Before a major speech on the subject last week, it had been two years since US President Barack Obama last waded into the complex arena of energy and climate change. His emphasis then was on an ‘all-of-the-above’ approach that put oil and natural gas on an even keel with alternative energy sources.

But on 25 June, citing “the overwhelming judgement of science”, as well as the country’s founding fathers, who charged political leaders “to make decisions with an eye on a longer horizon than the arc of our own political careers”, Obama broke a long silence on global warming.

The centrepiece of the president’s speech was a pledge to regulate carbon emissions from power plants new and old. The power sector produces some 40% of total US emissions, and administration officials have long said that they would fill the regulatory void if Congress failed to act. Although Obama did not make any specific promises last week, he did lay out a schedule and put the full weight of the White House behind these efforts, which is what they need and deserve.

These commitments are overdue. The US Environmental Protection Agency (EPA) has already proposed a regulation that would essentially ban the construction of new power plants unless they are equipped to capture and sequester carbon. That rule has languished for over a year, and under the new schedule will not be finished for almost another 12 months. Many of Obama’s most ardent supporters, as well as his critics, had long assumed that the EPA was already working on regulations for existing power plants. Apparently it wasn’t — at least, not in any serious way. Obama has now ordered the agency to issue a regulatory proposal next June and to finalize the rules a year after that, just in time for a major United Nations climate summit in Paris.

Obama’s ‘climate action plan’ contained a variety of other initiatives, including calls for a new round of appliance standards, fuel-economy regulations on heavy-duty vehicles and various efforts intended to prepare the country for a warmer climate. Much of the plan may seem old hat, but that is to the president’s credit. Over the years, his administration has cobbled together a broad set of policies that — along with a shift from coal to natural gas and renewables for electricity generation, as well as several years of economic woe — have markedly reduced greenhouse-gas emissions, which registered almost 7% below 2005 levels in 2011.

Obama urged politicians to live up to their obligations as caretakers of the future.

But the United States still has a long way to go if it is to fulfil its international commitment — a 17% reduction by 2020 — and pursue deep emissions reductions as the century wears on. Having secured historic fuel-economy regulations across the vehicle sector, Obama now has the opportunity to lay down an aggressive set of regulations for the power sector. It will be up to the EPA, working with states, businesses and environmentalists, to determine how to structure the regulations. Rather than focusing purely on technological upgrades such as requiring more efficient boilers, the EPA may be able to improve on broader incentives that would require deeper reductions while, for example, allowing utilities to work with customers to curb electricity demand.

Obama also hinted that he could deny the proposed Keystone pipeline from Alberta to the United States — if the state department’s ongoing analysis determines that it would significantly exacerbate greenhouse-gas emissions. In truth, oil from the tar sands is hardly the dirtiest resource from a climate perspective, but it is not the cleanest either. And even a cursory review of the local environmental impacts suggests plenty of reasons to shift investments towards cleaner alternatives. Regulating greenhouse-gas emissions from the power sector is by far the biggest opportunity, but if the administration feels it can justify a symbolic decision against Keystone and still move a workable and effective regulatory agenda forwards, then so be it.

Whatever form the regulations take, and however ingeniously the administration can work around political opposition, the full scale of the climate challenge is more than any president could accomplish independently of Congress. Obama urged politicians and public servants to rise above the political fray and think beyond the next election, to live up to their obligations not just as “custodians of the present, but as caretakers of the future”.

Obama is just six months into his second term, but these are the words of a president who no longer needs to worry about re-election. Obama is now thinking about his place in history. Although his broader climate agenda has been stymied in Congress, Obama has laid out a solid path forward. Now he must follow it through.