The National Weather Service reports that the annual average temperature for 2012 was one of the highest on record, in Columbia and across the country. The high temperatures, combined with low rainfall, greatly damaged the wheat and soybean crops in the Midwest this summer; the water level in the Mississippi River has been so low that some stretches have been closed to barge traffic, thereby disrupting the normal transportation of goods and commerce.
We recognize the consequences of this warmer climate in the summer. But the winter consequences might be less noticeable. Lower winter temperatures and precipitation help maintain water levels in rivers and lakes and recharge to the groundwater aquifers. If we have warmer temperatures, we are likely to have less precipitation in the form of snow and greater evaporation, thereby reducing the water stored in the lakes and rivers and recharging the aquifers.
Climate scientists argue that all this is a result of human-induced climate change caused by excessive use of fossil fuels and release of carbon dioxide, while skeptics contend that this is just another episode in the natural variability of climate and not necessarily caused by human intervention.
The naysayers point to the fact that our earth was warmer and had a higher concentration of carbon dioxide at times during its 4.5 billion-year history. This is true.
However, at no point during the earth’s history have we seen such a rapid increase in temperature or in atmospheric concentration of carbon dioxide in such a short period as in the past 50 years. We have seen a 1.3-degree increase in the past 100 years and 0.7-degree increase since 1979. The atmospheric carbon dioxide has increased from 315 to 385 parts per million since 1960.
In the past, changes of these magnitudes took place over 10,000 years or more.
One thing about 2012 is indisputable: No matter what the cause of the warmest year on record, or the massive drought in the United States, whether human influenced or natural, there are millions of acres of failed crops, hardship and suffering to thousands of farm-based families. Just as undeniable is that this hurts our economy.
Professor, USC Department
of Earth and Ocean Sciences