## The Scientific Basis

The fundamental climate change equation concerns the exchange of heat in the atmosphere. Heat is transmitted to the atmosphere from radiation from the Sun. Some of the heat energy is absorbed and some reflected. The amount of energy reflected depends on the albedo of the surface and can be affected by variables such as color, elevation, and shape. If more energy is retained than reflected, then the atmosphere will increase in temperature, but temperatures will decrease if the opposite is true. This equation is affected by the composition of the atmosphere, among many other factors. While the equation appears navigable, in fact the complexity of the atmosphere is such that it is extremely difficult to write accurately.

Scientists in the 19th century attempted to create the equation using the mathematical and analytical tools available. At that time, the number of atmospheric observations and the extent of their coverage were very limited. As observations improved in quality and quantity, the ability to model the equation improved. Scientists realized that the wind system was not consistent acround the world and, consequently, what happened in one part of the world was different from another part of the world, even with similar initial conditions. Consequently, it became a logical step to divide the surface of the world into smaller subsections on a grid basis and attempt to solve the equations and, hence, predict the weather, for each grid square.

However, these efforts failed as it became clear that solutions required contemporaneous computational power. It was practically impossible to predict the weather by solving equations for grid squares more quickly than weather elapsed in real time. Consequently, new forms of modeling were considered.

Serendipitously, World War II provided a significant boost to climate modeling because, for military purposes, the extent and range of atmospheric observations increased enormously. As the war gave way to the Cold War, that level of observation continued and, in some ways, intensified. The launching of satellites and attendant technology was also beneficial in this respect. These observations helped to reveal the global patterns of wind and wave circulation and helped to identify variations across the globe and the reasons for them.

Scientists had abandoned the idea of using a single equation (no matter how complex) to represent the whole atmosphere on practical grounds; now there was further proof that such an approach was flawed on scientific grounds. In the years since then, scientists have approached the problem by treating the relevant individual variables with increasing sophistication. For example, the first generation of models included as a variable the Earth's surface, which was posited to have properties that were an amalgam of both land and water. While this approach would give an approximate result at the global level, at lower levels the results would vary from real life conditions.

Subsequent iterations of models have increased the sophistication of the treatment of the surface by dividing land and sea areas, with different types of elevation and of albedo, as these clearly have an impact on the circulation of the atmosphere. In the third generation of models, land is now treated as having up to three levels: the base level of the ground itself, a possible layer of snow or ice overlaying the ground, and a possible third layer of vegetation. Because these conditions can change quite rapidly, it is clear that constant surveillance of both the atmosphere and the Earth's land cover are required. Areas such as the Amazon rainforest, for example, are being rapidly deforested; this can have a significant impact on how models should be constructed, since it has an impact upon the circulation of the atmosphere. For example, stubble burning in Indonesia annually produces a heavy pall of smoke over much of island Southeast Asia, affecting the atmosphere to the extent that it should be considered in climate models. Volcanic activity is less predictable, but can also have a strong impact upon the atmosphere.