Future of the Earth

Why The Atmosphere Flows

Thique Culture Religieuse

We live at the bottom of a layer of gas that covers the Earth the atmosphere. The Earth orbits the Sun about every 365 days and spins on an axis that is tilted about 23 degrees from the axis of its elliptic orbit (Figure 1.2). It is this tilt that is responsible for the change of seasons. When the northern hemisphere is tilted towards the Sun, it is northern hemisphere summer, and likewise for the southern hemisphere (Figure 1.2). FIGURE 1.1 The Sun-Earth system. The Earth is spinning on its...

Jet Streams And The Weather

Now, clearly, we are speaking here of average atmospheric and oceanic motions in some sense. There are many smaller scale motions that are very important, for example, sea breezes or the flows over mountainous terrain. Two very important features of atmospheric motions that I have not mentioned are the atmospheric jet streams. Jet streams are relatively narrow, very high velocity air currents that exist high in the atmosphere.5 Before about the middle of the 20th century, little was known about...

Why The Ocean Flows

In part, the ocean surface is driven by the winds.2 For example, look at a picture of the flow pattern in the north Atlantic Ocean Figure 1.3 . The trade winds blow the ocean surface water toward the west at low latitudes, whereas the westerlies blow the water toward the east at midlatitudes. At the same time, the rotation of the Earth forces the flow to pile up along the western boundary of the ocean the eastern boundary of the continent , producing the Gulf Stream. Easterly toward the west...

Early ideas about carbon dioxide

A number of scientists realized that the presence of CO2 and water vapor in the atmosphere enhanced the warmth of the Earth by allowing solar radiation to penetrate the atmosphere while trapping the lower temperature given off by the Earth. As far back as 1824, the great French mathematician Fourier4 had described the greenhouse effect of Earth's atmosphere, comparing it with a glass covering a container. FIGURE 2.1 The top panel shows the increase in CO2 between 1750 and 2000. The dots are...

The Global Energy Balance

Global Energy Balance Surface

The Earth is heated by radiation from the Sun. In turn, an equal amount of radiation must leave the top of the atmosphere for the Earth to maintain a balance so that it does not either heat up or cool down. The interaction of radiation with the atmosphere and the Earth's surface is very complicated. However, we can get a general picture of it by summarizing the Earth-atmosphere energy balance on average for the whole globe i.e., global average Figure 3.1 .1 Suppose that 342 W m2 of radiant...

Other Greenhouse Gases

The atmospheric concentrations of other important greenhouse gases have also been increasing.11 The concentration of methane, which was fairly constant from 1000 to 1800, has doubled since 1800. Nitrous oxide (N2O) has also increased since 1800, being nearly constant back to 1000. Why has the atmospheric concentration of methane increased This we do not know for sure. Rice paddies emit methane into the atmosphere. The increase in rice agriculture has probably contributed. Cattle and other...

Agriculture And World Food Supply

Obviously, predictions concerning the future of agricultural productivity depend on which of the various scenarios one uses. The ability of civilizations and agriculture systems to adapt to climate change also depends on such things as population growth, access to information, farming technology, and the ability of the people and the government to afford irrigation and fertilizer, among many other things. It also depends on the crop varieties that are grown in different locations and on the...

Details ofSRES Scenarios

The Intergovernmental Panel on Climate Change issued a special report on emissions called Special Report on Emissions Scenarios (SRES) that outlined several possibilities for future emission of CO2. Several are described below. SRES A1 A future world of very rapid economic growth, low population growth, and rapid introduction of new and more efficient technology. Major underlying themes are economic and cultural convergence and capacity building, with a substantial reduction in regional...

Introduction

On June 23, 1988, Doctor James Hansen testified before a congressional committee that he believed with a high degree of confidence that the greenhouse effect had already caused global warming. After that testimony, there has been an increasingly acrimonious debate between those who see the problem as the most serious one facing humans today and those who refuse to believe there is any problem at all. Accusations and counteraccusations have spilled over into such august publications as Nature...