Tundra ecosystems

Question 1

Past three decades, Alaska has warmed at twice the rate of global average, so

Answer 1

…we can examine ACTUAL and POTENTIAL impacts of global warming

Question 2

Issue: Rising Temperatures: Actual

Answer 2

Over past 50 years, temperature across Alaska increased by average of 1.9C (twice US average) but winters more dramatic - 3.5C

Question 3

Issue: Rising Temperatures: Potential

Answer 3

Average annual temps Alaska projected to rise by 2-4C by middle of century

Question 4

Issue: Rising Temperatures: Evaluation

Answer 4

Rising temps have many negative impacts but also some positive resulting from warmer summers. Number growing days increased by 20% - benefits for agriculture and forestry. Impact on aquaculture and fishing mixed - increase in salmon numbers, but also increase in jellyfish numbers (compete for food and clog nets) could outweigh any benefits.

Question 5

Issue: Thawing Permafrost and Ice: Actual

Answer 5

Permafrost in Alaska already begun to melt in response to rising temps last 50 years. Soil temps at 1m deep up 4C and 20m deep up 2.5C

Question 6

Issue: Thawing Permafrost and Ice: Potential

Answer 6

Models project permafrost will continue to thaw and may be lost entirely from large parts of Alaska by end of century

Question 7

Issue: Thawing Permafrost and Ice: Evaluation NEGATIVES

Answer 7

Impacts mostly NEGATIVE. More than 70% of land in Alaska vulnerable to subsidence if thawing occurs. Huge costs of maintaining infrastructure - buildings, pipelines, roads, airports will increase by $3-$6 billion by 2030. Melting already having negative impacts on transportation. Many of Alaska’s highways built on permafrost and number of permitted travelling days already reduced from 200 to 100. In rural areas, people depend on travelling along frozen rivers so becoming more difficult.

Question 8

Issue: Thawing Permafrost and Ice: Evaluation POSITIVES

Answer 8

A reduction in permafrost - easier to drill for oil in Alaska. State gets 90% of day-to-day finances from levies on oil and gas. Extra oil revenues, which have been in decline, can help pay for projects such as relocating climate change refugees from coastal regions such as Kivalina.

Question 9

Issue: Lakes and Wetlands: Actual

Answer 9

Warming climate in tundra - greater rates of evapotranspiration. Despite some localized increases in lake sizes due to melting permafrost, as a whole Alaska’s lakes and wetlands are decreasing.

Question 10

Issue: Lakes and Wetlands: Potential

Answer 10

Future pf thaw likely to increase lake size in areas of continuous pf and decrease in areas of fragmented pf.

Question 11

Issue: Lakes and Wetlands: Evaluation

Answer 11

Impact of lake and wetland change is NEGATIVE. Continued drying of lakes could affect waterfowl management in USA - Alaska has 81% of National Wildlife Refuge System. - potential to disrupt habitats for these migratory birds.. In addition waterfowl are an important food source for Alaskan Natives and other rural residents.

Question 12

ISSUE: Increased Wildfires - Actual

Answer 12

Climate change producing warmer, drier summers with more thunderstorms. Resulted in increase in wildfires in tundra.

Question 13

ISSUE: Increased Wildfires - Potential

Answer 13

Although precipitation levels projected to increase by 15-30% by end 21st C, increased evaporation will reduce water availability overall in tundra biome - increasing fire risk.

Question 14

ISSUE: Increased Wildfires - Evaluation

Answer 14

Impacts are partly positive and partly negative. Effects on habitats mixed. Burning improves habitats for eg berries and mushrooms and thus moose. However habitat for caribou badly affected. Lichen on which they depend in winter will take between 50-100 years to recover. Caribou critical food source for bears and wolves as well as Alaskan natives.
Exotic plant species that were introduced along roadways can spread to burned forests. Can be toxic for moose, which local people depend on for food; and can change suitability of forest for timber production and wildlife.
In addition, fires have negative impact on tundra’s ability to store carbon dioxide. A single large ire in 2007 released as much carbon into atmos as had been absorbed by entire Arctic tundra in previous 25 years.

Question 15

Overall Evaluation - Actual and Potential impacts of climate change on tundra ecosystem (Alaska) -

Answer 15

Overall, despite some benefits, in terms of increased growing season and funding resulting from oil exploration, the impacts of climate change on the tundra ecosystem are largely negative.