It is here and now

Global warming that is. Its effects are clearly visible and gaugeable according to the latest report by the UN's Intergovernmental Panel on Climate Change (IPCC):

From the poles to the tropics, the earth’s climate and ecosystems are already being shaped by the atmospheric buildup of greenhouse gases and face inevitable, possibly profound, alteration, the world’s leading scientific panel on climate change said Friday.
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The climate shifts would benefit some regions — leading to more rainfall and longer growing seasons in high latitudes, open Arctic seaways and fewer deaths from the cold.
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The new report, focusing on the effects of warming, for the first time describes how species, water supplies, ice sheets and regional climate conditions are already responding to the global buildup of heat. While the report said that assessing the causes of regional climate and biological changes was particularly difficult, the authors concluded with “high confidence” — about an 8 in 10 chance — that human-caused warming “over the last three decades has had a discernible influence on many physical and biological systems.”

At a news conference here, Martin Parry, the co-chairman of the team that wrote the new report, said widespread effects were already measurable, with much more to come.

“We’re no longer arm-waving with models,” he said. “This is empirical information on the ground.”
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The report said that given the current buildup of carbon dioxide and other long-lived greenhouse gases in the atmosphere, temperatures and seas would inevitably rise for decades. The worst effects would be felt in regions that are mainly poor and already facing dangers from existing climate and coastal hazards.

“It’s the poorest of the poor in the world, and this includes poor people even in prosperous societies, who are going to be the worst hit,” said Rajendra K. Pachauri, the chairman of the panel. “People who are poor are least-equipped to be able to adapt to the impacts of climate change, and therefore in some sense this does become a global responsibility in my view.”
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“The warnings are clear about the scale of the projected changes to the planet,” said Bill Hare, an author of the report and a visiting scientist at the Potsdam Institute for Climate Impact Research in Germany. “Essentially there’s going to be a mass extinction within the next 100 years unless climate change is limited,” added Dr. Hare, who previously worked for Greenpeace.

“These impacts have been known for many years, and are now seen with greater clarity in this report,” he said. “That clarity is perhaps the last warning we’re going to get before we actually have to report in the next I.P.C.C. review that we’re seeing the disaster unfolding.”

Will humanity be able to act before it's too late? Will our politicians muster the necessary courage?