Question 1 global temperature trends can be inferred from changes in and fossils; chemical isotopes found in sediments and glacial ice volcanic eruptions; fossils fossils; glacial ice thickness tree rings; silicon isotopes found in sediments 10 points question 2 impacts of global warming include all of the following except decrease in mortality because winter is warmer more human illness rising sea levels more extreme weather 10 points question 3 the best description of anthropogenic activities is human activities that decrease greenhouse gases in the atmosphere human activities that reduce carbon emissions through taxing fuel used for automobiles all activities by humans affecting the earth and its biosphere human activities that reduce carbon emissions through tax credits for reducing automobile emissions 10 points question 4 what has contributed to the loss of polar bears in arctic areas

1. fossils and chemical isotopes found in sediments and glacial ice

By studying the type of climate fossilized species preferred global temperature trends can be inferred. The changes in the concentration and type of isotopes are also an accurate measurement tool of these changes.

2. decrease in mortality because winter is warmer

The phenomenon known as global warming will bring more extreme weather. Thus, it is possible for some winters to be very cold and summers be very warm.

Even with warmer winters, the mortality will not decrease. Without a snow cover, pests such as mosquitoes and pathogens will thrive and live for longer periods of time. Thus, the spread of diseases will increase which will lead to potential increases in mortality.

3. all activities by humans affecting the Earth and its biosphere

Anthropogenic activities are all activities by humans affecting the Earth and its biosphere.

4. decline in sea ice

The main cause behind declining numbers of polar bears is the diminishing size of the sea ice. The bears use the ice as hunting ground where they stalk seals.