World View of Global Warming

Marine Biologist Rafe Sagarin points out some of the tide pool habitat that was found to have changed when he re-inventoried a 60-year-old study at Hopkins Marine Laboratory, Monterey California. Summer sea temperature has risen more than one degree in that time, and the re-survey showed many warm water tidepool animals had increased while those favoring colder water had decreased.

This nudibranch Hopkinsia rosea, discovered at and named for the Hopkins Lab, was numerous in the 1930s survey but not seen at all 60 years later. It is still found in other locations near Monterey, favoring cooler water. Other species, such as predatory snails and anemones showed great shifts in those thriving in warmer water south on the California coast.

Another series of observations of even longer duration shows changes in distribution and abundance of zooplankton and intertidal life in the western English Channel.   With data going back 70 years from the Marine Biological Association lab in Plymouth England, this study by Alan Southward, Stephen Hawkins and M. T. Burrowsc  clearly tracks the effects of rising temperatures.  The distribution of both plankton and tidepool organisms was shifted up to 120 miles, and there were increases or decreases of 2 to 3 orders of magnitude in abundance.  Warm water species increased in abundance and extended their range during periods of warming, while cold-water species declined or retreated.  Underlining the sensitivity of these ocean creatures is data showing that the reverse movement occurred during a period of cooling in the mid-20th century.

Biologist Camille Parmesan compared old records of the Edith’s checkerspot butterfly against current habitat from Mexico to Canada and found that the insect had moved its habitat slightly north in response to climate warming. She found the level of population extinctions is four times as high at the far southern end of the range (Mexico) than at the northern. This change in a sensitive insect was predicted from the twentieth century warming of about 1 degree F.          

The butterfly  pictured is laying eggs on Collinsia, an annual plant of Sierra Nevada high meadows.  Annual plants are more affected by weather shifts, and this is one of the factors in the butterfly population shifting as climate changes the habitat of both animals and their host plants.        

Dr. Parmesan later collaborated with many European biologists and lepidopterists to show that 2/3 of butterfly species with long observational records had shifted northward by from 22 to 150 miles, consistent with temperature increases in Europe.  No butterflies were found to have shifted to the south.  Parmesan has found many locations in Southern France with apparently intact food-plant habitat that no longer have well known butterflies like the Apollo (Parnassius apollo)..

Throughout the temperate zone, changes are being recorded in where and when plants bloom and thrive. One recent study by botanists at the Smithsonian's National Museum of Natural History reviewed records on the spring bloom time of 100 common Washington D.C. area plants. Eighty-nine of the 100 showed significantly earlier blooming. This one, the common lawn weed deadnettle, photographed at the National Arboretum, is blooming an average of 39 days earlier than in 1970.

American ornithologists are investigating climate change in several ways. Jeff Price of the American Birding Congress collects data from birders and scientists and reports changing migration and ranges for hundreds of North American species. This yellow warbler was an early migrant at Point Pelee National Park, Ontario.

Meanwhile Terry Root of Michgan University correlated regional temperatures with a 50 year record of bird arrival at Seney National Wildlife Refuge, Michigan. Comparing yearly records kept by now-retired field biologist Elizabeth Losey with current arrival times showed significantly early in-migration.

Even though the predicted range of climate warming has just begun, many ecologial responses are already clearly visible, as seen in these and other studies. Recent scientific reviews of biologial research show that strong effects are being seen in habitats from alpine meadows to coral reefs, and from the tropics to the poles.

Among the important review articles are Gian-Reto Walther et al., "Ecological responses to recent climate change." Nature 416 (28 March 2002), and Drew Harvell et al., "Climate Warming and Disease Risks for Terrestrial and Marine Biota," Science 296 (Jun 31 2002). World View of Global Warming will be documenting some of these studies in the coming months.

Tree swallow Tachycineta bicolor in nest hole at Point Pelee, Ontario

Another study showed the egg laying date of North American tree swallows advanced by up to nine days during the period from 1959 to 1991. Reported in 1999 by Peter O. Dunn, Univ. of Wisconsin and David W. Winkler, Cornell Univ, the research correlated 3450 nest records, taking into account differences of location, elevation and other breeding factors. "WE conclude," wrote the scientists, "that tree swallows across North America are breeding earlier and that the most likely cause is a long term increase in spring temperature."

Mountains are undergoing some of the most crucial changes due to global warming.  Besides the loss of glaciers, warming temperatures are driving the alpine zones farther up toward the summits.  Eventually, the highest alpine plants and animals will have nowhere to go.  This effect is being seen in and near Rocky Mountain National Park, where marmots are coming out of hibernation earlier, and in Great Basin mountains where some populations of pikas have disappeared apparently due to climate changes.         

Other research is focused on alpine trees and meadows, showing that mountain hemlocks and sub alpine firs are moving into meadow areas in Mt Rainier and Olympic National Parks -- and the effect is expected to accelerate if temperatures continue to rise rapidly.  In Yellowstone National Park,  the zone of life for the whitebark pine is moving up toward the summit of the mountains.  If this reduces the number of these pines, it will affect not merely scenery, because the seeds of the whitebark are a crucial part of grizzly bear diet.