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

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...

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,...

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

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

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...

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...

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...