We've known all along that pumping more heat into a chaotic system would manifest as more rapid state changes and greater extrema, i.e., more rapid shifts between more extreme conditions.  Even in my area, a temperate/mediterranean climate almost ideal for Anglo-Euros, we see a perceptible shifting of the goal posts with hotter hot spells transitioning more abruptly into colder cold spells.  The climate here is tempered by a massive heat sink in the form of a large shallow (geographically) and deep (vertically) bay.  Inland, in mountain ranges and valleys, hot spells are hotter, rainfall is lower and winds are higher than average.  Freakish windy weather damaged stonefruit crops this year and drought threatens the late summer crops.

Six scientists from some of the leading scientific institutions in the United States have issued what amounts to an unambiguous warning to the world: civilisation itself is threatened by global warming.

    They also implicitly criticise the UN's Intergovernmental Panel on Climate Change (IPCC) for underestimating the scale of sea-level rises this century as a result of melting glaciers and polar ice sheets.

    Instead of sea levels rising by about 40 centimetres, as the IPCC predicts in one of its computer forecasts, the true rise might be as great as several metres by 2100. That is why, they say, planet Earth today is in "imminent peril".

    In a densely referenced scientific paper published in the Philosophical Transactions of the Royal Society A some of the world's leading climate researchers describe in detail why they believe that humanity can no longer afford to ignore the "gravest threat" of climate change.

    "Recent greenhouse gas emissions place the Earth perilously close to dramatic climate change that could run out of control, with great dangers for humans and other creatures," the scientists say. Only intense efforts to curb man-made emissions of carbon dioxide emissions and other greenhouse gases can keep the climate within or near the range of the past one million years, they add.

footnote

Nomad may well scold us all as pollopequenistas (Chicken-Little-ists for the Spanish-impaired) but the science wonks are right to point this out

"Civilisation developed, and constructed extensive infrastructure, during a period of unusual climate stability, the Holocene, now almost 12,000 years in duration. That period is about to end," the scientists warn. Humanity cannot afford to burn the Earth's remaining underground reserves of fossil fuel. "To do so would guarantee dramatic climate change, yielding a different planet from the one on which civilisation developed and for which extensive physical infrastructure has been built," they say.

The foolish belief that civilisation is the base condition for agriculture -- rather than the other way around -- fuels, so to speak, the notion that "land is not productive" and that what we do to our climate, water, and soil is less important than the games we play in cities with money, laws, hierarchy, costumes, ranks, rituals, etc.

Without robust biotic infrastructure and the climatic stability it encourages -- a huge pyramid of life on whose narrow tip we perch, top predator species, rapidly simplifying and eroding the pyramid beneath us -- we don't eat, or breathe (oxygen, anyone?) or drink (watersheds that provide our potable water depend on snowpack for storage and on complex networks of vegetation, soil porosity, etc to slow its downward rush to the sea).  How often and how loudly do we have to say this?  We can't eat an iPod.  A car doesn't give milk.  We can't plant a dollar bill and grow a shirt.   Ubiquitous WiFi can't pollinate an orchard.  Industrial chemicals can destroy life, but they can't create it.  Our technologies are contrabiotic, i.e. they are corroding the pyramid of self-organising life out from under us.

If our civilisation falls -- all bets are off -- it could be said that it was because we allowed merchants, bankers, and engineers to dream that they were more important than farmers;  and then we tried to turn farmers into merchants, bankers, and engineers, and food into a fungible commodity and an industrial product.  We even tried to commodify the rain (Bechtel in Bolivia).

Or perhaps it was because we invented a new religion (neolib economics) that justified and promoted our worst habits better than any previous religion...

Or perhaps we really aren't, in the aggregate, any smarter than yeast?

The difference between theory and practise in practise ...