There has been a lot in the news about climate change. Most people do not understand the issue. It is correct that climate has always been changing.

Paleodimatologists have studied climate over the past several millenia and it is getting warmer. It has not been a constant rise in temperature, as there have been a couple mini ice ages along the way, but the general long-term trend has been warming. The concern is about the rate of change. Past changes have occurred relatively slowly. Scientific studies indicate that the rate of change has recently accelerated.

Civilization tends to adapt to show changes. Most infrastructure is designed to last for less than 100 years or so before rehabilitation or replacement. Climate changes can easily be accommodated in the process. Plants and animals tend to adapt to slow changes, and even people adapt. Most people are aware that if you are born and raised in a particular climate, you are more adapted to that climate.

Fred E. Camfield lives in Vicksburg. He is an executive committee member of the International Association for the Physical Sciences of the Oceans. E-mail reaches him at fecamfield@bellsouth.net.

The problems occur when significant climate changes occur over a relatively short period of time, e.g., during a person’s lifetime. Rapid changes can overwhelm civilization’s ability to adapt. Putting aside all the controversy about various interpretations, there is a consensus that the rate of global warming has increased. If you lived somewhere near mountains that had glaciers you would have noticed that the glaciers are shrinking. That is the case, for example, in the Pacific Northwest. Areas like my hometown in Washington State get their water supply from glacial melt, which requires a winter snowpack. If they get winter rains instead of snow as they seen in recent years, they end up with spring floods and a summer drought. My brother worries about the coming summer’s water supply. It would take significant time and money to develop alternate means of ensuring adequate water.

The water supply is only one issue. Scientists have been monitoring the Greenland Ice Cap. It has been estimated that a complete melting of that ice cap would raise global water levels by 6 feet. That is significant to coastal areas worldwide, and would put some smaller island nations underwater. An additional concern is the melting of Arctic permafrost. Melting permafrost would allow the decay of embedded plant material and release large amounts of methane. Methane, like carbon dioxide, is a greenhouse gas. Then there is the problem of increased carbon dioxide causing ocean acidification. That affects fisheries productivity.

Of perhaps more interest to local residents is the question of climate variability. Anyone who has been around very long knows that the climate varies from season to season and from year to year. There are hot years and cold years, wet years and dry years. Back around 1900, one of my grandfathers had a farm in South Dakota. He had moved there from Michigan along with his parents and various others. He had a couple of very good years, then was wiped out by a drought. Recent studies have shown that ocean temperatures in the North Atlantic affect rainfall in South Dakota. Scientists are still studying the cause and effect relationships between global climate and local climate variability.

This winter has seen some weird weather. The Pacific Northwest has had unseasonably warm weather that required the organizers of the Winter Olympics to haul in snow. In the South Atlantic region, we have had rare snowstorms extending from Texas to Florida. People going to Florida to find warm weather would have done better going to Vancouver. There have been unusual heavy rains and flooding in Arizona, and droughts in areas that expected rain.

Global warming causes changes in the ocean-atmosphere system. That includes changes in ocean temperatures and currents, and changes in associated atmospheric conditions, e.g., location of the jet stream, frequency of storms, and atmospheric temperature and moisture content. Most people have heard about El Niño and NOAA maintains a Web page that discusses that effect in detail (found at www.pmeLnoaa.gov/tao/elnino/nino-home.html). There are many other effects. Additional information about climate can be found at the government’s new Web site, www.cimate.gov, or at other sources. The relationship between global warming and local weather is very complex and difficult to model. Many scientific investigations are working on establishing those relationships. An example is a new Working Group of the Scientific Committee on Oceanic Research (www.scor-int.org) that will look at the climate effects of the Arguihas System. The Arguihas Current is off the southeastern coast of Africa which may seem like a long ways away from Vicksburg, but global systems are all interconnected. The International Union for Geodesy and Geophysics (www.iugg.org) addresses issues through a number of its Associations dealing with oceanography, atmospheric science, and cryospheric sciences (those are the snow and ice scientists).

So what causes global warming? Part of that is caused by natural processes. Natural processes can have a tipping point where once they are put in motion, they continue in motion until something causes a reversal. Some people worry about a tipping point that will set off another ice age or mini ice age. Another component of warming is anthropogenic (a fancy word for what people cause), and includes effects ranging from destruction of rain forests to industrial pollution and motor vehicle exhausts. The anthropogenic part is what all the debate is about.

People have been burning hydrocarbons since prehistory. Initially people used wood, then peat and coal when wood supplies ran low, then petroleum products. As poplulation has expanded, the burning of hydrocarbons has expanded. That has been aggravated by the disposal of waste material. When I was back home one year, I encountered an ugly yellow smoke plume extending across the horizon. The source was a waste burner at a sawmill, and the plume extended for 50 miles or more. There are similar problems from the burning of logging slash, and from the clear and burn practice in some developing countries to open up farmland.

Air pollution has also been aggravated by the industrial age producing fumes from mills, and by the emergence of affluent societies using motor vehicles. The problems are global, and fixing them will be expensive. It requires joint action, but everyone wants someone else to take responsibility. So, we have a lot of finger-pointing. The scientists study the complexities of cause and effect. The politicians debate policies, laws, and treaties. People talk about fuel efficiency and curbing emissions. Nuclear power is an option, but there is an anti-nuclear phobia (not i my backyard).

That’s where we are. There is still a lot left to do.