Two weeks ago, a chunk of ice the size of Manhattan broke off from the Wilson Ice Shelf in West Antarctica. Since most of it was already floating, it won't affect world sea levels very much, like the ice that sticks up above a glass of ice water. But with that shelf out of the way, more ice will slide off Antarctica, and that will raise world sea levels over the coming years. There's probably nothing we can do in the short range to stop it.

The snow lines on Mount Kilimanjaro in Africa and Mount Fuji in Japan are receding further up the mountain each year. All the glaciers in Glacier National Park and their counterparts in South America will probably be gone by 2020. That snow melt all runs down to the sea. And the greenhouse gases already in the atmosphere will finish the task.

If we continue our ways, some geographers predict a quarter billion climate refugees flooded out by rising oceans during this century.

The Nebraska Panhandle is into its eighth year of drought. Rates for storm insurance in hurricane-prone areas such as the U.S. Gulf Coast and Florida have risen as much as six-fold in recent years. Most climate scientists believe that global warming contributes to more erratic weather. Bad as it was, Katrina may have been only a sign of things to come.

The United Nations Panel on Climate Change (UNPCC) issued its first consensus report in 1989, and three major reports since. Each report sets forth a range of possible scenarios if greenhouse gases continue to rise. In each succeeding report, the conditions found 5 years later have pretty much matched the gloomiest scenario in the previous report. For example, the most recent report, based on 2005 data, warned of drastic melting of Arctic Sea ice and Greenland's glaciers. In both 2006 and 2007, the melting of Arctic Sea ice and Greenland's glaciers exceeded the worst predictions.

Most climate scientists believe that further damage is already locked in. Further rises in sea level, for example, or the permanent loss of thousands of species of plants and animals will result from greenhouse gases already in the atmosphere. But most of them also believe that there is still time, just barely, to change our habits and prevent catastrophic losses that would make the world unlivable. A few believe we have already passed the "tipping point."

Most of us can name helpful habit changes that we have made, or can adopt. We also know about further changes that are necessary in the foreseeable future. The easiest gains are from conserving simply using less energy.

Transportation accounts for about one-third the energy we use.

Walk! It's good for you.

Congress last fall set new auto fleet performance standards at 35 miles per gallon by 2015. Good! But Japan has already achieved 40 mpg.

Both federal and state governments encourage biofuels. Ethanol from grain represents only a modest gain over gasoline in use of fossil fuels, but it's a step in the right direction. Soy biodiesel represents a much bigger gain. Cellulosic ethanol will represent an even larger gain, especially if it is safely harvested from marginal cropland and/or waste. Among the technologies in view, hybrid and electric cars, powered by electricity from renewable generation, hold the greatest promise. Estimates of energy savings run as high as 80 percent without reducing miles driven.

Another third of our energy is used in heating and cooling buildings. Again, the easiest and quickest gains are from the energy we don't use. For new buildings or remodeling, we need to keep raising standards for insulation. Solar collectors, heat pumps (especially with deep well installations), strategic use of windows, shades and trees can all reduce energy use.

Coal has a terrible "carbon footprint." Texas and Kansas have deferred or cancelled plans for new coal-fired electrical plants. Nebraska Public Power is moving in the right direction with the development of new wind farms, although not as quickly as I'd prefer, considering Nebraska's potential for wind generated electricity. Southern Power District, on the other hand, is dragging its feet because "electricity from coal is cheaper." True, but only if no cost is assigned to the carbon dioxide pollution.

If Hastings completes its coal-fired Whelan 2 power plant, with the support of Grand Island through a power purchase contract, they'll be stuck with an obsolete plant through the lives of their grandchildren. U.S. Senators Dodd and Warner have proposed a "cap and trade" plan for new fossil fuel plants, similar to plans already in place in Europe. Such carbon offset contracts are trading in Europe for about $30 per ton of carbon. Whenever we adopt this or some other form of carbon tax, coal-fired electricity will become more expensive than less polluting alternatives.

In every facet of our life, little things like using compact fluorescent bulbs and turning off lights and unused appliances count up. Pay attention to the Energy Star ratings for all new appliances.

In short, our present habits of energy use are leading us toward collapse. Dramatic energy savings are possible without seriously impairing our lifestyles. Simplifying our lives would be good for us.

Don Reeves is a Quaker from Central City. In a continuing series, Central Nebraska Concerned Citizens take up topics that affect families in Central Nebraska and the world. Comments and suggestions for future topics may be sent to: CNCC07@hughes.net