Drought-damaged corn is seen near Brownville, Neb., Thursday, July 26, 2012. (Nati Harnik/AP)

On Thursday, the U.S. Drought Monitor reported the area of the Lower 48 in severe to exceptional drought expanded from 42 to 46 percent.

By one measure, the Palmer Drought Severity Index, drought conditions - covering 59.6 percent of the contiguous U.S. - are the fourth most extensive since 1895, only topped by 1934 (79.9 percent), 1939 (62.1 percent) and 1954 (60.4 percent) .

Visualization: Drought’s footprint (New York Times)

The effects of these dry conditions on agriculture have been devastating. On Wednesday, the U.S. Department of Agriculture (USDA) documented the seventh straight week of the deterioration of the corn and soybean crop:

During the week ending July 22, the portion of the U.S. corn crop rated in very poor to poor condition climbed to 45 percent . . . Soybeans rated very poor to poor rose to 35 percent..

U.S. grocery prices may rise 3 to 4 percent in 2013 due to the drought’s toll on crops, USDA said.

As grim as these circumstances seem, both economic and climatic data indicate they pale in comparison to certain droughts in the recent and more distant past.

While this year’s drought has surpassed 1988 and 1980 in terms of spatial extent, projections for 2012’s economic damages - estimated at around $12 billion - are substantially lower, says Roger Pielke, Jr., professor of environmental studies at University of Colorado. He blogged:

At $12 billion the 2012 drought would be about 10% of the cost of the 1980 drought and less than that when compared to 1988. The costs of the 2012 drought are sure to rise in coming weeks and months, but they have a long way to go to exceed the standards set in 1980 and 1988.

Meteorologist Steve Bowen of Aon Benfield, a global reinsurance firm told USA Today the 2012 drought could close the gap.

“If the intensity of this year’s drought is prolonged throughout the rest of the summer, it may not be out of the question to experience losses that rival something seen out of those 1980s events,” Bowen said.

While the droughts of the 1980s serve as the basis for economic comparisons with the current drought, the Dust Bowl drought(s) of the 1930s serve as the benchmark for climate comparisons. As extensive as this year’s drought is, it’s not close to rivaling the Dust Bowl in terms of duration, says John Nielson-Gammon, Texas state climatologist.

“At this point, we still have a ways to go before things dry out enough over a long enough period of time to give us another Dust Bowl....talking about the current drought like it’s the start of the next Dust Bowl is like talking about a no-hitter in the middle of the second inning,” Nielsen-Gammon told the New York Times.

And if we dig deeper into long-term climate records, we find even more extreme droughts, blogs Keith Kloor, a science writer. Kloor references a 2007 study on historic droughts in North America over the last 1,000 years, extracting this excerpt:

the occurrence of past “megadroughts” of unprecedented severity and duration, ones that have never been experienced by modern societies in North America. There is strong archaeological evidence for the destabilizing influence of these past droughts on advanced agricultural societies, examples that should resonate today given the increasing vulnerability of modern water-based systems to relatively short-term droughts.

So when we consider this year’s drought in the context of recent and more distant history - the glass is half full, or half empty. On the one hand, the situation could be a lot more dire. On the other hand, who says it won’t get that way? On how much worse the drought will get, the verdict is still out...