GOOD NEWS — kind of. So far this year, the country’s energy-related greenhouse-gas emissions are running at their lowest level in a quarter-century, the U.S. Energy Information Administration announced this month. Federal experts project that, at year’s end, the country’s climate tab will be the smallest since 1992, continuing a downward trend since its peak during the George W. Bush administration, when carbon dioxide levels seemed destined to rise inexorably. The encouraging findings reflect an increase in renewables and more fuel switching from coal to cleaner natural gas — driven by the much-maligned fracking boom. Both factors helped offset a slight rise in oil consumption spurred by low prices.

The nation still emits vast amounts of carbon dioxide; 1992 levels are way too high. Part of this year’s uptick in renewables came because higher water levels in areas formerly affected by severe drought meant hydroelectric facilities could produce more power, so similarly large increases in green power generation might be harder in future years. An unusually warm winter reduced heating-related emissions. And natural gas, though only about half as bad for the climate as coal, still produces a lot of greenhouse-gas emissions as it is extracted, transported and burned. In other words, it will not always be so easy to achieve emissions cuts of the size the country has seen during the past several years.

Meanwhile, the government cannot enforce the country’s centerpiece emissions-cutting policy, because the Supreme Court has stayed the Obama administration’s Clean Power Plan pending completion of a federal lawsuit, and Republican-led states are resisting it. The fate of the Clean Power Plan, the Paris Climate Agreement and much else rests on the results of next month’s presidential election. A GOP administration — and particularly one led by Donald Trump, who has called climate change a “hoax” — would undermine a range of federal emissions-cutting policies.

Even as energy experts continue to describe the challenge of transitioning the country’s sprawling energy system, scientists continue to articulate why that transition is necessary. Over the past several years, for example, experts have put more effort into defining the connections between climate change and natural disasters. The Proceedings on the National Academy of Sciences published a paper this month finding that climate change played a key role in encouraging wildfires in the western U.S. during the past several decades, “nearly doubling the forest fire area expected in its absence.” The experts reckon global warming’s effects on wildfires will intensify in coming years. The group published another paper finding that “the frequency of Sandy-level floods has approximately tripled since 1800, from once every 1,200 years to once every 400 years.” And, the authors projected, “when future changes in storm climatology were taken into account, the estimated frequency in 2100 varied from once in 23 years to once in 130 years.”

Natural variability, of course, still plays a predominant role in the weather. But global warming will make unusual phenomena more usual in a wide variety of natural systems humans would be better off not disturbing.