Why would there be a perpetual drought?

The historic droughts of the 1930s Dust Bowl and the 1950s were the results of natural and temporary increases in surface temperatures of the Pacific Ocean. Once ocean temperatures moderated, the droughts subsided.

The perpetual drought that scientists are projecting for the Southwest is not linked to a temporary change in ocean temperatures. Rather, it results from changes in planetary-scale climate dynamics driven by a rise in global average temperatures. As long as global averages remain elevated, the drought would remain.

How will the drought affect North Texas? It looks milder here.

There's no way to tell how any local area might fare. The projections are meant to indicate general trends over decades, not to predict local weather.

Still, the projections do indicate less rain over the region to replenish local supplies. Meanwhile, population increases are driving water demands ever higher.

The natural environment – native wildlife and plants – could be in trouble. Urbanization has already greatly reduced local habitats. Drier conditions could put more stress on natural ecosystems.

Could reducing carbon dioxide emissions slow or stop this perpetual drought?

Not immediately. Climate science indicates that carbon dioxide already in the atmosphere will continue to affect global temperatures for many decades.

However, scientists also say that reducing emissions now would help the planet start its recovery sooner. The longer emissions stay at their current level, the longer any recovery will take. Therefore, reductions today would help future generations.

What kinds of changes might a perpetual drought bring to our lifestyle in Dallas-Fort Worth?

People in North Texas might have to start thinking more like those in Amarillo or El Paso by choosing landscaping and building plans that are adapted to limited water supplies.

Especially during the hottest summer months, about 80 percent of municipal water use in North Texas is for irrigating landscaping. North Texas-native and drought-resistant plants can dramatically reduce water needs, lowering utility bills and easing the strain on water supplies and the natural environment.

In addition, building code changes can reduce water use and boost energy efficiency, reducing greenhouse gas emissions from fossil-fuel power plants. Better building technology is already available.

Would a new Dust Bowl bring about mass migration again? To where?

It's not likely that large numbers of people would take to the highways like the fictional Joad family of John Steinbeck's novel The Grapes of Wrath. However, farming communities that depend directly on surface water supplies could see people leaving for better opportunities.

Problems also could be in store for areas that need rainfall in order to supplement groundwater, such as the Texas Panhandle. If drought conditions proved to be perpetual, those areas could face irreversible changes, especially as aquifers decline.

Is more information available?

A nontechnical version of the drought study is at www.ldeo .columbia.edu/res/div/ocp/drought/science.shtml. The site also has links to the full scientific study.

The Intergovernmental Panel on Climate Change's new global warming reports, including nontechnical versions, are at www.ipcc.ch.

Randy Lee Loftis