36
1850–1900 baseline used throughout this book (i.e., the mean value of ΔT after
this adjustment, averaged over years 1850–1900, is by definition zero).
(ii) 1000 ybp to 1849: a temperature reconstruction based on various proxies, such
as tree rings, corals, etc. published by Jones and Mann ( 2004 ), archived by the
National Centers for Environmental Information (NCEI) of the US National
Oceanographic and Atmospheric Administration (NOAA) at:
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/jones2004/
jonesmannrogfig5.txt
Column 6 of this file tabulates global ΔT smoothed with a low pass filter, rela-
tive to their 1856–1980 baseline; 0.2657 °C has been added to place the mea-
surements on our 1850–1900 baseline.
Eras 2 and 3, ΔT is based on the European Project for Ice Coring in Antarctica
(EPICA) Dome C record (Jouzel et al. 2007 ) archived at:
http://www1.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/epica_domec/
edc3deuttemp2007.txt
This record is based on analysis of the isotopic composition of the ice core, which
is sensitive to temperature conditions at the time the ice formed. Two adjustments
have been applied. First, we have subtracted 0.4250 °C from each data point to place
the record on our 1850–1900 baseline. Second, since the ice core record represents
temperature anomalies in Antarctica, which are larger than for other parts of the
world, we have multiplied each data point by 0.463 to account for this difference.
This multiplicative factor, based on analysis of the relation between Arctic and
global warming over the modern time period (Chylek and Lohmann 2005 ), is in
good agreement with the climate model simulations of the relation between warm-
ing in Antarctica and throughout the world (Masson-Delmotte et al. 2006 ).
Eras 4 and 5, ΔT is based on changes in Earth’s surface temperature inferred
from observations of isotopic composition of the shells preserved in deep seas cores
(Hansen et al. 2013 ), archived at Columbia University:
http://www.columbia.edu/~mhs119/Sensitivity+SL+CO2/Table.txt
Data in column 6, labeled Ts, are used. The authors have related these deep sea core
inferences to 14 °C, which is the globally averaged surface temperature from 1961
to 1990. We have subtracted 14 °C from each data point to turn the record into an
anomaly relative the 1961–1990 baseline, then added 0.3134 °C to each data point
to place this record on our 1850–1900 baseline.
Era6, ΔT is based on the isotopic composition of marine carbonates corrected
for the influence of oceanic acidity and adjusted also for modeled variations of
ancient, atmospheric CO 2 (Royer et al. 2004 ) archived at:
http://www.realclimate.org/docs/Temp-summary-from-Royer-et-al-2004.xls
Data in column D of this file were used. The authors have estimated changes in deep
sea temperature relative to present. We have converted to surface temperature anom-
aly by multiplying their record by 2.5, the ratio of changes in global surface tempera-
ture to deep sea temperature according to equation 4.2 of Hansen et al. ( 2013 ). We
have interpreted present to mean the 1961–1990 baseline, so we have also added
0.3134 °C to the data so that this record is also reflective of our 1850–1900 baseline.
1 Earth’s Climate System