By Larry Kummer,
Editor of the Fabius Maximus website
Summary: Scientists and journalists bombard us with news about the coming climate catastrophe, described as certain unless we drastically change our economy. This has plunged many into despair. The hidden key to these forecasts is RCP8.5, the worst case scenario of the IPCC’s Fifth Assessment Report — often erroneously described as the “business as usual” scenario. Understanding this misuse of science reveals the weak basis of the most dire warnings (which set the mood at the Paris Conference), and helps explain why the US public assigns a low priority to fighting climate change despite the intense decades-long publicity campaign.
“We’re going to become extinct. Whatever we do now is too late.”
In the IPCC’s Fifth Assessment Report four scenarios describe future emissions, concentrations, and land-use. They are Representative Concentration Pathways (RCPs), the inputs to climate models that generate the IPCC’s projections. Strong mitigation policies lead to a low forcing level of 2.6 W/m2 by 2100 (RCP2.6). Two medium stabilization scenarios lead to intermediate outcomes in RCP4.5 and RCP6.0.
RCP8.5 gets the most attention, with its bold and dark assumptions. It is a useful and important scenario, a warning of what might happen if the 21st century goes badly. RCP8.5 is a useful and important scenario, a warning of what might happen if the 21st century goes badly. It should spur us to act. Unfortunately from its creation RCP8.5 has often been misrepresented as the “business as usual” scenario — and so became the basis for hundreds or thousands of predictions about our certain doom from climate change.
The result of this (part of a decade-long campaign) is widespread despair among climate scientists and more broadly, among Leftists. This misuse of RCP8.5 is a triumph of propaganda, but polls show its ineffectiveness (with climate change ranking at or near the bottom of public policy concerns). Yet each month brings more of the same.
What future does RCP8.5 describe?
“In 2002, as I edited a book about global climate change, I concluded we had set events in motion that would cause our own extinction, probably by 2030. I mourned for months …”
— “Apocalypse or extinction?” by Guy McPherson (Prof Emeritus of Natural Resources and Ecology, U AZ), Oct 2009.
The papers describing the RCP’s clearly state their assumptions, unlike most of those that follow them. RCP8.5 describes a bleak scenario, a hot and dark world in 2100 (since it’s powered by coal, perhaps literally dark) — even before considering the effects of climate change. Below are the key points, with graphs from “The representative concentration pathways: an overview” by Detlef P. van Vuuren et al in Climatic Change, Nov 2011. See this post for a more detailed look.
Rapid population growth and slow economic growth in RCP8.5
RCP8.5 assumes a doubling of Earth’s population to 12 billion by 2100, which is the high end of the current UN forecast. The UN gives a purely probabilistic forecast, not considering if the numbers are realistic. For example, this assumes the population of Africa grows from one billion to 5 billion, giving it a density roughly equal to that of China today (which requires a highly ordered society to survive). Nigeria’s population would rise from today’s 160 million to almost one billion in 2100. Possible, but hardly “business as usual”.
While population skyrockets, GDP would drastically slow — producing a massive increase in world poverty (reversing the trend of the past several decades).
Slow tech growth in RCP8.5 takes us back to a 19thC world
RCP8.5 assumes a slowing of technological innovation, most clearly seen in energy use. By 2100 energy efficiency has improved only slightly (reversing the current decades-long trend), so that despite GDP being one-third lower than under RCP2.6, energy consumption is over twice as large. Worse, we will have gone back to a 19th C-like future where the world in 2100 is powered by coal. This is possible, but not a “business as usual” scenario.
How did RCP8.5 come to describe a “business as usual” future?
— John Davies (geophysicist, senior research at the Cold Climate Housing Research Center), 22 February 2014.
This useful scenario was hijacked to serve the apocalyptic visions of activists. Did this happen from scientists’ deliberate misrepresentation (a noble lie?) or carelessness? Who can say? Here are some examples of climate scientists misrepresenting RCP8.5.
- Wrong from the beginning: “Compared to the scenario literature RCP8.5 depicts thus a relatively conservative business as usual case with low income, high population and high energy demand due to only modest improvements in energy intensity.” From “RCP 8.5: A scenario of comparatively high greenhouse gas emissions” by Keywan Riahi et al in Climate Change, November 2011.
- “RCP8.5 assumes a ‘business-as-usual’ approach.” From a guide to AR5 WG1 by Carolyn Symon (PhD, environmental science), by Cambridge U (Sept 2013).
- “The scenario with the most warming is the ‘business-as-usual’ RCP8.5, in which global mean temperature could be 4°C or more above pre-industrial times.” By Matt Collins (Prof, Climate Systems at Exeter U) at Climatica, Dec 2013.
- “Under a business as usual trajectory, the IPCC is saying 3.7 to 4.8 degrees by the end of this century“, said by Lesley Hughes (Prof Biology at Marcqarie U, lead author of WG2 in AR4 & AR5), March 2014.
- Ottmar Edenhofer (Prof at the Potsdam Inst, Co-Chair of WG3 for AR5) describes RCP8.5 as the “business as usual” scenario at the IPCC AR5 WGIII press conference, 13 April 2014.
- “What we see so far is that the only business-as-usual scenario among the RCPs is RCP8.5, a high-end business-as-usual scenario.” Said by John Nielsen-Gammon (Texas State Climatologist, Prof Atmospheric Sciences at Texas A&M), August 2014.
- “for business-as-usual greenhouse gases (RCP8.5 scenario) …” — Said by James Hansen (climate scientists, Columbia Earth institute), July 2015.
- “RCP8.5 is a scenario with unmitigated rise in greenhouse gas emissions.” — Said by Stefan Rahmstorf (Professor of Physics of the Oceans, Potsdam U) at RealClimate (Aug 2015). That’s true, but misleading by not mentioning the other assumptions.
Similar misrepresentations are commonplace by journalists and activists, such as these…
- “The awful truth about climate change no one wants to admit” by David Roberts (writer) at VOX, 15 May 2015. He describes RCP8.5 as “The red line is the status quo — a projection of where emissions will go if no new substantial policy is passed to restrain greenhouse gas emissions.”
- “The scenario with the most warming is the ‘business-as-usual’ RCP8.5” — in an article at Climatica (“You & the experts exploring climate science”).
Tales of nightmares based on RCP8.5
“Let a hundred flowers bloom and a hundred apocalyptic visions contend.”
— What Mao might say if he were a climate activist.
RCP8.5 became the basis for scores of studies describing horrific futures that appear almost inevitable (since large global public policy changes seem unlikely). But they seldom mention RCP8.5’s extreme assumptions. The following articles are examples of this year’s crop: most are from the past 3 months — part of the campaign to build hysteria for the Paris conference.
These misrepresentations of climate science are examples of the poor conduct by scientists that has characterized the public policy campaign about climate change, and which I believe caused the campaign to fail. That doesn’t mean that climate change will not have awful consequences. Merely that we’ll be unprepared for them.
- Draft summary of the sea level rise section of regulations for New York’s Community Risk and Resiliency Act: “RCP 8.5 … is generally considered to be the “business as usual” scenario.”
- “Ocean acidification in the surface waters of the Pacific-Arctic boundary regions“, Jeremy T. Mathis et al, Oceanography, 2015 #2 — “The continental shelves of the Pacific-Arctic Region (PAR) are especially vulnerable to the effects of ocean acidification (OA) … As aragonite in these shelf seas slips below the present-day range of large seasonal variability by mid-century, the diverse ecosystems that support some of the largest commercial and subsistence fisheries in the world may be under tremendous pressure. …The future simulation followed the high-emissions representative concentration pathway (RCP) 8.5 atmospheric CO2 scenario.”
- “End-of-century Manhattan climate index to resemble Oklahoma City today” says the hysterical press release by the Carnegie Institute about a study in Scientific Reports by Yana Petri & Ken Caldeira (Petri is a high school student), 4 August 2015. Based, of course on RCP 8.5.
- “Surge In ‘Danger Days’ Just Around The Corner” by Brian Kahn at ClimateCentral, 12 August 2015 — They describe RCP8.5 as “assuming current greenhouse gas emissions trends continue unabated”, but don’t mention the other assumptions.
- “If nations continue emitting at current levels, most land areas on the planet will be more than 5°C hotter than now by 2100.” Said by Christopher Field, an ecologist at the Carnegie Institution for Science. He was co-chairman of WG2 of AR5, and is the U.S. nominee to lead the IPCC. (13 August 2015 interview.)
- “It showed that if greenhouse gas emissions continued at their present rate, the Antarctic ice shelves would be in danger of collapse by the century’s end.” From “Antarctic ice is melting so fast the whole continent may be at risk by 2100” in The Guardian (Oct 2015). The underlying study used, of course, RCP 8.5 as its high-end scenario.
- “Interacting effects of climate change and habitat fragmentation on drought-sensitive butterflies” Tom Oliver et al, Nature Climate Change, October 2015 — “Under RCP8.5, which is associated with ‘business as usual’ emissions…”.
- “Increasing water cycle extremes in California and in relation to ENSO cycle under global warming“, Jin-Ho Yoon et al, Nature Communications, October 2015. “Both intense drought and excessive flooding are projected to increase by at least 50% towards the end of the twenty-first century…” It uses RCP 8.5 without any description or context, not even the usual mention of “business as usual”.
- “Climate change map shows Boston is an Atlantis in waiting” at the Boston Globe’s website, and the “Surging Sea Ice” interactive graphic at ClimateCentral — which describes RCP8.5 as the “unchecked pollution” scenario (no mention of rapid population growth or the tech slowdown). Both are based on “Carbon choices determine US cities committed to futures below sea level” by Benjamin H. Strauss et al, PNAS, Nov 2015 — which describes RCP8.5 as the “business as usual scenario”.
- “Future temperature in southwest Asia projected to exceed a threshold for human adaptability” by Jeremy S. Pal & Elfatih A. B. Eltahir, Nature Climate Change, in press (gated) — Describes RCP8.5 as a “business as usual scenario”. Reported in Time as “These Cities May Soon Be Uninhabitable Thanks to Climate Change“.
It’s not too late to restart the debate
Every day we begin anew. The public policy debate about climate change can restart if we can get climate scientists to test the models from the first three Assessment Reports. The results from the past quarter-century will give us valuable data about their reliability, and perhaps break the current deadlock.