Chicago — If you’re a scientist, this is one happy day.

Here in Chicago, the American Association for the Advancement of Science is opening its annual meeting, with 10,000 attendees from 60 countries attending 175 scientific symposia, seminars, and career-development workshops on topics that include astrophysics, molecular biology, and neuroscience.

The theme of the conference — the notion that the scientific evidence for climate change is “unequivocal” — was cited this morning by organizers as part of the stark contrast between the Bush and Obama administrations in their official approach to science.

Science in the Bush administration was ““almost totally ignored,” James Cornell, president of the International Science Writers Association, said an introductory session that reflected the celebratory mood of the gathering.

Evidence of that change could be seen today in Washington, where two former AAAS presidents — John Holdren, a Harvard University physicist, and Jane Lubchenco, an Oregon State University marine biologist — had their Senate confirmation hearing to be, respectively, White House science adviser and director of the National Oceanic and Atmospheric Administration.

Also in Washington, House and Senate negotiators are working on the final version of an economic-stimulus plan that includes some $15-billion to $20-billion in new money for federally sponsored research and development.

And if that were not enough for scientists, today of course is also the 200th anniversary of the births of both Charles Darwin, renowned as the originator of the theory of evolution, and Abraham Lincoln, the only U.S. president to hold a scientific patent. —Paul Basken