Terrorism and racism are the most discussed world issues on Twitter, according to a study of 173 million tweets.

The research, conducted by SOAS University of London, focused on how the site was used as a barometer for global trends.

Terrorism was found to be the most discussed issue from the UN's list of issues with 31 million tweets talking about the issue per year.

Racism was the second most talked about topic with 28 million tweets, followed by climate change in third and human rights in fourth.

Richard Hammond, a data researcher on the project, said: "We found in the course of our research that 88% of the tweets have negative connotations, which means that the subject is perceived by the individual as a problem that needs to be addressed or that cannot be resolved."

Tweets Per Year Mentioning UN Global Issues

  1. Terrorism, 31 million
  2. Racism, 28 million
  3. Climate, 22 million
  4. Human Rights, 12 million
  5. HIV/AIDS, 11 million
  6. Pollution, 19 million
  7. Disease, 10 million
  8. Poverty, 9 million
  9. Equality, 7 million
  10. Discrimination, 6 million