TUCSON, Ariz. — THIS summer the tiny town of Furnace Creek, Calif., may once again grace the nation’s front pages. Situated in Death Valley, it last made news in 1913, when it set the record for the world’s hottest recorded temperature, at 134 degrees. With the heat wave currently blanketing the Western states, and given that the mercury there has already reached 130 degrees, the news media is awash in speculation that Furnace Creek could soon break its own mark.

Such speculation, though, misses the real concern posed by the heat wave, which covers an area larger than New England. The problem isn’t spiking temperatures, but a new reality in which long stretches of triple-digit days are common — threatening not only the lives of the millions of people who live there, but also a cornerstone of the American food supply.

People living outside the region seldom recognize its immense contribution to American agriculture: roughly 40 percent of the net farm income for the country normally comes from the 17 Western states; cattle and sheep production make up a significant part of that, as do salad greens, dry beans, onions, melons, hops, barley, wheat and citrus fruits. The current heat wave will undeniably diminish both the quality and quantity of these foods.

The most vulnerable crops are those that were already in flower and fruit when temperatures surged, from apricots and barley to wheat and zucchini. Idaho farmers have documented how their potato yields have been knocked back because their heat-stressed plants are not developing their normal number of tubers. Across much of the region, temperatures on the surface of food and forage crops hit 105 degrees, at least 10 degrees higher than the threshold for most temperate-zone crops.