Challenges to proxy data integration

Integration of paleohydrologic data across sites Most traditional hydrologic climate-proxy indicators tend to reflect effective moisture availability, rather than rainfall, with poorly constrained temperature effects on evaporation. Rainfall variation is also spatially more heterogeneous and temporally more pronounced than temperature variation, because the atmospheric circulation patterns ultimately determining rainfall location and intensity depend on ocean currents, pressure contrasts...

How long will the Holocene last

The Holocene is a particularly long episode of stable climatic conditions compared with the three previous interglacial periods (Sirocko et al. 2007). Its stability certainly favored the establishment of modern civilizations. What explains the stability of the Holocene, and how long will it be Modeling the long-term evolution of climate requires taking into account changes in the spatial and seasonal distribution of incoming shortwave radiation (insolation) at the top of the atmosphere (Figure...

Ocean stability during the Holocene

So far we have examined the stability of the global climate system, which includes the ice sheets and carbon cycle. We now focus on the ocean-atmosphere system and anything external to this component of the climate system will be considered as a boundary condition or a forcing. The time-scale of ocean advective processes is of the order of a few thousand years. This provides a rough upper limit to the period of quasi-periodic oscillations that the ocean-atmosphere system may exhibit in the...

Proxy data and proxy reconstructions

The lack of widespread instrumental climate records prior to the mid-19th century requires that we turn to proxy data in our attempts to reconstruct how the climate has changed over past centuries. When, as is typically the case in studies of the past millennium, our interest is primarily in annually resolved climate variations, we must turn to high-resolution climate proxy data, such as tree rings, corals, ice cores, and historical documentary records. Mann et al. 1998 assembled a network of...

CO and CH changes and the Anthropocene hypothesis

In a series of stimulating publications, Ruddiman interprets the increase in atmospheric CO2 and methane at 8000 and 5000 years ago in ice-core records, respectively, as largely the result of human activity Ruddiman and Thomson 2001 Ruddiman 2003, 2005a,b Ruddiman's hypothesis of early anthropogenic influences on Holocene climate consists of three parts Oldfield 2005 . First, humans reversed a natural decrease in atmospheric CO2 concentrations 8000 years ago through the early development of...

References

Aaby, B. 1976 Cyclic climatic variations in climate over the past 5500 yr reflected in raised bogs. Nature, 263, 281-284. Aaby B. amp Tauber H. 1975 Rates of peat formation in relation to degree of humification and local environment as shown by studies of a raised bog in Denmark. Boreas, 4, 1-17. Alley R.B. 2000 The Two-Mile Time Machine - Ice Cores, Abrupt Climate Change, and our Future. Princeton University Press, Princeton and Oxford. Alley R.B. amp Agustdottir A.M. 2005 The 8k event cause...

The bc event an example of climate change with socioeconomic impacts

Subatlantic Climate

As pointed out by Oldfield this volume climate change can have important impacts on human society. The two fundamental characteristics of a change are its magnitude and rate. Although the former is obvious, the latter is often not taken seriously enough. Although every change causes problems of adaptation it is much easier to deal with if it occurs slowly. The climate shift around 850 cal. bc Sub-boreal-Sub-atlantic transition , one of the most important climate shifts during the Holocene, with...

Impacts on hydrologie and erosion regimes

Holocene reconstructions of hydrologic and erosion regimes stretching beyond the time-span of documentary records mainly depend on lake sediments or datable, alluvial sequences, supplemented in moist, temperate environments by peat stratigraphic evidence for hydrologic variability Verschuren and Charman, this volume . In the absence of significant human impacts on catchments, Holocene variability in hydrologic regimes and erosion processes can usually be ascribed to changes in climate e.g. Knox...

Radiocarbon dating and absolute chronologies

The development of radiocarbon dating by Willard F. Libby 1908-1980 in the early 1950s provided a means of deriving an absolute chronology in theory at least for events in the Holocene. Harry Godwin 1901-1985 was one of the first Holocene paleoecologists, along with Eric Willis, Donald Walker, and others, to take advantage of radiocarbon dating to provide an absolute chronology for pollenzone boundaries, peat-stratigraphic changes, and other events in the Holocene Godwin 1960 and to discuss the...

Introduction

The existence of an early to mid-Holocene thermal optimum is frequently referred to in the paleoclimate science literature. Early Holocene is here loosely defined as 11-8 ka, and mid-Holocene is loosely defined as 8-4 ka, both in terms of calendar years BP. The thermal optimum has been documented by a variety of paleocli-matic evidence, spanning many Northern Hemisphere high-latitude paleoclimatic archives, including ice cores, marine and limnic sediments, glacier records, and speleothems. A...

Transfer functions and the quantitative reconstruction of past climate

A major paradigm shift in Quaternary paleoclimate research occurred in the early 1970s. John Imbrie awarded the Vega Medal in 1999, 45 years after von Post and the late Nilva Kipp 1925-1989 revolutionized marine paleoceanography by developing transfer functions to reconstruct quantitatively summer and winter sea-surface temperatures and salinity from fossil foraminiferal assemblages preserved in a deep-sea core covering several glacial and interglacial stages Imbrie and Kipp 1971 . The idea of...

Holocene vegetation changes and atmospheric methane and carbon dioxide concentrations

Holocene Methane Concentration Graph

To what extent have changes in land-use and land-cover modified the atmospheric concentrations of both methane and carbon dioxide during the pre-industrial parts of the Holocene Forest clearance, followed by cultivation or pastoralism, reduces carbon sequestration in the terrestrial biosphere by generating an initial release to the atmosphere usually through burning, by diminishing the store of carbon in standing crops and soils, and by increasing the rate of carbon turnover. Moreover, Lal 2002...

Contributors

Carin Andersson Bjerknes Centre for Climate Research, All gaten 55, 5007 Bergen, Norway Richard W. Battarbee Environmental Change Research Centre, University College London, 26 Bedford Way, London WC1E 6BT, UK J rg Beer Swiss Federal Institute of Aquatic Science and Technology EAWAG , CH-8600 D bendorf, Switzerland H. John B. Birks Department of Biology, and Bjerknes Centre for Climate Research, University of Bergen, N-5007 Bergen, Norway, and Environmental Change Research Centre, University...

Reactions of the climate system to forcings

Sub Atlantic Sub Boreal Peat

It is well known that the climate system shows variability on vastly different time-scales. It is not yet clear as to what extent this variability is caused by internal processes within the climate system, and which role the different forcing factors play. The results of climate model experiments indicate significant internal variability, as well as a significant sensitivity to solar, volcanic, and greenhouse gas forcing see Goosse et al., this volume Claussen, this volume . During the...

Paleolimnology and paleohydrology

Although lake sediments and their contained fossils have been a source of paleo-environmental evidence since the 1940s e.g. Wright 1966 Digerfeldt 1972 , it was not until the late 1980s that the full potential of the paleolimnologic record began to be exploited. Paleolimnology is primarily concerned with the reconstruction of lake history from the sediments accumulating in the lake and from the fossils e.g. diatoms, chironomids, cladocerans, ostracods preserved in the sediments Battarbee 2000...

Human societies climate change and cultural collapse

How have human societies reacted to climate change in the past and what lessons may we learn for the future from the interactions between climate variability Figure 3.9 Biomass burning reconstructions for different parts of the world expressed as a charcoal index, derived from stratigraphic data, compared with the atmospheric CO2 concentration curve from the Taylor Dome, Antarctica Carcaillet etal. 2002 . 290 I Taylor Dome 280- Antarctica 290 I Taylor Dome 280- Antarctica notably the incidence...

Abbreviations acronyms and terminology

AMO Atlantic Multi-decadal Oscillation AO Arctic Oscillation also known as Northern Annular Mode AOGCM Atmosphere-Ocean General Circulation Model AUPs abrupt, unprecedented and persistent climate anomalies CCSM Community Climate System Model CFR climate field reconstruction CLIMAP Climate Mapping, Analysis, and Prediction CLIMBER CLIMate and BiosphERe Group - a climate model of the Climate System Department, Potsdam Institute for Climate Impact Research CLIO coupled large-scale ice-ocean COHMAP...

Inductive and deductive climate models

It has become customary to define three categories of global climate models Claussen etal. 2002 Renssen etal. 2004 Figure 4.2 . Conceptual models are made of a small number of differential equations designed to represent interactions between the major climate components. They are called inductive because the number of adjustable parameters is of the same order of magnitude as the number of differential equations number of degrees of freedom . Their primary purpose is to formulate a...

The impacts of past human activities on ecosystems

Although there has been a growing emphasis on the interpretation of pollen analytic and other biologic records as proxies for past climate change e.g. Birks 2003, this volume , the paleoecological evidence for major human impacts on past vegetation continues to grow, especially in Europe, where pollen taxonomy favors the identification of species and genera unambiguously indicative of human activities such as deforestation and the development of pastoralism and agriculture. Gaining some sense...

COHMAP and paleoclimate modeling

Cohmap 1988

The international COHMAP project represented a major paradigm shift in Holocene climate research with its close integration of paleoclimate proxy-data scientists with paleoclimate modelers. Although COHMAP started life in 1977 as Climates of the Holocene - Mapping based on Pollen Data, it quickly became global in its research area and in the climate proxies it considered. It changed its name to Co-operative Holocene Mapping Project. It was masterminded by John Kutzbach, Tom Webb, Herb Wright,...

Pollen analysis

The Swedish geologist Lennart von Post 1884-1951 Figure 2.9 presented in 1916 the technique of pollen analysis at the 16th Scandinavian meeting of natural scientists in Christiania now Oslo and demonstrated its potential as a technique for relative dating and for reconstructing past vegetation and past climate. Although the original idea of pollen analysis can be attributed to the Swedish botanist Gustaf Lagerheim 1860-1926 , it was von Post who had the vision of Figure 2.9 Lennart von Post...

Assimilation of observations

Classically, the information deduced from the analysis of observations and from model simulations is obtained from two different, clearly separated streams that are then combined to provide additional insight, in order to give more strength to the conclusions, or to propose a new interpretation. In the sections above, we have shown examples where a stronger coupling between modeling and data analysis could be very instructive. This is precisely the goal of the assimilation of observations or...

Peat stratigraphy megafossils and macrofossils

Blytt Sernander Vegetation Succession

The impressive occurrence of large fossil trunks and stumps megafossils of pine trees preserved in peat bogs in north-west Europe Figure 2.1a and b naturally attracted attention from naturalists as early as the late 18th century e.g. Tait, 1794 , and raised problems for many scientists who assumed that the environment did not change greatly. For example, in Scotland, Maxwell 1915 suggested that one of the greatest enigmas of natural science is presented in the remains of pine forest buried...