Solar Radiation

Past Present and Future

Pleistocene And Recent Sea Level Curves

Prediction and Mitigation of Future Climate Change Previous chapters in this book have described different climate-forcing mechanisms and shown how Earth's climate has been constantly changing since the planet formed. Climate-driving mechanisms include natural variations in Earth's orbit, plate tectonics, supercontinent cycles, massive volcanism, changes in solar luminosity, and changes in the atmosphere that alter its capacity to store and reflect heat. For the past 4.5 billion years, Earth's...

Structure of the Atmosphere

Solar Radiation Netherland Climate

The atmosphere is comprised of a sphere around Earth consisting of a mixture of gases, held in place by gravity. The most abundant gas is nitrogen (78 percent), followed by oxygen (21 percent), argon (0.9 percent), carbon dioxide (0.036 percent), and minor amounts of helium, krypton, neon, and xenon. Air pressure, or atmospheric pressure, is the force per unit area (similar to weight) that the air above a certain point exerts on any object below it. Atmospheric pressure causes most of the...

Supercontinents and climate

How Many Supercontinents Have There Been

The motion of the tectonic plates periodically causes most of the continental land masses of the planet to collide with each other, forming giant continents known as supercontinents. For much of the past several billion years, these supercontinents have alternately formed and broken up, in a process called the supercontinent cycle. The last supercontinent was known as Pangaea, which broke up about 160 million years ago to form the present day plates on the planet. Before that the previous...

Sudden draining of glacial lake terentiev BY glacier Retreat

Solar Radiation Glacier

The Columbia Glacier of south-central Alaska is a tidewater glacier surging at nearly 80 feet (24 m) per day out of the Chugach Mountains into Prince William Sound, releasing two cubic miles (8.3 km3) of ice every year into the Gulf of Alaska. It is one of the world's fastest-shrinking glaciers. The glacier presently covers an area about the size of Los Angeles but has lost nearly six square miles of area (15 km2) since the 1980s. With current rates of ice loss, it will lose another six square...

IS there a drought iN Las Vegas

Island Heightmap

Much of the desert Southwest region of the United States was settled in the past century following a century of historically high rainfall. Towns and cities grew, and the Bureau of Land Management diverted water from melting snows, rivers, and underground aquifers to meet the needs of growing cities. Some of the country's largest and newest cities, including Phoenix, Tucson, Denver, Las Vegas, Los Angeles, San Diego, and Albuquerque, have grown out of the desert using water from the Colorado...

Shrinking Glaciers

At the opposite end of climate extremes from deserts, Earth has experienced at least three major periods of long-term frigid climate and ice ages, interspersed with periods of warm climate. Most glaciers around the world are currently shrinking at rapid rates as a result of global warming. The earliest well-documented ice age is the period of the Snowball Earth in the late Proterozoic, although there is evidence of several even earlier glaciations. The late Paleozoic saw another ice age lasting...

Observed Shortterm climate changes and Their Effects

Melted Snow Cornfields

Instrumental and ice core records show that several components of the atmosphere and surface have significant changes in recorded climate history. First, the concentration of greenhouse gases such as carbon dioxide has increased dramatically since 1850, causing an increase in the atmospheric absorption of outgoing radiation, warming the atmosphere. Aerosols, which are microscopic droplets or airborne particles, have also increased, and these have the effect of reflecting and absorbing incoming...

Thermohaline circulation and climate

Thermohaline Zirkulation

Variations in formation and circulation of ocean water may cause some of the thousands of years to decadal scale variations in climate. Cold water forms in the Arctic and Weddell Seas. This cold salty water is denser than other water in the ocean, so it sinks to the bottom and gets ponded behind seafloor topographic ridges, periodically spilling over into other parts of the oceans. The formation and redistribution of North Atlantic cold bottom water accounts for about 30 percent of the solar...

Role of the Atmosphere in climate change

Interactions between the atmosphere, hydrosphere, biosphere, and lithosphere control global climate. Global climate represents a balance between the amount of solar radiation received and the amount of this energy that is retained in a given area. The planet receives about 2.4 times as much heat in the equatorial regions compared to the polar regions. The atmosphere and oceans respond to this unequal heating by setting up currents and circulation systems that redistribute the heat more equally....

Climate and Seasonality

Variations in the average weather at different times of the year are known as seasons, controlled by the average amount of solar radiation received at the surface in a specific place for a certain time period. The amount of radiation received at a particular point on the surface is determined by several things, including the angle at which the Sun's rays hit the surface, the length of time the rays warm the surface, and the distance to the Sun. As Earth orbits the Sun approximately once every...

Major Volcanic Eruptions and Climate Change

Henry Hudson Where Sail Map

Some of the larger, more explosive volcanic eruptions that the planet has witnessed in the past few hundred years have ejected large amounts of ash and finer particles called aerosols into the atmosphere and stratosphere, and it may take years for these particles to settle back down to Earth. They get distributed about the planet by high-level winds, and they have the effect of blocking out some of the Sun's rays, which lowers global temperatures. This happens because particles and aerosol...

Global Climate Changes That Lead to Droughts and Desert Formation

Thar Desert Latitude

As the global climate warms, some climate belts, especially deserts, are expanding to higher latitudes, displacing once-fertile regions. Deserts are the driest places on Earth, by definition receiving less than one inch (2.5 cm) of rain per year. Most deserts are so dry that more moisture is able to evaporate than falls as precipitation. At present about 30 percent of the global landmass is desert, and the United States has about 10 percent desert areas. With changing global climate patterns...

Global warming holes

Even though the global climate has been changing for billions of years by natural causes, it is clear that human activities are also presently changing the global climate, primarily through the introduction of greenhouse gases such as CO2 into the atmosphere while cutting down tropical rain forests that act as sinks for the CO2 and put oxygen back into the atmosphere. The time scale of observation of these human, or anthropogenic, changes is short, but the effect is clear, with a nearly one...

Astronomical Forcing of the climate

Medium-term climate changes include those that alternate between warm and cold on time scales of 100,000 years or less. These medium term climate changes include the semi-regular advance and retreat of the glaciers during the many individual ice ages in the past few million years. The last 2.8 Ma have been marked by large global climate oscillations that have been recurring at approximately a 100,000 year periodicity at least for the past 800,000 years. The warm periods, called interglacial...

Northern Hemisphere tilted toward the Sun at aphelion

Ciclos Milankovitch

Orbital variations that lead to variation in the amount of incoming solar radiation, including eccentricity, obliquity (tilt), and precession of the equinoxes the past two million years alone, Earth has seen the ice sheets advance and retreat approximately 20 times. The climate record as deduced from ice-core records from Greenland and isotopic tracer studies from deep ocean, lake, and cave sediments suggests that the ice builds up gradually over periods of about 100,000 years, then retreats...

Causes of Shortterm climate change

The Intergovernmental Panel on Climate Change issued new reports in 2007 which revealed that concentrations of some greenhouse gases have increased dramatically as a result of human activities, mostly starting with the early industrial revolution around 1750 and accelerating in the late industrial revolution around 1850. The greenhouse gases that show the most significant increases are carbon dioxide, methane, and nitrous oxide. Carbon dioxide (CO2) is the most significant anthropogenic...

Further Reading and Web Sites

Geomorphology of Desert Environments. Norwell, Mass. Kluwer Academic Publishers for Chapman and Hall, 1994. This is a comprehensive textbook describing the wide range of landforms and processes in desert environments. Ahrens, C. D. Meteorology Today, An Introduction to Weather, Climate, and the Environment. 6th ed. Pacific Grove, Calif. Brooks Cole, 2000. An introductory text for freshman college level on meteorology, weather, and climate. Ashworth, William,...

Natural Longterm Climate Change

Atmospheric Evolution, Plate Tectonics, Supercontinents, and Solar Evolution There are many controls that operate to change Earth's climate on different time scales. Some cause the global temperature to rise and fall with a time interval between warming and cooling influences of billions to hundreds of millions of years others operate on millions to tens of millions of years time frames. These very slowly operating forces include the very slow evolution of the composition of the planet's...

Carbon sequestration

Carbon dioxide is one of the major greenhouse gases whose rise in concentration in the atmosphere is responsible for the global rise in temperature during the past 200 years. Carbon dioxide is produced by many processes, both natural and by humans. It is the rapid rise in human, or anthropogenic, CO2 that is thought to be mainly responsible for the current episode of global warming. To reduce global warming, it will be necessary to reduce the release of CO2 to the atmosphere, so that the system...