In 2013, the author and colleagues made a projection of temperature
departures (from the 1961-1990 average) throughout the remainder of the 21st
century due both to Humanity and Nature. Two scenarios of human-caused
emissions of greenhouse gases and aerosol precursors were examined: (1) A
reference scenario with no emissions reductions, and (2) our Fair Plan to
Safeguard Earth’s Climate which zeroes emissions from 2020 through 2100.
Human-caused temperature changes from 1756 were calculated using an
engineering-type Simple Climate Model. Temperature changes due to Nature were
projected from our analyses of the observed temperature departures from 1850
through 2012. These natural changes were due to: (1) Three quasi-periodic
oscillations (QPOs), each of which we fit with a sine wave to project into the
future on a year-by-year basis; (2) Other QPOs that are too irregular to
predict yearly, and (3) stochastic noise. We projected natural variations (2)
and (3) by the 90% confidence interval of a Normal (Gaussian) probability
density function, with zero mean and standard deviation of 0.08˚C. Here we add
four more years of observed temperature departures to compare with our
projections made in 2013. Each of the additional four temperature departure
observations for 2013, 2014, 2015 and 2016 fits within the 90% envelop of
temperature departures, thereby rendering our projection accurate to date. Most
of the temperature changes during the 2012-2016 period were due to the annually
unpredictable natural variability. This evaluation will be repeated
quadrennially for the remainder of the author’s life.
Article by Michael E. Schlesinger,from University
of Illinois at Urbana-Champaign, Urbana, IL, USA
Full access: http://mrw.so/2LLhDS
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Image by John Andersen,from Flickr-cc.
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