Misconceptions About Abrupt Climate Change

Even though scientists have uncovered a great deal of information about the climate system and how it works, there are still some uncertainties, and because of them, some misconceptions. Some have stated that abrupt changes in climate are natural, that they have occurred throughout history. The reality is that while natural climate change has occurred and still does, a large component today is attributed to human interference. According to the American Geophysical Union, It is scientifically...

Acknowledgments

Global warming may be one of the most important issues influencing your decisions 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 those of your future descendants. 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 needs to be an...

Antarctica

The Antarctic Ice Sheet is the single largest mass of ice on Earth. It covers an area 5.4 million square miles (14 million km2), and its mass contains 11.58 million cubic miles (30 million km3) of ice. If global warming were to cause this entire sheet of ice to melt, it would raise sea levels about 215 feet (66 m). According to a study conducted by Isabella Velicogna and John Wahr, research scientists at the University of Colorado at Boulder's Cooperative Institute for Research in Environmental...

Hurricane Research

NOAA is heavily involved in hurricane research and is approaching the issue from several angles, such as conducting theoretical studies, developing sophisticated computer models, and collecting measurements in the field from actual hurricanes that can be analyzed. Because hurricanes are such complex storms, NOAA's goal is to improve scientific understanding of how and why they form why they behave as they do what mechanisms cause them to strengthen and weaken how they can be predicted how...

Print And Online Articles

Alley, Richard B. 'Abrupt Climate Change. Scientific American (November 2004), 62-69. This article introduces the concept of the shutting down of the thermohaline circulation, causing an ice age. Amos, Jonathan. Arctic Summers Ice-Free by 2013. BBC News. December 12, 2007. Available online. URL http news.bbc.co.uk 2 hi science nature 7139797.stm. Accessed June 17, 2009. Discusses melting of the ice and the Northwest Passage. Boswell, Randy. Northwest Passage in Unprecedented Ice Melt, Experts...

Glacial Retreat and Meltdown

Glaciers are dynamic formations, always changing and highly sensitive to the natural input from Earth's climate. Because of their dynamic nature, they are very useful measuring sticks, used by clima-tologists and other scientists to identify changes in the environment. Worldwide glacial retreat and meltdown is one of the most telling markers of global warming. When Earth's surface temperature begins to rise, these massive rivers of ice begin to melt and shrink in response. This chapter focuses...

The Cryosphere and Isostasy

Global warming has already caused temperatures to rise in the Arctic to the point that ice melt is becoming a serious issue. Although it may seem that the polar regions are so remote that there is not much concern for changes in these vast, barren, hostile areas on Earth's surface, just the opposite is true. It is these areas that serve as trigger pointspoints where if change begins to occur in global warming, points where crucial thresholds are reached, they may become unstoppable for the rest...

Global Warming Cycles

GLOBAL WARMING CYCLES Ice Ages and Glacial Retreat Copyright 2010 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...

Tropical Cyclones and Other Severe Weather

This chapter examines the effects of tropical cyclones and other extreme weather. It first looks at hurricanes and their connection with global warming and focuses on human activity that may be contributing to hurricanes. It presents storm surges, what they are, and why their prediction is important, as well as what scientists have to say about the trend of hurricanes in 2004 and 2005. Finally, this chapter touches on current research being conducted on hurricanes, tornadoes, and thunderstorms.

Variations In Sea Level

There are several factors that can cause variations in sea-level rise, such as the following the rebound (or rising up) of Earth's crust after the melting of ice from the last ice age plate tectonics and volcanism raising the height of the land's surface local subsidence of Earth's crust from groundwater extraction ground subsidence from sediment compaction changes in atmospheric wind patterns and ocean currents One factor that must be taken into account when calculating sea-level rise is the...

Historical Perspective

During the last ice age, huge ice sheets covered parts of North America, northern Europe, and parts of Asia. Because so much of Earth's water supply was locked up in ice, global sea level was 394 feet (120 m) lower than it presently is. Once the ice sheets began to melt, sea level began to rise. During that process, there were intermittent intervals when sea levels rose in rapid spurts called meltwater pulses. One such pulse occurred between 14,600 and 13,500 years ago, increasing sea levels by...

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...

Rising Sea Levels

Of all the potential results of global warming impacting humans, a rise in sea level is viewed as one of the most serious, harmful, and destructive. Rising sea level has the potential to have a negative impact on human survival, environmental health, and economics, hence the lifestyle of millions of people worldwide. Because of this, understanding sea-level rise through measurement, observation, and interpretation has been a key focus of many climatologists during recent years. Sea-level rise...

Arctic

A similar scenario is taking place in the Arctic regions of the Northern Hemisphere. NASA is currently monitoring the polar ice sheets with the Ice, Cloud, and Land Elevation Satellite (ICESat), which was launched in January 2003. Three times a year this satellite uses a laser beam to measure the elevation of the ice sheets with a high degree of precision. NASA scientists have determined that 9 percent of the mass of Arctic sea ice is melting away each decade. Meanwhile, a study conducted at...

North America

The North American glaciers located along the Rocky Mountains in the United States and Canada and the Pacific Coast Ranges from northern California to Alaska are nearly all in a state of active retreat. Since 1980, the rate of retreat has increased each decade. In the North Cascade Mountains alone (part of the Pacific Coast Ranges), there are more than 700 glaciers the area extends from central Washington to the Canadian border. These glaciers store a tremendous amount of water, equal to all...

Climate Research What the Experts

Climate research is a rapidly expanding field. The advent of more sophisticated technologies such as satellite monitoring systems and high-speed computers has enabled scientists to increase the efficiency of field research, collect and process more data, and be able to put meaning to large amounts of technical data that cross technical and professional boundaries from one science specialty to another, such as paleoclimatology, oceanography, meteorology, physics, chemistry, geography, geology,...

The Role Of Oceans In Climate Change

The oceans and atmosphere are closely linked to each other and form the most dynamic part of the climate system. In the atmosphere, external forcings such as variations in the Sun's energy and concentration of greenhouse gases directly affect the circulation patterns and temperature of the ocean-atmosphere system. There is also an internal relationship. Because both the ocean and atmosphere are constantly in motion, they generate their own internal fluctuations. Short-term fluctuations in wind...

Glacial Retreat

Glaciers today are retreating worldwide, not only in the polar regions, but also in the mid-latitude mountain ranges such as the Rocky Moun tains, Himalayas, Alps, Andes, Cascades, and Mount Kilimanjaro. They are retreating faster than what can be explained by historical rates. Because this glacial retreat became more pronounced after 1850, it is more likely correlated to anthropogenic (human-caused) actions. With the further progression of the industrial revolution, extensive use of fossil...

Ice Caps

An ice cap is a dome-shaped ice mass that covers an area less than 19,305 square miles (50,000 km2) in size. Ice caps are very responsive to the effects of albedo. Normally, they act as reflectors, redirecting the Sun's energy back out into space and keeping Earth cool. If the ice caps begin to melt, however, and darker surfaces are exposed, a negative feedback occurs, and Earth's surface begins to absorb the Sun's energy (heat) and accelerate the melting process. The Arctic ice cap has been...

Greenhouse Gas Emissions

Available online. URL www.eia. doe.gov environment.html. Accessed June 17, 2009. Lists official environmental energy-related emissions data and environmental analyses from the U.S. government. Contains carbon dioxide, methane, and nitrous oxide emissions data and other greenhouse gas reports. World Resources Institute Climate, Energy & Transport. Available online. URL www.wri.org climate publications.cfm. Accessed June 17, 2009. This Web site offers a...

Warning Signs Today

Scientists caution today that it is possible for abrupt climate change to occur simultaneously with global warming. In fact, according to the Woods Hole Oceanographic Institution, global warming is a destabilizing factor that makes abrupt climate change even more probable. A report issued by the U.S. National Academy of Sciences (NAS) stressed that available evidence suggests that abrupt climate changes are not only possible but likely in the future, potentially with large impacts on ecosystems...

The Day After Tomorrow

The Hollywood science-fiction film The Day After Tomorrow (2004), an action-packed thriller about abrupt climate change, caught the attention of moviegoers around the world. But was this film science or science fiction According to experts at the Ocean and Climate Change Institute and Woods hole Oceanographic Institution, the abrupt climate change depicted in the movie over a time span of just a few weeks could not happen that fast. The climate is a huge, complex interactive system involving...

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...

Trade Wind Changes

A study conducted by Gabriel Vecchi of the University Corporation for Atmospheric Research in Boulder has suggested that the trade winds of the Pacific Ocean are weakening because of global warming. There is a large wind system that circulates over the Pacific Ocean called the Walker circulation. Through the use of data collected in the field, as well as computer modeling, Vecchi has determined that the Walker circulation has weakened by roughly 3.5 percent since the 1850s. It is expected that...

Europe

According to research conducted by the WWF in the European Alps since 1980, melting has accelerated in the past two decades, glaciers there have decreased in size up to 20 percent. In the Alps of Switzerland, it has been reported that 84 of the 85 surveyed glaciers are retreating only one is advancing. Others in Sweden and Norway are also rapidly retreating. In one particular study in Norway, a group of research scientists from Swansea University, in the United Kingdom, launched the field study...

Future Projections

One of the key issues is that of future sea-level rise. Because the ocean's thermal inertia is so great (it can hold large amounts of heat over long periods of time), it will take decades for the oceans to adjust their levels to the heat absorbed. In fact, for the heating caused by greenhouse-gas emissions already released into the atmosphere, sea levels are still trying to find a point of equilibrium. Therefore, even if all greenhouse emissions stopped today, there would still be a lag time...

Global Warming

URL www.climateark.org. Accessed June 17, 2009. Promotes public policy to address global climate change through reduction of carbon and other emissions, energy conservation, alternative energy sources, and ending deforestation. Climate Solutions. Available online. URL www.climatesolu-tions.org. Accessed June 17, 2009. Practical solutions to global warming. Environmental Defense Fund. Available online. URL www.environ-mentaldefense.org. Accessed June 17, 2009. An...

Evidence Of Global Warming

Since the early 1900s, most of the glaciers around the world have been melting and retreating at rates faster than have ever been recorded. Since the beginning of the Industrial Revolution in the mid-1700s, scientists have noted that glaciers, which are extremely responsive to current temperature change, have been receding. Changes will continue to happen as long as the atmosphere continues to heat up. According to the IPCC, Ample evidence indicates that global warming is causing glaciers to...

Sealevel Rise

Sea levels are currently rising and are expected to continue rising, possibly even at an accelerated rate, over the next century and beyond. It is not caused by one simple mechanism it is the result of several processes, such as the melting of glaciers and ice caps from continents (the melting of ice already in the water does not affect the sea level) thermal expansion of the oceans' upper layers the melting of the Antarctic and Greenland Ice Sheets redistribution of terrestrial water storage...

Ice Shelves And Ice Sheets

An ice sheet is a mass of ice that covers at least 19,305 square miles (50,000 km2). In the past, ice sheets have covered different areas of Earth. Evidence of these ice sheets has been found in glacial deposits and landforms where they once existed. During the last ice age, the Laurentide Ice Sheet existed in North America, extending southward over Canada and the northern United States. During the same time, in Europe, the Weichselian Ice Sheet covered northern Europe. In South America, the...

Past Warmer Oceans

According to Karen Bice, a paleoclimatologist at the Woods Hole Oceanographic Institution, the tropical Atlantic Ocean may have once been as hot as 107 F (42 C) much higher than today's ocean temperatures. Bice believes this event occurred millions of years ago when CO2 levels in Earth's atmosphere reached extremely high levels. Scientists view these facts as something to take very seriously, because if it happened before, it could happen again, and because current climate models do not...

Causes Of Abrupt Climate Change

One of the overwhelming causes of abrupt climate change that scientists focus upon is the sudden shutdown or start-up of the meridional over turning circulation (MOC). Also commonly referred to as the thermohaline circulation, or great ocean conveyor belt, it is a complex network of ocean currents in the Atlantic. The Gulf Stream, which is the current that transports a significant amount of heat northward from Earth's equatorial region toward western Europe, helping to warm its climate, is part...

Computer modeling applications

A project supported by the Global Change Research Program of the USGS and conducted by the Northern Rocky Mountain Science Center at West Glacier Field Station took place in 2003 to model climate- induced glacier change in Glacier National Park from 1850 to 2100. The researchers created a 3-D computer model of the Blackfoot-Jackson Glacier Basin in Glacier National Park, Montana. Based on field evidence, the glacier had already decreased in area from 8.3 square miles (21.6 km2) in 1850 to 2.9...

Arctic Melt

According to an October 2, 2007, article in the New York Times, the Arctic ice cap shrank so much in the summer of2007 that it opened two previously ice-bound historic trade routes the Northwest Passage over Canada and the Northern Sea Route over Russia. This melt was more excessive than anything seen before, exposing 1 million cubic miles (4,168,182 km3) of open water. This event has captured climatologists' attention because the major meltdowns had not been predicted. They determined the...

Books

Greenhouse The 200-Year Story of Global Warming. New York Walker, 1999. This book looks at the enhanced greenhouse effect worldwide since 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 their effects on ecosystems....

Conclusions and a Glance into the Future

As climatologists study the past, observe the present, and build models based on this data to predict the fUture, they recognize that there are still a lot of unknowns about what exactly the future will bring. Many experts have likened the situation of global warming to a real-time scientific experiment being conducted on Earth, and the actions humans take such as burning fossil fuels dictate how this live experiment will turn out. Many scientists, including the more than 2,500 represented by...

Using Paleo Evidence To Predict The Future

Understanding Earth's past climate behavior provides priceless insight into what it may do in the future. Long winters and glacial advances are recorded in proxy data from glaciers, sea ice, and soil samples. Deep-sea sediment cores show that icebergs traveled as far south as the waters off the coast of Portugal. Scientists at NOAA use paleoclimatic data to identify abrupt climate changes. These intervals have occurred as global events and as local events some severe, others less severe. NOAA...

Sources Of Information

In order to understand Earth's ice ages, scientists must be able to piece together the past and determine exactly when in the geologic time This drill bit is tough enough and sharp enough to slice through meter after meter of solid ice. The bit is fitted in the core sleeve, a hollow tube into which the ice passes after being cut. (Lonnie Thompson, Byrd Polar Research Center, Ohio State University, NOAA Paleoclimatology Paleo Slide Set) table these events occurred. The principal techniques they...

How hurricanes n are named

Hurricanes are given names from lists that have been previously prepared. The names on the list are approved by the World Meteorological Organization (WMO) or by national weather offices. If a hurricane is extremely destructive, its name will be retired and never used again for a hurricane. For example, Katrina will not be used again. In the North Atlantic and northeastern Pacific, both male and female names are alternated in alphabetical order during a season. The gender of the season's first...

Abrupt Climate Change

One of the effects of climate change and global warming that concerns scientists today is the concept of abrupt climate change. Normally, significant changes that take place in the climate happen gradually over a long period of time thousands of years. The climate does not always take this long to change, however, and when the changes occur in a matter of years to decades, this is an extremely fast rate. This chapter looks at what qualifies as abrupt climate change, evidence of past...

Abrupt Changes In Climate

In the past, it was believed that major climate change could only occur gradually, that the climate system was so huge and complex that any significant changes would take centuries or longer to occur. All that thinking began to change when scientists started drilling ice cores in Antarctica and Greenland. Hidden within the ice cores were detailed preserved histories of past climate going back 110,000 years in year-by-year layers. Located within these ice cores are bubbles of atmospheric gas,...

Atlantic Freshwater

According to Curry at Woods Hole, several large areas of the North Atlantic have been getting fresher since the 1960s due to the effects of glacial meltwater flowing into the ocean and increased precipitation from an enhanced water cycle. Both Curry and Cecilie Mauritzen of the Norwegian Meteorological Institute have mathematically determined how much additional freshwater has been added to cause the change, how fast it entered ocean circulation, and where the freshwater was stored. Based on...

Breaking The Temperature Record

According to NASA scientists, 2005 was the warmest year in more than a century, followed by 1998, 2002, 2003, and 2004. Scientists also noted that in 2005, the Arctic region was unusually warm. Temperature calculations for the year are based on a multitude of temperature readings taken from field sites on land, from ships, and from satellites in space that continuously collect sea surface temperature data. A major point, according to NASA scientists, is that in 1998 (previously the warmest year...

Climate Cycles

Climatologists know that Earth has naturally cycled through several ice ages in the past. Interestingly, there is a theory that at least on four different occasions, Earth has been completely held within the grip of an ice age referred to as snowball Earth only to come out of that and switch to a tropical state referred to as hothouse Earth. Snowball Earth theory was first proposed by Brian Harland, a Cambridge geologist in 1964, when he discovered glacial deposits near the equator. Later it...

Cyclic Theory

Some climatologists view the incidences of hurricanes as part of a natural cycle. Some researchers at NOAA and Colorado State University have conducted studies that support the theory that the number and intensities of hurricanes follow in 50- to 70-year cycles called the Atlantic Multidecadal Oscillation (AMO). They believe the AMO is controlled by gradual changes in the North Atlantic Ocean currents. The AMO controls the flow and direction of the major wind systems. When the trade winds blow...

Glacial Isostasy

Glacial isostasy is the process by which Earth's lithosphere (crust and part of the upper mantle) is physically pressed down under the weight of an ice sheet. When the ice mass is later reduced or removed and the weight is lifted, it allows the crust to rebound (return to its original position). Similar to a person sitting on a sofa, when weight is applied to the cushions, the cushions depress to accommodate the weight. As soon as the weight (stress) is removed, the cushions return to their...

Drinking Water and Irrigation

Many communities depend on glacial meltwater each spring and summer for their drinking water. In tropical regions, the glaciers melt year-round, supplying drinking water to people and animals that would not have any other source of water for survival. According to the WWF, the Himalayan glaciers alone provide a year-round supply of water to more than 2 billion people. In the Ganga, if glaciers further shrink, up to 500 million people may suffer from a shortage of drinking water. There are...

Effects Of Sealevel Rise

The impacts of rising sea levels go beyond the world's coastlines. As global warming continues and sea levels rise, storm surges will increase in intensity, destroying land further inland from the coastal regions. Flooding will become one of the major problems, as well as several other negative impacts. As ocean waters move inland, freshwater areas will become contaminated with salt water. As saline water intrudes on rivers, bays, estuaries, and coastal aquifers, they will become unusable....

Glacial Morphology

Glaciers consist of snow that has accumulated year after year. Glaciers have a positive mass balance The accumulation of precipitation (usually in the form of snow) is greater over a year's time than the melting, leaving the glacier with a net increase in mass. As the snow deposit increases in thickness, the heavy snow burden presses down on the layers of snow accumulated beneath it. The extreme compression forces the snow to recrystallize. The grains of ice become similar in size and shape to...

How Glaciers Reflect Climate Change

Glaciers serve as one of the most valuable proxy tools in which to study climate change because they can range in age from hundreds to several thousands of years old. When a core is extracted from a glacier, the bubbles are analyzed in it, just as they are in ice cores. Analysis of the oxygen content reveals what the composition of the atmosphere was like at the time that layer of snow fell on the glacier. In addition, analyzing the 18O 16O ratio reveals what the temperature was like....

Ice Ageswhat They Are And Why They Occur

Ice ages occur when temperatures remain cool for extended lengths of time. When long intervals of cold prevail, the ice does not melt instead, ice caps and glaciers are able to advance, extending into lower latitudes, farther from the polar regions. Scientists have discovered evidence for this worldwide. For instance, during the last ice age 20,000 years ago, ice sheets advanced from the North Pole south to cover Canada, the New England states, the upper portions of the Midwest, Alaska,...

Impacts of glacial retreat

The melting and retreat of glaciers have the potential to impact millions of people. These impacts will be felt worldwide, although some areas will be affected more than others. The effects will involve drinking water and irrigation resources something that everyone in the world depends on the generation of electrical energy, the health of habitats connected to glacial regions, the presence and use of biochemical elements, flooding, and resulting sea-level rise. Each of these issues will have...

Measuring Sea Level

The earliest gauges used to measure the tides were simply measuring sticks attached to piers. By the mid-1800s, tide gauges using floats began to be used. Much of the difficulty in gathering data to calculate sea level was centered on the fact that the geographic distribution was weak there were simply not enough gauges distributed around the world to enable a reliable global model to be built. Most of the reliable records came from the United States and Europe. In addition to widespread...

Prominent Cooling Events

One of the most studied ice ages is that of the last one, when 20,000 years ago the global temperature was 9 F (5 C) lower than it is today and wooly mammoths and saber-toothed tigers roamed the present-day New York City area. During this period, commonly known as the Ice Age, one-third of the planet's land surface was covered with ice. In North America, an imposing ice sheet up to two miles (3.2 km) thick covered Canada and reached as far south as southern Illinois. Ice sheets also covered...

Tornado And Thunderstorm Research

Some believe one of the effects of global warming is an increase in extreme, violent weather events in the form of tornadoes and thunderstorms. In 2004, there were more tornadoes reported in the United States than since records have been kept. In Kansas alone, there were 124 reported tornadoes. According to NOAA's Storm Prediction Center in Norman, Oklahoma, nationwide, there were 1,555 tornadoes recorded from January through September 2004. This broke the previous record, set in 1998, by more...

Tracking The Oceans Circulation

To understand climate change, it is necessary to be able to look back in time and determine what Earth's past circulation patterns were like. Once this has been established, those patterns can be compared to today's, increasing knowledge about this complex system. This, in turn, gives climatologists the information they need to develop computer models to predict future ocean circulation. One of the biggest questions scientists have asked is whether there is some sort of a switch that can be...

The Water Cycleearths Water Stored In Ice And Snow

Earth's complete water cycle is very dynamic. The water cycle moves through its various states on or through Earth gas, liquid, and solid sometimes quickly, other times slowly. It moves most dynamically through the atmosphere as a gas (water vapor) and as a liquid through the atmosphere or on Earth as rain and in rivers. Water can transfer fairly rapidly through evaporation, condensation, clouds, and precipitation but it can also be stored for extremely long periods of time in various...

The Hockey Stick Theory

The hockey stick theory refers to a study conducted by Dr. Michael Mann of the Department of Geosciences at the University of Massachusetts and his associates Raymond S. Bradley and Malcolm K. Hughes. Using tree-ring proxy data, he reconstructed global climate for the past 1,000 years. The resulting graph resembles a hockey stick The majority of the time period represents little change in temperature and would-be the shaft of the stick a sharp upward rise in the 20th-century portion of the...

Understanding The Role Of Oceans In Regulating Climate

The circulation of the atmosphere coupled with the ocean currents carry heat from the Tropics toward the poles. This may seem to be a simple, unalterable process, but there are several factors that can come into play to alter the heat-carrying circulation patterns and cause a significant change in the climate. At one time, the importance of the world's oceans in shaping the climate was underestimated but, in fact, the upper few feet of the ocean alone store as much heat energy as that stored in...

Will There Be Another Ice

Although it is not possible to predict climate, scientists are very aware of the capacity of climate to change abruptly. In light of all the attention today on global warming, many people may think a future ice age is out of the question as long as the enhanced greenhouse effect that being consciously added to by humans persists. Climates can, and have, changed in unexpected ways. The Younger Dryas, for example, has caused much scientific debate over its cause. No known specific natural forcing...

South Pacific

In Indonesia, 80 percent of glacial mass disappeared between 1942 and 2000. According to the WWF, West Meren Glacier, in particular, receded 8,530 feet (2,600 m) from 1936 until it finally melted sometime Muir Glacier, in Alaska. The top image was taken in 1941 the bottom, in 2004. (National Snow and Ice Data Center. Top photo by William O. Field bottom photo by Bruce F. Molnia) Muir Glacier, in Alaska. The top image was taken in 1941 the bottom, in 2004. (National Snow and Ice Data Center. Top...

Cyclic Ocean Circulation That Influences Climate

There are cyclic circulation phenomena that occur in the ocean that play a direct role in climate over large areas of Earth. The most significant are the North Atlantic Oscillation (NAO) and ENSO. The most powerful of these cyclic anomalies is NAO. While it does not produce the violent weather effects as dramatic as those of El Ni o, NAO is much more consistent. NAO is a system involving two separate pressure systems and their relationship. The first is a high-pressure system that sits over the...

Past Glacial Evidence

Glacial erosion has significantly reshaped Earth's surface with several distinct types of erosional and depositional features over geologic time. When climatologists and other scientists study the landscape and find these features, they are able to unravel clues about the area's past climate and determine when glaciers existed in the area and what the climate was like at that time. For years, scientists believed that when ice began to melt, the actual process was fairly simple When a solid...

Largescale Salinity Changes

According to the Woods Hole Oceanographic Institution, tropical ocean waters have become much saltier over the past 40 years, while the polar waters have become much fresher. In addition to this, there is increased warming at Earth's surface, which has increased evaporation over the low-latitude (equatorial) oceans. When water is evaporated, it picks up freshwater, leaving the salt behind. Carried by Earth's circulation patterns, the freshwater moves toward the polar regions where it is...

Hurricanes And Global Warming

A hurricane is an intense tropical storm in which sustained wind speed exceeds 74 miles (119 km) per hour. According to the 2007 Fourth Assessment Report of the IPCC, it is more likely than not (meaning better-than-even odds) that there is a human contribution to the observed trend in the rise of hurricane intensity since the 1970s. The IPCC states that it is likely (more than 67 percent odds) that future tropical cyclones (hurricanes) will become more intense, with larger peak wind speeds and...

Hurricane Katrina And Global Warming

Hurricane Katrina struck Louisiana and Mississippi and other southeastern states in 2005 and wreaked so much havoc and destruction on those areas of the United States that many people have been looking at global warming and wondering if that was the cause. deep within minutes, and continued rising until it was more than 13.5 feet (4 m) deep. An anemometer in Massachusetts recorded sustained wind speeds of 121 miles (195 km) per hour. This reading holds the record today as the second-highest...

Southern Ocean Currents

It is not just currents in the Northern Hemisphere that are affected by global warming. Those in the Southern Hemisphere are faced with the same issues. Around Australia, the southern oceans are also being affected in the same way that those in the north are. As the glaciers and ice sheets melt in Antarctica, they are adding significant amounts of freshwater, which have a negative impact on the formation of the ocean's dense bottom layer of water. This layer is responsible for driving the...

Global Warming As A Trigger

Alley, a professor of geosciences at Pennsylvania State University and an associate at Earth System Science Center at Pennsylvania State University, in an article in Scientific American, Humans are pushing certain aspects of climate closer to the thresholds that could unleash sudden changes in climate . If global warming triggers climate change, humans will be presented with many challenges. Although it is true that some regions will become more habitable with warmer...

The Milankovitch Cycles

Earth's orbit does not remain fixed it varies over time. Major contributing factors to ice ages are these natural variations that occur between the Earth-Sun relationship. There are three natural cycles that have an effect on Earth's climate. The cycles have to do with Earth's axial tilt, its elliptical orbit around the Sun, and its wobble, or precession (the direction the North Pole points). These orbital parameters have cyclic occurrences (periodicities) that range from 22,000 to 100,000...