Though Republicans' anti-environment wing still seems loath to acknowledge it, the consensus on climate change has become virtually undeniable.
It's not just the documentable rise in recent decades of rising temperatures and the severe weather events linked to global warming - unusually fierce storms, unquenchable droughts, vast wildfires, prolonged deluges, historic snowmelt and flooding, and retreating glaciers and rising coastal waters.
It's also the convincing science that connects increasingly alarming weather patterns with the build-up of billions of tons of heat-trapping greenhouse gases into the atmosphere - gases formed by the burning of fossil fuels and the deforestation of the earth's largest forest systems, which have long served as carbon sinks.
A recent report by the National Academy of Sciences clearly states the connection: "Climate change is occurring, is very likely caused primarily by the emission of greenhouse gases from human activities, and poses significant risks for a range of human and natural systems."
As the atmosphere warms, scientists see it pulling more warm moisture into the air, creating more volatile storms and unstable weather patterns, and driving these conditions further north into previously stable areas. The recent historic flooding in the Mississippi river basin, for example, was aggravated by heavy rains on record deep snow packs that were melting earlier than normal, along with unusually heavy rains in the lower parts of the river basin. Tennessee's extremely wet spring fed directly into the dynamics of that rain-on-snow flooding. At the same time, Texas was unusually parched and plagued in virtually every county by record wildfires. The early melt of deep snowpacks is now spawning unusually heavy flooding in Montana.
Other continents now regularly experience similar unstable patterns. Australia's extreme weather has become legend. Russia joined the list with an epic heat wave and unyielding wildfires last year.
Rapid glacier melt in the Himalayas now regularly spawns ever-heavier floods along the vast rivers it feeds, from Pakistan to the west of India to Bangladesh on India's eastern border. Island nations everywhere, but especially the low islands in the Indian Ocean, fear being swamped by rising oceans and polar glacier melt.
The incremental changes in growing seasons, the changes in sustainable crops, flora and fauna, and animal migrations are similarly, and depressingly, documented. Vast and growing dead zones and coral die-off in the earth's precious oceans provide other evidence.
Political denial, however, seems nowhere so evident as in the United States, where Republicans, quite strangely, have unreasonably made political weapons of environmental issues, as if denial of studiously documented climate change has become their political badge of honor. Thus Republicans in Congress not only lambaste EPA rules and the Clean Water and Clean Air acts; they also aggressively urge more intensive drilling and mining for fossil fuels. They eschew energy efficiency initiatives and ridicule its advocates, while lampooning a more rational approach to international accords to restrain global warming.
The political aspect of their denial is apparent: Some of the richest political lobbies, the source of so many big campaign contributions, are those of the petroleum, gas and coal industries.
That linkage notwithstanding, politicians' larger interests should be the national interest in a sustainable economy and a healthier populace. Growing the nation's renewable energy industries and nurturing the civic responsibility of reducing our appetite for fossil fuels makes good economic sense for the future. They should be paramount. Germany and China, for instance, are racing ahead in solar energy - an industry initially created in America - while American solar companies move abroad to find a more welcome investment climate.
Regrettably, congressional Republicans have made it clear that they will not enact programs to reduce global warming. With Washington's inaction, it will remain virtually impossible for the United Nations to reach a binding international accord. That's a sad testament to a narrow national political vision, but it leaves state governments, cities and individuals plenty of elbow room to initiate energy efficiency programs on their own.