharply, the temperatures began a decline that lasted until the 1970’s, prompting the media and many scientists to fear a coming ice age.

Let me repeat, temperatures got colder after C02 emissions exploded. If C02 is the driving force of global climate change, why do so many in the media ignore the many skeptical scientists who cite these rather obvious inconvenient truths?”


Sep. 25, 2006 - James M. Inhofe 

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