The impact of global warming in North America
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The vast North American continent ranges from the lush sub-tropical climate of Florida to the frozen ice and tundra of the Arctic. Within these extremes are two wealthy industrialized countries with diverse ecosystems at risk. Yet the United States and Canada are two of the largest global emitters of the greenhouse gases that contribute to a warming climate. Examples of all 10 of the "hotspot" categories can be found in this region, including changes such as polar warming in Alaska, coral reef bleaching in Florida, animal range shifts in California, glaciers melting in Montana, and marsh loss in the Chesapeake Bay.
For North America we have many more hotspots than for some other regions of the world, although impact studies have been emerging in larger numbers in recent years from previously under-studied regions. This higher density of early warning signs in the US and Canada is due in part to the fact that these regions have more readily accessible climatic data and more comprehensive programs to monitor and study environmental change, in part to the disproportionate warming that has been observed over the mid-to-high-latitude continents compared to other regions during the last century, and in part to capture the attention of North Americans who need to take action now to reduce greenhouse gas emissions.
4. Edmonton, Canada -- Warmest summer on record, 1998. Temperatures were more than 5.4�F (3�C) higher than the 116-year average.
7. Glasgow, Montana -- No sub-zero days, 1997. For the first time ever, temperatures remained above 0�F (-17.8�C) in December. The average temperature was 10.9�F (6�C) above normal.
8. Little Rock, Arkansas -- Hottest May on record, 1998.
9. Texas -- Deadly heat wave, summer 1998. Heat claimed more than 100 lives in the region. Dallas temperatures were over 100�F (37.8�C) for 15 straight days.
10. Florida -- June heat wave, 1998. Melbourne endured 24 days above 95�F (35�C); nighttime temperatures in Tampa remained above 80�F (26.6�C) for 12 days.
11. USA -- Late fall heat wave 1998. An unprecedented autumn heat wave from mid-November to early December broke or tied more than 700 daily-high temperature records from the Rockies to the East Coast. Temperatures rose into the 70�F (20�C) as far north as South Dakota and Maine.
12. Eastern USA -- July heat wave, 1999. More than 250 people died as a result of a heat wave that gripped much of the eastern two-thirds of the country. Heat indices of over 100�F (37.8�C) were common across the southern and central plains, reaching a record 119�F (48.3�C) in Chicago.
13. New York City -- Record heat, July 1999. New York City had its warmest and driest July on record, with temperatures climbing above 95�F (35�C) for 11 days -- the most ever in a single month.
39. Chesapeake Bay -- Marsh and island loss. The current rate of a sea-level rise is three times the historical rate and appears to be accelerating. Since 1938, about one-third of the marsh at Blackwater National Wildlife Refuge has been submerged.
40. Bermuda -- Dying mangroves. Rising sea level is leading to saltwater inundation of coastal mangrove forests.
42. Hawaii -- Beach loss. Sea-level rise at Waimea Bay, along with coastal development, has contributed to considerable beach loss over the past 90 years.
65. Glacier National Park, Montana -- All glaciers in the park will be gone by 2070 if retreat continues at its current rate.
68. Interior Alaska -- Permafrost thawing. Permafrost thawing is causing the ground to subside 16-33 feet (4.9-10 m) in parts of interior Alaska. The permafrost surface has warmed by about 3.5�F (1.9�C) since the 1960's.
69. Barrow, Alaska -- Less snow in summer. Summer days without snow have increased from fewer than 80 in the 1950's to more than 100 in the 1990's.
71. Bering Sea -- Reduced sea ice. Sea-ice extent has shrunk by about 5 percent over the past 40 years.
72. Arctic Ocean -- Shrinking sea ice. The area covered by sea ice declined by about 6 percent from 1978 to 1995.
135. Canadian Rockies - Disappearing glaciers. The Athabasca Glacier has retreated one-third of a mile (0.5 km) in the last 60 years and has thinned dramatically since the 1950s-60s. In British Columbia the Wedgemont Glacier has retreated hundreds of meters since 1979, as the climate has warmed at a rate of 2�F (1.1�C) per century, twice the global average.
136. Alaska - Increasing rate of retreat. A study of 67 glaciers shows that between the mid-1950s and mid-1990s the glaciers thinned by an average of about 1.6 feet (0.5 m) per year. Repeat measurements on 28 of those glaciers show that from the mid-1990s to 2000-2001 the rate of thinning had increased to nearly 6 feet (1.8 m) per year. Alaska has experienced a rapid warming since the 1960s. Annual average temperatures have warmed up to 1.8�F (1�C) per decade over the last three decades, and winter warming has been as high as 3�F (2�C) per decade.
16. Mexico -- Dengue fever spreads to higher elevations. Dengue fever has spread above its former elevation limit of 3,300 feet (1,006 m) and has appeared at 5,600 feet (1,707 m).
19. Central America -- Dengue fever spreads to higher elevations. Dengue fever is spreading above its former limit of 3,300 feet (1,006 m) and has been reported above 4,000 feet (1,219 m).
23. Lake Mendota, Wisconsin -- Fewer days of ice cover. The number of days per year with ice cover has decreased by 22 percent since the mid-1800s.
24. Mirror Lake, New Hampshire -- Earlier spring ice-out. The ice-covered period has declined by about half a day per year during the past 30 years.
25. Nenana, Alaska -- Early river thaw. During 82 years on record, four out of the five earliest thaws on the Tanana River occurred in the 1990's.
26. Washington, D.C. -- Cherry trees blossoming earlier. Average peak bloom from 1970-1999 came April 3, compared to April 5 from 1921-1970.
28. California -- Butterfly range shift. Edith's Checkerspot Butterfly has been disappearing from the lower elevations and southern limits of its range.
31. Olympic Mountains, Washington -- Forest invasion of alpine meadow. Sub-alpine forest has invaded higher-elevation alpine meadows, partly in response to warmer temperatures.
33. Alaska -- Sea bird population decline. The black guillemot population is declining from 1990 levels because melting sea ice has increased the distance the birds must fly to forage for food and reduced the number of resting sites available.
34. Canadian Arctic -- Caribou die-offs. Peary caribou have declined from 24,000 in 1961 to perhaps as few as 1,100 in 1997, mostly because of major die-offs that have occurred in recent years after heavy snowfalls and freezing rain covered the animals' food supply.
35. Monterey Bay , California -- Shoreline sea life shifting northwards. Changes in invertebrate species such as limpets, snails, and sea stars in the 60-year period between 1931-1933 and 1993-1994 indicate that species' ranges are shifting northwards, probably in response to warmer ocean and air temperatures.
36. Monteverde Cloud Forest, Costa Rica -- Disappearing frogs and toads. A reduction in dry-seson mists due to warmer Pacific ocean temperatures has beenlinked to disappearances of 20 species of frogs and toads, upward shifts in the ranges of mountain birds, and declines in lizard populations.
38. U.S. West Coast -- Sea bird population decline. A decline of about 90 percent in sooty shearwaters from 1987 to 1994 corresponds to a warming of the California Current of about 1.4�F (0.78�C).
46. Pacific Ocean, Mexico -- Coral reef bleaching.
53. Caribbean -- Coral reeef bleaching.
54. Florida Keys and Bahamas -- Coral reef bleaching.
55. Bermuda -- Coral reef bleaching.
76. New England -- Double normal rainfall, June 1998. Rainfall in Boston on June 13-14 broke a 117-year-old record, closing Logan Airport and two interstate roads. Vermont, New Hampshire, Rhode Island, and Massachusetts each received more than double their normal monthly rainfall.
78. Black Hills, South Dakota -- Record snowfall, 1998. At the end of February, the Black Hills received 102.4 inches (260 cm) of snow in five days, almost twice as much snow as the previous single-storm record for the state.
79. Texas -- Record downpours, 1998. Severe flooding in southeast Texas from two heavy rain storms with 10-20 inch (25.4-50.8 cm) rainfall totals caused $1 billion in damage and 31 deaths.
80. Santa Barbara, California -- Wettest month on record, 1998. 21.74 inches (55.22 cm) of rain fell in February, the most rain in a month since record keeping began.
81. Mount Baker, Washington -- World record snowfall, 1999. 1,140 inches (2,896 cm) of snow fell between November 1998 and the end of June 1999, a world record for most snowfall in a single winter season.
82. Florida -- Worst wildfires in 50 years, 1998. Fires burned 485,000 acres (196,272 hectares) and destroyed more than 300 homes and structures.
84. Florida, Texas, Louisiana -- Driest period in 104 years, April-June 1998. San Antonio received only 8 percent of its normal rainfall in May. New Orleans suffered its driest and hottest May in history.
85. Mexico -- Worst fire season ever, 1998. 1.25 million acres burned during a severe drought. Smoke reaching Texas triggered a statewide health alert.
86. Nicaragua -- 2.2 million acres (890,308 hectares) burned, 1998. Over 15,000 fires burned in 1998, and the blazing acreage included protected lands in the Bosawas Biosphere Reserve.
89. Eastern USA -- Driest growing season on record, 1999. The period from April-July 1999 was the driest in 105 years of record-keeping in New Jersey, Delaware, Maryland, and Rhode Island. Agricultural disaster areas were declared in fifteen states, with losses in West Virginia alone expected to exceed $80 million.
102. North America - Genetic adaptation to global warming in mosquito. Ecologists have identified the first genetic adaptation to global warming in the North American mosquito Wyeomyia smithii. Modern mosquitoes wait nine days more than their ancestors did 30 years ago before they begin their winter dormancy, with warmer autumns being the most likely cause. Higher temperatures, enhancing mosquito survival rates, population growth and biting rates, can increase the risk of disease transmission.
109. Colorado - Earlier emergence from hibernation. Marmots are emerging from hibernation on average 23 days earlier than 23 years ago. This coincides with an increase in average May temperatures of about 1.8�F (1�C) over the same time period.
110. Southeast Arizona - Earlier egg-laying. Mexican jays are laying eggs 10 days earlier than in 1971. The earlier breeding coincides with a nearly 5�F (2.8�C) increase in average nighttime temperatures from 1971 to 1998.
114. Alaska - Changing vegetation patterns. Comparison of photographs taken in 1948-50 to those taken in 1999-2000 of the area between the Brooks Range and the Arctic coast show an increase in shrub abundance in tundra areas, and an increase in the extent and density of spruce forest along the treeline. The increased vegetation growth is attributed to increasing air temperatures in Alaska, on average 1.8�F (1�C) per decade over the last three decades.
115. Western Hudson Bay, Canada - Stressed Polar Bears. Decreased weight in adult polar bears and a decline in birthrate since the early 1980s has been attributed to the earlier spring breakup of sea ice. Rising spring temperatures have shortened the spring hunting season by two weeks over the last two decades.
116. Banks Island, Canada - Expanded Ranges. The Inuit now regularly see species common much further south that previously were never seen on the island, such as robins and barn swallows. Thunder and lightning, never before recorded in Inuit oral history, have also been reported.
