Climate Science Dials Back the ‘Worst Case Scenario’

By Anthony Watts – Re-Blogged From WUWT

A surprising comment published January 29th in the leading scientific journal Nature said; “Emissions – the ‘business as usual’ story is misleading – Stop using the worst-case scenario for climate warming as the most likely outcome — more-realistic baselines make for better policy.” This has thrown a monkey wrench in hundreds of studies and media stories that previously predicted dire climate consequences in the future due to increased carbon dioxide (CO2) in our atmosphere.

The consequences were predicted by a computer model called Representative Carbon Pathways (RCP) and the worst case scenario model, RCP8.5 had been cited over 2500 times in scientific journals and in hundreds of media stories as the primary need for “urgent action” on climate. Predictions from RCP8.5 model suggested maximum global temperature increases of nearly 6°C (10.8°F) by the year 2100, shown in Figure 1.

clip_image002Figure 1 – Image Credit: Neil Craik, University of Waterloo

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Nature Has Been Removing Excess CO2 4X Faster than IPCC Models

By Roy W. Spencer, Ph. D. – Re-Blogged From WUWT

Note: What I present below is scarcely believable to me. I have looked for an error in my analysis, but cannot find one. Nevertheless, extraordinary claims require extraordinary evidence, so let the following be an introduction to a potential issue with current carbon cycle models that might well be easily resolved by others with more experience and insight than I possess.

Summary

Sixty years of Mauna Loa CO2 data compared to yearly estimates of anthropogenic CO2 emissions shows that Mother Nature has been removing 2.3%/year of the “anthropogenic excess” of atmospheric CO2 above a baseline of 295 ppm. When similar calculations are done for the RCP (Representative Concentration Pathway) projections of anthropogenic emissons and CO2 concentrations it is found that the carbon cycle models those projections are based upon remove excess CO2 at only 1/4th the observed rate. If these results are anywhere near accurate, the future RCP projections of CO2, as well as the resulting climate model projection of resulting warming, are probably biased high.

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