It’s an old joke: everybody talks about the weather, but nobody does anything about it. The same, unfortunately, is true for the climate.

They are talking about it. They were at it again in Honolulu last week, discussing mandatory, internationally binding commitments on greenhouse-gas emissions (although Russia and India refused to allow any mention of that subject in the final statement). At the Bali meeting in December, China even hinted that it might consider something like binding emission caps in the long run. But there is no sense of urgency.

Not, at least, the sense of urgency that would be required to take actions that would invalidate the prediction, in the latest issue of the journal Science, that climate change may cost southern Africa more than 30 percent of its main crop, corn, by 2030. No part of the developing world can permanently lose one-third of its main food crop without descending into desperate poverty and violence.

Even some parts of the developed world would be in deep trouble at that point. One part of the developed world, Australia, is already in trouble, with its farmers facing what may be a permanent decline in the country’s ability to grow food, although Australia’s overall wealth is great enough to cushion the blow. But elsewhere, the mentality of “It can’t happen here” persists.

The two Democratic candidates for the presidency in the United States promise 80-percent cuts in emissions by 2050, and John McCain for the Republicans promises 50-percent cuts by the same date, and nobody points out that such a leisurely approach, applied in every country, condemns the world to a global temperature regime at least three or four degrees Celsius warmer than today.

Nobody points out that those are average global temperatures that take into account the relatively cool air over the oceans, and that temperatures over land would be a good deal higher than that. Few people are aware that these higher temperatures will prevent pollination in many major food crops in parts of the world that are already so hot that they are near the threshold, and that this, combined with shifting rainfall patterns, will cause catastrophic losses in food production.

But here is a bulletin from the front. Over the past few weeks, in several countries, I have interviewed a couple of dozen senior scientists, government officials, and think-tank specialists whose job is to think about climate change on a daily basis. And not one of them believes the forecasts on global warming issued by the Intergovernmental Panel on Climate Change just last year. They think things are moving much faster than that.

The IPCC’s predictions in the 2007 report were frightening enough. Across the six scenarios it considered, it predicted “best estimate” rises in average global temperature of between 1.8 and 4.0 degrees Celsius by the end of the 21st century, with a maximum change of 6.4 degrees Celsius in the “high scenario”. But the thousands of peer-reviewed scientific papers that the IPCC examined in order to reach those conclusions dated from no later than early 2006, and most relied on data from several years before that.

It means that the IPCC report took no notice of recent indications that the warming has accelerated dramatically. While it was being written, for example, we were still talking about the possibility of the Arctic Ocean being ice-free in late summer by 2042. Now it’s 2013.

Nor did the IPCC report attempt to incorporate any of the “feedback” phenomena that are suspected of being responsible for speeding up the heating, like the release of methane from thawing permafrost. Worst of all, there is now a fear that the “carbon sinks” are failing, and in particular that the oceans, which normally absorb half of the carbon dioxide that is produced each year, are losing their ability to do so.

Maybe the experts are all wrong. Here in the present, out ahead of the mounds of data that pile up in the rear-view mirror and the studies that will eventually get published in the scientific journals, there are only hunches to go on. But while the high-level climate talks pursue their stately progress toward some ill-defined destination, down in the trenches there is an undercurrent of suppressed panic in the conversations. The tipping points seem to be racing toward us a lot faster than people thought.