High-resolution palaeoclimatic records for the last millennium: interpretation, integration and comparison with General Circulation Model control-run temperatures

Palaeoclimatology provides our only means of assessing climatic variations before the beginning of instrumental records. The various proxy variables used, however, have a number of limitations which must be adequately addressed and understood. Besides their obvious spatial and seasonal limitations, different proxies are also potentially limited in their ability to represent climatic variations over a range of different timescales. Simple correlations with instrumental data over the period since ad 1881 give some guide to which are the better proxies, indicating that coral- and ice-core-based reconstructions are poorer than tree-ring and historical ones. However, the quality of many proxy time series can deteriorate during earlier times. Suggestions are made for assessing proxy quality over longer periods than the last century by intercomparing neighbouring proxies and, by comparisons with less temporally resolved proxies such as borehole temperatures. We have averaged 17 temperature reconstructions (representing various seasons of the year), all extending back at least to the mid-seventeenth century, to form two annually resolved hemispheric series (NH10 and SH7). Over the 1901–91 period, NH10 has 36% variance in common with average NH summer (June to August) temperatures and 70% on decadal timescales. SH7 has 16% variance in common with average SH summer (December to February) temperatures and 49% on decadal timescales, markedly poorer than the reconstructed NH series. The coldest year of the millennium over the NH is ad 1601, the coldest decade 1691–1700 and the seventeenth is the coldest century. A Principal Components Analysis (PCA) is performed on yearly values for the 17 reconstructions over the period ad 1660–1970. The correlation between PC1 and NH10 is 0.92, even though PC1 explains only 13.6% of the total variance of all 17 series. Similar PCA is performed on thousand-year-long General Circulation Model (GCM) data from the Geophysical Fluid Dynamics Laboratory (GFDL) and the Hadley Centre (HADCM2), sampling these for the same locations and seasons as the proxy data. For GFDL, the correlation between its PC1 and its NH10 is 0.89, while for HADCM2 the PCs group markedly differently. Cross-spectral analyses are performed on the proxy data and the GFDL model data at two different frequency bands (0.02 and 0.03 cycles per year). Both analyses suggest that there is no large-scale coherency in the series on these timescales. This implies that if the proxy data are meaningful, it should be relatively straightforward to detect a coherent near-global anthropogenic signal in surface temperature data.

[1]  J. Lough,et al.  The potential of massive corals for the study of high-resolution climate variation in the past millennium , 1996 .

[2]  Z. De’er.  Evidence for the existence of the medieval warm period in China , 1994 .

[3]  F. Luther,et al.  Detecting the climatic effects of increasing carbon dioxide , 1985 .

[4]  Thomas C. Peterson,et al.  A new method for detecting undocumented discontinuities in climatological time series , 1995 .

[5]  E. Cook.  Temperature histories from tree rings and corals , 1995 .

[6]  R. Villalba.  Climatic Fluctuations in Northern Patagonia during the Last 1000 Years as Inferred from Tree-Ring Records , 1990, Quaternary Research.

[7]  R. Bradley,et al.  'Little Ice Age' summer temperature variations: their nature and relevance to recent global warming trends , 1993 .

[8]  John F. B. Mitchell,et al.  The second Hadley Centre coupled ocean-atmosphere GCM: model description, spinup and validation , 1997 .

[9]  Walter Munk,et al.  Spectra of low-frequency ocean waves , 1959 .

[10]  P. Jones,et al.  Unusual twentieth-century summer warmth in a 1,000-year temperature record from Siberia , 1995, Nature.

[11]  P. Jones,et al.  Tree-Ring Density Reconstructions of Summer Temperature Patterns across Western North America since 1600 , 1992 .

[12]  G. Manley.  Central England temperatures: Monthly means 1659 to 1973 , 1974 .

[13]  David Parker,et al.  Interdecadal changes of surface temperature since the late nineteenth century , 1994 .

[14]  Edward R. Cook,et al.  Climatic change over the last millennium in Tasmania reconstructed from tree-rings , 1992 .

[15]  D. Peel.  Ice core evidence from the Antarctic Peninsula region , 1992 .

[16]  P. Jones,et al.  Adjusting variance for sample-size in tree-ring chronologies and other regional-mean timeseries , 1997 .

[17]  Claude N. Williams,et al.  An Approach to Adjusting Climatological Time Series for Discontinuous Inhomogeneities , 1987 .

[18]  T. Wigley,et al.  A Comparison of Evidence for Late Holocene Summer Temperature Variations in the Northern Hemisphere , 1983, Quaternary Research.

[19]  H. Fritts,et al.  Tree Rings and Climate. , 1978 .

[20]  K. Briffa,et al.  Global Surface Air Temperature Variations During the Twentieth Century: Part 1, Spatial, Temporal and Seasonal Details , 1992 .

[21]  S. Johnsen,et al.  Inter-comparison of Ice Core δ(18O) and Precipitation Records from Sites in Canada and Greenland over the last 3500 years and over the last few Centuries in detail using EOF Techniques. , 1996 .

[22]  P. Jones,et al.  Climate Since A.D. 1500 , 1992 .

[23]  M. Allen,et al.  Human Influence on the Atmospheric Vertical Temperature Structure: Detection and Observations , 1996, Science.

[24]  Thomas C. Peterson,et al.  Creation of homogeneous composite climatological reference series , 1994 .

[25]  K. Trenberth,et al.  Satellite versus Surface Estimates of Air Temperature since 1979 , 1996 .

[26]  The Little Ice Age , 1989 .

[27]  J. Lough,et al.  Coral skeletons: Storage and recovery of environmental information , 1996 .

[28]  Andrew Sturman,et al.  El Niño Southern Oscillation and Climatic Variability , 1998 .

[29]  S. Manabe,et al.  Simulated ENSO in a Global Coupled Ocean–Atmosphere Model: Multidecadal Amplitude Modulation and CO2 Sensitivity , 1997 .

[30]  Malcolm K. Hughes,et al.  Was there a ‘medieval warm period’, and if so, where and when? , 1994 .

[31]  P. Jones,et al.  Data bases for isolating the effects of the increasing carbon dioxide concentration , 1985 .

[32]  D. Deming.  Climatic warming in north america: analysis of borehole temperatures. , 1995, Science.

[33]  John F. B. Mitchell,et al.  Global and regional variability in a coupled AOGCM , 1997 .

[34]  The Potential Effect of GCM Uncertainties and Internal Atmospheric Variability on Anthropogenic Signal Detection , 1998 .

[35]  F. Taylor,et al.  A multicentury stable isotope record from a New Caledonia coral: Interannual and decadal sea surface temperature variability in the southwest Pacific since 1657 A.D , 1998 .

[36]  Helmut E. Landsberg,et al.  Methods in Climatology , 1945 .

[37]  Raymond S. Bradley,et al.  Are there optimum sites for global paleotemperature reconstruction , 1996 .

[38]  三上 岳彦.  Proceedings of the International Symposium on the Little Ice Age Climate , 1992 .

[39]  J. Lough,et al.  Several centuries of variation in skeletal extension, density and calcification in massive Porites colonies from the Great Barrier Reef: A proxy for seawater temperature and a background of variability against which to identify unnatural change , 1997 .

[40]  Keith R. Briffa,et al.  Estimating Sampling Errors in Large-Scale Temperature Averages , 1997 .

[41]  M. Hulme,et al.  Climates of the British Isles : Present, Past and Future , 1999 .

[42]  Fritz H. Schweingruber,et al.  Tree-ring variables as proxy-climate indicators: Problems with low-frequency signals , 1996 .

[43]  Fritz H. Schweingruber,et al.  Tree-ring based reconstruction of summer temperatures at the Columbia Icefield, Alberta, Canada, AD 1073-1983 , 1997 .

[44]  P. Jones,et al.  Hemispheric Surface Air Temperature Variations: A Reanalysis and an Update to 1993. , 1994 .

[45]  Shaopeng Huang,et al.  Inference of ground surface temperature history from subsurface temperature data: Interpreting ensembles of borehole logs , 1996 .

[46]  R. Villalba,et al.  A 3620-Year Temperature Record from Fitzroya cupressoides Tree Rings in Southern South America , 1993, Science.

[47]  E. Mosley‐Thompson,et al.  Climatological significance of δ18O in north Tibetan ice cores , 1996 .

[48]  T. Wigley,et al.  Decadal timescale links between Antarctic Peninsula ice-core oxygen-18, deuterium and temperature , 1993 .

[49]  S. Manabe,et al.  Model assessment of the role of natural variability in recent global warming , 1994, Nature.

[50]  Anders Moberg,et al.  HOMOGENIZATION OF SWEDISH TEMPERATURE DATA. PART I: HOMOGENEITY TEST FOR LINEAR TRENDS , 1997 .

[51]  Jean Jouzel,et al.  Climatic Variations and Forcing Mechanisms of the Last 2000 Years , 1996 .

[52]  Y. Bergeron,et al.  Reconstruction of high resolution ground temperature histories combining dendrochronological and geothermal data , 1995 .

[53]  K. Briffa,et al.  A 1,400-year tree-ring record of summer temperatures in Fennoscandia , 1990, Nature.

[54]  C. Folland,et al.  A NEW DAILY CENTRAL ENGLAND TEMPERATURE SERIES , 1992 .

[55]  L. Thompson.  Climatic Changes for the last 2000 Years Inferred from Ice-Core Evidence in Tropical Ice Cores , 1996 .

[56]  D. Parker,et al.  A new daily central England temperature series, 1772–1991 , 1992 .

[57]  M. Miles.  CLIMATE: PRESENT, PAST AND FUTURE, VOL. 2. CLIMATE HISTORY AND THE FUTURE. , 1978 .

[58]  D. G. Watts,et al.  Spectral analysis and its applications , 1968 .

[59]  V. Conrad.  METHODS IN CLIMATOLOGY , 1946 .

[60]  J. Rabassa,et al.  Fuegian floating tree-ring chronology from subfossil Nothofagus wood , 1996 .

[61]  David A. Rhoades,et al.  ADJUSTMENT OF TEMPERATURE AND RAINFALL RECORDS FOR SITE CHANGES , 1993 .

[62]  H. E. Wright,et al.  Palaeoecological Events During the Last 15,000 Years: Regional Synthesis of Palaeoecological Studies of Lakes and Mires in Europe. , 1996 .

[63]  H. Lamb,et al.  CLIMATE AND HISTORY , 1980 .

[64]  J. Lean,et al.  Reconstruction of solar irradiance since 1610: Implications for climate change , 1995 .

[65]  Malcolm K. Hughes,et al.  Global Temperature Patterns , 1998, Science.

[66]  P. Jones,et al.  Summer Temperature Patterns over Europe: A Reconstruction from 1750 A.D. Based on Maximum Latewood Density Indices of Conifers , 1988, Quaternary Research.

[67]  D. Fisher,et al.  Signal and noise in four ice-core records from the Agassiz Ice Cap, Ellesmere Island, Canada: details of the last millennium for stable isotopes, melt and solid conductivity , 1994 .

[68]  J. M. Gregory,et al.  Climate response to increasing levels of greenhouse gases and sulphate aerosols , 1995, Nature.

[69]  Peter W. Glynn,et al.  Eastern Pacific sea surface temperature since 1600 A , 1994 .

[70]  K. Briffa,et al.  Seasonal temperatures in Britain during the past 22,000 years, reconstructed using beetle remains , 1987, Nature.

[71]  Malcolm K. Hughes,et al.  Global-scale temperature patterns and climate forcing over the past six centuries , 1998, Nature.

[72]  J. Overpeck,et al.  Hypothesized causes of decade-to-century-scale climate variability: Climate model results , 1993 .

[73]  D. Peel,et al.  Climate changes in the Atlantic Sector of Antarctica over The Past 500 Years from Ice-Core and Other Evidence , 1996 .

[74]  P. Jones,et al.  Climatic variations over the last 500 years , 1992 .

[75]  H. Lamb.  Climate: present, past and future , 1977 .

[76]  B. Santer,et al.  Detecting greenhouse-gas-induced climate change with an optimal fingerprint method , 1996 .

[77]  Benjamin D. Santer,et al.  Estimates of low frequency natural variabilit in near-surface air temperature , 1996 .

[78]  Fritz H. Schweingruber,et al.  Fennoscandian summers from ad 500: temperature changes on short and long timescales , 1992 .

[79]  H. Alexandersson.  A homogeneity test applied to precipitation data , 1986 .

[80]  Keith R. Briffa,et al.  Interpreting High-Resolution Proxy Climate Data — The Example of Dendroclimatology , 1995 .

[81]  Tom M. L. Wigley,et al.  Towards the detection and attribution of an anthropogenic effect on climate , 1995 .

[82]  T. V. van Ommen,et al.  Seasonality in late-Holocene climate from ice-core records , 1997 .