Supplement to

The Medieval Climate Anomaly in OceaniaSebastian Lüning1*, Mariusz Gałka2, Felipe García-Rodríguez3, Fritz Vahrenholt4

_____________________________________

1Institute for Hydrography, Geoecology and Climate Sciences, Hauptstraße 47, 6315 Ägeri, Switzerland. E-mail: luening@ifhgk.org

2Mariusz Gałka, Department of Geobotany and Plant Ecology, Faculty of Biology and Environmental Protection, University of Lodz, 12/16 Banacha Str., Lodz, Poland. E-mail: gamarga@wp.pl

3Felipe García-Rodríguez, Centro Universitario Regional Este, CURE-Rocha, Ruta 9 y Ruta 15 s/n, Uruguay. Present address: Programa de Pós-Graduação em Oceanografia Física, Química e Geológica, Instituto de Oceanografia, Universidade Federal do Rio Grande, Av. Itália, km 8, Cx.P. 474, 96201-900, Rio Grande, RS, Brazi. E-mail: felipegr@fcien.edu.uy

4Fritz Vahrenholt, Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany. E-mail: fritz.vahrenholt@chemie.uni-hamburg.de

*Corresponding author

Contents of this file:

Overview page

Introduction................................................................................2

Table S1: Sources of data, age model control..........................3

MCA in New Guinea and SE Australia

Text S1: Site descriptions New Guinea and SE Australia.........4

Figure S1: MCA Correlation New Guinea and SE Australia......4

MCA in Tasmania

Text S2: Site descriptions Tasmania.........................................5

Figure S2: MCA Correlation Tasmania......................................6

MCA in New Zealand

Text S3: Site descriptions New Zealand....................................8

Figure S3: MCA Correlation Campell Is. & South Island...........9

Figure S4: MCA Correlation North Island..................................11

References...............................................................................12

1

IntroductionThe Supplementary Information contains a detailed description of the 15 sites identified for Oceania (Texts S1-S4). Selected series contain at least one data point in the MCA and ideally show continuous data coverage over the past 1000 years or at least large parts of it. The palaeotemperature and other data are visualised in four correlation panels (Figures S1-S4). The source of tabulated data and level of age control are listed in Table S1. Site references are cited in Table 1 in the main paper. The location map is shown in Fig 1.

2

DataTable S1. Source of tabulated data and site coordinates for Oceania temperature proxy correlations (Figs. S1-S4). The age data column lists either the number of radiometric age dates or other chronological methods for the last 2500 years for the respective site. trc=tree ring counting. Location map in Fig. 1.

No. Locality Country Coordinates Age dates

Proxies Data source

1 MD98-2176 Indonesia 5.003°S, 133.445°E

2 Mg/Ca, δ13C, δ18O of Globigerinoides ruber

https://www.ncdc.noaa.gov/paleo-search/study/5917

2 MD03-2611 Australia 36°43.8‘S, 136°32.9’E

7 Uk’37 SST, Globorotalia truncatulinoides, δ18O Globigerina bulloides

SST from https:// doi.pangaea.de/10.1594/PANG AEA.737245, G. truncatulinoides and δ18O of G. bulloides from Kerstin Perner

3 Grotto of Oddities

Australia 35.723760°S, 148.491538°E

6 δ13C Digitized from McGowan et al. 2018

4 Cradle Mountain Australia 41.609028°S, 145.936024°E

trc Tree ring width Digitized from Allen et al. 2017

5 Mt. Read Australia 41.839939°S, 145.540094°E

trc Tree ring width https :// www.ncdc.noaa.gov/ paleo-search/study/1003979

6 Duckhole Lake Australia 43.36455°S, 146.87492°E

5 chlorophyll Original: https://www.ncdc.noaa.gov/paleo-search/study/20452; detrended: 21-year filtered data digitized from Saunders et al. 2013

7 South Tasman Sea

Australia 43°58‘S, 150°24‘E

5 sea surface radiocarbon reservoir ages

Raw data from Supplement of Komugabe‐Dixson et al. 2016

8 Mount Honey New Zealand 52°34‘17“S, 169°9‘46“E

6 pollen From Matt McGlone

9 Fiordland New Zealand 45.274891°S, 167.849071°E

5 δ18O Digitized from Lorrey et al. 2008

10 Mount Cook Glaciers

New Zealand 43.598389°S, 170.162487°E

>50 10Be boulder and radiocarbon kill ages

Digitized from Schaefer et al. 2009

11 Oroko Swamp New Zealand 43.233344°S, 170.283199°E

trc Tree ring width https:// www.ncdc.noaa.gov/ paleo-search/study/1003986, https:// www.ncdc.noaa.gov/paleo- search/study/22555

12 Cave in NW Nelson District

New Zealand 40.666770°S, 172.433426°E

5 δ18O Digitized from Williams et al. 2005

13 Hawkes Bay New Zealand 38.876076°S, 177.640645°E

9 δ18O Digitized from Lorrey et al. 2008

14 Caves in Waitomo district

New Zealand 38.224158°S, 175.051975°E

3 δ18O, δ13C Five-point-running mean master curve digitized from Williams et al. 2004

15 northern North Island

New Zealand 35.978061°S, 173.836441°E

trc Tree ring width Archaeological (Ar) chronology digitized from Boswijk et al. 2014

- Australasian reconstruction by Gergis et al. (2016)

Australasia Sites 5 & 11 and Palymra

- Tree rings, δ18O corals

https://www.ncdc.noaa.gov/paleo-search/study/12915

3

Text S1

NEW GUINEA & SE AUSTRALIA

1- MD98-2176

This marine core has been taken from a water depth of 2382 m south of West Papua in eastern Indonesia (Fig. 1). Stott et al. (2004) measured Mg/Ca ratios of calcium carbonate produced by the surface-dwelling planktonic foraminifer Globigerinoides ruber from which they inferred the sea surface temperature (SST). The Medieval Climate Anomaly (MCA) is characterized by a major warming phase (Fig. S1).

Figure S1. Temperature development in New Guinea and southeast Australia during the past 1500 years based on palaeoclimate proxies. 1: MD-98-2176 (Stott et al. 2004); 2: MD03-2611 (Moros et al. 2009; Perner et al. 2018); 3: Grotto of Oddities (McGowan et al. 2018). Red shading indicates warming, blue represents cooling. MCA=Medieval Climate Anomaly (dark gray shading 1000-1200 AD). Light grey interval 900-1500 AD marks general envelope of Oceania warming. SST=sea surface temperature. Site listings in tables 1 and S1, location map in Fig. 1.

4

2- MD03-2611

This marine core has been retrieved from a water depth of 2420 m in the Murray Canyon in southeast Australia (Fig. 1). Moros et al. (2009) measured oxygen stable isotopes of the planktonic foraminifer Globgerina bulloides which is a deeper dwelling species that lives at 50-100 m water depth range and reflects conditions of the Flinders Undercurrent here. The δ18O shows a prominent millennial-scale cyclicity which might represent temperature changes (Moros et al., 2009). The MCA forms part of a multi-century period of more negative δ18O which could be interpreted as a warm phase (Fig. S1). As this potential warm phase persists steadily throughout the Little Ice Age (LIA), alternative interpretations should be investigated, e.g. sea water salinity effects on δ18O and age model issues. Piston core MD03-2611 encompasses the last 10,000 years, but notably lacks the last 600 years which are infilled-by data from Multicore MUC05. Despite originating from the same site, the age models of both cores differ markedly in the overlap period over the past 1500 years (Moros et al. 2009: their fig. 2), which could also explain the unexpectedly long MCA-LIA “warming”. The alkenone SST data from Perner et al. (2018) are, unfortunately, of too low resolution to allow shedding further light on the MCA temperature development at this coring site (Fig. S1).

3- Grotto of Oddities

This cave at about 1000 m above sea level (asl.) forms part of the Yarrangobilly Caves karst complex, located in Kosciusko National Park in the Australian Alps (Fig. 1). McGowan et al. (2018) reconstructed the temperature development for the past 2000 years based on carbon isotopes in a stalagmite. They documented an oscillation of multicentennial warm and cold phases that also includes a warm period which is shown for 1150-1450 AD (Fig. S1). Error bars of two key 230Th age dating samples of the last millennium represent ±2δ values of 228 to 240 years (see their Table S2 in Supplement of McGowan et al., 2018). Therefore, it cannot be discarded that the warm phase could be in fact 150 years older than the interpretation presented by McGowan et al. (2018), which would synchronize this warming with the typical MCA warm phase reported from other parts of the world (e.g. Lüning et al. 2017; Neukom et al. 2011; Ljungqvist et al. 2012) and regional cave data series from New Zealand (sites 9, 13, 14; see detailed descriptions below).

Text S2

TASMANIA

4- Cradle Mt

This tree ring study area is located at a height of 900-960 m asl. in the Cradle Mt - Lake St Clair National Park in central northwest Tasmania (Fig. 1). Allen et al. (2017) have published indexed tree ring values for the long-lived conifer Athrotaxis selaginoides from tree cores of

5

both living and dead specimens that were collected at three different times over the past three decades. The MCA is characterized by generally higher index values, thus suggesting a warmer climate (Fig. S2). Nevertheless, equally warm episodes may have occurred during the LIA, e.g. 1500-1600 and 1700-1800 AD. Accelerated growth was recorded for the 20th Century, in part probably because of the modern warming, but also possibly further enhanced by fertilization as a consequence of anthropogenic increase in the atmospheric CO2 concentration (Zhu et al., 2016).

Figure S2. Temperature development in Tasmania during the past 1500 years based on palaeoclimate proxies. Panel shows a traverse from northeast (left) to southwest (right). 4: Cradle Mountain, Gaussian Window, n=30 (Allen et al. 2017); 5. Mt Read, PCR 50 year LOESS smoothing (Cook et al. 2000); 6: Duckhole Lake, annual temperature undetrended and detrended (Saunders et al. 2013); 7: South Tasman Sea, radiocarbon reservoir age (Komugabe‐Dixson et al. 2016). MCA=Medieval Climate Anomaly, EAC=East Australia Current. Location map in Fig. 1.

5- Mt Read

This is a classical tree ring study area located 950 m asl. at the north west edge of the West Coast Range of Tasmania (Fig. 1). The area lies 40 km southwest of the Cradle Mt site. A

6

group led by Edward Cook analysed tree rings of the sub-alpine Huon pine Lagarostrobos franklinii of both living and subfossil specimens, to reconstruct past warm-season (November-April) temperatures (Cook et al. 1991; Cook et al. 2000; Cook et al. 1992). Generally, warm temperatures are inferred for the period 900-1500 AD, including the MCA (Fig. S2). In a global tree ring series quality assessment, Esper et al. (2016) highly ranked the Mt Read dataset as class A and B in Data Homogeneity, Sample Replication and Climate Signal. Weaker scores (class C) were achieved in Growth Coherence and Chronology Development, thus indicating some inconsistencies in either tree-ring width (TRW) or maximum latewood density (MXD) and the detrending method performed to remove tree-age related growth trends from the raw measurement series.

Accelerated ring-width growth at Mt Read during the past two decades is statistically unprecedented for the past 1048 years (Fig. S2). Allen et al. (2014) identified a decoupling between temperature and ring-growth for this period. The relationship between temperature and growth has varied over time since the start of instrumental records. The recent increased growth at the site, which is higher than what would be expected based on a linear temperature model alone, may be consistent with a number of hypotheses. Firstly, it could be an atmospheric CO2 fertilization effect in 20th Century in tree growth (Gedalof and Berg 2010). Secondly, the wider tree rings in the 20th Century could be due to a sampling bias because (1) fast-growing trees live shorter, therefore they are underrepresented in the ancient portion of the tree ring data set, and (2) big‐tree selection bias caused by sampling only the biggest trees in a population (slow-growing small trees are underrepresented in recent times as they did not reach the minimum sample diameter) (Brienen et al. 2012).

6- Duckhole Lake

This small and relatively shallow sinkhole lake lies about 150 m asl. in southern Tasmania (Fig. 1). Saunders et al. (2013) carried out non-destructive scanning reflectance spectroscopy measurements within the visible spectrum (380–730 nm) on a sediment core. The reflectance from 650 to 700 nm represents the concentration of chlorophyll derivatives, which in the core is highly significantly correlated to total organic carbon (TOC). The authors observed that during the instrumental calibration period of the past 100 years, chlorophyll and TOC were significantly correlated to mean annual temperature. By extrapolating such a relationship back to the past millennium, Saunders et al. (2013) suggest a cold MCA (Fig. S2). The lower third of the MCA is unfortunately missing, as the study only starts around 1070 AD. Saunders et al. (2013) briefly discussed the possibility that the derived temperature curve might have to be detrended to account for potential long-term trends in the time series that are caused by non-climatic processes. In that case, the documented part of the MCA may have been relatively warm (Fig. S2). Generally, the palaeotemperature results from this study have to be treated with caution, as also stated by Saunders et al. (2013) themselves.

A fundamental assumption of the calibration-based approach is that the relationship between the proxy and the reconstructed variable does not change over time. While the authors apply this assumption, they also accept that further studies from southern Tasmania will be required to test the reproducibility of the results, i.e., transfer functions can always be re-validated by enlarging the training-set itself. Saunders et al. (2013) cannot rule out that further back in time precipitation may have influenced plant growth, thus resulting in a more complex response of chlorophyll-based proxies to temperature and precipitation. This is

7

particularly relevant because precipitation and winds have undergone marked changes during the last millennia (Fletcher et al. 2018; Beck et al. 2017; Saunders et al. 2012). A good example for such a variability is the period 1450-1600 AD, which has to be excluded from the temperature reconstruction, as it was considered by Saunders et al. (2013) as a ‘no-analogue’ situation compared to the calibration dataset. The interval is also lithologically different as it consists of a dark brown, highly organic layer which differs markedly from the rest of the sediment core.

The study represents a worthwhile attempt to introduce a rather cheap and fast methodology to the suite of Australasian palaeotemperature reconstructions. Nevertheless, it is still very much unclear how robust the resulting temperature interpretation of the case study location is on a millennial-scale scale. TOC-based temperature reconstructions traditionally work best in polar and high altitude regions (e.g. Fabrés et al. 2000; Monien et al. 2011; Stroup et al. 2015), neither of which Tasmania belongs to.

7- South Tasman Sea

Komugabe‐Dixson et al. (2016) collected black corals from various sites in the Tasman Sea at depths ranging between 150 and 950 m (Fig. 1). The age of the corals was radiometrically determined by means of the U-Th technique. Their organic chitin-protein skeletons are built using particulate organic carbon (POC) recently exported from the surface ocean. The sea surface radiocarbon age archived in the corals appears slightly older compared to the atmosphere due to the lag caused by air-sea exchange of CO2 and dilution through oceanic mixing and circulation. This ‘Sea surface radiocarbon reservoir age’ (R) is a sensitive tracer of ocean circulation. In the Tasman Sea, variations in R mostly refer to changes in the East Australian Current (EAC) and it southward extension which transports warm water southwards. Older R ages suggest a weaker EAC, whilst younger R ages indicate a stronger EAC. Komugabe‐Dixson et al. (2016) found that the majority of the MCA was dominated by intermediate R ages (Fig. S2). The youngest R ages occurred just after the MCA during the period 1200-1450 AD. During this time, the EAC appears to have been stronger, transporting more warm water to the south. Even though, the MCA appears to have been relatively warmer than during the LIA, when phases with particularly old R ages ocurred (Fig. S2). Unfortunately, the MCA is only represented by three three datapoints which is a much lower data density than e.g. during the LIA. More data on the MCA might help to better understand the differences between MCA and the low R phase 1200-1450 AD.

Text S3

NEW ZEALAND

8- Mount Honey

This site is located on Campbell Island which is located in sub-Antarctic waters, about 650 km to the south of mainland New Zealand (Fig. 1). The Mount Honey peat bog profile analyzed by McGlone et al. (2010) lies at 120 m altitude, close to the upper limit of continuous woody vegetation. Their summer temperature reconstruction based on pollen

8

suggests climatic warming during the period 950-1400 AD (Fig. S3). Dracophyllum is particularly sensitive to climate warming (Wilmshurst et al. 2004), and showed a sharp increasing trend in relative abundance during the MCA in the Mt Honey sediment core.

Figure S3. Temperature development in Campbell Island and South Island (New Zealand) during the past 1500 years based on palaeoclimate proxies. Panel shows a traverse from south (left) to north (right). 8: Mt Honey (McGlone et al. 2010); 9: Fiordland (Lorrey et al. 2008); 10: Mt Cook glaciers (Schaefer et al. 2009); 11: Oroko Swamp, 50 year LOESS smoothing (Cook et al. 2002); 12: Cave in NW Nelson District (Williams et al. 2005). Red shading indicates warming, blue represents cooling. MCA=Medieval Climate Anomaly. Location map in Fig. 1.

9- Fiordland

Lorrey et al. (2008) compiled a master speleothem for western and southern South Island (Fiordland) based on stalagmites from several caves (Fig. 1). The period 925-1400 AD is characterized by more positive δ18O values, which the authors interpret as evidence for a warm phase (Fig. S3).

9

10- Mount Cook Glaciers

The Aoraki (Mount Cook) lies in the Southern Alps and with 3724 metres represents New Zealand’s highest mountain (Fig. 1). Schaefer et al. (2009) studied 10Be boulder ages from Mueller Glacier moraines and identified a series of mid to late Holocene glacier advance phases that alternated with periods of glacier retreat. The MCA is bracketed by two glacier advance episodes that occurred just before 1000 AD and around 1400 AD, suggesting warmer conditions with reduced glacier activity during the MCA itself (Fig. S3). The cool phases in Fig. S3 are centred on the arithmetic means of the moraine ages published by (Schaefer et al., 2009: blue bars in their Fig. 3). Multidecadal to -centennial glacier dynamics is most probably linked to the ocean cycles and associated temperature variability (Mackintosh et al. 2017), rather than changes in precipitation (Chinn et al. 2005). In a pioneer study, Burrows (1989) had suggested a series of glacier expansion episodes for the past 4000 years based on radiocarbon dating of soils that were killed by advancing glaciers. Two of the proposed advance phases overlapped with the MCA (695-1050 AD, 1090 AD). Nevertheless, the results have to be treated with caution as the radiocarbon method has meanwhile significantly improved, thus indicating the need of a study update.

11- Oroko Swamp

This is a classical tree ring site on the west coast of New Zealand’s South Island (Fig. 1), about 40 km north of the summit of Mt Cook (site 10). Cook et al. (2002) published a tree ring chronology for the endemic conifer Lagarostrobos colensoi (silver pine). The summer temperature reconstruction derived from this chronology is characterized by a marked warm period 1100-1300 AD. The first part of the MCA appears to be cold in this study. A particularly cold phase occurred 1500-1650 AD in the LIA. The quality of the Oroko tree ring dataset was recently systematically evaluated by Esper et al. (2016) who ranked the chronology highly as class A and B in the categories ‘Sample Replication’, ‘Data Homogeneity’ and ‘Chronology Development’. The latter refers to the detrending method used to remove tree-age related growth trends from the raw measurement series. Weaker scores of class C were achieved in the categories ‘Climate Signal’ and ‘Growth Coherence’. The second parameter refers to the correlation between the tree-ring width (TRW) and latewood density (MXD) measurement series.

12- Cave in NW Nelson District

Williams et al. (2005) studied stalagmites from caves near Punakaiki and Paturau at the northwestern end of New Zealand’s South Island (Fig. 1). All sites are located within 5 km of the coast and at altitudes of less than 170 m asl. The oxygen isotope master series shows generally more positive δ18O values during the period 850-1500 AD, thus indicating higher temperatures (Fig. S3). The warmest years appear to have occurred in the centuries subsequent to the MCA. The same region was also studied by Wilson et al. (1979) who had already proposed the same general pattern, i.e. a warm first half of the 2nd millennium, followed by a colder LIA, even though the data resolution was significantly lower.

10

13- Hawkes Bay

Lorrey et al. (2008) studied oxygen isotopes in the Disbelief and Te Reinga caves that are located on the eastern side of New Zealand’s North Island (Fig. 1). Their master speleothem record shows a phase of more positive δ18O values, hence higher temperatures, during the period 700-1200 AD (Fig. S4). A particularly cold period was inferred for 1450-1600 AD during the LIA. The last 300 years are unfortunately missing in this record.

Figure S4. Temperature development in North Island (New Zealand) during the past 1500 years based on palaeoclimate proxies. Panel shows a traverse from southeast (left) to northwest (right). 13: Hawkes Bay (Lorrey et al. 2008); 14: Waitomo (Williams et al. 2004); 15: kauri tree rings northern North Island (archaeological samples) (Boswijk et al. 2014). Red shading indicates warming, blue represents cooling. MCA=Medieval Climate Anomaly, SST=sea surface temperature, cps=counts per second. Location map in Fig. 1.

11

14- Caves in Waitomo district

These caves are located on the western side of North Island. Williams et al. (2004) published an oxygen master curve of stalagmite oxygen isotopes combining various Waitomo District caves. The period 950-1350 AD is characterized by more positive δ18O values, thus suggesting a warm period for this time (Fig. S4).

15- Northern North Island

This is a tree ring site in northern North Island (Fig. 1) based on kauri (Agathis australis) which has been sampled and analyzed over the past few decades (Boswijk et al. 2006; Cook et al. 2006). The most recent publication that includes the MCA is that from Boswijk et al. (2014) who distinguished tree ring width chronologies for material of subfossil swamp and archaeological origin. Fowler et al. (2008) identified El Niño-Southern Oscillation (ENSO) as the dominant 20th century driver of inter-annual variability of kauri radial growth. Wide tree rings are typically formed during El Niño phase under cool-dry conditions. Narrower rings are associated with La Niña and warm-wet conditions. The archaeological timbers and logging relicts show reduced kauri ring width during most of the MCA, suggesting a warm-wet climate (Fig. S4). An exception forms the earliest phase of the MCA when wider rings are developed, hinting to cool-dry climate. This phase appears to coincide with the solar Oort Minimum. Also the swamp chronology yields generally thin tree rings across the MCA, but differs in some other aspects from the archaeological kauri chronology. Boswijk et al. (2014) therefore caution that additional data will be necessary before tree ring chronologies from this region can be reliably used for comprehensive palaeoclimatic reconstructions. The MCA interval still suffers from low sample depth and low statistical quality.

References

Allen KJ, Cook ER, Buckley BM, et al. 2014. Continuing upward trend in Mt Read Huon pine ring widths – Temperature or divergence? Quaternary Science Reviews 102: 39-53.

Allen KJ, Fenwick P, Palmer JG, et al. 2017. A 1700-year Athrotaxis selaginoides tree-ring width chronology from southeastern Australia. Dendrochronologia 45: 90-100.

Beck KK, Fletcher M-S, Gadd PS, et al. 2017. An early onset of ENSO influence in the extra-tropics of the southwest Pacific inferred from a 14, 600 year high resolution multi-proxy record from Paddy's Lake, northwest Tasmania. Quaternary Science Reviews 157: 164-175.

Boswijk G, Fowler A, Lorrey A, et al. 2006. Extension of the New Zealand kauri (Agathis australis) chronology to 1724 BC. The Holocene 16: 188-199.

Boswijk G, Fowler AM, Palmer JG, et al. 2014. The late Holocene kauri chronology: assessing the potential of a 4500-year record for palaeoclimate reconstruction. Quaternary Science Reviews 90: 128-142.

Brienen RJW, Gloor E and Zuidema PA. 2012. Detecting evidence for CO2 fertilization from tree ring studies: The potential role of sampling biases. Global Biogeochemical Cycles 26.

Burrows CJ. 1989. Aranuian radiocarbon dates from moraines in the Mount Cook region, New Zealand. New Zealand Journal of Geology and Geophysics 32: 205-216.

12

Chinn T, Winkler S, Salinger MJ, et al. 2005. Recent glacier advances in Norway and New Zealand: A comparison of their glaciological and meteorological causes. Geogr. Ann. 87A: 141-157.

Cook E, Bird T, Peterson M, et al. 1992. Climatic change over the last millennium in Tasmania reconstructed from tree-rings. The Holocene 2: 205-217.

Cook E, Bird T, Peterson M, et al. 1991. Climatic Change in Tasmania Inferred from a 1089-Year Tree-Ring Chronology of Huon Pine. Science 253: 1266-1268.

Cook ER, Buckley BM, D'Arrigo RD, et al. 2000. Warm-season temperatures since 1600 BC reconstructed from Tasmanian tree rings and their relationship to large-scale sea surface temperature anomalies. Climate Dynamics 16: 79-91.

Cook ER, Buckley BM, Palmer JG, et al. 2006. Millennia‐long tree‐ring records from Tasmania and New Zealand: a basis for modelling climate variability and forcing, past, present and future. Journal of Quaternary Science 21: 689-699.

Cook ER, Palmer JG and D'Arrigo RD. 2002. Evidence for a ‘Medieval Warm Period’ in a 1,100 year tree‐ring reconstruction of past austral summer temperatures in New Zealand. Geophysical Research Letters 29: 12-11-12-14.

Esper J, Krusic PJ, Ljungqvist FC, et al. 2016. Ranking of tree-ring based temperature reconstructions of the past millennium. Quaternary Science Reviews 145: 134-151.

Fabrés J, Calafat A, Canals M, et al. 2000. Bransfield Basin fine-grained sediments: late-Holocene sedimentary processes and Antarctic oceanographic conditions. The Holocene 10: 703-718.

Fletcher MS, Bowman DMJS, Whitlock C, et al. 2018. The changing role of fire in conifer-dominated temperate rainforest through the last 14,000 years. Quaternary Science Reviews 182: 37-47.

Fowler AM, Boswijk G, Gergis J, et al. 2008. ENSO history recorded in Agathis australis (kauri) tree rings. Part A: kauri's potential as an ENSO proxy. International Journal of Climatology 28: 1-20.

Gedalof Ze and Berg AA. 2010. Tree ring evidence for limited direct CO2 fertilization of forests over the 20th century. Global Biogeochemical Cycles 24.

Gergis J, Neukom R, Gallant AJE, et al. 2016. Australasian Temperature Reconstructions Spanning the Last Millennium. Journal of Climate 29: 5365-5392.

Komugabe‐Dixson AF, Fallon SJ, Eggins SM, et al. 2016. Radiocarbon evidence for mid‐late Holocene changes in southwest Pacific Ocean circulation. Paleoceanography 31: 971-985.

Ljungqvist FC, Krusic PJ, Brattström G, et al. 2012. Northern Hemisphere temperature patterns in the last 12 centuries. Clim. Past 8: 227-249.

Lorrey A, Williams P, Salinger J, et al. 2008. Speleothem stable isotope records interpreted within a multi-proxy framework and implications for New Zealand palaeoclimate reconstruction. Quaternary International 187: 52-75.

Lüning S, Gałka M and Vahrenholt F. 2017. Warming and Cooling: The Medieval Climate Anomaly in Africa and Arabia. Paleoceanography 32: 1219-1235.

Mackintosh AN, Anderson BM, Lorrey AM, et al. 2017. Regional cooling caused recent New Zealand glacier advances in a period of global warming. nature communications 8: 14202.

McGlone MS, Turney CSM, Wilmshurst JM, et al. 2010. Divergent trends in land and ocean temperature in the Southern Ocean over the past 18,000 years. nature geoscience 3: 622.

McGowan H, Callow JN, Soderholm J, et al. 2018. Global warming in the context of 2000 years of Australian alpine temperature and snow cover. Scientific Reports 8: 4394.

Monien P, Schnetger B, Brumsack H-J, et al. 2011. A geochemical record of late Holocene palaeoenvironmental changes at King George Island (maritime Antarctica). Antarctic Science 23: 255-267.

Moros M, De Deckker P, Jansen E, et al. 2009. Holocene climate variability in the Southern Ocean recorded in a deep-sea sediment core off South Australia. Quaternary Science Reviews 28: 1932-1940.

13

Neukom R, Luterbacher J, Villalba R, et al. 2011. Multiproxy summer and winter surface air temperature field reconstructions for southern South America covering the past centuries. Climate Dynamics 37: 35-51.

Perner K, Moros M, De Deckker P, et al. 2018. Heat export from the tropics drives mid to late Holocene palaeoceanographic changes offshore southern Australia. Quaternary Science Reviews 180: 96-110.

Saunders K, Grosjean M and Hodgson D. 2013. A 950 yr temperature reconstruction from Duckhole Lake, southern Tasmania, Australia. The Holocene 23: 771-783.

Saunders KM, Kamenik C, Hodgson DA, et al. 2012. Late Holocene changes in precipitation in northwest Tasmania and their potential links to shifts in the Southern Hemisphere westerly winds. Global and Planetary Change 92-93: 82-91.

Schaefer JM, Denton GH, Kaplan M, et al. 2009. High-Frequency Holocene Glacier Fluctuations in New Zealand Differ from the Northern Signature. Science 324: 622-625.

Stott L, Cannariato K, Thunell R, et al. 2004. Decline of surface temperature and salinity in the western tropical Pacific Ocean in the Holocene epoch. Nature 431: 56-59.

Stroup JS, Kelly MA, Lowell TV, et al. 2015. Late Holocene fluctuations of Quelccaya Ice Cap, Peru, registered by nearby lake sediments. Journal of Quaternary Science 30: 830-840.

Williams PW, King DNT, Zhao J-X, et al. 2004. Speleothem master chronologies: combined Holocene 18O and 13C records from the North Island of New Zealand and their palaeoenvironmental interpretation. The Holocene 14: 194-208.

Williams PW, King DNT, Zhao JX, et al. 2005. Late Pleistocene to Holocene composite speleothem 18O and 13C chronologies from South Island, New Zealand—did a global Younger Dryas really exist? Earth and Planetary Science Letters 230: 301-317.

Wilmshurst JM, Bestic KL, Meurk CD, et al. 2004. Recent spread of Dracophyllum scrub on subantarctic Campbell Island, New Zealand: climatic or anthropogenic origins? Journal of Biogeography 31: 401-413.

Wilson AT, Hendy CH and Reynolds CP. 1979. Short-term climate change and New Zealand temperatures during the last millennium. Nature 279: 315-317.

Zhu Z, Piao S, Myneni RB, et al. 2016. Greening of the Earth and its drivers. nature climate change 6: 791.

14