A look at weather extremes and the big-picture climate connections.

New York’s One-Inch Escape From Hurricane Irene

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A taxi sits in flood water on Coney Island after Hurricane Irene hit New York, on August 28. Credit: Emmanuel Dunand/Getty Images/AP

New York City dodged a bullet with Hurricane Irene, but big trouble passed more closely than most people think. If the storm surge had pushed the waters of New York Harbor about one inch higher, it could have been enough to overcome some of Lower Manhattan’s outer defenses and flood the subway system, FDR Drive, the PATH and the Brooklyn-Battery Tunnel, if history is a guide.

At 8:42 AM on Sunday morning, close to the peak of an unusually tall high tide, the water reached 4.8 feet above the average high tide level, as measured by a gauge at the Battery. It was the sixth-highest level ever recorded for New York Harbor. The tallest mark came during a hurricane in 1821, at 6.5 feet. The most recent incident topping Irene was the December Nor’easter of 1992, which reached about one inch higher at the Battery and caused enough area flooding to shut down the entire subway system and PATH trains for several days. Unless the city has substantially raised its defenses since then, 4.8 feet put Irene in risky territory. (Check out Climate Central's map of NYC neighborhoods within five vertical feet of the high tide line.)

Lots of things could have tipped the balance this time, but didn’t. If Irene had moved more quickly, or blown more fiercely (she was downgraded to a Tropical Storm shortly before crossing over Manhattan). If she had arrived about 12 hours earlier, during a slightly higher tide. But perhaps the most important element shaping Irene’s outcome was...

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Raging Rivers: Track the Aftermath of Irene

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Irene’s rains may have subsided, but she has left no shortage of water in her wake.

As predicted by many forecasters, inland flooding has become Hurricane Irene's greatest legacy, responsible for the majority of the storm's death toll.

Sept. 1 Update:

According to the U.S. Geological Survey, in the wake of Irene, rivers in ten different states have set all time record high levels. Rivers in Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania and Vermont all set records. While the waters are no longer rising, many of the rivers are still flooding (such as the Passaic River in New Jersey).

The Schoharie River in upstate New York has seriously damaged the town of Prattsville. The Ottauquechee River in Central Vermont washed out bridges and flooded a propane supplier, carrying tanks of the explosive gas downriver. The pictuaresque towns of Quechee and Woodstock, Vermont sustained millions of dollars in damage. And at least 10 rivers in the Northeast have set all time record high water levels. According to Vermont officials, the flooding in the wake of Irene has been that state's worst since at least 1927. 

The flooding isn't only the result of Irene. The tropical storm storm struck a region that was already waterlogged after record August rains. For example, New York City's John F. Kennedy Airport recorded its wettest day of all-time on August 14, when 7.80 inches fell in 24-hours. Recent studies have found...

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Globe Records its Seventh-Warmest July on Record, Arctic Melt Speeds Up

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Abnormally warm conditions in much of the United States, Northern Europe, Western and Eastern Russia, and parts of the Arctic helped propel July 2011 to the seventh-warmest July on record, the National Oceanic and Atmospheric Administration (NOAA) reported yesterday. This makes July the 317th month in a row that global average surface temperatures were above normal. The year-to-date is now the 11th warmest period on average.

In the U.S., July was the fourth-warmest such month on record, with long-lasting heat waves affecting nearly all areas east of the Rocky Mountains. Along the West Coast, however, conditions were cooler-than-average. The heat toppled thousands of records (see our interactive data explorer for details on record warm overnight temperatures), and Oklahoma set a particularly notable record, showing the highest-ever statewide average monthly temperature for any month in any state in the US since instrument records began in 1895.

Some of the temperature records set during July 2011, according to data from NOAA. Credit: Russell Freedman.

As I wrote on July 20: "The current heat wave is consistent with climate science research, which shows that as the climate warms, heat waves in general are becoming more likely. Such heat waves can be especially deadly when they feature high humidity and unusually warm overnight low temperatures that prevent people from cooling off after a hot day. On July 19 alone, 317 record warm minimum temperatures were either set or tied in the U.S., according to the National Climatic Data Center. Of those records, 84 eithe...

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Preparing Philly for the Future

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Three years ago, the City of Philadelphia set a goal to become America's greenest city. With its Greenworks plan in place and already hitting milestones, the City of Brotherly Love is well on its way to becoming — if not the greenest city in the country — more environmentally responsible. 

As part of a recent Climate Central report on what the new climate "normals" mean for Philadelphia, Dr. Heidi Cullen sat down with Katherine Gajewski, the city's Director of Sustainability. Here, Gajewski shares her thoughts on what sustainability means to Philadelphia, how the city is preparing for the expected increase in hot and wet weather, and whether Philadelphians are making a connection between extreme weather and climate change. 

 

Record Warm Nighttime Temperatures: A Closer Look

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By David Kroodsma

July was hot: Washington, D.C., Oklahoma City, Philadelphia, and Austin set records for not just their warmest July in history, but their warmest month on record. The heat prompted people to hide indoors, crank up the air conditioning, or attempt stunts such as cooking eggs on the roof. But what made this month unusual wasn't only the hot days, but rather the hot nights.

Even though repeat heat waves brought sizzling hot days, overnight temperatures broke far more records: According to the National Climatic Data Center (NCDC), in July there were 6,106 record high minimum temperatures, and "only" 2,722 record high daytime temperatures.

Curious about these numbers, I looked more into the past decade of temperature records, and also spoke with Climate Central’s staff scientists. Have nights generally warmed faster than days? And if so, why? 

I downloaded data from NCDC's database of more than 5,000 weather stations across the United States. For each day since January 1, 2000, I looked at four possible records — two for the nighttime low temperatures (record low minimum and record high minimum), and two for the daytime high temperatures (record high maximum and record low maximum).

 

 

Since 2000, in the average month, record highs (high maximum temperature) beat out record lows (low minimum temperature) by a two to one margin. This is exactly what has been found in previous peer reviewed studies — including this study, published in Ge...

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