As world leaders meet in Poznan, Poland this week and next to discuss efforts to reduce greenhouse gas emissions causing global warming, it's worth remembering that scientists have known climate change could be a problem for a long time.

Irish scientist John Tyndall first speculated that human-induced global warming might be possible back in 1861 and Nobel Prize-winning chemist Svante Arrhennius had confirmed climate change (with laborious pencil and paper calculations rather than the shortcut of computers) by the end of the 19th century. And a little magazine called Scientific American published an article on the phenomenon back in 1959 that holds up today.

Even back then, the rudimentary outlines of the much-maligned "hockey stick" were visible, showing human-induced warming temperatures over time, despite the fact that U.S. geochemist Charles Keeling had only begun his annual measurements of carbon dioxide (CO2) levels in the atmosphere in Hawaii a year earlier. And the outcome was clear: average global temperatures would rise much the way that a closed car heats up in the sun.

Some things have changed since the article appeared: Scientists today know more about the interaction of sunshine, or solar insolation as they like to call it, and the atmosphere as well as the role of the ocean in absorbing excess CO2. Humans are pumping out a lot more that CO2 through fossil fuel burning, agriculture and deforestation than in the 1950s. And average temperatures rose by only around 1.3 degrees Fahrenheit (0.72 degree Celsius) rather than by 3.6 degrees F (2 degrees C) by 2000 that Canadian physicist Gilbert Plass had predicted in the article (though parts of the Arctic and Antarctic have heated up more than that).

It wasn't just the scientists who knew either. U.S. President Lyndon Johnson noted the looming problem in a message to Congress back in 1965 after being briefed on the issue. Question is: will President Barack Obama take steps to forestall those dangers? And, if so, what will his administration—and, more broadly, the world's governments—do?

Credit: ©Kutay Tanir/