> I've not seen a sensible rebuttal. No one discusses the massive increase in the utterly predictable 'greening of the planet' that has and is taking place as a result of the CO2 increase. This translates to $billions in crop production. We only hear of negative effects. Estimates of the lowering of temperature supposedly linked to lowering of emissions after 50-100 years, cite decreases imperceptible to a human and hedged with uncertainties as to their origin and statistical treatment. And so on.

We have discussed it. You're the one that hasn't heard about the effects.

"We can't count on plants to slow down global warming"
http://www.theguardian.com/environment/climate-consensus-97-...

"Research published in Science today found that increased levels of carbon dioxide in the atmosphere cause soil microbes to produce more carbon dioxide, accelerating climate change."
http://www.eurekalert.org/pub_releases/2014-04/nau-sfa042414...

We not only understand that plan CO2 absorbtion does not increase after a certain threshold, but that the effect is much worse on phitoplakton, which is the big recycler of atmospheric CO2.

"Plankton are showing the effects of a warming climate as marine populations worldwide experience a regime shift caused by climate change. In northern oceans, biogeographical boundaries are shifting northward as warm-water species displace cold-water species, causing trophic cascades. Ocean acidification is accelerating and threatening the long-term survival of many marine species."
http://bioscience.oxfordjournals.org/content/56/8/642.full

"Tropical rainforests are becoming less able to cope with rising global temperatures according to a study that has looked back over the way they have responded to variations in temperature in the past half a century.

For each 1C rise in temperature, tropical regions now release about 2 billion extra tonnes of carbon-containing gases – such as carbon dioxide and methane – into the atmosphere, compared to the same amount of tropical warming in the 1960s and 1970s, the study found."
http://www.independent.co.uk/news/science/climate-change-rai...

Multiple papers have cited that the ecosystem shift (which is objectively observable) produced by current temperature trends goes far beyond what species can adapt to rapidly, cause a severe, irrecoverable loss in biodiversity. You talk about "no significant increase in global temperature", and yet all serious credible models by independent agencies not only indicate the contrary, but are supported by actual, empirical evidence beyond mere temperature readings, which include the observation that glacier melt is increasing.

"The World Glacier Monitoring Service, based at the University of Zurich in Switzerland and with partners in 30 countries, has been compiling data on changes in glaciers over the last 120 years. And it has just compared all known 21st century observations with data from site measurements, aerial photography and satellite observations and evidence from pictorial and written sources. Altogether, the service has collected 5,000 measurements of glacier volume and changes in mass since 1850, and 42,000 records of variations in glacier fronts from records dating back to the 16th century.

And the evidence is clear: the glaciers are in retreat, worldwide, and the retreat is accelerating."
http://www.theguardian.com/environment/2015/aug/04/speed-gla...

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Now that I've presented and abundant pile - yet only a fraction of the available - evidence, I'm going to rant on the subject:

You seem a like a smart fellow in being able to ask the questions about it, but as a layperson who has been following the latest research on climate science and glaciology, you're severly underestimating the extent of your ignorance on the matter and the considerations of what is settled science.

* It has been understood for quite a while already that the projected temperature increases will result in a significant global reduction of crop yield and arable land. If you had been sufficiently informed to be a climate skeptic with useful questions to contribute to a "debate", this would not even be a point of contention. You cannot equate your personal ignorance on the matter with your assumption of what climate scientists currently undersand

* The evidence of glacial melt in response to temperature increase is so massively overwhelming that whatever questioning a very tiny minority of less-than-credible climate scientists and geologists have over collection methods for temperature data is crushed by the preponderance of good records of glaciers across the world, with photographic evidence to boot.

* The effects of rising temperatures, by themselves, are only a small fraction of the total effects of changing climate, which are far, far riskier. Atmospheric temperature increases are a walk in the park considering the totally catastrophic effects of ocean acidification and the increase of the ocean's heat mass and its effect in changing ocean currents.

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Finally, I'm going to talk about whatyou say is a "calm apprasial of pros and cons":

Once again, the overwhelming evidence that we currently have is that we continue under the "business as usual" scenario, there is one, and only one path that we are taking: that of an accelerated mass extinction event with a cost of human life that we cannot begin to understand.

The consequences of a loss of 25% of arable land in the world are incalculable. The loss of phitoplankton, the base of the entire food chain, implies a global change in available energy in all ecosystems. The change of atmospheric CO2 concentrations implies a reduction of nutrients in the plants that we consume.

Above all, once ecosystems degrade beyond a certain point, they are gone for good; they do not recover. We are only beginning to understand the immense cost of trying to recover collapsed fish stocks. Once the real effects of ocean acidifycation kick in, you can say goodbye to the formation of healthy hard-shelled ocean organisms, because they simply cannot adapt rapidly enough (this we know experimentally and through obsevation of affected ecosystems).

And the more we keep poking these known feedback loops, the greater the chance of permanent destabilization. I wonder if you're aware of the methane clathrates in the Siberian permafrost and how a lot of glaciologists consider that this may be a ticking time bomb that, if breached, can lead to an extinction event of the level of the Permian-Triassic event.

People that matter have been very calmly, against all odds, been discussing this year after year in the IPCC reunions and international meetings for all sorts of global treaties. They also understand that there is a non-trivial probability that we are, for all intents and purposes, already fucked and heading towards the worst predicted scenarios.

What do you consider to be an acceptable level of risk to play around with mass extinction? 1%? 2%? 5%? I personally think that if this is the behavior that we're taking towards the environment every time some essential component is in play, even if we go through this one effectively, civilization won't last even 500 years at its exponential pace of growth.

The maturity of humanity will depend on its ability to recognize that its destinity is not separate from the environment that supports it. You complain about poverty? Well, I'd say that supporting life on the planet concerns the poor about a million times more.