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What we hear regarding the dangers of climate change is based on predictions of future atmospheric carbon concentrations and corresponding predictions of global temperatures. Those predictions are not “data” in the normal, positive sense. They do not represent “the way things are” or “the way things have been”, though one might hope the initial model conditions align with reality. Nor can the predictions be relied upon as “the way things will be”. Climate scientists normally report a range of outcomes produced by models, yet we usually hear only one type of consequence for humanity: catastrophe!

Models Are Not Reality

The kinds of climate models quoted by activists and by the UN’s Intergovernmental Panel on Climate Change (IPCC) have been around for decades. Known as “carbon forcing” models, they are highly simplified representations of the process determining global temperatures. The primary forecast inputs are atmospheric carbon concentrations over time, which again are themselves predictions.

It’s usually asserted that climate model outputs should guide policy, but we must ask: how much confidence can we have in the predictions to allow government to take coercive actions having immediate, negative impacts on human well being? What evidence can be marshaled to show prospective outcomes under proposed policies? And how well do these models fit the actual, historical data? That is, how well do model predictions track our historical experience, given the historical paths of inputs like carbon concentrations?

Faulty Inputs

The IPCC has been defining and updating sets of carbon scenarios since 1990. The scenarios outline the future paths of greenhouse gas emissions (and carbon forcings). They were originally based on economic and demographic modeling before an apparent “decision by committee” to maintain consistency with scenarios issued in the past. Roger Pielke Jr. and Justin Ritchie describe the evolution of this decision process, and they call for change:

Our research (and that of several colleagues) indicates that the scenarios of greenhouse gas (GHG) emissions through the end of the twenty-first century are grounded in outdated portrayals of the recent past. Because climate models depend on these scenarios to project the future behavior of the climate, the outdated scenarios provide a misleading basis both for developing a scientific evidence base and for informing climate policy discussions. The continuing misuse of scenarios in climate research has become pervasive and consequential—so much so that we view it as one of the most significant failures of scientific integrity in the twenty-first century thus far. We need a course correction.

One would certainly expect the predicted growth of atmospheric carbon to evolve over time. However, as Pielke and Ritchie note, the IPCC’s baseline carbon scenario today, known as RCP8.5 (“Representative Concentration Pathway”), is remarkably similar to the “business as usual” (BAU) scenario it first issued in 1990:

The emissions scenarios the climate community is now using as baselines for climate models depend on portrayals of the present that are no longer true. And once the scenarios lost touch with reality, so did the climate, impact, and economic models that depend on them for their projections of the future. Yet these projections are a central part of the scientific basis upon which climate policymakers are now developing, debating, and adopting policies.

The authors go on to discuss a few characteristics of the BAU scenario that today seem implausible, including:

“… RCP8.5 foresees carbon dioxide emissions growing rapidly to at least the year 2300 when Earth reaches more than 2,000 ppm of atmospheric carbon dioxide concentrations. But again, according to the IEA and other groups, fossil energy emissions have likely plateaued, and it is plausible to achieve net-zero emissions before the end of the century, if not much sooner.”

Pielke and Ritchie demonstrate that the IPCC’s baseline range of carbon emissions by 2045 is centered well above (actually double) the mid-range of scenarios developed by the International Energy Agency (IEA), and there is very little overlap between the two. However, global carbon emissions have been flat over the past decade. Even if we extrapolate the growth in atmospheric CO2 parts per million over the past 20 years, it would rise to less than 600 ppm by 2100, not 1,200 ppm. It’s true that a few countries (China comes to mind) continue to exploit less “carbon efficient” energy resources like coal, but the growth trend in concentrations is likely to continue to taper over time.

It therefore appears that the IPCC’s climate scenarios, which are used broadly as model inputs by the climate research community, are suspect. As one might suspect: garbage in, garbage out. But what about the climate models themselves?

Faulty Models

The model temperature predictions have been grossly in error. They have been and continue to be “too hot”. The chart at the top of this post is typical of the comparisons of model projections and actual temperatures. Before the year 2000, most of the temperature paths projected by the particular model charted above ran higher than actual temperatures. However, the trends subsequently diverged and the gap has become more extreme over the past two decades.

The problem is not merely one of faulty inputs. The models themselves are deeply flawed, as they fail to account adequately for natural forces that strongly influence our climate. It’s been clear for many years that the sun’s radiative energy has a massive impact on temperatures, and it is affected not only by the intensity of the solar cycle but also by cloud cover on Earth. Unfortunately, carbon forcing models do not agree on the role that increased clouds might have in amplifying warming. However, a reduction in cloud cover over the past 20 years, and a corresponding increase in radiative heat, can account for every bit of the warming experienced over that time.

This finding not only offers an alternative explanation for two decades of modest warming, it also strikes at the very heart of the presumed feedback mechanism usually assumed to amplify carbon-induced warming. The overall effect is summarized by the so-called carbon sensitivity, measured as the response of global temperature to a doubling of carbon concentration. The IPCC puts that sensitivity in a range of 1.5C to 4.5C. However, findings published by Nic Lewis and Judith Curry are close to the low end of that range, as are those found by Frank Bosse reported here. The uncertainties surrounding the role of cloud cover and carbon sensitivities reveal that the outputs relied upon by climate alarmists are extreme model simulations, not the kind of reliable intelligence upon which drastic policy measures should be taken.

The constant anxiety issued from the Left on the issue of climate change, and not a little haranguing of the rest of us, is misplaced. The IPCC’s scenarios for the future paths of carbon concentration are outdated and seriously exaggerated, and they represent a breach of scientific protocol. Yet the scenarios are widely used as the basis of policy discussions at both the domestic and international levels. The climate models themselves embed questionable assumptions that create a bias toward calamitous outcomes.

Yet Drastic Action Is Urged

The UN’s 2021 climate conference, or COP26 (“Conference of the Parties …”) is taking place in Glasgow, Scotland this month. Like earlier international climate conferences, the hope is that dire forecasts will prompt broad agreement on goals and commitments, and that signatory countries will translate these into policy at the national level.

Things got off to a bad start when, before COP26 even began, the G20 nations failed to agree on a goal of “net-zero” carbon emissions by 2050. Another bad portent for the conference is that China and India, both big carbon emitters, will not attend, which must be tremendously disappointing to attendees. After all, COP26 has been billed by Prince Charles himself as “the last chance saloon, literally”, for saving the world from catastrophe. He said roughly the same thing before the Paris conference in 2014. And Joe Brandon … er, Biden, blurted some hyperbole of his own:

Climate change is already ravaging the world. … It’s destroying people’s lives and livelihoods and doing it every single day. … It’s costing our nations trillions of dollars.

All this is unadulterated hogwash. But it is the stuff upon which a crisis-hungry media feeds. This hucksterism is but one form of climate rent-seeking. Other forms are much more troubling: scary scenarios and model predictions serve the self-interest of regulators, grant-seeking researchers, interventionist politicians, and green investors who suckle at the public teat. It is a nightmare of scientism fed by the arrogance of self-interested social planners. The renewable energy technologies promoted by these investors, politicians, and planners are costly and land-intensive, providing only intermittent output (requiring backup fossil fuel capacity), and they have nasty environmental consequences of their own.

The precautionary principle is no excuse for the extreme policies advocated by alarmists. We already have economically viable “carbon efficient” and even zero-carbon energy alternatives, such as natural gas, modular nuclear power, and expanded opportunities for exploiting geothermal energy. This argues against premature deployment of wasteful renewables. The real crisis is the threat posed by the imposition of draconian green policies to our long-term prosperity, and especially to the world’s poor.