The Science of Paleoclimatology

When climatologists study the current climate, they have a wealth of information at their fingertips. For example, they can obtain data from instruments, such as barometers, anemometers, thermometers, and rain gauges at weather observatories around the world to collect data for rainfall amounts, temperature, evapotranspiration rates, humidity, wind speed and direction, and major flow of air currents, such as the jet stream. Climate data can be collected from the mountains and valleys of all...

Landforms of cold environments

Cold climates are known for many distinct types of landforms. These landforms are associated with freezing and subfreezing temperatures along with the presence of water. Cold climate processes are often linked to frost action. During the last major ice age, ice covered nearly one-third of the Earth's surface. The Northern Hemisphere was buried under a massive ice sheet up to 2 miles (3.2 km) thick in places. The ice extended from the North Pole southward to southern Illinois. Greenland was...

Glossary

Adaptation an adjustment in natural or human systems to a new or changing environment. Adaptation to climate change refers to adjustments in natural or human systems in response to actual or expected climatic changes. aerosols tiny bits of liquid or solid matter suspended in air. They come from natural sources such as erupting volcanoes and from waste gases emitted from automobiles, factories, and power plants. By reflecting sunlight, aerosols cool the climate and offset some of the warming...

Acknowledgments

Global warming may very well be one of the most important issues you will have to make a decision on in your lifetime. The decisions you make on energy sources and daily conservation practices will determine not only the quality of your life, but also that of your future descendents. I cannot stress enough how important it is to gain a good understanding of global warming what it is, why it is happening, how it can be slowed down why everybody is contributing to the problem and why everybody...

Ancient Lake in Darfur Middle East

Eman Ghoneim of the Boston University Center for Remote Sensing in Massachusetts was using radar satellite imagery taken of the northwestern Sudan to map ancient hydrology when she discovered evidence that an enormous lake once existed in the region a sharp contrast to the very arid, parched environment that exists there today. This discovery confirmed that the climate in this part of the Sahara was once humid enough to support a green region with ample water and vegetation. Because radar waves...

Cave environments

Unique rock formations in caves display a climate record of their own and serve as proxy indicators of past moisture conditions. In the southwestern United States, more than 100 caves exist whose formations tell a story of what the climate was like long ago. In addition, because the formations in caves are preserved underground, they are protected from the harsh weathering and erosional processes to which features on the Earth's surface are subjected. The wonderland of geological formations...

Central and north amerioa

Some of the most notable past civilizations that have been directly influenced by climate are the Maya of Central America and the Anasazi of the American Southwest. The Maya (also referred to as Mayans) were Central-American Indians. They were one of the greatest civilizations of the Western Hemisphere. Advanced for their time, they were well known for their extensive practice of agriculture, construction of enormous stone buildings and pyramid temples, artistic smithing of gold and copper, and...

Climate Change and Past Civilizations

Climate has played a prominent role in shaping civilization and cultures throughout time. Civilizations exist where they do because of several key features, many of which are directly related to climate. For instance, major cities are located where rainfall is plentiful enough to allow cultivation of crops and a supply of drinking water to large populations. They are located where temperatures are suitable for growing food and living comfortably. Because climate can change, what may be suitable...

Climate reconstruction resolution

When past climate is reconstructed, it is important to keep several factors in mind. When the climate record is preserved, integrity depends on whether a site is disturbed or left relatively untouched. Another important factor is how fast the record is accumulated. This determines how protected the site is from disturbance. If a site is left exposed for a long period of time, chances of it being contaminated or damaged are greater. When climate data is retrieved from sedimentary rocks, it is...

Climate time line AT A glance

Climatologists have been able to reconstruct paleoclimatic periods over the Earth's geologic past. The following list summarizes the major climate change episodes. Faint Young sun Paradox snowball earth Hothouse Earth The Pleistocene Climates 10,000 years to 2 MYA Penultimate Interglacial Period Dansgaard-oeschger events Heinrich events Holocene Recent Climate 10,000 years ago to today Younger dryas cooling Mid-Holocene Thermal Maximum Late Holocene Neoglacial fluctuations The little ice Age As...

Conclusions and a Glance into the Future

Other than purely for the sake of knowledge, one of the key reasons scientists have such an interest in understanding the climate of the Earth's ancient past is so they can understand how the atmosphere and climate respond under varying conditions. The Earth's climate is an extremely complex system, and a change in any single component can have far-reaching effects on both a short- and long-term basis. For this reason, the more scientists understand about the past, the better they can predict...

Contents

The Science of Paleoclimatology 1 The Purpose of Paleoclimatology 2 What Prehistoric Change Reveals about the Future 7 Key Climate Intervals in the Earth's Past 16 Ancient Climates 2 Million to 4.6 Billion Years Ago 22 Evidence for Snowball Earth 29 The Pleistocene Climates 10,000 Years to 2 Million Years Ago 32 The Holocene Recent Climates 10,000 Years Ago Climate Time Line at a Glance 39 Geochronology and Climate Proxies 42 Radiometric Dating Techniques 42 The Discovery and Use of Radioactive...

Coral

Coral reefs record small variations in the climate that can tell scientists about growing conditions in the oceans. Corals that grow near the ocean surface provide annual records of tropical climates that extend back over the past several centuries. They therefore serve as proxies of the upper ocean environment for sea-surface temperature and salinity. When scientists want to inspect a core of coral, they must carefully extract a sample using a hydraulic drill connected to a compressor on a...

E

See Penultimate Interglacial Period Egypt 125, 138, 138-139 electromagnetic spectrum 132-133 electrons 54 Environmental Protection Agency 171c early climate change in 126-127 flooding (2002) 173c heat wave (2003) 129, 173c landforms of cold environments 69 winter after Mount Pinatubo eruption 156 evaporites 75-76, 146 evapotranspiration 14 evolution 102 extinctions 17, 101-102

F

See also ice-albedo feedback fire 111-112 floods 66, 103, 173c Florida 112, 129 food chain 103 98-100, 99 forcing. See climate forcing forests 137 fossil(s) 43-44, 47, 62, 84, 97-98, 99 fossil desert sands 146 fossil pollen 111-112 Fourier, Jean-Baptiste 169c Fourier, Joseph 169c freeze-thaw cycle 61, 64, 65, 69 freshwater 9, 34, 35, 145 freshwater forcing 145 Fridriksson, Adolf 126 frost 69 furrows 72 future issues 152-165

Forams

Some of the best fossils to use as proxy data are forams and diatoms. They have been used worldwide to piece together the picture of past climate. Forams and diatoms are shelled microorganisms found in aquatic and marine environments. One of the factors that makes them so versatile is that there are benthic types (those that are bottom dwellers) and planktonic types (those that float in the water), enabling them to represent a large range of the ocean environment. The shells of forams are...

G

GCMs (global climate models) 153-157 139-142, 141 geological-geochemical proxies 56 geological oceanographers 84 geologic periods 18, 24. See also specific periods, e.g. Quaternary geologic timescale 17-21, 166 geology 134 geomorphic landform proxies 58-72, 63 arid environments 61-69, 64, 65 cold environments 69-72, 71, 72 defined 56 geologic evidence 60-61 geomorphology 59 Ghoneim, Eman 135-136 giant bison 98 GIS. See geographic information system GISS. See Goddard Institute for Space glacial...

Geochronology and Climate Proxies

In order to determine when significant past climatic events occurred and changes shaped the Earth, climatologists must have a way to determine the geologic time period during which these events took place. They must be able to build an accurate climate time line. This chapter focuses on the various methods scientists use today to determine these specific intervals. It will look at both radiometric and nonradiogenic dating methods. It will also explore the importance of climate resolution and...

Geological and Geochemical Proxy Data

The geologic record truly serves as a record set in stone of valuable information concerning climate change and the relationships between the Earth's physical systems and the life that occupies the planet. As climates change, they exact forces on the landscape that change the arrangement of the Earth's surface features, as illustrated in the previous chapter but they also alter the Earth's surface and subsurface features in chemical ways. Although these alterations may not always be obvious,...

Global Warming Trends

GLOBAL WARMING TRENDS Ecological Footprints Copyright 2009 by Julie Kerr Casper, Ph.D. All rights reserved. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval systems, without permission in writing from the publisher. For information contact Facts On File, Inc. An imprint of Infobase Publishing 132 West 31st Street New York NY 10001 Library of Congress...

Greenhouse Gas Emissions

Energy Information Administration homepage. U.S. Department of Energy. Available online. URL www.eia.doe.gov environment.html. Accessed October 26, 2007. This Web site lists official environmental energy-related emissions data and environmental analyses from the U.S. government. The site contains U.S. carbon dioxide, methane, and nitrous oxide emissions data and other greenhouse reports. World Resources Institute Climate, Energy & Transport homepage. World Resources Institute. Available...

H

Half-life 44-46, 49, 50 Hansen, James 5, 149-151 Harland, W. Brian 27 Haug, Gerald 116, 117 heat waves 129, 173c Heinrich, Hartmut 34-35 Heinrich Events 34-35 hickory 148 historical (written) data 56-57 Hodell, David A. 118 Hoffman, Paul F. 27 Hohokam people 122-123 Holland 37 Holocene epoch 4, 35-40, 66, 81-82, 158 horizons, of soil profile 76-78, 77 horn 71 human activity 5, 8, 40, 111, 170c. See also anthropogenic climate change humid climates 75 Hurricane Andrew 129 Hurricane Katrina 129,...

Ice Cores

Another significant area by which climate proxy data are gathered is from ice cores. The most popular places for obtaining ice cores are in Greenland and Antarctica because they represent long histories of ice accumulation. Many ice cores are collected and then sent to and stored at the National Ice Core Laboratory in Denver, Colorado, where they are further analyzed. Ice cores contain a wealth of information about the climate. Ice cores can contain an uninterrupted, detailed climate record...

Loess

Loess is a homogeneous, fine yellow soil that has been deposited across 1 million square miles (2.6 million sq. km) of land that covers several areas of the world Asia, Europe, and North America. It ranges in thickness from area to area and can be as thick as 10 feet (3 m) in some locations. Loess (rhymes with us) originated from glacial processes. As the massive weight of the glacial ice moved across the Earth's surface, the ice ground along the rock slowly and abraded and pulverized it into a...

Mineral duEs To PAsT cLIMATE

Like tree rings, ice cores, oxygen isotopes, and coral, minerals are another proxy used to reconstruct past climates. They can leave specific clues about not only the environment they were formed in but the ancient climate as well. Minerals react with both water and the atmosphere by being shaped and physically and chemically weathered. The most useful are those that exist within specific environmental settings, such as arid areas, tropical areas, and polar areas. According to Dr. Vivien...

N

See North Atlantic Oscillation NASA. See National Aeronautics and Space Administration National Aeronautics and Space Administration (NASA) climate change modeling 143-145 climate research 143-151 current temperature records 149-151 methane in ice cores 89 minerals as proxy data 146-147 ocean-atmosphere model 145 sediment layers in tidal marshes 147-148 testing of climate modeling 155-156 use of paleoclimatic data for computer modeling 2-3 National Assessment of the Potential Consequences...

O

Obama, Barack 169c ocean(s) 84-85, 107 ocean circulation 99-100 ocean currents 9-10, 30, 34-35, 99100 ocean temperatures 82, 98. See also sea surface temperature ODP (Ocean Drilling Program) 83-84 oil price spike (2008) 169c oil wells 169c old-growth forests 137 orbit, of Earth 19-22, 33, 36 orbital tuning 53-54 oxides 75 oxygen 32 oxygen-16 88 oxygen-18 33, 53, 54, 88 oxygen isotopes in clay 147 and coral 107 and dendrochronology 104 for determining droughts 119-120 for determining past...

P

Western 150 pack rat middens 100, 100-103, 101 Palaeozoic 30 (PETM) 32 paleoclimatic data. See proxy data paleoclimatology xvi, 1-15 and climate forecasting 7-8 and climate modeling 157 and climate patterns 12-15 and oceans 41 origin of term 2 primeval forests 137 purpose of 2-7 remote sensing for 134 to track rate of climate change 8-12 paleolimnology 82-83 Paleomap Project 163, 164 paleosoils 75, 79 palm fossils 112 Pangaea 30 Pangaea Ultima 164-165 parent element 44-46, 50 particulates 88,...

Pack Rat Middens

Another proxy method that scientists use to reconstruct past periods of climate change is through analysis of plant remains from fossil pack rat middens. The U.S. Geological Survey (USGS) is currently involved in research along these lines in the southwestern United States. Fossil pack rat (also known as wood rat) middens (crystallized urine) often con -tain abundant fossilized remains of leaves, twigs, fruits, seeds, bones, shells, and other dateable materials. These findings help reconstruct...

Potassium Argon

Potassium-argon is one of the simplest dating methods and has a halflife of 1.3 billion years. It can be used on rocks within a wide range of ages a few thousand years to billions of years. Potassium is present in most rock-forming minerals, and in samples that have Potassium-40 in them, there is generally enough Argon-40 present that the rock can be accurately dated, even if there is only a small amount of Argon-40 present. Potassium is a common element found in clay minerals, tephra, micas,...

Preface

We do not inherit the Earth from our ancestors we borrow it from our children. This ancient Native American proverb and what it implies resonates today as it has become increasingly obvious that people's actions and interactions with the environment affect not only living conditions now, but also those of many generations to follow. Humans must address the effect they have on the Earth's climate and how their choices today will have an impact on future generations. Many years ago, Mark Twain...

Soils And Mineralogy Composition

Soil is composed of minerals (rock, clay, silt, and sand), air, water, and organic (plant and animal) material. The chemistry of soils and rocks is also affected by climate, and through the study of paleosoils (ancient soils), scientists can infer what past climate was like. In humid climates such as jungles, for instance, the soluble minerals are dissolved and washed out of the soil. Because only certain minerals do this, soils of humid climates are characteristically missing or deficient on...

The holocenerecent climates years ago to present

The Holocene brings geologic time up to the present day. The major ice sheets of the last ice age reached their maximum extent about 18,000 years ago and then began retreating around 14,000 years ago. However, this time span was not one of a continual upward trend in temperatures. The climate varied from significant cooling to thermal episodes. There were four notable periods of climatic cooling or warming during this period (1) the Younger Dryas Cooling, (2) the Mid-Holocene Thermal Maximum,...

Uranium Lead

The uranium-lead technique has been used the longest it was introduced in 1907. There is more than one useful uranium-lead dating sequence. Natural uranium consists of two isotopes, U-235 and U-238. As shown in the chart on page 47, these two isotopes decay at different rates to produce lead-207 and lead-206, respectively. Because of this, it is possible to get two age estimates for each sample. Because U-235 has a half-life of 704 million years and U-238 has a half-life of 4.5 billion years,...

Using New Technology to Discover the Past

Continual advances in technology have made it possible for scientists to discover new clues about what the Earth's climate was once like. Two methods, remote sensing and geographic information systems, have proved particularly helpful. Scientists can now locate areas where major rivers once existed that are now arid desert, areas that once supported large lakes, and areas where a different climate fostered now-extinct ecosystems. This chapter looks at the field of remote sensing and how...

Vegetation

In geological formations, it is more common to find fossil remains of plants than of animals, meaning that vegetation plays a key role in the reconstruction of ancient climates. If a specific species of vegetation is found in a geologic formation that is tens of million of years old, it gives scientists an idea of what the climate was like. If a palmlike tree fossil is found at a high northern latitude, it can be inferred that conditions at one time were much warmer than they are today. When...

WEB siTEs Global Warming

Ecological Internet. Available online. URL www.climateark.org. Accessed October 23, 2007. A Web site that promotes public policy that addresses global climate change through reduction in carbon and other emissions, energy conservation, alternative energy sources, and ending deforestation. Climate Solutions homepage. Atmosphere Alliance and Energy Outreach Center. Available online. URL www.climatesolutions.org. Accessed October 23, 2007. A Web site that offers practical...

The Science Of Remote Sensing

Remote sensing is the collection and measurement of information by a device not in physical contact with what it is observing. Common remote sensing devices include eyes, cameras, binoculars, microscopes, telescopes, video cameras, and satellites. When a 35-mm camera takes a photograph, for instance, a hard-copy print of the object is the output. If the picture were of a house, the photo interpreter would gain useful information such as the shape of the house, number of floors, number of...

The Rise Of Civilization

Increasing evidence points to recent global warming as a consequence of human activities, such as the burning of fossil fuels and deforestation coinciding with rising levels of CO2 in the atmosphere. But scientists also know there are natural variations at work on the environment at the same time. One of the biggest questions climatologists must face is how to tell the difference between natural change and human impact as it occurs now and into the future. Experts point out that future change...

Proxy Data Geomorphic Landforms

Climate has left its mark in several places on the planet in the chemical and physical structures of the land, the oceans, and life. These climate artifacts, called climate proxies, reveal climate patterns that can extend backward in time hundreds of thousands, even millions, of years. When this proxy evidence is combined with present-day observations of the Earth's climate and is entered into computer models, this paleoclimatic data (paleo means ancient) can help scientists predict future...

Ancient climates million to billion years AGo

Climate change of ancient Earth has been determined primarily through the study of plate tectonics and the reconstruction of the locations of the Earth's landmasses, oceans, and waterways as well as geologic evidence of atmospheric CO2. Much of the paleoclimatic reconstruction of the Earth's ancient climate has been accomplished through the mapping of past positions of the continents and plotting of the distributions of rock types that form in specific climate regions. Certain formations, such...

C

119-120 caliche 61 California 129 Callendar, Guy S. 170c cap and trade programs 173c carbon-12 51 carbon-13 85 carbon-14 50 carbonates 30, 54, 146 carbonate sedimentary rocks 66, 93 carbon cycle 85 carbon dioxide in climate modeling 4, 144, 155, 157 and feedback 8, 20 and glacial periods 19 during Hothouse Earth period 30, 31 in ice cores 89-90 levels in late 1800s 169c during Little Ice Age 38 in ocean xvi during Palaeozoic 30 and paleoclimatology 74-75 plate tectonics and 19 during...

Key Climate Intervals in the Earths Past

Milankovitch And Glacials

This chapter looks at the Earth's climate over geologic time and demonstrates when key long- and short-term changes took place. Cli-matologists have been able to reconstruct a representative climatic time line by tapping into natural storehouses of data, such as corals, ocean and lake sediments, ice cores, fossil pollen, tree rings, and other physical clues left behind from natural processes. These types of data, known as proxy data, are natural records of climate variability. Through the...

Nonradiogenic dating methods

Other dating techniques are available that do not use the radiometric properties of materials. These techniques are often used on objects dating from the past 100,000 years of the Earth's history and involve correlating physical phenomena with natural cycles. The most well-known technique is dendrochronology, also known as tree-ring dating. Other cyclical techniques include analyzing ice cores and varves annual sediment layers from lakes . These methods will be discussed in greater detail in...

Journal Articles

Ancient Mega-lake Discovered in Darfur. New-Scientist 4 12 07 . Available online. URL www.newscientist. Accessed January 4, 2009. This article discusses how remote sensing was used to locate an immense underground reservoir in the Middle East. Broad, William J. Long-Term Global Forecast Fewer Continents. New York Times 1 9 07 . Available online. URL www.nytimes. Accessed October 9, 2008. This article presents ideas on where the Earth's continents will one day be and how...

The discovery and use a of radioactive decay

Natural radioactive decay was discovered by Henri Becquerel, a French physicist, in 1896. shortly afterward, Ernest Rutherford, a British physicist, described the structure of an atom. These two discoveries are what prompted the idea of using radioactivity as a tool with which to measure geologic time. Then, in 1907, Professor B. B. Boltwood, a radiochemist at Yale university, published the first list of geologic ages of formations based on the use of radioactivity as a true laboratory dating...

Radiometric dating techniques

When talking about dating objects and determining when a particular event took place or a specific climate existed on Earth, it is important to understand the difference between relative age and absolute age, because both are often referred to when discussing past climate. Relative dating is simply determining if something is older or younger than something else. It does not provide an exact numerical age, only a comparable ranking. This follows what geologists refer to as the law of...

What some models say about north america

Considerable ongoing research is aimed at predicting what the future climate will be like for North America in light of natural changes as well as anthropogenic human-caused global warming. Extreme drought is one of the expected consequences of increased global warming, especially in the American Southwest, where it has already been projected to be severe by several models. The Drought Research Lab at Lamont-Doherty Earth Observatory at Columbia University in New York has identified and studied...

Climate proxies

Clues to past climate can be contained in many indicators that clima-tologists refer to as climate proxies. Proxy means substitute. The term is used because climatologists cannot obtain direct temperature or other climatic data from proxies but can only infer past climatic conditions based on information obtained from the proxies themselves. As an illustration, it is possible to infer the climate of an area just by looking at a photograph. If the photograph, such as that shown on the facing...

The pleistocene climates years to million years ago

There is much more geologic evidence for the younger geologic ages, such as the Quaternary period, which spans the last 2 million years of the Earth's history. During the Quaternary, global climate has alternated between times of warmth and frigidity interglacial and glacial episodes. The Quaternary is separated into two epochs, the Pleistocene 10,000 years to 2 million years ago and the Holocene 10,000 years to the present . The Pleistocene is best known for its glacial and interglacial...

Information systems

A GIS is a computer system capable of capturing, storing, analyzing, and displaying geographically referenced information. A GIS operator can look at various types of data for a specific area and analyze them in order to make intelligent decisions. A GIS can be used for scientific studies, resource management, and development planning. For example, a GIS might assist climatologists in determining areas where sea level rise will be the most disruptive, where desertification is spreading, how...

Landforms of arid environments

Wind Pediment Landform

Water has enormous erosive potential in arid environments. Changes in climate causes stream terraces to form. Stream terraces are formed when streams carve downward into floodplains, leaving steplike benches along the sides of a valley. In present-day landscapes, when geologists find older stream terraced surfaces that have no obvious connection to a modern drainage system, it provides a clue to the area's past climate. Sometimes old terraces have been weathered in such a way as to expose some...

The Mysterious saraswati River India

Saraswati River Satellite

Some 10,000 years ago, there were believed to be many mighty rivers that flowed from the Himalayas and that allowed civilizations to prosper in the green, fertile, cool climate on the riverbanks in northwestern India, such as Rajasthan. Archaeologists have determined that ample precipitation and large flowing rivers enabled settlers to be prosperous farmers. Then, 6,000 years ago, one of the mightiest rivers, the Saraswati, dried up, forcing inhabitants in the area to relocate elsewhere. Over...

Modeling abrupt climate change

In their efforts to predict future climate change and possible effects of global warming, scientists at NASA are looking at well-documented events from the past as blueprints for the future. They believe that by focusing on a past event and entering relevant data and associated proxy data into a computer model, if the model is developed correctly and its output matches the actual conditions that resulted in the past, then that working model can be used with today's observations to predict...

Pangaea uLtimathe FuTuRE

Future World 50ma

Scientists are interested in what the future may be like and how the Earth may eventually look. What will its climate be like How will its ecosystems function How many of the changes will be natural, and how many will be human caused In the case of plate tectonics, geologists have been able to trace the movement of the Earth's plates backward in time in order to determine the geographic positions of the continents and the resulting climates that affected them, such as tropical, polar, or...

Carbon Nitrogen

Pertinent to younger geologic formations, a radiometric method that is often used is one that specifically dates carbon-bearing sediments. Carbon-14 is continuously produced in the Earth's upper atmosphere through the bombardment of nitrogen by neutrons from cosmic rays. The process creates radiocarbon, which then becomes uniformly mixed with the nonradioactive carbon in the atmosphere. This process differs from other methods because it dates the carbon-bearing pieces of evidence directly...

World warmth edging ancient levels

GISS scientists have determined that the Earth's current temperatures are now reaching a level that has not been reached in thousands of years. According to NASA global warming expert, Dr. James E. Hansen, based on a joint study conducted by NASA GISS, Columbia University, Sigma Space Partners, Inc., and the University of California at Santa Barbara, the Earth is surpassing the warmest levels it has seen since the last ice age, which ended about 12,000 years ago. Careful calculations have shown...