Question

changes in biodiversity are caused by a range of drivers. a driver is any natural or human - induced factor that directly or indirectly causes a change in an ecosystem. the graph pictured shows the impact of drivers on the biodiversity of different biomes. the cell color indicates the impact to date of each driver on biodiversity in each biome over the past 50 - 100 years. the arrows indicate the trend in the impact of the driver on biodiversity. horizontal arrows indicate a continuation of the current level of impact; diagonal and vertical arrows indicate progressively increasing trends in impact. consider the polar biome. which driver is having the greatest impact on the biodiversity of this biome? a pollution b habitat change c climate change d overexploitation the polar bear is one of the 10 most endangered species in the us, critically threatened by the effects of human population. a polar bear is fit to swim 100 miles for food, in search of mates or, more recently, just some ice to stand on. with five inches of blubber keeping this enormous bear prepared for subzero temperatures, the largest member of the bear family has remarkably adapted to arctic conditions. based on the biodiversity data offered in the graph and what you know of human impacts on the environment, what is most likely to be the greatest threat to polar bears? a polar bears are losing habitat to expanding human population growth. b polar bears are losing food sources due to overfishing in the area. c polar bears are facing extinction due to effects of the ozone hole over the arctic region. d polar bears are nearing extinction due to the extreme impacts that human - caused climate change has had on the arctic.

Explanation:

The graph (though partially obscured) and context about polar biomes indicate climate change is the primary driver of biodiversity loss there, as it directly melts sea ice—critical habitat for polar bears. For the polar bear question, human-caused climate change's impact on Arctic sea ice loss is the well-documented greatest threat.

Answer:

First question: C. climate change
Second question: D. Polar bears are nearing extinction due to the extreme impacts that human-caused climate change has had on the Arctic.