Climate Change at Rocky Mountain National Park

Rocky Mountain National Park (RMNP) protects 415 square miles of spectacular mountain environments in northern Colorado. It is home to a diversity of ecosystems – alpine, subalpine, and montane – that are each uniquely adapted to the climate zone of their elevation. This is why, as I learned during a recent visit,  climate change is a serious issue for the park.

According to the National Park Service, the average annual temperature in RMNP has increased 3.4°F over the past century. A report from a weather station inside the park (Grand Lake), shows that the number of frost-free days has increased from an average of 65 in the mid-20th century to an average of 100 in this past decade.


In the 20th century, the area including Rocky Mountain National Park experienced a warming trend. The five-year rolling average (thick red line) allows the viewer to look beyond annual variability to focus on long-term trends. (Analysis of PRISM data, original source Daly 2008). Credit: NPS

This warming trend, says the NPS, has caused a number of environmental changes in RMNP. The winter snowpack is melting approximately 2 to 3 weeks earlier, resulting in less water being available for people, plants, and animals during the summer. There has been an explosive increase in the number of mountain pine beetles surviving the now warmer winter months, allowing them to devour more trees. The phenology, or the timing of natural events, can also be thrown out of sync when warm spring weather arrives earlier than normal. Wildflowers that bloom before the arrival of butterflies, for example, can leave the insects with a reduced food source. This puts a kink in how the larger food chain fits together.

In the park’s alpine tundra region, the American Pika is at particular risk. According to scientists, this small furry relative of the rabbit can only live at high elevations in cool, rocky environments. They say it cannot survive in temperatures above 75°F for more than a few hours.  While other species adapted to lower elevations can move upslope as average temperatures rise, the pika has nowhere to go.

American Pika on the rocky terrain of RMNP's alpine tundra region.  Image Credit: The Weather Gamut.

The American Pika, a native of RMNP, is sensitive to even small changes in climate.  Image Credit: The Weather Gamut.

Another impact of climate change is the spreading of non-native plant species that can thrive in the now warmer environment of RMNP. While Cheatgrass, a native of Eurasia, is found throughout the western US, it used to be limited to lower elevations.  Now, it is found as high as 9,500 feet in parts of RMNP. In addition to crowding out native plants and changing the look of the landscape, this invasive species is highly flammable. Its presence increases the danger of wildfires – something the West certainly does not need.

While these are just a few examples of the observed and expected impacts climate change is and will have on RMNP, scientists are continuing to research how additional increases in temperature will affect this national treasure.

Denali’s Wood Frogs Freeze for the Winter

While traveling in Alaska recently, I had the opportunity to visit Denali National Park and Preserve.  Its landscape, which includes Mt. McKinley – the highest mountain in North America – and its diverse wildlife were nothing short of impressive.  However, it was the tiny wood frog – the park’s only amphibian – that peaked my curiosity when I learned how it survives the region’s subarctic winters.

Situated at roughly 63°N latitude, winters in Denali are long and extremely cold.  From October to March, temperatures can range from 20°F to as low as -40°F.  These cold conditions drive many creatures to hibernate in dens or migrate south. The wood frog, however, makes it through winter by burrowing into leaf litter and literally freezing solid until spring.

According to wildlife biologists, a wood frog responds to falling temperatures by converting glycogen in its liver into glucose (sugar) and pumping it throughout its body.  Acting like a natural anti-freeze, the glucose lowers the freezing point of water inside the frog and protects its tissues and organs.  As temperatures continue to drop, however, the frog does eventually freeze.

Throughout the winter, the frog is essentially lifeless.  Its heart stops beating and it does not breathe.  Yet, as temperatures rise in spring, the frog thaws and comes back to life. While scientists are not exactly sure how this amazing resurrection works, they have noted that the wood frog’s heart and liver freeze last and thaw first.

Although the wood frog can be found across North America, the Alaskan wood frog is known to endure colder temperatures and freeze for longer periods of time than its southern cousins.  It is also the only frog found north of the Arctic Circle.


Wood Frog

Image Credit: NPS

Record Large Dead Zone is Forecast for the Gulf of Mexico

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

Temperature Influences Alligators

Temperature affects all living things in some way.  This is especially true of alligators.  While exploring the wetlands of South Carolina last week, I became much more aware of how ambient temperatures drive almost all aspects of their lives.

As cold-blooded reptiles, alligators are ectothermic.  They rely on external sources to regulate their body temperature.  For example, they lay out in the sun to warm up and float in water to cool down.  Temperature also affects an alligator’s ability to eat.  As temperatures decrease, so does its metabolism.  In fact, when temperatures fall below 70°F they stop feeding since they will not be able to digest what they consume.  If temperatures fall even further, into the 50°F range, alligators become inactive or dormant and ride out the colder weather in dens.

Environmental temperature also plays a critical role in determining the gender of baby alligators.  Through a process known as temperature-dependent sex determination (TSD), eggs that incubate at 93°F or higher all become males while temperatures below 86°F produce all females. Temperatures that hover in between create a mixture of both sexes. Scientists do not know exactly why this process developed, but they have found that it tends to produce more females than males.


An alligator basks in the sun along the edge of a swamp in South Carolina.

Image Credit: The Weather Gamut

Groundhog Day 2013

Today is Groundhog Day, the halfway point of the winter season.

According to folklore, on this particular date, the weather conditions of the second half of winter can be forecast by the shadow of a prognosticating groundhog.  Upon emerging from its burrow, if the groundhog sees its shadow, there will be six more weeks of winter.  If it does not see its shadow, then spring will arrive early.

In New York City, our local weather-groundhog is “Staten Island Chuck”. This year, he did not see his shadow and is predicting an early arrival of spring-like conditions for the city.

Staten Island Chuck, officially known as Charles G. Hogg VII

Staten Island Chuck, officially known as Charles G. Hogg VII

Image Credit:

Birds and Climate Change

The 112th Christmas Bird Count was held in New York City this past weekend.  This annual survey gives scientists a picture of how the avian population is changing in a given area. The analysis of recent CBC studies by the Audubon Society shows that climate change is having a serious impact on the songbird population in North America.

Migration is a regular seasonal event for many species of birds.  In general, they fly north in the spring to breed and south in the autumn to find food.  The changing amount of available daylight in the sky signals the birds to begin their great treks. Their food sources such as insects, on the other hand, are mostly driven by temperature.  As global temperatures rise, spring warmth is arriving earlier and unbalancing the migration cycle.  This means that by the time migratory birds arrive at their northern breeding grounds, they will have missed the peak bug season. This in turn, affects the birds’ ability to feed their young and therefore the overall population count.

Studies are showing that some species of birds are adapting to the changing climate by shifting their winter ranges northward. Those who have not been able to adapt are predicted to go extinct as global temperatures continue to rise.  Birds that do not migrate may see an increase in number as winters grow shorter and food sources are renewing themselves earlier.  In any case, the variety of songbirds we see at our backyard feeders throughout the winter will be changing.

Major Migratory Bird Flyways in North America

Image Credit: U.S. Fish and Wildlife Service

Cricket as Thermometer

Snapple Real Fact #237, listed under the bottle cap, states, “The number of times a cricket chirps in 15 seconds, plus 37, will give you the current air temperature.”

Intuitively, this makes sense as all living things react to the weather in some way.  Crickets are cold-blooded insects and the ambient temperature directly affects their metabolic rate. As the temperature goes up, their energy level increases and they can produce more chirps.  As the temperature drops, the rate of chirping declines.

I have seen a few versions of the cricket-thermometer equation.  Most differ according to the species of cricket.  Others vary in time duration. The first person to study the correlation between air temperature and cricket chirps was  Amos Dolbear, a physics professor at Tufts University in the late 1800’s.  His equation measures the number of snowy-tree cricket chirps heard in one minute.

It states:  T= 50 + [(N-40)/4]   …where T= temperature and N= number of chirps per minute.  This is now known as Dolbear’s Law.

A simplified version, more akin to the Snapple fact, is: T= N14 + 40  … where T= temperature and  N14= number of chirps heard in 14 seconds.

These equations are for temperature readings in degrees Fahrenheit.

Snowy Tree CricketSnowy Tree Cricket  

Photo credit: Wikipedia