Rick Perry requested a major disaster declaration for all but two of the state’s 254 counties. Arizona is now fighting the largest fire in its history. Since 1970, the fire season throughout the American West has increased by 78 days. Extreme droughts in central China and northern France are currently drying up reservoirs and killing crops.

• Melting Ice. An enormous mass of ice, four times larger than the island of Manhattan, broke off from northern Greenland last year and slipped into the sea. The acceleration of ice loss in both Greenland and Antarctica has caused another upward revision of global sea-level rise and the numbers of refugees expected from low-lying coastal areas. The Arctic ice cap, which reached a record low volume last year, has lost as muchthe “public square.” In ancient Athens, it was the Agora. In the Roman Republic, it was the Forum. In the Egypt of the recent Arab Spring, “Tahrir Square” was both real and metaphorical — encompassing Facebook, Twitter, Al-Jazeera and texting.

In the America of the late-18th century, the conversation that led to our own “Spring” took place in printed words: pamphlets, newsprint, books, the “Republic of Letters.” It represented the fullest flower of the Enlightenment, during which the oligarchic power of the monarchies, the feudal lords and the Medieval Church was overthrown and replaced with a new sovereign: the Rule of Reason.

The public square that gave birth to the new consciousness of the Enlightenment emerged in the dozen generations following the invention of the printing press — “the Gutenberg