Sometimes the long-run effects of an action can drastically affect how valuable the action is, and can even make something that seems on the surface to be beneficial to be actually harmful.

Consider the poor meat-eater problem:

• Saving human lives, and making humans more prosperous, seem to be obviously good in terms of direct effects.
• However, humans consume animal products, and these animal products may cause considerable animal suffering, as well as increase greenhouse gas emissions.

For example, in the early 1980s the average person in China ate around 30 pounds of meat per year, and the population was under one billion. In the 2010s, people were much richer, and the average person ate around 140 pounds of meat per year. Additionally, the total population had grown by 380 million. As shown below, the total meat consumption in China increased dramatically in this time.

The poor meat eater problem suggests that indirect effects may make working on global poverty less effective than is commonly assumed.

Although it is very difficult to quantify these effects, one estimate suggests that each additional $1,000 per year for a relatively poor individual may cause between 1 and 190 days of animal suffering.

Sources:

• https://forum.effectivealtruism.org/posts/YH4zm6JDLELnPyLP9/quantifying-the-impact-of-economic-growth-on-meat
• https://www.motherjones.com/environment/2018/07/the-chinese-are-eating-more-meat-than-ever-before-and-the-planet-cant-keep-up/
• http://www.earth-policy.org/plan_b_updates/2012/update102