Braving frigid cold, at least 35,000 demonstrators gathered in Washington on Sunday for the largest climate change rally in history. With a second climate and clean energy rally planned for Earth Day on April 22, Sundayâs demonstration had the feel of a first act, an opening statement of what the burgeoning U.S. climate movement is demanding from a government that for decades has denied and delayed action on the most urgent problem of our age.

The primary aim of the demonstrators was to press President Obama to make good on his pledge in the State of the Union address to âdo more to combat climate change.â Above all, they urged him to say no to the Keystone XL pipeline, which would transport carbon-heavy tar sands oil from Canada to the U.S. Gulf Coast. Building that pipeline would be like lighting a fuse to the second-largest pool of carbon on earth, according to writer Bill McKibben, whose 350.org group co-sponsored the rally with the Sierra Club, Americaâs oldest and largest grassroots environmental group.
âKeystone isnât simply a pipeline in the sand for the swelling national climate movement,â says K.C. Golden, the policy director at Climate Solutions, a clean energy group in Seattle. âItâs a moral referendum on our willingness to do the simplest thing we must do to avert catastrophic climate disruption: stop making it worse.â
Environmentalists arenât alone in making this argument. A recent report by the eminently establishment International Energy Agency warned that two thirds of the worldâs fossil fuel reserves must stay in the ground if humanity is to have a 50-50 chance of limiting temperature rise to 2 degrees Celsius. That 2C used to be considered a relatively safe limit, but scientists now consider it the boundary between âdangerousâ and âextremely dangerousâ climate change. After all, they point out, look at the impacts already being experienced today, after weâve experienced only 1C of warming. In 2012 alone, the United States endured its hottest summer on record, its worst drought in 50 years, and the superstorm horrors of Hurricane Sandy.
One disquieting sign of the dangers climate change is already posing was evident right under demonstratorsâ feet on Sunday, on the grounds of the Washington Monument, where they assembled before marching to the White House. Just south of Constitution Avenue, a new levee is being built, linking the grounds of the monument with those of the World War II Memorial. Its purpose? To protect the White House, the National Archives, buildings containing the Justice Department, the FBI, the Environmental Protection Agency, the IRS, the Commerce Department, and other key federal agencies from flooding caused by torrential rains or hurricanes.
A study by the Federal Emergency Management Administration had determined that this section of Washington, known as the Federal Triangle, had less than 100-year flood protection. In other words, the heart of the nationâs capital was roughly as vulnerable to flooding as much of New Orleans was prior to Katrina. Hence, the new levee.
The 17th Street Closure, as itâs called, boasts a counter-intuitive design: cars can drive right through it, at least most of the time. Thatâs because most of the time the mid-section of the leveeâcomprised of aluminum panels that will extend across 17th Streetâis dismantled. All thatâs permanent are the leveeâs two wings, stone-clad cement walls that curl away from the roadway and embed into the higher ground on either side of 17th Street. Only when government scientists determine there is a risk of flooding will the middle of the levee be put in place. Workers will fetch the aluminum panels from a storage site in suburban Maryland and fasten them between the leveeâs wings, creating a barrier 12 and a half feet tall.

The 17th Street Closure will help provide Federal Triangle with 185-year flood protection, says Ashley Williams, a spokesperson for the Army Corps of Engineers, which has supervised the project. But flood protection is not necessarily equivalent to hurricane storm-surge protectionâno small matter, given that the nearby Potomac River connects to the Atlantic Ocean via the Chesapeake Bay.
At 12.5 feet, the completed levee should suffice against the storm surges of most Category 1 or 2 hurricanes, says Phetmano Phannavong, an engineer who serves as the DC Floodplain Manager for the city government. But a Category 3 hurricane would bring 18.1 feet of storm surge, according to a 2009 Army Corps of Engineers report; a Category 4 storm surge could reach 26.1 feet. A Category 3 or 4 storm surge thus âprobably would overtop the levee, so the area behind [it] would be flooded,â says Phannavong.
The problem is, climate change is expected to bring more big storms, including perhaps an increase in Category 3, 4, and 5 hurricanes. And why didnât the levee design take this into account? The relevant government agencies could not locate sufficient funding to build a stronger levee, says Phannavong.
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Together, the new Washington levee and the climate movementâs calls to block the Keystone XL pipeline illustrate a crucial fact about the climate crisis, a fact that has been largely overlooked since Hurricane Sandy put the issue back on the public agenda: there are two halves to the climate challenge, and both must be addressed simultaneously if real progress is to follow.
On the one hand, the inevitability of rising temperatures and more extreme weather dictates that we put in place protective measures now: better levees against flooding, less wasteful water systems to manage droughts, more tree cover, and cooling centers to handle heat waves. Climate experts refer to such measures as adaptation. At the same time, however, we must attack the underlying problemâthe global warming that is driving these impactsâby reducing the amount of heat-trapping gases in the atmosphere. This second task, known as mitigation, will require a rapid global phase-out of oil, gas, coal, and other fossil fuels and replacing them with climate-friendly energy sources, including wind, solar, geothermal, and vastly improved energy efficiency.
The mantra invoked by experts is that climate policy must aim to âavoid the unmanageable and manage the unavoidable.â That is, we must slash the atmospheric concentration of carbon dioxide enough to avoid an unmanageable amount of climate change; as a recent World Bank report declared, âthere is no certainty that adaptation to a 4-degrees-C world is possible.â And we must achieve this even as we also do sufficient adaptation to enable our societies to manage the sizable climate impacts that, alas, are now unavoidable.
In short, adaptation and mitigation are twin imperatives. At this late date, to do only one or the other is to guarantee failure. Take it from the Dutch, the worldâs indisputable leaders in adaptation. The Netherlands is now preparing for 1.5 meters (roughly five feet) of sea level rise by the year 2100, and its experts are thinking ahead to what happens if seas rise even higher than that. âUp to two meters, we think we can do the job,â Pier Vellinga, one of the top climate scientists in The Netherlands, told me in an interview for HOT: Living Through the Next Fifty Years on Earth. Beyond that, he said, âeven Dutch engineers get a bit worried.â
Unfortunately, neither President Obama nor most other U.S. political, economic, and media voices appear to grasp the dual nature of the climate challenge confronting us. The one silver lining of Hurricane Sandy was that it refocused public attention on climate change. But this attention has focused overwhelmingly on the adaptation side of the challenge, while ignoring the mitigation imperative.
âItâs good that New York governor Andrew Cuomo, who frankly hadnât done much on climate change, is now saying itâs a big deal,â says Rohit Aggarwala, formerly the top climate change adviser to New York mayor Michael Bloomberg. The risk, Aggarwala cautions, âis that we swing so completely towards adaptation that we ignore that the best way to prevent things like Hurricane Sandy in future is to mitigate climate change.â
Ron Sims, a former three-term county executive in Seattle, King County, Washington, literally wrote the book on how governments must deal with both halves of the climate challenge. His approach was the model for Bloombergâs policies in New York and for similar initiatives in Chicago and elsewhere. During Obamaâs first term, Sims served as the No. 2 official in the Department of Housing and Urban Development, which perhaps explains why he is unwilling to endorse most environmentalistsâ disappointment with Obamaâs climate leadership to date.
âIâm not going to just blame the president,â says Sims. âItâs pox on all of us. If you want the president to do something, you need to provide the broad, vocal base of public support. With the civil rights movement, it was the upswelling of popular support that made it happen. If people do nonviolent demonstrations at large scale, walking with their kids and grandkids, maybe then weâll see people in government acting more courageously against climate change. Maybe Bill McKibben is correct: people need to get in the streets.â