Global Warming

Introduction

The phrase global warming refers to a phenomenon in which the Earth's surface temperature increases from its long-term averages generally because of an atmospheric blanket of greenhouse gases (GHGs; primarily carbon dioxide, methane, and chlorofluorocarbons) that serve to trap reradiated solar energy from escaping into space. This blanket of greenhouse gases is responsible for providing Earth a generally temperate, stable, and life-sustaining climate. In common parlance, global warming is often used interchangeably with climate change. In the present context, though, it is used in a more limited sense as a driver of global climate change.

Thesis statement: Global warming the effects of a man made possible catastrophe, Can we stop the cycle??

Discussion

Causes and Effects

The duration of our current interglacial period will be determined in no small part by the extent of warming caused by the greenhouse effect. A closely related concept is albedo, a measure of the extent to which a surface reflects light from the sun. Dark-colored objects (e.g., oceans and forests) have low albedo values because they absorb a greater percentage of solar energy than do lighter-colored bodies; light-colored objects (e.g., glaciers and ice caps) have high albedo values, as they reflect a greater proportion of solar radiation.

A change in terrestrial albedo—resulting from the melting of a glacier to reveal the darker land mass underneath or from human urbanization or conversion of forests to agricultural uses—can have a significant effect on radiative forcing by increasing the amount of solar energy absorbed in the visible spectrum and reradiated as heat. A decrease in albedo generally correlates with an increase in radiative forcing and global mean surface temperature. Radiative forcing is a measure of the net solar and infrared radiation trapped in the Earth's atmosphere. Because of its direct relation to global mean surface temperature—positive forcing drives warming, negative forcing drives cooling—scientists use it to study the effects of natural and anthropogenic causes of global warming. Natural sources of radiative forcing include the earth, clouds, and naturally occurring greenhouse gases. Anthropogenic contributions to radiative forcing include greenhouse gas (positive forcing) and particulate (negative forcing) emissions caused by human activity, and land use changes resulting from human development activities.

One consequence of the melting of so much frozen fresh water from the Arctic ice is the potential disruption of the oceanic thermohaline circulation driven by water temperature and salinity. In the Atlantic Ocean, this circulation is responsible for the Gulf Stream, which delivers warmer, equatorial waters to northern Europe, moderating its mean surface temperatures and climate.

Scientists are concerned that the melting of the Greenland ice cap caused by global warming will interfere with the Gulf Stream by dumping enormous volumes of fresh water into the North Atlantic, thereby decreasing the salinity (and density) of waters that normally sink to the ocean floor and return to the Southern Hemisphere. At the rate it is presently occurring, global warming will have a significant effect on environmental and human systems over the next century and beyond. Increased surface temperatures will result in sea level ...