Sediments

Sediments, pieces of worn rock and other natural debris, both on land and from the bottom of the oceans, tell scientists a story about what past climate conditions were like on Earth. On land, sediments can become trapped in snow and ice in the oceans, they are trapped deep on the floor of the ocean. Sediments at the Earth's surface can be preserved over time by being deposited, undisturbed and cemented together over the years, and then subjected to great heat and pressure, when they are...

S

Safsaf Oasis, Egypt 138, 138-139 Sager, Will 83 Sahara 130, 136, 138, 138-139 salinity 107, 145 salt 76 Samson, Perry 21 San Andreas Fault 164 sand dunes 67, 68-69, 82 sand dust transport 68 sand sea 68-69 Saraswati River, India 136-137 satellites satellite data 3, 6, 132, 137, 140 Schmidt, Gavin 3, 38, 89, 143-145, 155 Schrag, Daniel P. 27 Scotese, Christopher R. 162, 164 Seager, Richard 160-161 sea level 33-34, 112, 130, 151, 172c sea surface temperature 107, 110, sediment 79, 81-85, 111,...

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...

I

Ice age(s) xiv, 61, 62, 69, 84-85, 97 ice age cycles 7, 34, 35 ice-albedo feedback 11-12, 28, 35 icebergs 34 and CO2 temperature correlation 171c 2 and Dansgaard-Oeschger Events 34 drought evidence in 120 proxy data in 85-90 Iceland 126 ice sheets 53, 90, 92 IEA (International Energy Agency) 173c image processing 133 Inconvenient Truth, An 173c India 125-126, 136-137 Indian Ocean 150 Indus Valley civilization 125 Industrial Revolution 6 infrared radiation 135 insect fossils 102-103 insurance...

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...

W

And cave environments 92 and cave formation 93 and erosion in arid environments 61 and landforms of cold environments 69 and Mayan civilization's decline 118, 120 drought water vapor 170c wavelengths 132-133 weather 5 weathering 60-61, 63-66, 92, 147 Weiss, Harvey 13, 14, 117 wet environments 94 wetlands 79, 89 wildfires 148 wind 81

Modeling the earths climate

Today, several scientific endeavors are attempting to model the Earth's weather and climate for a variety of reasons, such as for farming, urban- ization, and emergency preparedness and for economic, scientific, political, and humanitarian reasons. GISS has taken a lead and become one of the premier groups involved in modeling climate in order to better understand it. One of the main goals of the researchers is to be able to anticipate the effect climate change will have on society and the...

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...

Adaptations today

While climate may not be the sole cause of failures of past civilizations (issues such as political unrest and warfare also cause collapses), it has repeatedly been, if not the main contributor, at least a key contributor to the stability of a society. Because of this, many researchers believe that humans today can learn much from the experiences of past civilizations. History is also helping scientists improve predictions through modeling and other developing technologies. But even with all of...

A

And Dansgaard-Oeschger Events 34 extinction v. adaptation during 102 historical evidence for 10-13 in Iceland 126 modeling of 4-5, 143-145 need for greater understanding of 40 and proxy data 59 and Snowball Earth 29 absolute dating 43 active remote sensing 133-134 adaptation 102, 127-130 aerosols 3 138-139 Ager, Thomas 113 agriculture climate history data 6 and global warming 128 during Little Ice Age 38 in Mayan civilization 116, 119, 120 origins 117 and Saraswati River 136-137 Akkadian Empire...

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...

Key Uncertainties

The earliest-kept records of temperature measured officially by thermometers began in western Europe in the late 1600s. As more weather reporting stations came into existence and began recording official temperatures, by the early 1900s temperature networks had been established nearly worldwide. The exceptions were the polar regions. Collections began there in the 1940s and 1950s. Today, NOAA compiles the records from a climatology network of more than 7,000 stations worldwide so that studies...

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...

The Faint Young sun Paradox

The inability to find more evidence for early glaciation has always stumped scientists because they expected to find evidence supporting abundant glacial events. By studying the evolution of stars in the universe, astronomers have been able to recreate the history of the Sun. The models they have developed indicate that the early Sun was about 30 percent less bright than it is today. These calculations presented a mystery for climatologists, because a decrease of just a few percentage points in...

ViDence For I Snowball Earth

The Phanerozoic is composed of three eras the Palaeozoic, Meso-zoic, and Cenozoic. It was during this time that the landmasses of the Earth came together in the supercontinent called Pangaea. Scientists believe that during the Palaeozoic there was increased volcanic activity and that atmospheric CO2 in the early part of this period may have been high based on evidence geologists have found in carbonate minerals from the time. Some estimates have been made that the atmospheric concentration of...

The Earths Geologic Past

Being able to look to the past has helped climatologists better understand long-term processes relating to the Earth's climate. Although lack of usable data means that much of the most ancient time intervals is not understood as well as are more recent time intervals, as new discoveries are made and analysis techniques are improved, the Earth's past climate history becomes clearer. In order to put the Earth's past in a historical context, it must be looked at on a timescale that spans 4.6...

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...

LiMATE 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...

Potassiumargon

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,...

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...

Books

Greenhouse The 200-Year Story of Global Warming. New York Walker, 1999. This book looks at the enhanced greenhouse effect worldwide after the Industrial Revolution and outlines the consequences to the environment. Friedman, Katherine. What if the Polar Ice Caps Melted Danbury, Conn. Children's Press, 2002. This book focuses on environmental problems related to the Earth's atmosphere, including global warming, changing weather patterns, and effects on ecosystems. Gelbspan,...

R

Radar 134-136, 138 radioactive decay 44, 45, 47, 54 radioactivity 54 radiocarbon dating. See carbon-nitrogen dating patterns 15 and origins of agriculture 117 and speleothem research 95 and weathering in arid environments 65-66 rain forests 79 rapid climate change. See abrupt climate change rate of climate change 8-12 red horn coral 112 reforestation 38 regolith 78 relative dating 43 remote sensing 131-142, 141 reservoirs 119, 158-159 resolution 133 Richardson, Gill 118 Rind, David 38 Rio...

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...

U

Uncertainties 40-41 UNFCCC (United Nations Framework Convention on Climate Change) 171c United Nations 171c United Nations Conference on Environment and Development 171c United Nations Framework Convention on Climate Change (UNFCCC) 171c United States Global Change Research Program 172c University of Arizona Laboratory of Tree Ring Research (LTRR) 107 unsaturated zone 93 U.S. Geological Survey (USGS) alluvial fan studies 66, 68 computer modeling 113 geological oceanography 84 Great Plains sand...

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...

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,...

Heinrich events

Some scientists have suggested that the Dansgaard-Oeschger events are related to the Heinrich events. Hartmut Heinrich, a marine geologist, described these events as episodes during the last ice age when major icebergs cleaved off ice sheets and drifted to sea. His proof of this was found in ocean-bottom sediment cores that contain the eroded sediments the ice had originally scoured and carved off the landmasses as it moved over land. He claimed that as the icebergs melted and added freshwater...

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...

The Pleistocene Climates10000 Years To 2 Million Years

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...

The Holocenerecent Climates10000 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,...

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...

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...

Thermoluminescence

Thermoluminescence is another dating technique. It does not rely directly on half-lives but uses the fact that radioactive decay causes some electrons to end up in a state of higher energy. The longer the radioactivity, the more high-energy electrons collect. If the material is then taken into a lab and heated, it puts the higher-energy electrons back into their normal orbits. As the orbits return to normal, a small amount of light is given off. This measurement can be calculated into an age....

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...

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...

Late Holocene Neoglacial fluctuations

This period was witness to a number of climate fluctuations spread over 4,500 years. Overall, experts say that temperatures were lower during this time than during the Mid-Holocene Thermal Maximum. From 2,500 to 4,500 years ago, a cooling period called the Iron Age neoglacia-tion occurred. The climate then heated around the time of the birth of the Roman Empire but cooled again during the Dark Ages (476-1000 c.E.). After this period, the climate warmed during what was referred to as the...

T

Tambora, Mount 39 Tang dynasty 126 technology 131-142 temperature. See also ocean temperatures sea surface temperature current 149-151 dendrochronology to estimate 104 during geologic periods 24 and greenhouse gases in ice cores 90 and growth of civilizations 115 and historic CO2 levels 8-10 of ice sheets 88 and origins of agriculture 117 and paleolimnology 83 and speleothem research 94-95 vegetation as indication of 111 temperature records 40 Teotihuacan civilization 120, 122...

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...

Fossils

One of the key ways scientists have been able to identify climate change is through the discovery of fossils. During the last ice age, for instance, animals indigenous to cold habitats lived much farther south than would be possible today, such as reindeer and wolverine. Likewise, scientists know that musk ox, a cold-climate species that currently lives in the Arctic, roamed as far south as Mexico City during the last ice age. A mastodon tooth was discovered off the coast of New Jersey. This...

Mid Holocene Thermal Maximum

The Mid-Holocene Thermal Maximum occurred about 6,000 years ago. Paleoclimatologists have determined that this period was somewhat warmer than it is today. Scientists have uncovered a significant amount of evidence relating to this period and have made great strides in understanding the global issues concerning the cause and extent of temperature change. Changes in the Earth's orbit eventually combined to alter the amount of solar radiation that was reaching various areas of the Earth,...

Rubidiumstrontium

Rubidium has a half-life of 48.8 billion years. This method is used on old igneous and metamorphic rocks. Sometimes, there can be confusion with this method if a rock sample contains some minerals that are older than the bulk of the rock. This may occur during formation if the rock accidentally picks up an unmelted mineral from the surrounding rock that the magma passes through. Problems can also arise if the rock has undergone some metamorphism. In this case, if some parts of the rock...

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...

Lifeformsfossils

Various life-forms are used by paleoclimatologists to reconstruct the Earth's climate changes through time. They include fossil evidence, forams (foraminifera), pack rat middens, and insects. Fossils are important because they provide a conclusive record as to what animals and other life-forms existed in a specific geographic environment during a specific period. Fossils of forams, in particular, are especially helpful because they have broad geographical ranges. Pack rat middens (crystallized...

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,...

Climate Patterns

Climatologists have determined that climate change is not only constant but that it also occurs at multiple time scales. It occurs at geologic time scales of millions of years, and nested within that at scales of hundreds of thousands of years, and within that at tens of thousands of years to thousands, hundreds, and even decades and annual scales. Long-term changes are seen in changes in the Earth's tilt, axis, and precession. Cycles are seen in ice ages. Shorter-term changes are seen in...

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,...

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...

Nonradiogenio 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...

CarbonNitrogen

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...

THE stoRies MarsHEs TELL

Scientists at NASA and Columbia University have unraveled important pieces of the climate puzzle in the marshes of the lower Hudson Valley near New York City. Through analysis of sediment layers from tidal marshes in an estuary, Dee Peterson and Dorothy M. Peteet have discovered valuable proxy data in preserved pollen from various plants and seeds. Working with a team of scientists from Columbia University, they have uncovered physical evidence permanently recorded in these sediments of two...

L

(LTRR) 107 lacustrine sediments 81 lake bottom sediment cores 82-83 lakes, ancient 62 Lamont-Doherty Earth Observatory Drought Research Lab (Columbia University) 157-158, 160 land management 127 LANDSAT satellite 138 La Ni a 159, 160 Last Glacial Maximum 4, 66 late Cretaceous 112 Late Holocene Neoglacial Fluctuations 36 LeGrande, Allegra 144, 145 LIDAR (light detection and ranging) 135 Little Ice Age 7, 36-40, 127, 148, 169c long-term climate patterns 12, 18-19 LTRR (Laboratory of Tree Ring...

Rate Of Change

One important concept of paleoclimatology is to be able to track the changes in greenhouse gas concentrations by the heating or cooling of the Earth's surface. Scientists know that when the atmosphere warms up, carbon dioxide is released from the oceans. In addition, if the Earth's orbit changes and triggers a warming period, it can also increase greenhouse gases. When this happens, it triggers the greenhouse effect. This creates a positive feedback that encourages more warming. Conversely,...

Middle EasT Far EasT AND EuRoPE

Abrupt climate change, droughts, cold periods, and flooding have also played a major role in other areas of the world. In the Middle East, the harsh arid climate has often been an issue, and some believe it may partially explain some of the long-standing animosities among peoples there. People lived in northern Mesopotamia relying on annual rainfall in order to farm and grow their food for more than 1,000 years, and their society flourished. Archaeologists have found evidence, however, that...

What Prehistoric Change Reveals About The Future

An important part of being able to make forecasts of the Earth's future climate is to know how the Earth's climate has varied in the past and what mechanisms have made it vary. If paleoclimatology can help create past climate and give scientists a better idea of how climate has changed throughout time, it gives them important insight as to how today's actions will influence the trend of future climate, especially concerning global warming. Since scientists have maintained a detailed record of...

Ancient Climates2 Million To 46 Billion Years

Paleoclimate 6billion

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...

Dating using Thorium230

Dating techniques using thorium are employed on oceanic sediments that are older than the range that radiocarbon techniques can detect. Uranium that is present in seawater eventually decays to thorium-230 (called ionium), is precipitated into the ocean floor sediments, and is stored. Thorium-230, which is part of the uranium-238 decay series, has a half-life of 80,000 years. Protactinium-231, which is derived from uranium-235, has a half-life of 34,400 years. Both can be used for age...

Key Climate Intervals in the Earths Past

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...

Penultimate Interglacial Period

The Penultimate Interglacial period occurred about 125,000 years ago, and at that time Northern Hemisphere summers were slightly warmer than today, roughly 1.7-3.3 F (1-2 C) warmer. This interglacial is also referred to as the Eemian interglacial and is attributed to changes in the Earth's orbit. One interesting thing to note is that because climatologists consider this period to have had similar temperatures to those we are currently facing with global warming, they have used the geologic...

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...

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...

Biotic Proxies

Climate proxies allow multiple independent pieces of a complex puzzle to be put together to create a master picture of the Earth's past climates. Each piece, no matter how small, makes an important contribution in the effort not only to understand when and where climate change occurred but also how and why. Knowing the answers to these questions is important because it strengthens the community's understanding of the sensitivity of the Earth's climate, how it responds to global warming, and the...

Orbital Tuning

Orbital tuning is an important dating technique climatologists use to study past climate. This refers to a procedure of linking cycles of incoming solar radiation with the Earth's ice volume responses to determine age. As discussed earlier regarding the Milankovitch cycles, astronomers have calculated the solar radiation signal over time and have determined that cycles at 41,000 and 23,000 years have produced regular climatic responses. Because of this correlation, these predictable climate...

Younger Dryas Cooling

One of the more notable periods of cooling is known as the Younger Dryas Cooling. This period occurred 10,000 to 11,000 years ago, which coincides with the geologic boundary of the Pleistocene and Holocene epochs. Glacial ice advanced from the north and moved southward to about 45 N latitude (roughly the same latitude as Minneapolis, Minnesota, and Portland, Oregon). This was a significant advance, because ice levels proceeded within about 10 of where they had reached during the last glacial...

Dendrochronology

Www Plicher Tree

Dendrochronology is the study of past climate change through examination of tree ring growth. Andrew Ellicott Douglass from the University of Arizona first used this specialized branch of science in the early 1900s. Douglass was the first to realize that the wide rings of certain species of trees were produced during years with ample rainfall and favorable growing conditions. Every year, a tree adds a new layer of wood to its trunk and branches, which create the annual rings that are visible...

What some models say about north america

Crops Killed Dust Bowl

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...

The Mysterious saraswati River India

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...

Olimate 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 little Ice

The Earth's climate remained relatively warm until approximately 1450 c.E., then it took another turn toward cold. The subsequent cold period lasted from 1450 to 1890 and has become known as the Little Ice Age. The Little Ice Age was a time of renewed glacial advance and affected the North Atlantic, Europe, Asia, and North America. It alternated between colder and less cold periods. The two coldest time segments occurred in the 1600s and 1800s. The 1500s and 1700s were less cold. Because the...

Sons AND mineralogy composition

Fertile Soil 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...

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...

Geologic evidence

The geologic processes that evolve most abruptly are those that dominate and determine the appearance of a landscape. Factors such as climate, rock type, steepness of terrain, presence of water, and presence of wind are all contributing factors to a landscape's ultimate appearance. When landscapes are young and are being actively uplifted, the gradient is steep. When water, such as from a river, begins to erode under the force of gravity, it moves downslope with great erosive power. Young...

Safsaf Oasis Egypt

Visions of the Sahara today do not invoke images of major rivers and connecting multiple tributaries. Today the landscape looks like vast, open areas of nothing but sand for miles in all directions. As in the previous examples, even though the surface may not show any signs of water, this does not mean that water did not flow and cut tributaries at one time, only to later dry up and become covered with sand. At one time, abundant rivers in the Safsaf, Egypt, carved channels through canyons and...

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...

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...

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...

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...

Hothouse Earth

Earth Warming

During the mid-Cretaceous period, 90 to 120 million years ago, the Earth was much warmer than today. Often referred to as Greenhouse World, the Earth's warmth extended even to the high (polar) latitudes. This evidence is supported by the abundance of fossil records of plants and animals at polar locations that are found only in warm environments. For instance, corals were discovered far from the equator. Warm-water animals and plants have also been found in polar locations. Scientists have...

Landforms Of Arid Environments

Landforms Arid Climates Picture

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...

Landforms Of Cold Environments

Glacial Eskers Photos

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...

Snowball Earth

There is one theory concerning the Earth being in a nearly frozen state 635 million years ago that climate scientists debate an episode referred to as Snowball Earth. The term Snowball Earth describes the coldest state in which a planet can exist. In order for this to happen, the global mean temperature would have to be -74 F (-50 C). Most of the solar radiation would be reflected back into space by the high albedo of the snow and ice covering the planet. There is evidence that supports this...

Chronology

Ca. 1400-1850 Little Ice Age covers the Earth with record cold, large glaciers, and snow. There is widespread disease, starvation, and death. 1800-70 The levels of CO2 in the atmosphere are 290 ppm. 1824 Jean-Baptiste Joseph Fourier, a French mathematician and physicist, calculates that the Earth would be much colder without its protective atmosphere. 1827 Jean-Baptiste Joseph Fourier presents his theory about the Earth's warming. At this time many believe warming is a positive thing. 1859 John...

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...

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...

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 Purpose Of Paleoclimatology

Before written records were kept, scientists did not have the convenience or luxury of accessing easily available, ready-to-use data. Instead, they used older, existing data that could have been interpreted in a meaningful way. This is where paleoclimatology comes into play. Paleoclimatol-ogy is the study of climate prior to the availability of recorded data, such as temperature data, precipitation data, wind data, storm data, and other measurements of the weather. The word comes from the Greek...

Pangaea Ultimathe Future

Pangea Ultima

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...