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25 September 2009

How natural and anthropogenic influences alter global and regional

GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L18701, doi:10.1029/2008GL034864, 2008

How natural and anthropogenic influences alter global and regional
surface temperatures: 1889 to 2006
Judith L. Lean1 and David H. Rind2
Received 2 June 2008; revised 1 August 2008; accepted 8 August 2008; published 16 September 2008.

Abstract
To distinguish between simultaneous natural and
anthropogenic impacts on surface temperature, regionally
as well as globally, we perform a robust multivariate
analysis using the best available estimates of each together
with the observed surface temperature record from 1889 to
2006. The results enable us to compare, for the first time
from observations, the geographical distributions of
responses to individual influences consistent with their
global impacts. We find a response to solar forcing quite
different from that reported in several papers published
recently in this journal, and zonally averaged responses to
both natural and anthropogenic forcings that differ distinctly
from those indicated by the Intergovernmental Panel on
Climate Change, whose conclusions depended on model
simulations. Anthropogenic warming estimated directly
from the historical observations is more pronounced
between 45S and 50N than at higher latitudes whereas
the model-simulated trends have minimum values in
the tropics and increase steadily from 30 to 70N.
Citation: Lean, J. L., and D. H. Rind (2008), How natural and
anthropogenic influences alter global and regional surface
temperatures: 1889 to 2006, Geophys. Res. Lett., 35, L18701,

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