RMBL Phenology Research

Global vs Local Climate Change and Effects on Phenology

Dr. David Inouye – outstanding in his field!

Climate scientists have shown that 2000-2010 is the warmest decade on record. One major prediction from climate change researchers is that growing season length will increase with increased global-scale warming. Using billy barr’s observations, biologist David Inouye and others showed that, as of 1999, the start of the growing season (snow melt date) around Gothic has not changed significantly since the early 1970s (Inouye et al., 2000). In contrast, many scientists that work at lower elevations have substantial evidence for lengthening growing seasons, earlier spring migrations, and earlier reproduction in a variety of different organisms. Inouye believes that this disconnect is a problem for both 1) migrating species that visit the high Rockies during the summer and 2) hibernating resident species, such as the marmot.

Listen to Colorado Matters as Dan Meyers speaks with billy barr, RMBL accountant, and Dr. Inouye from the University of Maryland. To listen to this interview (Colorado’s Marmots and Climate Change) click here – type in inouye to search for the radio program.

Major Points from Inouye et al., 2000

Photo from RMBL Archives
The timing of snow melt, which is the start of the growing season around the lab, has not changed since 1973. But robins are arriving earlier and marmots are emerging from hibernation earlier. Many plants’ phenology is tied to the date of snow melt, which isn’t changing, therefore the growing season at RMBL is not lengthening. Snowfall may be increasing, so why isn’t snow melt date increasing? Increasing overnight low temperatures in April may result in earlier spring melting. Migratory species may be responding to warming at their wintering grounds by migrating earlier, but have to wait for snow to melt at their breeding grounds.


If migrating species arrive early and less food is available does this affect the timing of life events, their phenology?

Photo by billy barr
From 1975-1999, Inouye and others show that the first date of permanent snowpack is 13.4 days earlier, increasing the period of winter snow cover. Longer snow cover means that marmots spend more time hibernating and less time on other activities. So, increasing the amount of snow cover on the date of emergence of marmots means a longer period of time between emergence and feeding.

How does emergence date affect marmot populations?

Inouye and others predict that the earlier start and longer duration of snow pack combined with increasing spring temperatures will disrupt phenological patterns for other hibernating species. If disjunction between climate change at low and high altitudes continues to expand, migrating species will also encounter problems.

Next step – You will test this hypothesis using an additional ten years of data in the Biology of Climate Change assignment. But first, check out the data on billy barr’s interactive data visualizer!