“Global Warming 20 Years Later: Tipping Point Nears” by James Hansen:
June 23, 2008, 1:00am

My presentation today is exactly 20 years after my 23 June 1988 testimony to Congress, which
alerted the public that global warming was underway. There are striking similarities between
then and now, but one big difference.
Again a wide gap has developed between what is understood about global warming by
the relevant scientific community and what is known by policymakers and the public. Now, as
then, frank assessment of scientific data yields conclusions that are shocking to the body politic.
Now, as then, I can assert that these conclusions have a certainty exceeding 99 percent.
The difference is that now we have used up all slack in the schedule for actions needed to
defuse the global warming time bomb. The next President and Congress must define a course
next year in which the United States exerts leadership commensurate with our responsibility for
the present dangerous situation.