On June 23, 1988, NASA climate scientist James Hansen told the US Senate it was time to acknowledge that climate change was happening and take action to limit its effects.
Thirty years later, the world has continued to burn fossil fuels faster and faster, cranking planet-warming carbon dioxide levels higher
than they've been for millions of years.
Without taking action soon, it'll cost future generations trillions to try to deal with the problem.
Exactly 30 years ago, James Hansen, the director of NASA's Institute for Space Studies, told the US Senate that the question of the day — whether climate change was happening — was no longer in doubt.
"It is time to stop waffling so much and say that the evidence is pretty strong that the greenhouse effect is here," Hansen told reporters at the time.