There’s plenty of uncertainty surrounding President Barack Obama’s plan to “degrade and ultimately destroy” the Islamic State: How limited or open-ended is it? How will Congress respond? What will it cost?

But one thing was always certain.

Any announcement of increased military operations in the Middle East would be used as a reason to jettison the restraints on Pentagon spending that Congress put in place with its ten-year plan for deficit reduction.

Actually, some lawmakers didn’t wait for Obama’s speech to make this pitch. Rep. Mac Thornberry, R-Texas., angling to be the next chair of the House Armed Services Committee, traveled a few days beforehand to the heart of the naval shipbuilding industrial complex in Virginia. There, he argued that “a dangerous world” required reversing the military budget’s downward trend.

As world leaders adjust to the new outlook for increased Middle East instability, they’re also getting ready to gather on September 23 at the United Nations to chart a more effective global response on climate change.

Despite growing efforts to reduce carbon emissions around the world, the UN’s World Meteorological Organization recently disclosed that concentrations of nearly all greenhouse gases are greater than ever before recorded, and increased more in 2013 than in any previous year. It also reported that extreme weather events — more frequent and intense heat waves, droughts, hurricanes, and flooding — have increased fivefold since the 1970s.

So it’s also certain that the climate challenge requires more attention and resources. But any new Pentagon spending surge could come at the expense of U.S. investments that would bring this country’s greenhouse gas emissions in line with the targets world leaders, including our own, have set.

While regulation is the most important instrument governments can use to control emissions, money is the next most important tool. The United States has contributed more than any other nation to climate change. Between the public and private sectors, it must make investments in clean energy and transportation that comprise a large part of the “clean trillion” that the International Energy Agency says the world needs to spend each year through 2050 phasing out its reliance on oil, gas, and coal for energy to avert a climate catastrophe.

Since 2008, I’ve tracked the progress toward a better balance between U.S. federal spending on traditional instruments of military force and on climate change. My new findings show that the gap between these two budget categories has narrowed slightly: Between 2008 and 2013 the proportion of security spending on climate change grew from 1 percent of military spending to 4 percent.

These spending priorities are hardly commensurate with the role U.S. military strategy now assigns to climate change: a major threat to U.S. security. Nor is the $24 billion the federal budget devoted to climate security in 2013 remotely sufficient to bring greenhouse gas emissions under control or deal with the consequences of extreme weather and the other problems global warming introduces.

A slightly increased climate budget is playing a minor role in narrowing the gap between spending on military and climate security. But it’s mostly due to the decline in the Pentagon budget, resulting from a combination of the Budget Control Act and declines in the separate war budget, as U.S. forces departed Iraq and Afghanistan.

Now even this modest change is threatened, as Congress contemplates resuming its post-9/11 surge in Pentagon spending while continuing to do nothing about climate change.

My new report also looks at how the U.S. balance between military and climate security spending compares to the record of its nearest “peer competitor,” China.

The Asian giant’s environmental record is unquestionably problematic. Yet according to the best available sources, China strikes a far better balance than the United States in the allocation of its spending on military force and on climate change. Beijing’s 2013 climate security spending, at $162 billion, nearly equaled its military spending, at $188.5 billion.

Meanwhile, Washington shoveled $575 billion into military expenditures and devoted merely $24 billion to dealing with climate change.

Here’s one example of what this looks like. For the price of four more Littoral Combat Ships — currently the budget calls for 16 more than the Pentagon even wants — the federal government could double the Energy Department’s entire budget for renewable energy and energy efficiency.

Economists like to call these trade-offs “opportunity costs.” The term “opportunity,” though, hardly describes the task of averting the worst effects of climate change. It’s a necessity.

Miriam Pemberton is a research fellow at the Institute for Policy Studies and director of its Peace Economy Transitions Project. She is also the co-author of the new report, “Combat vs. Climate: The Military and Climate Budgets Compared.”