A roseate spoonbill passes under a gull over an island in Barataria Bay on the coast of Louisiana. The island is home to thousands of brown pelicans, egrets and roseate spoonbills. According to a new report, global warming will threaten the survival of more than half of the 588 bird species in the United States and Canada before the turn of the century.

A roseate spoonbill passes under a gull over an island in Barataria Bay on the coast of Louisiana. The island is home to thousands of brown pelicans, egrets and roseate spoonbills. According to a new report, global warming will threaten the survival of more than half of the 588 bird species in the United States and Canada before the turn of the century. John Moore/Getty Images

David Yarnold is president and chief executive of the National Audubon Society. Gary Langham is the group’s chief scientist.

Maryland could lose the flashy orange-and-black Baltimore oriole — its state bird and the mascot of its Major League Baseball team — before the end of this century because of global warming.

The common loon, Minnesota’s state bird and an iconic species across much of the northern United States, may not be able to raise its young anywhere in the contiguous 48 states by 2080. The bobolink, a charismatic grassland songbird, could be pushed into the boreal forests of Canada, where it would be unlikely to survive. The District’s official bird, the wood thrush, could move out of town.

And the list goes on. The roseate spoonbill, the sandhill crane, the rufous hummingbird and the scarlet tanager are all threatened by global warming.

Today, National Audubon Society scientists released the largest and most comprehensive examination of birds and climate change ever undertaken in North America. The results are alarming: Of the 588 species we studied, 314 will lose 50 percent or more of their current ranges by 2080 unless the greenhouse-gas emissions that cause global warming are significantly reduced. More than half our birds are threatened by global warming, and many will be driven toward extinction if we do not act.

Migration destination unknown (Bonnie Berkowitz and Cristina Rivero/The Washington Post/Source: National Audubon Society)

Over the past seven years, our team has analyzed more than 30 years of bird observations from the North American Breeding Bird Survey, the Audubon Christmas Bird Count and data from leading climatologists in the United States and Canada. This intensive analysis gives us an unprecedented ability to project where birds are most likely — and unlikely — to survive in the future.

Imagine: Within two generations, nine states could discover that their state birds are at risk. Our national emblem, the bald eagle, brought back from the brink of extinction when we banned the pesticide DDT, faces the prospect of a nearly 75 percent decrease in its current range in the next 65 years. The graceful white trumpeter swan, the friendly backyard brown-headed nuthatch and the coastal black skimmer could lose more than 99 percent of their current ranges. Dozens more species face similarly shocking declines.

Dire as all this sounds, the reality is likely worse. We don’t yet have data for Central and South America, where many of our birds spend the winter. Some birds aren’t well surveyed and couldn’t be included in our study, and we took a cautious approach to processing the data. If we know for sure today that half our birds are at risk, it’s likely that many more are as well.

We examined the fundamental relationship between birds and climate variables, such as seasonal precipitation and temperature fluctuations. Every species has a tolerance zone for climate conditions. For example, humans would not survive long in Antarctica without appropriate gear or supplies. Similarly, if the climate gets too hot, too cold, too wet or too dry, birds will be forced to leave their homes.

Some species will be able to colonize in new areas as the climate in those places changes. But many birds will simply run out of suitable places to find food and reproduce as they push farther north, move to higher elevations or encounter unfamiliar habitats or new competitors.

So what can we do?

The situation may be grim, but it is not hopeless. To give birds a fighting chance, two actions are critical: Protecting the places that we know birds will need today and in the future, and reducing the pace and severity of global warming.

The impact of climate change on biodiversity should become a key component of conservation planning at every level of government, from local land-use decisions to federal strategies for managing millions of acres of government property and parks. The fate of many of our birds will depend on their ability to colonize new areas as they become suitable because of climate change.

Conservation planning must take into account both the projected loss and potential shift in geographic ranges of bird species for the next 10 to 80 years. Our report shows, for example, that three-fourths of the most important habitats for climate-threatened species are not protected or even being considered for protection. We can buy birds time by protecting those places that the report describes as “strongholds,” areas identified as the most climatically stable for birds. They are the bridges to the future.

We also must address the root cause of the problem — global warming — by cutting the carbon emissions that threaten birds and people.

Why does protecting birds matter? We could give you pages of scientific and conservation reasons. But what sets these dramatic findings apart from other reports on global warming is the personal connection so many Americans feel to the birds we’ve grown up with and the memories their songs evoke, whether it’s the wail of the common loon echoing across a fog-shrouded lake or the melody of a wood thrush on a sultry summer evening. Every one of us has a stake in preserving those connections for our children and grandchildren.

Birds can’t vote. They can’t create a backyard sanctuary. They can’t save the Everglades or Long Island Sound or the Prairie Potholes of the Dakotas. But we can.