Meeting Products

Mann et al. (1999) Geo. Res. Let. 26(6):759.

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Caption: This figure forms the basis for the claim that 1998 was the warmest of the millennium at that time in the Northern Hemisphere, even when full account is taken of the increasing uncertainties associated with reconstructions of individual years prior to AD 1600. The reconstruction also indicates that there are statistically valid links between pre-20th century temperature variability and both solar and volcanic forcing, whereas during recent decades, there is every indication of an increasingly strong correlation between the temperature trend and the influence of atmospheric CO2.

Mann, M. et al (1999) Northern Hemisphere Temperatures During the Past Millennium: Inferences, Uncertainties and Limitations, Geophysical Research Letters, 26, 6, p.759

Modified from Joussaume et al. (1999) GRL 26: 859-862.

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Caption: The change in zonal average annual precipitation (mm/y) between 6kBP and the control, averaged over all land cells between 20W-30E (North Africa), b) latitudinal distribution of biome types (desert, steppe, xerophytic and dry tropical forest/savannah) for all available data points for today and 6kBP over the longitudes 20W-30E, and c) zonal average annual precipitation (mm/y) in the control simulation, averaged over all land cells between 20W-30E, compared to the climatology of Legates and Willmott ( Int. J. Climatol., 111, 1990). In Figure 3a, the two heavy dashed lines indicate the amount of annual mean precipitation that would be required to produce steppic biomes in now desertic regions (footnote 1). This diagram also provides a graphical representation of the shifts of the simulated desert-steppe limit at 6kBP: the limit is shifted from the present day position (15-16N, at the intersection between the dashed curves and the zero line) to the latitude of intersection between the simulated change of annual precipitation and the dashed curves (amount required to shift biomes).

Joussaume, S., et al. Monsoon Changes for 6000 Years ago: Results of 18 Simulations from the Paleoclimate Modelling Intercomparison Project (PMIP). Geophysical Research Letters, 26, 859-862. 1999.

Modified from Indermühle et al. (1999) Nature 398: 121-126.

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Caption: The Taylor Dome CO2 record provides a unique high resolution record of atmospheric CO2 concentration during the Holocene, showing that the carbon cycle has not been in steady state during the past 11,000 years. The inset in the upper figure shows the period for which overlapping records from Taylor Dome and Byrd, which have been harmonized using a Monte Carlo method and are presented as a continuous trace, with 1 sigma (pale blue envelope) and two sigma (dark blue line) error bands.

A. Indermühle et al (1999) Holocene carbon-cycle dynamics based on CO2 trapped in ice at Taylor Dome, Antarctica, Nature,  398, 121-126.

From Dunbar R and Cole J eds. (1999) PAGES ARTS Report 99-1.

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Caption: Tropical SST's and locations of current coral paleoclimate research. Mean January SST map from NMC SST data was available at  http://ingrid.ldgo.co-lumbia.edu; coral sites represent the work of many investigators and may be incomplete. Records that extend beyond about 120 years are shown in magenta; gray circles represent both sites where long records are in progress and shorter published records. Numbered sites are: 1. Galápagos; 2. Panamá (Chiriquí); 3. Tarawa (Kiribati); 4. Kiritimati Island (Line Islands, Kiribati); 5. Nauru; 6. Vanuatu; 7. New Caledonia; 8. Abraham Reef, Great Barrier Reef; 9. Cebu, Philippines; 10. Seychelles; 11. Malindi, Kenya; 12. Bermuda. These records have the potential to provide seasonally resolved records of changing sea surface temperature and salinity. Among other things, they help to provide a reconstruction of ENSO variability beyond the instrumental and documentary record which shows that the ENSO mode has changed in terms of both periodicity and amplitude on decadal to century timescales.

R. Dunbar and J. Cole eds. (1999) Annual Records of Tropical Sysytems (ARTS) Recommendations for Research, PAGES Workshop Report, Series 99-1, 72 pgs.

Status Report and Implementation Plan. To order a hardcopy of this report, contact the communications officer.

Modified from Thompson L (1998) Science 282: 1858-1864.

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Caption: This interhemispheric comparison of stable isotope records includes two tropical sites (Sajama and Huascaran), two Northern Hemisphere sites (Guliya and GISP 2) and two Southern Hemisphere sites (Byrd Station and Vostok). This shows the global extent of the LGS and the climatic reversal (cooling) during deglaciation.

Thompson L (1998) Science 282: 1858-1864

Modified from von Graffenstein et al. (1998) Climate Dynamics 14: 73-81.

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Caption: This figure shows (a) accumulation and (b) temperature records in the Greenland GISP2 ice core and (c) temperature records derived from oxygen isotope measurements on ostracod tests in the sediments of Ammersee, southern Germany. These records show a climatic instability event which occurred around 8200 years BP, during the Holocene. The event was large both in magnitude, as reflected by a temperature signal in Greenland of order 5°C, and in its geographical extent, as indicated by the close correlation of the signal in these two locations. The dramatic event is also seen in the methane record from Greenland (not shown here) indicating possible major shifts in hydrology and land cover in lower latitudes.

Von Graffenstein et al (1998) "The cold event 8200 years ago documented in oxygen isotope records of precipitation in Europe and Greenland" Climate Dynamics, 14, 73-81.

Modified from Gagan et al. (1998) Science 279: 1014-1018.

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Caption: Comparison between sea surface temperatures calculated from coral Sr/Ca ratio (blue curves) and 18O (upper red curve) for modern (left) and 5,350 yrs BP (right) Porites corals from Orpheus Island, central Great Barrier Reef, Australia. Differences in seawater 18O (lower red curves), relative to the modern mean, are obtained by removal of the temperature component of the 18O signal. The horizontal lines show the mean 18O of seawater, as defined by the seven 18O values (squares) falling in the austral winters (vertical lines). Relative to the mid-Holocene, the modern coral indicates cooler average water temperatures (by 1.2°C and the characteristic interannual variability in salinity (~18O seawater) that accompanies the ENSO cycle (from Gagan et al. 1998).

M. Gagan, et al. (1998) Temperature and surface-ocean water balance of the mid-Holocene tropical western Pacific, Science,  279, 1014-1018.

Modified from Biffra et al. (1998) Nature 393: 450-455.

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Caption: Over the last 600 years, all the known (and several, as yet unidentified) major volcanic eruptions are marked by changes in mean tree ring density (linked to lower spring/summer temperatures) for a set of records covering much of the boreal forest zone in the Northern hemisphere. The Volcanic Explosivity Index VEI is a rough measure of magnitude. Note that most events have an annual impact, but the impact of strong events, as in 1641 and 1816, lasted for 3 years. The general down-turn in the curve over the last 30 years or so is not explicable in climatic terms, since it contrasts with every other line of evidence for the same period. The likely implication is that there is a change in physiological response linked perhaps to CO2 enrichment and/or hydrology/soil moisture status.

K. Briffa et. al. (1998) Influence of volcanic eruptions on Northern Hemisphere summer temperature over the past 600 years, Nature,  393, 450-455

Modified from Blunier et al. (1998) Nature 394: 739-743.

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Caption: GRIP, Byrd and Vostok isotopic and CH4 records on the common time scale (GRIP timescale in years before 1989). For the data of Byrd, a solid line shows the lower-temperature scenario, and the shaded area indicates the range of gasage-ice age difference for the two temperature scenarios. The CH4 scale at lower left corresponds to the GRIP values; Byrd and Vostok values were lowered by 200 and 400 ppbv, respectively, for better visibility. The numbers on the top of the GRIP isotopic record indicate the location of Dansgaard-Oeschger events; ACR is the location of the Antarctic Cold Reversal. Antarctic warmings are indicated by A1 and A2; dotted lines show the location of Greenland warmings 1, 8 and 12 in the Antarctic cores. The Byrd δ18O variation between 25 and 17 kyr BP shows most likely local climate characteristics because: (1) it is not seen in the Vostok or in the Dome C record, and (2) it is not compatible with the climate mechanism seen during events A1, A2 and also the ACR present in all Antarctic records.

Blunier et al., 1998, Nature 394, 739-743