Dan Reicher, director of climate change and energy initiatives at Google, summed up the effort to pass a U.S. climate-change bill as an “epic, epic struggle.”

This summer, the U.S. House of Representatives passed a climate-change bill that aims to reduce carbon emissions and make investments in renewable energy. The Senate has recently taken up the task of stitching together a bill and, well, the positive and the frustrating aspects of the American political process are on full display. Climate-change legislation languishes and wallows in several Senate committees, and the vested interest of the few hold it captive. On Wednesday, top Democrats said there likely won’t be any climate-change legislation until next year.

This legislative impasse has an immense, tragic importance for our generation.

It would all be inconsequential if it wasn’t absolutely urgent for the United States to act and act soon. In December, 192 nations will meet in Copenhagen to forge one of the most difficult international agreements ever — a comprehensive climate-change treaty. The Copenhagen conference is seen by many as one of the last opportunities for the world to lock in a process that reduces greenhouse gases in time to stave off disaster.

Copenhagen will not only be a historic gathering of world leaders, scientists, and thought leaders — it’ll be a critical one as well. The time that remains — the window that we have for a climate-change deal for the world’s 6 billion people — is closing.

It’s an understatement to only suggest that the stakes are high. But success in Copenhagen hinges largely on what the United States will do domestically and will commit to in Copenhagen. If American negotiators head into Copenhagen without a clear domestic position, other countries are unlikely to follow suit on a binding deal.

For all our trumpeting of American leadership in the world — and our almost instinctive belief in American exceptionalism — on the most critical issue facing the world today, the world’s greatest power is missing.

But why? What’s holding us back?

Right now, there are 2,810 climate lobbyists registered in Washington, D.C. That’s five lobbyists for every member of Congress. In the lead-up to the House vote on June 26, more than 460 new businesses and interest groups lobbied Congress on its climate-change legislation, according to the Center for Public Integrity, a nonprofit investigative journalism organization. We’re unable to decipher how much money they actually spent on specific climate-change lobbying efforts, because businesses don’t have to detail their expenses for each separate issue they are lobbying in Congress. But say we assume that the issue consumed only 10 percent of their time. That amount comes to more than $27 million in the second quarter, according to the same group.

Not all of these efforts are aimed at defeating climate change. But a lot of them are, and even more are aiming to slow down the pace of change and dilute the level of carbon-reduction targets that scientists say are necessary. Many of the global-warming deniers of the ’90s now argue that climate-change legislation will reduce jobs and hurt the economy. While embracing global warming as fact, their lobbying efforts focus on making sure they can still make a profit in the old-energy economy.

The election of President Obama brought hope in the U.S. and foreign capitals around the world that we would renew our commitment to work multilaterally to address the world’s toughest problems.

Change is in fact hard.

And on the defining challenge of this generation and the next, it is the efforts of those vested in the status quo that are largely inhibiting progress. It’s a generational failing or, more harshly, a generational atrocity.

How old will you be in 2050? By then, those who are blocking progress now probably won’t be alive. But you will be, when the consequences of our inaction on climate change will really come to bear.