World Unsuitable for ‘human life to flourish’: Up to 3B will live in extreme heat by 2070, study warns May 4, 2020May 5, 2020 Doyle Rice, USA TODAY Comments Off on Unsuitable for ‘human life to flourish’: Up to 3B will live in extreme heat by 2070, study warns By 2070, up to 3 billion people are likely to live in climate conditions that are "warmer than conditions deemed suitable for human life to flourish."