US President Barack Obama challenged his conservative climate critics in the annual State of the Union address to Congress on 20 January, arguing that they cannot shy away from modern climate science. A day later, pushed to take a position, 15 Republicans voted in favour of an amendment affirming the idea that humans have a role in climate change. Five went a step further, voting for a Democratic amendment stating that human activity “significantly contributes to climate change”. And this is progress?

Although both amendments attracted a majority of the US Senate, neither achieved the 60-vote threshold required for approval. These votes are of course purely symbolic, but political types are already busy reading the tea leaves for the 2016 presidential elections. For some, the fact that any Republicans, however few, felt compelled to endorse basic climate science is a positive sign that the party is once again worried about how the issue of climate change will play with US voters. We can only hope that it will at last get the attention it deserves in a major US election, but it is hard to get too excited.

The five Republicans who voted in favour of the Democratic amendment that made the strongest connection between human activity and climate change deserve credit for doing so. But the flip side is that 49 out of the 54 Republicans in the Senate voted against an amendment that merely states mainstream scientific theory, as vetted by countless researchers, studies and assessments over the course of more than a quarter of a century. And 39 refused to agree to a statement that linked human activity and climate change in any way. Moreover, it is not clear that any of the Republicans, or indeed many of the Democrats, are prepared to actually do anything significant about it.

The upshot is that little has changed. Obama has started to bypass Congress to push forward with his own climate regulations wherever possible, and he is right to do so (see page 535). If there is any criticism to be laid at his feet, it is not that he has been too ambitious with his regulatory powers, as suggested by Republicans, but that he has not been ambitious enough. His administration could certainly be more aggressive with its planned rules for power-plant emissions, as well as with methane regulations it is developing for the oil and gas sector. These regulations will help to determine whether the United States can capitalize on the shift from coal to natural gas and renewables, such as wind and solar, that has helped to reduce the nation’s emissions in recent years.

“Obama has started to bypass Congress to push forward with his own climate regulations, and he is right to do so.”

For their part, Republicans have focused their energy on the Keystone XL oil pipeline from the Canadian tar sands to the US Gulf Coast, with leadership in both houses of Congress putting legislation approving it at the top of their agenda. Environmentalists have done the same, arguing that Keystone represents a step in the wrong direction that will merely drive up greenhouse-gas emissions by promoting the development of a dirty energy source. The reality is that the pipeline, on its own, would not have a significant impact on either the US economy or the global climate.

It will be up to Obama to decide whether the pipeline is in the national interest, once the state department finishes its review of the project. The president has said that the pipeline will benefit Canadian oil producers rather than US consumers, given that petrol prices — already lower than they have been in a long time — are driven by the international oil market. He has also said that he will approve the project only if it does not “significantly exacerbate” the problem of carbon pollution.

In the end, Obama has plenty of wiggle room in terms of how he defines both ‘national interest’ and ‘significant exacerbation’. There are surely better places to invest from a public perspective, but there are also better ways to guide private investments, including oil pipelines. One of them is to enact comprehensive climate legislation that clarifies the cost of carbon and the basic economics for all energy and infrastructure investments. That he has not done this is Obama’s biggest failure on the environmental front.

All is not lost. If the United States can continue to reduce its own emissions and help to secure meaningful action abroad, then historians may yet look back at Obama’s presidency as a turning point in the battle against global warming. One thing, however, seems clear enough: the president’s environmental legacy will not be determined by his decision on the Keystone XL pipeline.