The current drought has caused fire, troubled farmers and left UA researchers hoping for rain.

Although precipitation has been predicted throughout this week and pouring rain hit the UA campus yesterday, the last official measurable rainfall in Tucson fell Mar. 14, 111 days ago, according to the National Weather Service.

"From late fall to the present has definitely been one of the driest years of this century," said David Meko, a research specialist with the UA Laboratory of Tree Ring Research. He said a drought is defined by its length and intensity, and it is too early to put this one into perspective.

In the early 1950s, there was a drought throughout the Southwest, worse than the "dustbowl" droughts of the 1930s, Meko said. He said the century has been marked by big swings in rainfall. From 1900-1920, a wet period soaked the Southwest but was then followed by drought, Meko said.

A dry phase in the natural wind pattern, called La Nina, caused the dryness this winter, said Thomas Swetnam, a professor of dendrochronology with the Laboratory of Tree Ring Research. Dendrochronology is the science of dating climatic changes by studying the growth of tree rings.

Swetnam said the previous two or three years produced more rain than usual. He said periods of drought historically follow rainy periods.

Tree ring records indicated the potential for significant forest fire danger this year, Swetnam said. He said the danger was so great, the lab issued a warning to Southwestern fire prevention officials.

"What we see are particular years when fires are synchronized on most mountains," Swetnam said, "We can see that fire years are well correlated with drought."

In response to the warning and its own findings, the U.S. Forest Service allocated more funds to fire management and added manpower, Swetnam said.

Swetnam said if the monsoon fails to bring rain, like last year, more fires could occur.

"A week of rain, and the situation would be much improved," Swetnam said.

The current drought has hit some farmers and ranchers hard, said Diana Liverman, director of the Latin American Area Center. She said the drought's effects on an individual farmer or rancher depends on his or her economic security before the drought.

When grazing land dries up, ranchers face serious problems, Liverman said. She said ranchers who seed the land can sustain their herds, while others are forced to sell their cattle at reduced prices.

Location of grazing land is also important, Liverman said. For example, if the land is hillside, it is less likely to retain water.

Liverman said farmers with poor or no irrigation systems and those relying on their farming income are in particular jeopardy.

The natural desert flora is also affected, said Lawrence Howery, a rangeland research specialist with the School of Renewable Natural Resources.

Though drought effects depend on the topography, or lay of the land, much of the southwestern vegetation could still be damaged, Howery said.

The vegetation needs a good monsoon season to begin the recovery process, Howery said. Because of the drought's severity, it is difficult to determine the "lag time" between rain and recovery.

Another question scientists are looking at is if human activity is causing this climate problem.

The answer, said Lisa Graumlich, director of the Institute for the Study of Planet Earth, is "a very cautious 'yes.'"

Her opinion is shared in the Intergovernmental Panel on Climate Change's findings. The panel includes contributions from hundreds of scientists worldwide, she said.

"It is the aggregate of human activity that's affecting the makeup of the atmosphere," Graumlich said. Atmospheric changes affect the world, she said.

"In the future we will see more climate variability with more intense anomalies," Graumlich said.

Though southern Arizona ranchers are suffering, she said, there are some suffering less.

A group of ranchers, in association with several scientists, have created a "grass bank," Graumlich said. "Grass banks" leave a reserve of good grazing land in times of drought.

"If I had anything that I really urge people to do is stop thinking of changes in climate as acts of God that are emergencies," Graumlich said. She said plans should be established to help people adapt to climatic change.

Meko said the deficit of rainfall and hot conditions are stressful on the environment, but that human activities do not cause the stress.