Table of Figures

Click on smaller image or figure number to view figure.

Figure 1 Figure 1:
Distribution of annual resolution proxy indicators used in this study. Dendroclimatic reconstructions are indicated by "tree" symbols, ice core/ice melt proxies by "star" symbols, coral records by "C" symbols. Long historical records and instrumental "gridpoints" series are shown by squares (temperature), or diamonds (precipitation). Groups of "+" symbols indicate principal components of dense tree ring sub-networks, with the number of such symbols indicating the number of retained principal components. Sites are shown dating back to at least 1820 (red), 1800 (blue-green), 1750 (green), 1600 (blue), and 1400 (black). Certain sites (e.g., the Quelccaya ice core) consist of multiple proxy indicators (e.g., multiple cores, and both oxygen isotope and accumulation measurements).


Figure 2 Figure 2:
Distribution of the (1082) nearly continuous available land air/sea surface temperature gridpoint data available from 1902 onward indicated by shading. The squares indicate the subset of 219 gridpoints with nearly continuous records extending back to 1854 that are used for verification. Northern Hemisphere (NH) and global (GLB) mean temperature are estimated as areally-weighted (ie, cosine latitude) averages over the Northern hemisphere and global domains respectively. The large rectangle indicates the tropical Pacific SST sub-domain discussed in the text. The small rectangle in the eastern tropical Pacific shows the traditional NINO3 region.


Figure 3:
Empirical orthogonal functions (EOFs) for the five leading eigenvectors of the global temperature data from 1902-1993. CLICK on the time history ("Principle Component") of the associated pattern from 1902-1993, which are also listed below.

View Principle Component 1
View Principle Component 2
View Principle Component 3
View Principle Component 4
View Principle Component 5


Figure 4:
Spatial patterns of (top) calibration beta and verification beta (middle) and r-squared (bottom) statistics. The calibration statistics are based on the 1902-1980 data, while the verification statistics are based on the sparser 1854-1901 instrumental data (see Figure 2) withheld from calibration. For the beta statistic, values that are insignificant at the 99% level are shown in gray, while negative, but 99% significant values are shown in yellow, and significant positive values are shown in two shades of red. For the r-squared statistic, statistically insignificant values (or any gridpoints with unphysical negative values of correlation) are indicated in gray. The color scale indicates values significant at the 90% (yellow), 99% (light red), and 99.9% (dark red) levels (these significance levels are slightly higher for the calibration statistics which are based on a longer period of time). More details regarding significance level estimation are provided in MBH98.

 

Figure 4
Figure 5 Figure 5:
Histogram of calibration residuals for NH series. A Gaussian parent distribution is shown for comparison, along with the +/- 2 standard error bars for the frequencies of each bin. The distributions is consistent with a Gaussian distribution at a high (95%) level of confidence. The distribution of residuals for the NINO3 index (not shown) is consistent with a Gaussian distribution at a 99% level of confidence.

Figure 6:
Northern Hemisphere (NH) Mean Temperature Reconstruction from AD 1400-1980, shown with raw instrumental NH series (red) through 1998. The low-frequency trend (timescales longer than 40 years emphasized) is shown by the thick curve. The blue shaded region indicates the 2 standard error uncertainty limits in the reconstruction (see MBH98 for details).

 


Figure 7 Figure 7:
Reconstructed Northern Hemisphere (NH) mean temperature series vs. raw instrumental NH series from 1854-1980. For the purposes of a meaningful comparison, the NH spatial means have in this case been diagnosed in both the raw data and reconstructions from the sparse gridpoint coverage of the verification period from 1854-1901, and the dense coverage of the calibration period from 1902-1980.

View Larger Image
View Sparse Instrumental Data
View Dense Instrumental Data

 


Figure 8:
Reconstructed Northern Hemisphere (NH) mean temperature series based on full latitudinal coverage (red) vs. the average reconstructed series for the extratropical latitude band 30N-70N (blue).

Raw Latitude Band Data
Recon Latitude Band Data

 

Figure 8
Figure 9 Figure 9:
Comparison of reconstructed NH (red) and North American (blue) regional temperature variations during past centuries.

Raw Regional Band Data
Recon Regional Band Data
View Northern Hemisphere Data
View North American Data


Figure 10
Figure 10:
Reconstructed Principal Component (RPC) series for the first 5 eigenvectors (see Figure 3) back in time, along with their 20th century instrumental counterparts.

View Larger Image   View RPC #1 Data   View RPC #2 Data
View RPC #3 Data   View RPC #4 Data   View RPC #5 Data

 


El Nino events during 1791.
Figure 11:
Global temperature pattern reconstructions for two historically documented very strong El Nino events during 1791 (top) and 1878 (bottom).

 

El Nino events during 1878.
1834 - Warmest Europe 1822 - Second Warmest Europe
1838 - Coldest Europe Figure 12:
Global temperature pattern reconstructions for three years associated with unusually warm or cold anomalies in the European sector during 1834 (top left), 1822 (top right), and 1838 (left).

 


1816 - Figure 13:
Global temperature pattern reconstructions for the so-called "Year without a summer" 1816.

 


NH mean temperature & estimates of the histories - click here for better viewing and data. Figure 14:
Relationship of Northern hemisphere mean (NH) temperature reconstruction to estimates of three candidate forcings (see MBH98) between 1610 and 1995.
Click here or on image for better viewing and access to data.

The time axis denotes the center of a 200 year moving window. One-sided (positive) 90%, 95%, 99% significance levels for correlations with the different forcing agents. These are approximately constant over time, and are thus represented by their average values over time for simplicity in the plot. Significance levels for CO2 and solar irradiance are nearly identical, and the 90%,95%, and 99% one-sided (positive) significance levels are shown by the horizontal dashed lines, while the one-sided (negative) 95% significance significance for DVI is shown by a horizontal dotted line. The lower dotted line indicates the 99% two-sided significance level for correlation with GHG. This latter feature is added to demonstrate that the apparently negative (and thus, seemingly spurious) correlation of NH with GHG observed during the late 18th/early 19th century nevertheless does not achieve statistical significance if the a priori physical requirement of a positive relationship between CO2 and temperature is not taken into account in the hypothesis test. The gray bars indicates two different 200 year windows of data in the moving correlation, with the long-dashed vertical lines indicating the center of the corresponding windows.

 


As above, but employing varying value of lag of temperatures relative to forcing - click here for larger image. Figure 15:
Relationship between NH series and forcings as above, but employing varying value of lag of temperatures relative to forcing. Symbols are same as above. The first 5 panels make use of the 200 year window used above. In the first panel, we repeat the zero-lag case shown above for comparison, while the 2nd panel shows the results for 1 year lag, the 3rd panel 10 year lag, and the 4th panel 15 year lag. The 5th panel shows the results based on employing 100 year moving window in the time-dependent attribution analysis, and with a 15 year lag in the relationship of temperature to forcings. For lags much larger than 1 year, the relationship of temperatures to volcanic forcing is not physically meaningful, and is quite small. Thus, the relationship to volcanic forcing is not shown in the 3rd, 4th, and 5th panels.


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