There could also be errors in our estimates of the magnitudes
of other climate forcing terms — especially aerosol cooling — or, as mentioned earlier, time lags in how the climate system responds.
As discussed above, keeping global climate close to the Holocene range requires a long - term atmospheric CO2 level of about 350 ppm or less, with
other climate forcings similar to today's levels.
Nature 458, 1163 - 1166 (30 April 2009) may be the underlying basis for the UK Governments concentration on carbon dioxide and so downplaying
other climate forcing agents such as methane and black carbon.
I have claimed above that perhaps a solar signature is likely hidden in the GHG signature and
in other climate forcing as well.
Beginning to disentangle the PDO effects
from other climate forcings in the temperature record requires consideration of a full cool / warm cycle from 1947 to 1998.
Adding another 20 ppmv of CO2, or another 40, or 80, will not result in any measurable change in the planet's temperature, because many
other climate forcings overwhelm the tiny effect.
What they found was, in Hansen's words, «that human - produced greenhouse gases should become a dominant forcing and even
exceed other climate forcings, such as volcanoes or the Sun, at some point in the future.»
As discussed above, keeping global climate close to the Holocene range requires a long - term atmospheric CO2 level of about 350 ppm or less, with
other climate forcings similar to today's levels.
From his recent Plos One paper: «As discussed above, keeping global climate close to the Holocene range requires a long - term atmospheric CO2 level of about 350 ppm or less,
with other climate forcings similar to today's levels.
Other climate forcings, such as solar variability and volcanic activity, are more clearly external to the Earth's climate system.
In it, he has made clear that he feels that apart from greenhouse gases,
other climate forcings (the changes that affect the energy balance of the planet) are being neglected in the scientific discussion.
To arrive at an attribution statement for the degree of temp rise due to human GHG emissions with such startling confidence, you MUST know with equal confidence the contributions from
all other climate forcings operating over that period.
As the Sun provides an explicit external forcing, a better understanding of its cause and effect in climate change could help us evaluate the importance of
other climate forcings (such as past and future greenhouse gas changes).
Ignored in these calculations are significant contributions from methane (natural gas), black carbon, and
other climate forcings.
The actual fufure development of emissions and
other climate forcings is inherently unknown, so how can you expect an estimate of their respective likelihood?
So, I think the original post should have also addressed the lack of
other climate forcings (volcanism, solar insolation fluxes) that might have resulted in climate feedbacks affecting the carbon cycle that would have, in turn, resulted in the on - going increase of CO2 (ppmv) in the atmosphere.
The committee hopes that this report will be useful to the U.S. Climate Change Science Program in mapping future research directions to improve our knowledge of radiative and
other climate forcings, their variability, and their impacts on climate.
Research Program on Modeling Future Climate Change: Effects of Increased Atmospheric Carbon Dioxide and Other Climate Forcings