Tag Archives: WRN

U.S. National Climate Assessment: 2014

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The White House released the third US National Climate Assessment (NCA) report yesterday. It clearly states that climate change is not a distant problem of the future; it is happening now and impacting every region of this country.

Issued every four years to assess how climate is changing in the US, this latest report says: “Summers are longer and hotter, and extended periods of unusual heat last longer than any living American has ever experienced. Winters are generally shorter and warmer. Rain comes in heavier downpours. People are seeing changes in the length and severity of seasonal allergies, the plant varieties that thrive in their gardens, and the kinds of birds they see in any particular month in their neighborhoods.” In terms of agricultural production, “Corn producers in Iowa, oyster growers in Washington state and maple syrup producers in Vermont are all observing climate-related changes that are outside of recent experience.”

“U.S average temperature,” according to the report, “has increased by 1.3°F to 1.9°F since 1895, and most of this increase has occurred since 1970. The most recent decade was the nation’s and the world’s hottest on record, and 2012 was the hottest year on record in the continental United States.” Over the next few decades, temperatures are projected to rise another 2°F to 4°F.  By the end of the century, our average temperature could soar by 10°F if greenhouse gas emissions continue to increase unchecked.

While similar in theme to the recently released IPCC report from the UN, this assessment focuses solely on the United States. Emphasizing the fact that rising temperatures will affect different parts of our vast country in different ways, the NCA breaks the nation down into specific regions. It details the current and future impacts of climate change in each one. Here are some regional highlights:

Northeast: Increased frequency and duration of heat waves; Increased flooding due to sea level rise and extreme rain events

Southeast: Increased frequency and intensity of extreme heat events; Decreased availability of fresh water; Increased threat from sea level rise

Mid-west: Increased frequency of extreme heat events; Increased heavy downpours and flooding; Decreased air quality

Southwest: Increased heat, drought, and wildfires; Increased insect outbreaks

Northwest: Decreased summer water supplies due to earlier snow melt; Increased threat from sea level rise; Increased insect outbreaks and wildfires

Alaska: Warming twice as fast as the rest of the nation; Loss of sea ice, melting glaciers, thawing permafrost; Increased wildfires

Hawai’i: Increased saltwater intrusions from sea level rise; Decreased availability of fresh water

As a nation with over 95,000 miles of coastline, the report also addresses the issues of ocean warming and acidification.

Written by over 300 NOAA scientists and endorsed by dozens of other experts from both the public and private sector (including two oil companies), the NCA concludes that, “Climate Change presents a major challenge for society.” It goes on to say, “There is mounting evidence that harm to the nation will increase substantially in the future unless global emissions of heat trapping greenhouse gases are greatly reduced.” While this comprehensive report does not offer policy, it does emphasize the urgent need for both adaptation and mitigation at all levels of government.

The colors on the map show temperature changes over the past 22 years (1991-2012) compared to the 1901-1960 average for the contiguous U.S., and to the 1951-1980 average for Alaska and Hawai'i. Image Credit: NCA

Change in annual average temperature, 1991-2012. Credit: NCA

 

IPCC Report: Impacts and Vulnerabilities

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The UN’s Intergovernmental Panel on Climate Change (IPCC) released the second part of its fifth assessment report (AR5) earlier this week.  Focused on impacts, vulnerability, and adaptation, it emphasizes that climate change is happening now and is a serious threat to human civilization.

Authored by more than 300 scientists from 70 countries, the report states, “In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans.” If left unchecked, according to this 2007 Nobel Prize winning group, the risks will only increase.

Of the many hazards listed in the massive report, one of the most significant involves global food production.  Crop yields – especially wheat and corn – are forecast to decrease 2% per decade through 2100 while demand is expected to grow by 14% per decade through 2050.  Renewable freshwater supplies are also likely to become stressed as weather patterns shift and dry areas become even drier.  According to the report, “Each degree of warming is projected to decrease renewable water resources by at least 20% for an additional 7% of the global population.”

Another dire finding in the report concerns coastal communities around the globe. It states, “Due to sea-level rise throughout the 21st century and beyond, coastal systems and low-lying areas will increasingly experience adverse impacts such as submergence, coastal flooding and coastal erosion.”

Some of the other potential vulnerabilities mentioned in the report include political instability, economic losses, and threats to human health.

To minimize these grim possibilities, the IPCC emphasizes that, “Mitigation is considered essential for managing the risks of climate change.” If greenhouse gas emissions continue to rise, we can expect an additional 6-7°F increase in global temperature by 2100. “Large magnitudes of warming increase the likelihood of severe, pervasive and challenging impacts,” according to the report. The current international goal is to keep the temperature increase below 2°C (3.6°F).

The third part of this report, the mitigation section, is due out later this month.

Below is a short video summary of the IPCC Working Group II report ….

Video Credit: IPCC and YouTube

Cold Winters and Climate Change

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Cold and snowy weather – the type that has dominated this winter across much of the United States – can lead some people to question the validity of global warming.  According to scientists, however, these frosty conditions are not entirely unexpected in our changing climate.

Cold temperatures are a natural part of winter.  Our astronomical seasons – winter, spring, summer, and fall – are generated by the tilt of the Earth’s axis and the movement of the planet around the sun.  During the winter months, our hemisphere is tilted away from the sun and receives the least amount of solar energy all year.  So, even as our average global temperature goes up, winter will continue to be cold relative to the other seasons.

The tilt of the Earth during different seasons. Image Credit: NASA

The seasons are caused by the tilt of the Earth as it rotates on its axis and revolves around the sun.  Image Credit: NASA.

Although global warming will not change the tilt of the Earth’s axis, it is affecting the moisture content of our atmosphere.  Increasing levels of greenhouse gases are warming the air and allowing it to hold more water vapor.  As a result, when storms develop they produce more intense precipitation.  In winter, that includes snow, sleet, and freezing rain when given the appropriate temperature range.

This year, we have experienced a number of arctic outbreaks from the now famous polar vortex.  Each one provided a deep pool of cold air that helped produce significant snowfall throughout the eastern two-thirds of this country. While the occasional cold snap is part of the season’s natural variability, they have been lasting longer recently. Some scientists suggest this is the result of arctic amplification – a tendency for the arctic to warm more rapidly than the mid-latitudes. As the temperature difference between the two regions decreases, the jet stream slows down and takes a wavier shape. The larger the waves, the slower they move, and the weather associated with them – warm or cold – stays in place longer.

It is also important to remember that climate change is a complex global phenomenon that involves much more than what is happening in our own backyards.  While it has been a brutally cold and snowy winter for many of us in the Northeast and Midwest, the western states are in the midst of a serious drought and Alaska has been experiencing record high temperatures.  Beyond our borders, much of the rest of the world has been unusually warm.  For example, the recent Olympic Winter Games in Sochi, Russia were the warmest in history. In the southern hemisphere, Australia sweltered through a record heat wave in early January. Experts say it is not unusual to see regional variability with climate change, but overall the Earth’s atmosphere is unequivocally warming.

This short video by the Yale Climate Forum highlights the issue of cold weather and climate change in the context of the 2013-14 winter season….

Video Credit: Yale Climate Forum and YouTube

Weather and Health: Extreme Cold

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Persistent frigid temperatures have been gripping a large part of the United States recently.  In these conditions it is important to remember that, like extreme heat, extreme cold can be very dangerous.

Extreme cold causes the body to lose heat faster than it can be generated.  Prolonged exposure, according to the CDC, can cause serious health problems, including hypothermia and frostbite.

Hypothermia is a condition of unusually low body temperature – generally below 95°F.  It impairs brain functions, limiting a victim’s ability to think and move.  Symptoms include severe shivering, drowsiness, confusion, slurred speech, and fumbling.  If left untreated, it can be fatal.

Frostbite is a localized injury to the skin and underlying tissues caused by freezing.  It can cause permanent damage and extreme cases often require amputation.  Areas of the body most often affected include the nose, ears, cheeks, fingers and toes. Signs of frostbite include, numbness, skin discoloration (white or greyish-yellow), and unusually firm or waxy feeling skin.

While the symptoms of both hypothermia and frostbite can range in severity, victims generally require immediate re-warming and professional medical attention.

To stay safe in cold weather, the American Red Cross recommends:

  • Avoiding prolonged exposure to extremely low temperatures
  • Wearing layers of clothing to keep warm
  • Using hats and gloves to minimize the loss of body heat

The Polar Vortex

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The Polar Vortex has been making headlines across most of the United States recently.  But, what exactly is it?

According to NOAA, the northern hemisphere polar vortex is a high altitude low-pressure system anchored over the Arctic.  More specifically, it is “the pattern of winds around the North Pole.”  It is always present, but tends to be stronger in the winter.

The configuration of the polar vortex – smooth or wavy – determines how much cold air escapes the region. Driven by the temperature difference between north and south, these winds typically circle the pole from west to east in a smooth pattern that bottles up the Arctic’s cold air.   When these winds weaken, the pattern becomes wavy and cold air pushes southward.

The connection between warming conditions in the Arctic (decreasing the temperature difference between north and south) and extreme weather events in the mid-latitudes is an active area of research. Some scientists suggest that increasing Arctic temperatures may be responsible for disrupting the pattern of the polar vortex.

The polar vortex is shown in purple. Image Credit: NOAA

Polar Vortex configuration: Smooth vs Wavy.  Image Credit: NOAA

Natural Disasters and Public Health

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Weather-related natural disasters have occurred throughout human history.  Their frequency and intensity, however, have been on the rise in recent years and health professionals have taken notice.

According to a report recently published in the New England Journal of Medicine, there were three times as many natural disasters between 2000 and 2009 as compared to 1980 through 1989. Dividing the events into two major categories, climate-related (storms, floods, heat-waves, etc.) and geophysical (volcanic eruptions, earthquakes, etc.), the report found that 80% of the increase was due to a rising number of climate-related disasters.

The report explains, “During recent decades, the scale of disasters has expanded owing to increased rates of urbanization, deforestation, and environmental degradation and to intensifying climate variables such as higher temperatures, extreme precipitation, and more violent wind and water storms.”  It also cautions that “natural disasters, particularly floods and storms, will become more frequent and severe because of climate change.”

Impacting nearly five billion people since 1990 (approximately 217 million people per year), each disaster has generated serious public health concerns including large numbers of fatalities, injuries, and the outbreak of disease.

EM-DAT International Disaster Database, Center for Research on Epidemiology of Disasters, University of Louvain.

Geophysical Disasters vs Climate-related Disasters                                                                            Graph Credit: EM-DAT International Disaster Database, Center for Research on Epidemiology of Disasters, University of Louvain.

NYC Updates Hurricane Evacuation Zones

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Super-storm Sandy devastated New York City last autumn.  In its wake, emergency management officials have re-drawn the city’s hurricane evacuation zones.

The new zones are based on improved data from SLOSH (sea, lake, and overland surges from Hurricanes), a national Weather Service computer model designed to estimate storm surges.  This new system takes the width of a storm and its wind field into account whereas the old zones were primarily based on a hurricane’s Saffir-Simpson category.

NYC’s new zones are labeled 1 through 6, with zone 1 being the first to be evacuated in the event of a storm.  This system is numeric to avoid confusion with FEMA’s flood zone maps used for insurance purposes.

Go to nyc.gov/hurricane to see if you live or work in an evacuation zone.

NYC's new hurricane evacuation zones.

NYC’s new hurricane evacuation zones.

Image Credit: nyc.gov

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

Heat Index

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Temperature is one of the basic elements of weather.  Our perception of it, however, is often influenced by other factors.  In summer, this is usually humidity.

The heat index, developed in the late 1970’s, is a measure of the apparent or “real feel” temperature when heat and humidity are combined.  Since the human body relies on the evaporation of its perspiration to cool itself, the moisture content of the air affects comfort levels. Basically, as humidity levels increase, the rate of evaporation decreases and the body can begin to feel overheated.  For example, an air temperature of 92°F combined with a relative humidity level of 60% will produce a heat index value of 105°F.

The National Weather Service issues heat advisories when the heat index is forecast to be at least 95°F for two consecutive days or 100°F for any length of time.  Extended exposure to high heat index values can lead to serious health hazards.

Heat-IndexImage Credit: NOAA