Key Findings of Heartland’s “Why Scientists Disagree About Global Warming”

Below is a list of statements extracted from the “Key Findings” section of the Heartland NIPCC report.

Your annotations on this page will be duplicated over the original report. The full report can be found here.

from section: “Why Scientists Disagree”

claim #0.1

Extensive survey data show deep disagreement among scientists on scientific issues that must be resolved before the man-made global warming hypothesis can be validated.

claim #0.2

IPCC, created to find and disseminate research finding a human impact on global climate, is not a credible source. It is agenda-driven, a political rather than scientific body, and some allege it is corrupt.

claim #0.3

IPCC assumes its implicit hypothesis is correct and that its only duty is to collect evidence and make plausible arguments in the hypothesis’s favor.

from section: “Flawed Projections”

claim #1

IPCC and virtually all the governments of the world depend on global climate models (GCMs) to forecast the effects of human-related greenhouse gas emissions on the climate.

claim #2

GCMs systematically over-estimate the sensitivity of climate to carbon dioxide (CO2), many known forcings and feedbacks are poorly modeled, and modelers exclude forcings and feedbacks that run counter to their mission to find a human influence on climate.

claim #3

Doubling the concentration of atmospheric CO2 from its pre-industrial level, in the absence of other forcings and feedbacks, would likely cause a warming of ~0.3°C to 1.1°C, almost 50 percent of which must already have occurred.

claim #4

Model outputs published in successive IPCC reports since 1990 project a doubling of CO2 could cause warming of up to 6°C by 2100. Instead, global warming ceased around the end of the twentieth century and was followed (since 1997) by 19 years of stable temperature.

claim #4.2

Earth has not warmed significantly for the past 18 years despite an 8 percent increase in atmospheric CO2, which represents 34 percent of all extra CO2 added to the atmosphere since the start of the industrial revolution.

from section: “False Postulates”

claim #5

Neither the rate nor the magnitude of the reported late twentieth century surface warming (1979–2000) lay outside normal natural variability.

claim #6

The late twentieth century warm peak was of no greater magnitude than previous peaks caused entirely by natural forcings and feedbacks.

claim #7

Historically, increases in atmospheric CO2 followed increases in temperature, they did not precede them. Therefore, CO2 levels could not have forced temperatures to rise.

claim #8

Solar forcings are not too small to explain twentieth century warming. In fact, their effect could be equal to or greater than the effect of CO2 in the atmosphere.

claim #9

Though a future warming of 2°C would cause geographically varied ecological responses, no evidence exists that those changes would be net harmful to the global environment or to human well-being.

from section: “Unreliable Circumstantial Evidence”

claim #10

Melting of Arctic sea ice and polar icecaps is not occurring at “unnatural” rates and does not constitute evidence of a human impact on the climate.

claim #11

Best available data show sea-level rise is not accelerating. Local and regional sea levels continue to exhibit typical natural variability – in some places rising and in others falling.

claim #12

The link between warming and drought is weak, and by some measures drought decreased over the twentieth century. Changes in the hydrosphere of this type are regionally highly variable and show a closer correlation with multidecadal climate rhythmicity than they do with global temperature.

claim #13

No convincing relationship has been established between warming over the past 100 years and increases in extreme weather events. Meteorological science suggests just the opposite: A warmer world will see milder weather patterns.

claim #14

No evidence exists that current changes in Arctic permafrost are other than natural or are likely to cause a climate catastrophe by releasing methane into the atmosphere.

from section: “Summary of NIPCC’s Findings on Physical Science” (only showing claims non-redundant with the above)

claim #15

The overall warming since about 1860 corresponds to a recovery from the Little Ice Age modulated by natural multidecadal cycles driven by ocean-atmosphere oscillations, or by solar variations at the de Vries (~208 year) and Gleissberg (~80 year) and shorter periodicities.

claim #16

No close correlation exists between temperature variation over the past 150 years and human-related CO2 emissions. The parallelism of temperature and CO2 increase between about 1980 and 2000 AD could be due to chance and does not necessarily indicate causation.

claim #17

The causes of historic global warming remain uncertain, but significant correlations exist between climate patterning and multidecadal variation and solar activity over the past few hundred years.

claim #18

Forward projections of solar cyclicity imply the next few decades may be marked by global cooling rather than warming, despite continuing CO2 emissions.