Monthly Archives: July 2013

Hottest Decade on Record for Planet Earth: 2001-2010

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Climate scientists have noted it for years, but now it is official. The first decade of the 21st century was this planet’s hottest on record.

According to a report recently released by the World Meteorological Organization, Earth’s combined average temperature – over both land and sea surfaces – for the decade of 2001-2010 was 58.05°F.  That is 0.85°F above the long-term norm.  As hot as this period was, this new record does not come as much of a surprise.  Every year in the decade except 2008 was among the top ten warmest on record.

Analyzing data from 139 countries, the report showed that the decade was also marked by extreme weather around the globe. Floods were the most frequent type of event, but droughts impacted the largest number of people worldwide.  Massive hurricanes and scorching heat waves also caused serious problems.  While improved early warning systems for storms and floods helped save countless lives, heat related deaths increased dramatically from the previous decade. In total, extreme weather events during this ten-year period claimed the lives of more than 370,000 people.

Weather and Health: Sun Exposure

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Summer is a season when many people spend time outdoors in the sun.  Overexposure to its UV rays, however, can cause a number of health problems, including sunburn, eye damage, and even skin cancer  This is why public health officials recommend taking precautions when the UV Index climbs above three.

The UV index is a scale that measures the intensity of the sun’s ultraviolet radiation. Readings vary from place to place as local factors affect the amount of UV light that reaches the ground. These include, the thickness of the ozone layer, latitude, season, elevation, and cloud cover. Developed by the NWS and EPA in the early 1990’s, it informs the public about the daily risk of unprotected exposure to the sun.

UV_Index

Chart Data: EPA

Long Duration Heat Wave in NYC

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Temperatures have been soaring in New York City. Today was our third consecutive day with temperatures in the 90s and more are on the way.

Forecasters say this heat wave – the second this month in NYC – will be of unusually long duration.  Temperatures are expected to reach the mid-90s everyday for another three to four days. Humidity levels will also remain high, making it feel even hotter.  Heat index values, which combine temperature and humidity, are projected to persist in the triple digits.

While these conditions are oppressive, they are also very dangerous.  Extended exposure can cause a number of serious health hazards.  According to the CDC, extreme heat is one of the leading causes of weather related deaths in this country.

To help people beat the heat, the city is operating cooling centers.  To find one near you, go to nyc.gov.

Rip Currents

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The dog days of summer have arrived!  As millions of people head to beaches to beat the heat, it is important to remember that the ocean is a dynamic environment that can pose a number of hazards for swimmers.  Chief among these are rip currents.

Rip currents are strong, localized channels of water that move away from the shoreline. They can form on any beach with breaking waves and easily pull swimmers out to sea in a matter of seconds.  According to the U.S. Lifesaving Association, rip currents are responsible for 80% of all surf zone rescues. Nationally, they cause more than one hundred deaths every year.

While rip currents are a serious hazard for all beach goers, they are a natural part of the near-shore ocean circulation.  They develop when wind driven waves break strongly in one area and weakly in another, creating a circulation cell as the water looks for a way back out to sea.  This usually happens at a break in an underwater sandbar or along a jetty or pier. Extending seaward for hundreds of yards, rip currents typically travel at one to two feet per second.  However, they strengthen when onshore wind speeds pick up and wave height and frequency increase.

If caught in a rip current, do not try to swim against it.  Instead, swim parallel to the shoreline until you are out of the current and then make your way back to the beach.

rip-currentImage Credit: NOAA

Weather History: Death Valley Heat Record

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One hundred years ago today, the temperature at California’s Furnace Creek in Death Valley National Park soared to 134°F.  To this day, that is the highest air temperature ever recorded on Earth.

Situated in the Mojave Desert and 282 feet below sea level, Death Valley is the lowest and driest place in the United States.  Its unique geography traps hot desert air and helps to heat it even further.  While the area does have seasons, summer is extremely hot.  From June through August, daytime highs in the triple digits and over-night lows in the 90s are not uncommon.

The heat wave that gripped the southwestern U.S. last month had some people thinking the Death Valley record might be broken, especially when the temperature reached 129°F on June 30th.  While this set a new monthly record for June, the century old world record still stands.

Death Valley, CA

Death Valley, CA

Image Credit: NPS

Public Display Thermometers

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New York City, like most large cities, is a heat island.  With miles of paved surfaces, it is generally warmer than surrounding rural areas.

Within city limits, public display thermometers – on banks and gas stations – demonstrate this phenomenon on a micro scale. They are often positioned in the sun and over a concrete or asphalt surface that absorbs heat. As a result, they can read 5°F to 10°F higher than the city’s official air temperature taken in the more bucolic conditions of Central Park.

Gas station thermometer reads 104F, but the official high temeprature for the day was 92F.

The thermometer on this NYC gas station reads 104°F, but the official high temeprature for the day was 92°F.

Image Credit: The Weather Gamut

Record Large Dead Zone is Forecast for the Gulf of Mexico

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Heavy spring rains across the American mid-west have mitigated the region’s extensive drought.  However, they are expected to cause a record large dead zone in the Gulf of Mexico this summer.

According to a recently released forecast from NOAA and its research partners, the University of Michigan and Louisiana State University, the Gulf dead zone this year could grow as large as 8,561 square miles. If it reaches this size, which is roughly equal to the state of New Jersey, it will be the largest dead zone ever recorded in the Gulf.

Dead zones are areas in large bodies of water that do not have enough oxygen to sustain aquatic life.  They are usually caused by nutrient pollution from agricultural run-off.  Specifically, excessive amounts of fertilizers – nitrogen and phosphorus – create massive algae blooms.  When the algae die, they sink to the bottom where they are decomposed by bacteria. This process uses up most, if not all, of the available oxygen in the water.  As a result, fish flee the area and immobile bottom dwelling organisms, like clams, die.

The Midwest is this nation’s agricultural breadbasket and its farmers use fertilizers to help grow an enormous amount of crops.  It is also the watershed of the Mississippi River.  As such, the flooding rains that swept through the area this spring have significantly increased the nutrient load of the water that is flowing into the Gulf of Mexico.

A large dead zone will likely have serious economic ramifications for the Gulf region’s multi-million dollar fishing industry.

Agricultural run-off is the main source of nitrogen and phosphorus that cause the annual Gulf of Mexico dead zone.

Watershed of the Mississippi River runs through America’s agricultural heartland and ultimately drains into the Gulf of Mexico.

Image Credit: Donald Scavia/University of Michigan

NYC Monthly Summary: June 2013

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One word can sum up the weather in New York City this June, wet. Receiving 10.10 inches of rain in Central Park, which is 5.69 inches above average, this was the second wettest June ever recorded in the Big Apple.  Nearly half of this impressive total came down in one day when the remnants of Tropical Storm Andrea passed through the area, breaking a daily rainfall record. Given this abundant precipitation, it is interesting to note that NYC’s top three wettest Junes have all occurred in the past eleven years.

In terms of temperature, the city finished the month with an average reading of 72.7°F.  That is 1.7°F above normal.  While New York did not technically have a heat wave this June, the last week of the month was extremely hot and humid.  In fact, heat index values were high enough for the NWS to issue a heat advisory for the city.

JuneRain_NYC

Table: The Weather Gamut