No matter who or what is ultimately deemed responsible for last week's dramatic landslide that caused a major portion of East 26th Street to collapse onto adjoining CSX tracks, it's clear that unusually heavy rains played a role. The hillside was destabilized, at least in part, by a torrential downpour that brought as much rain in a few days as Baltimore normally sees in the entire month of April.

What's worrisome is that this vulnerability — a city's aging infrastructure pitted against unusually severe weather — is likely to become an even greater problem in the future. At least that's one of the concerns raised this week by the National Climate Assessment, which found that climate change is already having an adverse impact on the nation.

The government report released Tuesday singles out the Northeast, Maryland included, as particularly vulnerable because of the combination of aging infrastructure and heavy rains. Between 1958 and 2010, the region has witnessed a 70 percent increase in the amount of precipitation falling in the heaviest precipitation events, defined as 1 percent of daily events.

In other words, it isn't that the Northeast is getting more rain, it's that the storms delivering that rain are much more severe. Last week's disaster in Charles Village illustrates the consequences. But it isn't just about the rare retaining wall here or steep hillside there. Flash flooding from storms like Hurricane Irene in 2011 can shut down subway systems, wash out roads and bridges, undermine railroads, cause widespread bacterial contamination and leave millions without power.

Those accustomed to thinking about climate change as a distant, or even semi-distant future event measured in centimeters of sea level rise or feet of melting glaciers, may find the report jarring. The reality is that the effects of man-made greenhouse gases are already being felt, from oceans that are becoming more acidic to rivers more prone to flooding. Not all the impacts are bad — the warming of the Great Lakes offers the prospect of a longer shipping season, for instance — but the damaging impacts are extremely worrisome.

And it isn't just coastal communities. As the authors note, there are consequences for human health, the water supply, energy, transportation, forests and ecosystems. The Northeast is in danger not just because of heavy rains but because there are 64 million people living there, and supporting them requires a massive and complex infrastructure that needs to be better protected against the increasingly harsh climate.

That level of investment is obviously not taking place today. Nor has the nation taken sufficient steps to slow down the burning of fossil fuels, the chief source of greenhouse gas emissions. What modest measures have been taken, from mandating greater fuel efficiency in cars to regulating power plant emissions, have been hard-won. Meanwhile, climate deniers are still braying away, clinging to the false hope that they know better about what the future holds than hundreds of leading climate scientists who have spent a lifetime analyzing the data.

Here are the basics: Average U.S. temperatures have increased 1.3 degrees to 1.9 degrees since 1895, according to written records. There are more heat waves and more heat-related deaths than ever before, and the forecast is that the number of 100-degree-plus days will increase, with the worst of them as much as 10 to 15 degrees hotter than today by 2080.

Reducing greenhouse gas emissions could ameliorate many of the worst effects of global warming but not all of them. There is simply too much carbon dioxide building up in the atmosphere, and it's going to last too long to assume that the impact can be averted entirely, only blunted. As the report concludes, that means that Americans will need to make choices between mitigation and adaptation — not just burning less coal, for example, but planting more carbon-dioxide-absorbing trees and changing farming techniques to match the new realities.

Hurricanes Irene and Sandy gave the Northeast a taste of what is to come. We ignore the facts of climate change at our own peril. The real danger is not that there will be more landslides like the one Baltimore experienced a week ago but that we'll do little or nothing to prepare for the near-certainty of them and other such challenges in the future.

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