In 1954, workers at Michigan State University began spraying the elm trees on campus annually with DDT to kill disease-carrying bark beetles. In the spring of 1955, large numbers of dead robins were found on the campus. Observers thought perhaps the robins died after eating earthworms contaminated by DDT the previous spring. Suggest how scientists could have investigated the scientific validity of this idea.

Will increasing atmospheric levels of CO₂ make you sneeze as well as itch?

Scientists studying the effects of rising CO₂ levels have looked at ragweed, whose pollen is the primary allergen for fall hay fever. They grew ragweed in three levels of CO₂: a pre-industrial concentration of 280 ppm, a year 2000 level of 370 ppm, and a projected level of 600 ppm. They found that pollen production increased by 131% and 320% in the plants exposed to the recent and projected CO₂ levels, respectively.

What was the hypothesis of this experiment?

Do the results support the hypothesis?

Given what you know about climate change, what other variables would you like to test, and what other measurements would you like to take?

Scientists around the world are collaborating to understand how deforestation, climate change, and natural processes will interact to affect one of the most productive and biodiverse ecosystems on Earth. Journalists must be concise when reporting science news. Why might journalists and the public struggle to understand and discuss ecosystems ecology and global warming?

Do you drink coffee? A lot of people do—coffee is a major tropical crop, valued at over $100 billion per year. The most popular species of coffee, Coffea arabica, originated in Africa and is now planted extensively in Central and South America. The pest called the coffee berry borer beetle (Hypothenemus hampeii) moved along with the coffee and is a major problem for coffee farmers, sometimes destroying half of the coffee crop in mature plantations. Evaluate this statement: Leaving some natural forest in and around coffee plantations is a 'win-win' situation—a win for ecosystems and a win for farmers.

Most scientific experts agree that climate change is already occurring and has potentially catastrophic consequences for all of life on Earth. The Paris Agreement of 2015 represented a global consensus on the need to reduce greenhouse gas emissions. However, in 2017 the United States announced its intention to withdraw from the Agreement in 2020. Go online to research and summarize the main agreements reached in this historic global climate accord and the U.S. government's reasons for withdrawing. What roles do you think scientists, politicians, and citizens will need to play to cut emissions and limit global warming?

What community property does the red arrow in the model represent? a. high resilience b. low resistance c. high resistance

What is a biodiversity “hotspot”?

a. an area where an all-taxon survey is under way

b. a habitat with high NPP

c. an area with high species richness and high threat to those species

The population size of mountain pine beetles in the American Northwest has long been held in check by freezing temperatures during the winters. As winters warm, populations of pine beetles are increasing, killing whitebark pine forest. Grizzly bears rely on the nuts of whitebark pine trees. Do you think climate change is affecting the fitness of the grizzly bear population?

a. No, because climate change is affecting the beetles, not the bears.

b. Yes, because climate change is decreasing the food supply of the bears, which means they will be less strong.

c. Yes, because climate change is decreasing the food supply of the bears, which is likely to reduce their ability to survive or reproduce.

Human impacts such as habitat destruction, climate change, and pollution are causing a rapid decline in insect diversity. Pose an argument for why conservation efforts to preserve plant diversity, like Homegrown National Park, are essential for conserving insect diversity.