The big environmental challenge facing us is climate change. Most people have at least a vague idea of what is happening, but very few have a good sense of the nature and extent of the potential consequences. In simplest terms, two of the gasses released by our agricultural and industrial activities, methane and carbon dioxide (CO2), are potent “greenhouse” gasses (GHGs), which trap heat in the atmosphere that would otherwise be radiated into space. As these gasses accumulate in the atmosphere and it heats up, other effects occur. Some, such as increased photosynthesis in the presence of CO2, would tend to remove CO2 and counterbalance the warming. Others, such as the melting of ice and snow, increase heat absorption and accelerate the warming effect.
Fifteen years ago, it was possible to argue a) that the data showing atmospheric warming might be an artifact of poor measurements and inconsistent records, b) that natural counterbalancing effects might well neutralize the effects of increased GHGs, creating a stable situation, and/or c) that the consequences of warming might be beneficial or neutral to human society. Since then, however, massive amounts of information have been acquired from satellites, ice cores, ocean sediments, and many other sources, and the analysis of this data now leaves very little room for scientific argument: the air and the oceans are heating up as a result of human activity, the average temperature at the poles is rising even faster than expected, and the consequences of continued, unlimited GHG emissions will be global temperature rising by 3 degrees Celsius or more, which will be economically and environmentally disastrous.
The specific consequences of warming for any particular location are hard to model, but the basic outlines are now reasonably clear. Most people assume that an average global increase in temperature of 2˚ Celsius (4.2˚ Fahrenheit) would mean that a typical day would be that much warmer everywhere in the world, but that’s not true. Temperatures would hardly change at all at the equator. Instead, most of the temperature increase would be concentrated in a warming of the oceans and temperate zones, and a major rise in temperatures at the poles, melting the polar ice, raising sea levels, and, most importantly, severely disrupting the existing pattern of ocean currents and atmospheric circulation that controls our climate and weather.
In simple terms, a warmer climate will be a much less predictable, much more violent, and much more energetic climate. Centuries of experience with rainfall, storms, hurricanes, and tornadoes will become unreliable. Already, annual fire seasons are getting worse in the US and elsewhere. Flash floods are becoming more common and doing more damage. Droughts, floods, blizzards, and windstorms are becoming increasingly common. Farmers who are used to getting a reliable amount of rainfall will increasingly have to deal with too much or too little. Our cities and our magnificent internal waterways will increasingly be flooded or strangled by too much or too little water.
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