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Sins of emission part 2

26 Feb 2020 | Science Notes

We reported last week on efforts by whistle-blowers in the climate science community to get their colleagues to stop using the RCP8.5 emission scenario as the so-called “business-as-usual” story since it is impossibly too high, which means it is deliberately misleading. Those authors recommended looking at the mid-range scenarios. But a new study from experts at the University of Colorado and the University of British Columbia shows the mid-range is also excessive. Actual emissions are lower than 83% of the last batch of IPCC scenarios, and are already lower than 73% of the scenarios teed up for use in the next IPCC report. In fact by 2040, global emissions will likely be lower than the lowest of all IPCC projections, even without any more climate policy. Funny the “we believe the science” crowd remains so silent on all these developments.

Roger Pielke Jr. summarizes this new work, of which he is a coauthor, in his Forbes column. Pielke is one of the small band of whistleblowers, although even he sometimes falls into the trap of insisting that while it is important to stop exaggerating the warming threat as a whip with which to drive policy, we should nevertheless act as if the exaggerations were true. He writes:

There should be no question by now that carbon dioxide emissions cause global warming and that more aggressive policy is needed to do more to rein in emissions.

Except the whole rationale for global climate policy is to try and get the future emissions path from the top end to the bottom end of the scenario range. If emissions are already at or even below the bottom end, then the need for “more aggressive policy” vanishes. That point notwithstanding, he soon gets to the heart of the story:

The divergence between the real-world observations of carbon dioxide emissions and the baseline scenarios of the IPCC is expected to widen over the next several decades. According to projections of major energy outlooks, by 2040 carbon dioxide emissions (from FF) may fall below the entire range of IPCC AR5 and AR6 baseline scenarios, even assuming that no new major climate policy efforts are undertaken between now and then.

With no new policy we will get to the outcome that policy makers are saying we need to get to. Which is not an argument for even more new policy, it is an argument for no new policy. And it is an argument for fixing the misleading models:

Ultimately, there is no good reason why climate science and policy should continue to rely on models that are now out-of-date with respect to the evolution of the real world. Climate science and policy are far too important not to update scenarios and provide policy makers with more accurate maps to help guide how we travel into the future.

The more accurate the map, the more likely it leads to the conclusion that the need for aggressive climate policy has just been blown to pieces. At long last a few experts have begun pointing this out. It’s too soon to hope that such commentary marks a serious course correction, but it’s a beginning.

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