This story was originally published by Slate and is reproduced here as part of the Climate Desk collaboration.

Of all the measures that U.S. conservationists hold dear, none is more sacrosanct than the Endangered Species Act. Since its introduction in 1973, the ESA has been the major tool used to restore declining populations of hundreds of native wild animals and plants. The law is most celebrated when its designation can be revoked when a species bounces back from near extinction: The gray wolf and bald eagle are two of its major success stories. The law’s popularity is nearly universal; polls show that some 90 percent of Americans, regardless of political affiliation, support keeping it in place.

ESA defenders often tout its near-perfect record of keeping the endangered species on its list from extinction — 99 percent of species listed are still around, according to the Center for Biological Diversity. That sure sounds good, but practically speaking, the law — which has stayed largely unchanged for the past 25 years — has a lot of issues. Assessments of its success really depend on how you define “success” — as many of its critics point out, only about 1 percent have been successfully rehabilitated and removed from the list. And between 1990–2010, biannual assessments of the 1,292 listed species found that just over half were continuing to decline even with ESA protections. Another 35 percent were stable. Just 8 percent were improving.

Why isn’t the ESA more effective? The reasons are myriad, but they boil down to the problem that by the time most species are listed, they’re too far gone for the act to be able to do much to revive them, both from a cost and feasibility perspective. And it doesn’t help that there’s more demand than ever before.

The main problem, which isn’t likely to be addressed by the present administration, has been chronic underfunding. While government spending on endangered species protection has more than doubled since 1998 to roughly $1.4 billion in 2014, those expenditures haven’t kept pace with the rapidly multiplying stressors affecting wild species, including climate change, industrial development, and a U.S. population that increased more than 15 percent in the same time period. Compared to the rest of the federal budget, $1.4 billion is paltry — it pales in comparison to the $533 billion spent on defense that same year or the $39 billion budgeted for homeland security.

Complicating this challenge, some conservationists say, is the rapidly lengthening roster of species needing protection. On top of the more than 1,600 U.S. species already on the endangered list (many of which require complex habitat management and recovery programs that can take decades to succeed), there are presently more than 350 others waiting for consideration. The backlog is so acute that that some species have been on the waiting list, with their prospects for recovery steadily dimming, for more than a dozen years.

Another problem is that even when species are listed, they don’t often get the help they need. The Ecological Society of America, for instance, published a report last year detailing several of what it called “shortcomings” in the law’s current implementation (it also recommended strategies for addressing them). A main issue raised in the report is the ESA’s lack of a clear and uniform system for prioritizing fund allocation — a problem that has historically led to disproportionate spending among species on the endangered list. Between 1998 and 2012, the report found, some 80 percent of ESA expenditures went to support just 5 percent of listed species, most of them animals with outsized popular appeal (like whales and seals) and game species (like steelhead trout and Chinook salmon). Conversely, 80 percent of species on the list got less than 5 percent of spending — and many, especially plant species, got none at all.

Ya-Wei Li, vice president of endangered species conservation at Defenders of Wildlife, explained that the ever-heavier burdens placed on the law have forced it to function “like a chaotic, overcrowded emergency room — a place of last resort.” While…