U.S. Secretary of State John Kerry delivered an impassioned plea on Thursday to climate negotiators meeting in Lima, Peru, to put aside their concerns over individual responsibility, and to focus instead on pitching in to do all they can to forge an international agreement to slow – and eventually reverse – the effects of climate change.

“I know how angry some people are about the predicament they’ve been put in by big nations that have benefitted from industrialization for a long period of time,” Mr. Kerry told an audience that filled to capacity the sweltering press room.

“But the fact is we simply don’t have time to sit around going back and forth about whose responsibility it is to act. Pretty simple, folks: It’s everyone’s responsibility, because it’s the net amount of carbon that matters, not each country’s share.”

His comments came on the second-to-last scheduled day of the two-week Conference that is intended to lay out the framework of a pact to be passed next December in Paris.

Mr. Kerry acknowledged in a speech that lasted more than half an hour that the world’s biggest carbon emitters must contribute more than other countries to finding a solution.

The United States and other industrial nations “have contributed significantly to this problem – before, I might add, we fully understood the consequences,” he said. “And we recognize the responsibility we have now to lead the global response.”

But, he added, that doesn’t let other countries off the hook. “Ultimately, every nation on Earth has to apply current science and make state-of-the-art energy choices if we’re going to have any hope of leaving our future to the next generation to the safe and healthy planet that they deserve.”

Speaking as U.S. President Barack Obama’s “lead international advocate” on climate change, the former U.S. Senator – wearing a green tie — noted that his personal interest in climate change dates back to the 1980s.

He said his country – the world’s second-largest carbon emitter behind China — “is well on its way to meeting our international commitments to seriously cut our greenhouse gas emissions by 2020” by targeting emissions from transportation and power sources, which account for some 60 per cent of the country’s production of greenhouse gases.

In addition to requiring cars and trucks to double their fuel efficiency, President Obama has proposed regulations to curb carbon emissions from new power plants and from existing power plants. “We’re going to take a bunch of them out of commission,” Mr. Kerry said.

Since President Obama took office in January 2009, energy use in the United States has become more efficient, wind energy production has more than tripled, and solar energy production has increased by more than tenfold, Mr. Kerry said.

“As a result, we’re emitting less overall than we have at any time in the last 20 years,” he said, noting that the United States recently announced its goal to reduce emissions by at least 26 per cent from 2005 levels by 2025.

“That will put us squarely on the road to a more sustainable and prosperous economy. And the upper end of this target would also enable us to cut our emissions by 83 per cent by 2050 – which is what science says we need to do to meet the goal of preventing over two degrees of Celsius warming.”

Mr. Kerry’s audience in Lima was composed of hundreds of journalists and advocates for action on climate change, including former U.S. Vice President Al Gore. But Mr. Kerry appeared to direct some of his remarks to the U.S. capital, in Washington, D.C., more than 5,000 kilometres northward.

“I challenge anyone who has thought about the science or listened – actually listened carefully to national security experts tell us that these dangers are real – I challenge them to tell us otherwise and to show us otherwise,” he said.

“This is pretty logical stuff, and it’s astounding to me that even in the United States Senate and elsewhere, we have people who doubt it.”

Rapid movement on the energy front is needed, he said.

“The technology is out there. Make no mistake, it’s out there now. None of this is beyond our capacity. And the question – and it really is still open to question; it’s why we’re here and it’s why we’re going to Paris – is whether or not it’s beyond our collective resolve.”

He called on his audience in Lima and elsewhere “to demand resolve from your leaders – speak out, make climate change an issue that no public official can ignore for even one more day, let alone for one more election. Make a transition towards clean energy the only policy that you’ll accept. And make it clear that an ambitious agreement in Paris is not an option, it’s an urgent necessity.”

The worst thing that can happen if the skeptics prove right would be that many new jobs would be created, economies would be kicked into gear, people would be healthier, and the world would be more secure, he said.

“But what happens if the climate skeptics are wrong? Catastrophe.”