TABLE 1.

The eight components used to craft messages of different impact levels.

Message characteristic	Meaning	Level in high-impact message	Level in med-impact message	Level in low-impact message
Impact	Does the message state the concrete impact of donating?	A concrete measure of the averted carbon dioxide emissions per dollar donated.	A statement that emissions are averted, but with no concrete measure.	A statement that emissions are averted, but with no concrete measure.
Motives	Does the message invoke altruistic or self-interested motives?	A statement that a donation will help preserve the environment.	A statement that a donation will help preserve the environment.	A statement that a donation will give a feeling of satisfaction.
Endorsement	Is the charity endorsed by an authority figure?	An endorsement by a policy researcher from a well-known university.	An endorsement by a policy researcher from a well-known university.	No endorsement by an authority figure.
Co-benefits	Does the message mention positive side effects of donating?	A statement that donations also increase employment in developing countries.	No mention of positive side effects of donating.	No mention of positive side effects of donating.
Frame	Is the message framed in terms of climate or a different issue?	Framed in terms of climate change.	Framed in terms of climate change.	Framed in terms of air pollution and its impact on human health.
Proximity	Does the message focus on consequences of the issue that are nearby in space and time?	Emphasis of consequences in the same country and year of the study.	Emphasis of consequences in a different continent and future century.	Emphasis of consequences in a different continent and future century.
Social norms	Does the message mention how the reader’s peers feel about the issue?	A statement that university students are concerned about the issue.	No mention of university students.	No mention of university students.
Growing risk	Does the message emphasize that the issue is increasing in severity?	A statement that the risk is growing more urgent each year.	No mention of the growing risk.	No mention of the growing risk.