Lecture 4-2

Cultural Responses to Climate Change:

Lessons from the Holocene

• 8000-4000 多年前的全新世温暖期，是近万年来的最暖时期，全球各地的温度比现在高 2-5 摄氏度。那个时期的地球远比现在暖湿，人类生存条件奇佳，人类的发展出现飞跃，埃及文明﹑两河流域文明﹑印度河流域文明和中国黄河文明相继诞生，人类从此进入文明社会。这段时期也被古气候学家称为“人类最适宜气候期”。

• 在距今 4000-3700 年和距今 3100-2900 年，及 17 世纪附近，有过三次千年尺度的寒冷期，出现了严重的低温冷害﹑洪涝﹑乾旱﹑沙漠化灾害，造成印度河文明在 3900 年前突然湮灭﹑环地中海文明在三千年前衰落等悲剧的出现

• Native global flood stories are documented as history

or legend in almost every region on earth

• Old world missionaries reported their amazement at

finding remote tribes already possessing legends with

tremendous similarities to the Bible's accounts of the

worldwide flood

• Ancient civilizations such as (China, Babylonia,

Wales, Russia, India, America, Hawaii, Scandinavia,

Sumatra, Peru, and Polynesia) all have their own

versions of a giant flood

南北朝

南北朝( (

公元公元420-589

420-589

年年 ))

隋隋 --

盛唐盛唐) ( 570-770

) ( 570-770

年年 ))

唐后期寒冷期( 780 - 920

年 )

北宋时期(960 - 1127)

温暖

南宋（1110 – 1190

）寒冷

元朝

元朝 (1271- 1368)

(1271- 1368)

近 1000 年来气候旱涝变化周期的缩短与朝代演替频率的加快

Climate - Society Theories“Cultural Determinism”:the culture in which we are

raised determines who we are at emotional and behavioral levels – Culture alone determines culture.– Prevalent throughout 18th-19th century Europe

“Environmental determinism” – Human culture is determined by the environment.

• Charles Darwin “Origin of Species”, 1870’s  

“Possiblism”– Compromise: The natural environment influences the

range of available (possible) human choices.

Overview

• Climate of the last 10,000 years (Holocene):– Punctuated by large and persistent climate

changes every ~1000-2000 years.

• Cultural responses to past climate change: – The Classic Maya and Akkadian empires.

• We can learn about our future by studying the past.

Introduction

• Water availability is the critical factor regulating life in semiarid environments.

• Cultures can and do adapt to interannual to decadal changes in climate.

• How have cultures responded to longer-term (decade to century-scale) changes?

Combine detailed and well-dated paleoclimate and archeological records.

What do we know about the climate of the last 1,000 years?

• Instrumental climate records are too short (100-200 years).

• Longer records of past climate change (paleoclimate):– Glaciers– tree rings – corals – lake and ocean sediments

Tree-ring record of drought in the American SW

wet

dry

The 1930s Dust Bowl

• Six year drought (1933-1938), well-documented.

• Due to wanton farming practices( 肆意耕作实践 ) and over-capitalization.

• Cost over $1 billion in 1930’s dollars, federal relief programs.

• US was better prepared for a longer drought in 1950s.

Sea Surface Temperature Anomaly 1932-1939

OBSERVED

Contour interval = 0.2°C

A cold, La Nina-like, tropical Pacific Ocean

La Niña state

Warm water accumulates in far western Pacific. Equatorial water is cooler than in the normal state

The Dust Bowl Precipitation Anomaly (1932-1939)

GOGA MODEL

GOGA MODEL = Global Sea Surface Temperature Specified

Contour interval = 2 mm/month

OBSERVED

What about BEFORE the instrumental record?

Tree ring evidence for drought

Thickness of tree rings in some species is sensitive to rainfall.

Narrow band = dry climate

Cook et al., Science(2004)

A Longer Perspective on Drought:Tree Ring Reconstructions

Past droughts have been longer and more severe

drier

wetter

Medieval Droughts

Similar pattern as modern drought.

Conditions persisted MUCH longer (20-40yrs)

‘ Mega-droughts’

40 years

30 years

25 years

22 years

Drought and the Anasazi (ancestral Pueblo)

Classic example of cultural impacts of climate change.

Studies of the Four Corners region show population crashes related to megadroughts

Benson et al. (2006)

Nu

mb

er

of h

ab

itatio

n s

ites

Anasazi depopulation of the SW US

The “Great Drought” spanned 1272-1298 AD (~26 years).

Other factors: Warfare, balkanization, religion.

Mesa Verde, CO

Interannual-Decadal Variability

– Severe droughts lasting decades are common (many per millennium).

– This mode of climate variability is present in the instrumental record (that is, expected).

– Cultures can and do readily adapt to these variations.

Is this the full range of natural climate variability at socially-relevant timescales?

Holocene Climate

The Holocene represents the present warm period (last ca. 12,000 years).

It’s “Our Time”, spanning the emergence of agriculture and civilizations.

– How stable was it?– What factors influenced Holocene climate

change?

Mechanisms of Holocene Climate Change

– Long-term: Earth orbital variations (millennia)– Shorter-term: Solar variability, volcanic eruptions

and greenhouse gases (century-scale)

– Ocean-atmosphere interactions (El-Niño, NAO…)– Natural, unforced variability (random)

Stable or Unstable Holocene?

Unstable! Persistent 1500±500 year variability

The Little Ice Age and Medieval Warm Period were the most recent of these events...

Most of the variability over the past 1000 years due to solar variability and volcanism.

Cultural Responses to Holocene Climate Change

• Paleoclimate records document large climate changes which persisted for many centuries to millennia.

• Climate transitions can be very abrupt.• Regional to global (?) extent.

• What impact did these climate perturbations have on complex societies living at the time?

• Examples:– Akkadian Empire (ca. 4200 yrs BP)– Classic Maya Empire (ca. 1200 yrs BP)

Akkadian Imperial Collapse (4200 yrs BP)

• First empire imperialized Mesopotamia between 4300-4200 yr BP.

• Imperialization linked productive rainfed (semiarid) agriculture of northern Mesopotamia (Sumer) with south.

• Collapse occurred near 4170±150 yr BP (Weiss et al., 1993).

• Collapse was previously attributed to political disintegration.

Tell Leilan, NE Syria

• Weiss et al. (1993) excavated this former Akkadian imperial town.

• Their results suggested rapid abandonment due to onset of aridity.

• At right, a ~600m2 excavated residential occupation with roadway.

Deep-Sea Sediment Record of Mesopotamian Climate

Cullen et al. (2000) tested the Weiss et al. (1993) claim using the deep-sea sediment record to reconstruct changes in Mesopotamian climate.

– Late Holocene aridity record should be preserved in deep-sea sediments.

EuphratesTigris

Nile

30 40 50 6040

30

20

10

Dust source areas Summer surface winds & dust transport vectors

M5-422

Tell Leilan

Dr. Heidi CullenThe Weather Channel !

Mesopotamian Dust

Dust storm over Mesopotamia (May, 2000)

Same dust storm, 10 days later, over the Gulf of Oman

Climate Change and Akkadian Collapse

Cullen et al. (2000)

Akkadian Collapse

• Onset of ~300 year period of greatly increased aridity near 4025±125 yr BP coincides with Akkadian collapse at 4170±150 yr BP (within dating uncertainty). – How widespread was the collapse?

• Enhanced aridity at this time also reported for Turkey, Israel, and Egypt.

• Nd and Sr isotopes confirm dust is from a Mesopotamian source similar to Tell Leilan.

• Volcanic glass shards found at Tell Leilan and in the deep-sea are geochemically correlative.

Classic Maya Culture (300-900 AD)

Classic Maya culture ruled Mesoamerica from 250 to 850 AD.

Late Classic culture (550-850 AD) known for highly stratified society, vast trade networks, and widespread construction of urban centers and monumental stellae.

8-15 million people across Yucatan Peninsula

Tikal (Guatemala)

Classic Maya Collapse (800 AD)

Classic Maya empire collapsed at peak intellectual and cultural development at 900 AD.

Lowland urban abandonmentEnd of monument constructionCultural disintegration

Why did this great civilization fall?

Factors cited: Deforestation, overpopulation, warfare, religious and social upheaval. Largest urban center: Palenque

1. Why did Copán collapse? 2. Was the end a gradual decline or a rapid fall?

The spongy-looking areas at the back of the skull are caused by a lack of iron in the diet. This person suffered from malnutrition.

80 percent of the skeletons found at Copán show evidence of anemia.

Sociopolitical Causes of CollapseSociopolitical Causes of CollapseThe sociopolitical The sociopolitical

causes include: causes include: peasant revolts peasant revolts

resulting in the resulting in the overthrowing of the overthrowing of the elite class elite class

inter-site warfare inter-site warfare between Maya city-between Maya city-states states

invasions by peoples invasions by peoples from outside the from outside the Maya civilization Maya civilization

failure of centralized failure of centralized political authority political authority

Copan sacrificial alter

On one of these unfinished sides, the Maya text shows a date, equivalent to February 10, A.D. 822. The remaining text was never finished.

There are no known monuments at Copán dated after A.D. 822.

Natural Causes of CollapseNatural Causes of CollapseNatural causes include Natural causes include

factors such as: factors such as: soil exhaustion due to soil exhaustion due to

slash-and-burn slash-and-burn agriculture agriculture

water loss and erosion water loss and erosion of topsoil evident by of topsoil evident by increased increased sedimentation in lakes sedimentation in lakes

natural disasters such natural disasters such as earthquakes and as earthquakes and hurricanes hurricanes

climatic change climatic change disease disease insect infestations insect infestations overpopulationoverpopulation

Copan Great Ball Court

Natural Causes Natural Causes of Collapseof Collapse

When examining the natural causes that could have incited or When examining the natural causes that could have incited or enhanced the collapse, a further set of both human-induced and enhanced the collapse, a further set of both human-induced and natural climatic factors of the Yucatan Peninsula need to be natural climatic factors of the Yucatan Peninsula need to be consideredconsidered

Some scientists theorize that the paleoclimate of the region was Some scientists theorize that the paleoclimate of the region was not only different than the present day climate, but that the not only different than the present day climate, but that the natural climatic variability of the past could have included a natural climatic variability of the past could have included a period of intense drought that occurred at the time of the Classic period of intense drought that occurred at the time of the Classic Maya CollapseMaya Collapse

Water deficit on the Yucatan © NOAA

Symptoms of the CollapseSymptoms of the Collapse

Rapid depopulation of the countryside and ceremonial Rapid depopulation of the countryside and ceremonial centers in 50 to 100 years, centers in 50 to 100 years,

Abandonment of administrative and residential structuresAbandonment of administrative and residential structures

Copan East Plaza with Temple of Inscriptions and alter Q; R: Copan East Plaza and Temple 11 with Popol Nah.

Symptoms of the Symptoms of the CollapseCollapse

Cessation of: building construction, carving of Cessation of: building construction, carving of sculptured monuments, manufacture of sculptured monuments, manufacture of pottery, stonework, jade carvings, Classic pottery, stonework, jade carvings, Classic calendar and writing systems. calendar and writing systems.

Above: Copan temple; Above R: corbeled block-work used by Maya; lBelow R: Copan sculpture.

Yucatan Modern ClimateYucatan Modern Climate Before studying the paleoclimate of Before studying the paleoclimate of

the region, it is important to understand the region, it is important to understand the region's modern climate. the region's modern climate.

Temperature is uniformly warm on the Temperature is uniformly warm on the Yucatan Peninsula with a mean annual Yucatan Peninsula with a mean annual temperature of 25temperature of 25oo C. C.

Precipitation increases from north to Precipitation increases from north to south with minimum values of 500 south with minimum values of 500 mm/yr along the NW coast to a mm/yr along the NW coast to a maximum of 2500 mm/yr in the maximum of 2500 mm/yr in the southern lowlands. southern lowlands.

Rainfall is highly seasonal with the Rainfall is highly seasonal with the rainy season occurring in the summer, rainy season occurring in the summer, May through September, and the dry May through September, and the dry season during winter, October through season during winter, October through April. April.

All of the Yucatan is marked by an All of the Yucatan is marked by an annual water deficit that is lowest in the annual water deficit that is lowest in the southern Yucatan and highest along southern Yucatan and highest along the NW coast. the NW coast. Koeppen Climate classification © NOAAKoeppen Climate classification © NOAA

Lake SedimentsLake Sediments The raw material for The raw material for

paleoenvironmental studies is paleoenvironmental studies is sediment that accumulates in an sediment that accumulates in an ordered manner through time and ordered manner through time and records changes in past climate records changes in past climate conditions. conditions.

The sediments are analogous to a The sediments are analogous to a magnetic cassette tape recording, magnetic cassette tape recording, and the challenge for and the challenge for paleoclimatologists is to "play paleoclimatologists is to "play back" the tape. back" the tape.

Fossil pollen preserved in lake Fossil pollen preserved in lake sediments are often used to sediments are often used to reconstruct vegetation changes reconstruct vegetation changes that can be influenced by climate. that can be influenced by climate.

Sediment core from Lake Chichancanab

Lake Sediment CoresLake Sediment CoresScientists reconstructed the past Scientists reconstructed the past climate of the Maya civilization climate of the Maya civilization by studying lake sediment cores by studying lake sediment cores on the Yucatan Peninsula. on the Yucatan Peninsula. The first area of study, Lake The first area of study, Lake Chichancanab, is located in the Chichancanab, is located in the center of the Yucatan.center of the Yucatan.Lake Chichancanab is a long Lake Chichancanab is a long (26-km), narrow (2 km) lake, (26-km), narrow (2 km) lake, consisting of a series of basins consisting of a series of basins that are connected during high that are connected during high water level. water level.

Jason Curtis holding core form Lake Chichancanab

Lake ChichancanabLake Chichancanab Sediment cores Sediment cores

were collected from were collected from the central basin in the central basin in a water depth of 6.9 a water depth of 6.9 m. m.

The lake lies in a The lake lies in a fault depression fault depression caused by normal caused by normal faulting. The steep faulting. The steep hills on the eastern hills on the eastern side of the lake side of the lake represent the fault represent the fault line. line.

Lake SedimentsLake Sediments Pollen cannot be used to Pollen cannot be used to

reconstruct climate during the reconstruct climate during the Classic Period because the Classic Period because the Maya severely altered regional Maya severely altered regional vegetation through clear cutting vegetation through clear cutting of the forest for agricultural of the forest for agricultural purposes. purposes.

It would be impossible to tell, It would be impossible to tell, whether a given vegetation whether a given vegetation change was caused by climate change was caused by climate or human agricultural activity. or human agricultural activity.

Because of this, scientists rely Because of this, scientists rely upon geochemical (elemental upon geochemical (elemental and isotopic) evidence for and isotopic) evidence for climatic change found trapped in climatic change found trapped in the shells of tiny Crustacea the shells of tiny Crustacea called ostracods. called ostracods.

Oxygen IsotopesOxygen Isotopes One of the most important tools used to One of the most important tools used to

reconstruct the ratio of evaporation to reconstruct the ratio of evaporation to precipitation is oxygen isotopes . precipitation is oxygen isotopes .

Lake water (HLake water (H22O) contains both the light O) contains both the light isotope (isotope (1616O) and heavy isotope (O) and heavy isotope (1818O) of O) of the element oxygen. the element oxygen.

When water evaporates, the lighter isotope When water evaporates, the lighter isotope (H(H22

1616O) evaporates at a faster rate than the O) evaporates at a faster rate than the heavier isotope (Hheavier isotope (H22

1818O) because it has a O) because it has a higher vapor pressure. higher vapor pressure.

The reverse happens when water The reverse happens when water condenses. As long as evaporation equals condenses. As long as evaporation equals precipitation over the lake, the lake is at a precipitation over the lake, the lake is at a steady state and the ratio of steady state and the ratio of 1818O to O to 1616O will O will be constant. be constant.

However, if climate becomes drier and However, if climate becomes drier and evaporation exceeds precipitation, the lake evaporation exceeds precipitation, the lake volume will be reduced and the ratio of volume will be reduced and the ratio of 1818O O to to 1616O in lake water will increase. O in lake water will increase.

Illustration From Curtis, et al © 2007

Oxygen IsotopesOxygen Isotopes Alternatively, under wet climatic Alternatively, under wet climatic

conditions, the lake level will rise and conditions, the lake level will rise and the ratio of the ratio of 1818O to O to 1616O will decrease. In O will decrease. In closed basin lakes, the ratio of closed basin lakes, the ratio of 1818O to O to 1616O in lake water is controlled mainly by O in lake water is controlled mainly by the balance between evaporation and the balance between evaporation and precipitation.precipitation.

The The 1818O to O to 1616O ratio of lake water is O ratio of lake water is recorded by aquatic organisms, such recorded by aquatic organisms, such as gastropods and ostracods that as gastropods and ostracods that precipitate shells of calcium carbonate precipitate shells of calcium carbonate (CaCO(CaCO33). ).

Scientists can measure the Scientists can measure the 1818O to O to 1616O O ratio in fossil shells in sediment cores to ratio in fossil shells in sediment cores to reconstruct changes in reconstruct changes in evaporation/precipitation through time, evaporation/precipitation through time, thus inferring climatic change. thus inferring climatic change.

Illustration © From Curtis, et al © 2007

Hydrology: Closed Basin LakesHydrology: Closed Basin Lakes This study consisted of This study consisted of

taking sediment cores taking sediment cores from two different lakes from two different lakes centrally located on the centrally located on the Yucatan.Yucatan.

Both Lakes Both Lakes Chichancanab and Chichancanab and Punta Laguna are Punta Laguna are considered to be considered to be closed-basin lakes. closed-basin lakes.

The geology of Yucatan The geology of Yucatan is karst (porous is karst (porous limestone), many of the limestone), many of the lakes are perched lakes are perched above the water table above the water table and isolated and isolated hydrologically by clay-hydrologically by clay-basin seals. basin seals.

Illustration From Curtis, et al © 2007

Closed Basin Closed Basin LakesLakes

Closed-basin lakes have Closed-basin lakes have simple water budgets, and simple water budgets, and typically receive water by typically receive water by precipitation, slope wash, precipitation, slope wash, and groundwater seepage, and groundwater seepage, while losing a majority of while losing a majority of their water through their water through evaporation.evaporation.

Therefore the lake Therefore the lake volume, dissolved solute volume, dissolved solute concentrations and oxygen concentrations and oxygen isotopic ratios are largely isotopic ratios are largely controlled by the ratio of controlled by the ratio of evaporation to evaporation to precipitation.precipitation.

This characteristic makes This characteristic makes closed-basin lakes closed-basin lakes climatically sensitive to the climatically sensitive to the changing conditions of changing conditions of evaporation or evaporation or precipitation. precipitation. Illustration From Curtis, et al © 2007

Sedimentation RatesSedimentation Rates When the cores are returned to the lab, they are split When the cores are returned to the lab, they are split

in two halves. One-half of the core is sampled and in two halves. One-half of the core is sampled and the other half is archived for future use. the other half is archived for future use.

The core that was sampled from Lake Chichancanab The core that was sampled from Lake Chichancanab had a total length of 4.9 m with a basal radiocarbon had a total length of 4.9 m with a basal radiocarbon age of 9000 years BP. age of 9000 years BP.

The sedimentation rate averaged about 0.5 mm per The sedimentation rate averaged about 0.5 mm per year. year.

The core was sampled continuously at 1-cm intervals The core was sampled continuously at 1-cm intervals over its length. over its length.

A 1-cm sample in the Lake Chichancanab core A 1-cm sample in the Lake Chichancanab core represents about 20 years of deposition. represents about 20 years of deposition.

The sedimentation rate determines the temporal The sedimentation rate determines the temporal resolution of study and as a result, scientists are able resolution of study and as a result, scientists are able to reconstruct climatic changes that lasted for to reconstruct climatic changes that lasted for multiple decades or longer. multiple decades or longer.

The sediments of Chichancanab consisted of The sediments of Chichancanab consisted of alternating layers of organic matter, calcite, and alternating layers of organic matter, calcite, and gypsum. gypsum.

Punta Laguna CorePunta Laguna Core The total core length from Punta The total core length from Punta

Laguna was 6.3m with a basal Laguna was 6.3m with a basal age of 3300 years. age of 3300 years.

The sedimentation rate averaged The sedimentation rate averaged 2 mm/year, which is about four 2 mm/year, which is about four times greater than the times greater than the sedimentation rate in the core sedimentation rate in the core from Chichancanab. from Chichancanab.

A 1-cm sample for the Punta A 1-cm sample for the Punta Laguna core represents only 5 Laguna core represents only 5 years of deposition, permitting the years of deposition, permitting the resolution of much shorter climatic resolution of much shorter climatic events. events.

Sediments in the Punta Laguna Sediments in the Punta Laguna core are composed almost core are composed almost entirely of calcium entirely of calcium carbonate(CaCOcarbonate(CaCO33). ).

Above and previous cores are similar representation taken from recent Trinidad expedition.

Lake Chichancanab Core Lake Chichancanab Core ResultsResults

Data from the Lake Chichancanab core supports the Data from the Lake Chichancanab core supports the following interpretation that begins at the base of the following interpretation that begins at the base of the core: core:

From 9200 to 7800 years BP, there was no lake at the coring site as From 9200 to 7800 years BP, there was no lake at the coring site as indicated by the absence of aquatic microfossils and the presence indicated by the absence of aquatic microfossils and the presence of land snails. of land snails.

Beginning at about 7800 years BP, the lake began to fill but the Beginning at about 7800 years BP, the lake began to fill but the salinity was much higher than today. salinity was much higher than today.

Evidence for this includes high sulfur content indicating gypsum Evidence for this includes high sulfur content indicating gypsum precipitation, very high precipitation, very high 1818O and O and 1616O ratios in both ostracods and O ratios in both ostracods and gastropods, and the occurrence of a benthic foraminifera, Ammonia gastropods, and the occurrence of a benthic foraminifera, Ammonia beccarri. beccarri.

Foraminiferas are almost exclusively marine forms but this species Foraminiferas are almost exclusively marine forms but this species can tolerate a wide range of salinity (7 to 67 ppt); however, it only can tolerate a wide range of salinity (7 to 67 ppt); however, it only reproduces between 13 and 40 ppt. The large number of specimens reproduces between 13 and 40 ppt. The large number of specimens of A. beccarri suggests salinities of at least 13 ppt (the modern lake of A. beccarri suggests salinities of at least 13 ppt (the modern lake salinity is only 4 ppt). salinity is only 4 ppt).

Data from Lake ChichancanabData from Lake Chichancanab

Oxygen Oxygen Isotope Isotope ResultsResults

This slide compares the oxygen isotope record on the same species This slide compares the oxygen isotope record on the same species of gastropod between the two lake cores: Punta Laguna (above) and of gastropod between the two lake cores: Punta Laguna (above) and Chichancanab (below). Chichancanab (below).

Note that the Punta Laguna record is much higher resolution owing to Note that the Punta Laguna record is much higher resolution owing to higher sedimentation rates than Chichancanab. higher sedimentation rates than Chichancanab.

Within the error of the radiocarbon age models, the period of higher Within the error of the radiocarbon age models, the period of higher mean mean 1818O values in Punta Laguna correlates with the interval of O values in Punta Laguna correlates with the interval of increasing sulfur and oxygen isotope values in Chichancanab. increasing sulfur and oxygen isotope values in Chichancanab.

From Curtis, et al 2007 ©

Punta Punta Laguna Laguna Oxygen Oxygen Isotope Isotope ResultsResults

The oxygen isotope data measured on ostracods from Punta Laguna The oxygen isotope data measured on ostracods from Punta Laguna sediments have been converted from radiocarbon years to calendar sediments have been converted from radiocarbon years to calendar years and compared to Mayan cultural periods. years and compared to Mayan cultural periods.

Superimposed upon the mean changes in the record are distinct peaks Superimposed upon the mean changes in the record are distinct peaks that represent arid climate conditions. that represent arid climate conditions.

These peaks occur at 585 A.D., 862 A.D., 986 A.D., 1051 A.D. and These peaks occur at 585 A.D., 862 A.D., 986 A.D., 1051 A.D. and 1391 A.D. Error is approximately +/-50 years. 1391 A.D. Error is approximately +/-50 years.

From Curtis, et al © 2007

Ostracod Climate DataOstracod Climate Data

From Curtis, et al © 2007

Comparison of Ostracod Data and Comparison of Ostracod Data and Maya Cultural PeriodsMaya Cultural Periods

The first peak at 585 A.D. coincides with the early/late Classic boundary. The first peak at 585 A.D. coincides with the early/late Classic boundary. This boundary is associated with the "Maya Hiatus", which lasted between This boundary is associated with the "Maya Hiatus", which lasted between

530 and 630 A.D. 530 and 630 A.D. The Maya Hiatus was marked by a sharp decline in monument carving, The Maya Hiatus was marked by a sharp decline in monument carving,

abandonment in some areas and social upheaval. abandonment in some areas and social upheaval. This event may have been drought-related. This event may have been drought-related.

From Curtis, et al 2007

Comparison of Ostracod Data Comparison of Ostracod Data and Maya Cultural Periodsand Maya Cultural Periods

During the next 200 years from 600 to 800 A.D., the late Classic During the next 200 years from 600 to 800 A.D., the late Classic Maya flourished and reached their cultural and artistic apex. Maya flourished and reached their cultural and artistic apex.

The next peak in 18O/16O occurs at 862 A.D. and coincides with The next peak in 18O/16O occurs at 862 A.D. and coincides with the collapse of Classic Maya civilization between 800 and 900 A.D. the collapse of Classic Maya civilization between 800 and 900 A.D.

The earliest Postclassic Period was also relatively dry between 986 The earliest Postclassic Period was also relatively dry between 986 and 1051 A.D. At about 1000 A.D., mean oxygen isotope values and 1051 A.D. At about 1000 A.D., mean oxygen isotope values decrease indicating a return to more humid conditions. decrease indicating a return to more humid conditions.

From Curtis, et al 2007

Cariaco Basin (Venezuela)

Annual laminations

Some of the best available climate records for the lowland Maya region

ResultsResults Although a Postclassic Although a Postclassic

resurgence occurred in resurgence occurred in the northern Yucatan, the northern Yucatan, city-states in the city-states in the southern lowlands southern lowlands remained sparsely remained sparsely occupied.occupied.

These findings These findings support a rather strong support a rather strong correlation between correlation between times of drought and times of drought and major cultural major cultural discontinuities in discontinuities in Classic Maya Classic Maya civilization. civilization. Tikal Temple I and Temple II

Cariaco Basin laminated sediments

Mayan collapse occurred during a 150-year drought!

wet

dry

Climate Change and Classic Maya

Collapse

0 1 2

Haug G H, Gunther D, Peterson L C D, et al. 2003. Climate and thecollapse of Mayan civilization. Science, 299: 1731- 1735

What can be learned from these examples?

Complex societies are sensitive to climate change.

Paleoclimate records document changes in climate which surpassed modern variability.

Other social factors in each case may have contributed to observed collapse.

Collapse occurred despite evidence that these cultures had large buffering capacities.

Conclusions

Modern and ancient cultures:- Thrive in marginal environments.- Plan for the future based on recent past (regrettably)- Learn and adapt (fortunately).

Only ancient cultures experienced century-scale drought.

Their past can be a guide to our future.

Lessons from the past

Complex societies are both adaptive and vulnerable to climate change.

Past climate changes far surpassed modern variability.

Collapse occurred despite large buffering capacities.

• Effects of Deteriorated Environment Event

on the Neolithic Culture of China, around 5

000 a BP• A number of environmental records reveal that there was a rapid

environmental deterioating event all over the world ca 5000 a BP

• During this period, there was a movement of vegetations zone to south

in the southern China

• lower sea level along the coast in the southern and eastern China, and

desertificat ion in some sites of northern China

• there was a fargoing regradation or discontinuity of Neolithic culture in

China

• there were also many records of the state of culture development

consistent with the environmental changes all over the world.

A. 敦德冰芯氧同位素 B. 岱海湖面变化 C. 螺髻山温度变化 D. 青海湖温度变化 E. 藏东南年均温变化 F. 大地湾孢粉浓度变化 G. 博斯腾湖碳同位素变化 H. 长白山地区温度变化 I. 华南地区海平面变化 J. 察素齐孢粉浓度变化 K. GRIP 冰芯甲烷浓度变化 L . 长江中下游地区温度变化 M. 洱海碳同位素变化

前仰韶文化期 ( 8. 3~ 6. 9 ka B. P. )

仰韶文化期 ( 6. 9~ 5. 0 ka B. P. )

龙山文化期 ( 5. 0~ 4. 0 ka B. P. )

6. 9 ka B. P. 前后出现一次寒冷气候 , 终止了前仰韶文化

5. 0 ka B. P. 前后的一次寒冷气候，终止了仰韶文化期

4 ka B. P. 前后，结束了大暖期气候 , 也结束了新石器文化 , 中国历史进入文明史阶段

　环境变化影响史前文化的原因

• 气候变化导致生态系统的变化• 生态系统的变化导致植被的变化• 植被的变化又导致影响人类生存的生物营养源

的变化• 进而导致人类文化的变化