First the bad news, and please bear with me as this may take some time.
The impact of climate change, existential in its nature and all consuming in its scope, will be far more severe and felt far earlier than previously thought.
The latest scientific research presented at this week's meeting of climate scientists in Copenhagen confirms what many had privately feared: we are on track for the worst case scenario set out by the Intergovernmental Panel on Climate Change two years ago, and the instabilities in the climate system coupled with the fact that many natural carbon sinks are beginning to fail mean that it could be worse still.
All the latest climate science suggests global average temperatures are rising in line with expectations, but carbon emissions are rising faster than anticipated and natural systems are responding more dramatically than expected to even modest temperature rises.
For example, sea levels have risen an average of 3mm a year since 1993, an increase of 50 per cent on the average rate of sea level increase during the 20th century. The rise is faster than expected because previous models failed to anticipate the rate at which glaciers would move into the sea. Based on the current trends sea levels will not rise by between 18cm and 59cm by 2100 as predicted by the IPCC, but by more than one metre putting a tenth of the global population at risk of coastal flooding.
Similarly, new evidence reveals that the world's major carbon sinks, the tropical rainforest, Siberian permafrost and the oceans, are all much more sensitive to even small average temperature increases than previously thought. According to one model a temperature increase of just two degrees would result in 20 to 40 per cent of the Amazon dying off, releasing yet more CO2 into the atmosphere. The worst case scenario predictions that rising temperatures will result in more warming gases being released triggering runaway climate change are already being realised.
All this means that we are currently on track for warming of around five to six degrees by the end of the century.
What does that mean?
Well, one of the themes of the conference was that climate scientists have not adequately communicated the severity of the situation to political and business leaders. If they did choose to put aside their rigorous scientific terminology for a moment, they would likely settle on a one word assessment of our prospects, Anglo Saxon in origin and not to be used in polite company.
At five to six degrees below pre-industrial temperatures we were in the midst of the last ice age; at five to six degrees above we would be facing the end of civilisation as we know it.
That might sound like hyperbole, but at five to six degrees warmer vast swathes of the tropical and sub tropical regions would become uninhabitable, sea levels would rise by at least a metre putting coastal cities and entire countries at risk of inundation, the rainforests would be effectively wiped out, acidification of the oceans would create giant dead zones, and mass migration would spark near unprecedented levels of global conflict. One scientist predicted the global population could crash to just one billion people - between 2050 and 2100 the world could be literally decimated.
And the really scary thing is that most previous climate studies have been far too optimistic in their predictions. This time, if they are even half right we are on a path towards utter devastation.
For many people, 2100 may be too distant a prospect for these threats to register, even given the fact that modern life expectancies mean that a child born today in one of then lucky northern countries has a fair chance of being around to see it. But another scary component of these warnings is that we won't wake up in 2100 and everything will suddenly change. Based on the current emissions and warming trends the climate change impacts already being felt in many regions could become unmanageable within the next 20 to 30 years.
How should we feel about these predictions? Anxious, angry, and energised to take action, ought to cover it - though you'd be forgiven for opting for just plain terrified.
The bigger question though is where do we go from here?
Scientists at this week's meeting divide into two camps: those who believe it might just still be possible to limit warming to around two degrees above pre-industrial levels - a scenario that would still put the climate system under extreme stress. And those who believe the best we can hope for is to limit warming to three or four degrees and pray this does not do so much damage to the carbon sinks that it triggers runaway global warming. "Hope" and "pray" might not be particularly scientific terms, but after three days in Copenhagen this seems to be the crux of it.
To give us the slightest chance of avoiding catastropic levels of climate change we need a far greater sense of urgency than has been displayed to date. Political and business leaders need to act, and they need to act now.
To this end, the scientific, political and business community need to instigate an immediate change in the terminology they are using to describe global warming. Environmental campaigner George Monbiot's suggestion this week that we should substitute the passive "climate change" for the more accurate "climate breakdown" might seem like a semantic side issue, but if adopted widely enough it could have a huge impact.
If the full scale of the threat can be accurately communicated then there is a chance that a meaningful international deal can be reached later this year in Copenhagen, built around deep and binding emission reduction targets and the rapid mobilisation and adoption of clean technologies.
We also need to increase the focus on the short term benefits that accrue from a low carbon economy.
Talk of saving our grandchildren has not worked so far and sadly humanity is too short sighted for that to change any time soon. Unfortunately, by the time we realise, sometime in the 2030s, that it is our lives and livlihood at risk it will be too late to do anything.
As explicitly as economists, scientists and politicians warn of the catastrophe that will be reaped in the second half of the century, they need to highlight the cost savings, health benefits, risk reduction, job creation and investment returns that will accrue today for low carbon economies. It needs to become self evident that low carbon growth is not just the only long term option, but better in the short term too.
Most of all, it is critical that the temptation to succumb to despair is resisted. The challenge may be even more daunting than previously thought, but, as numerous speakers at the conference pointed out, it can be overcome.
One of the most compelling observations offered up by Professor Dan Kammen of the University of California, Berkeley, was that the US could save energy equivalent to its entire annual fuel imports simply by replicating the level of efficiency attained by New York and California across the rest of the countries. Time and again the point was made that the technologies needed to decarbonise economies are here now, tried and tested and ready to go.
Moreover, the price tag for deploying them really is remarkably small. One study suggested that subsidies of just €10 to €20bn a year would allow the solar and wind energy industry to account for around 40 per cent of the global electricity mix by 2050. Similarly, £50bn could make the ambitious plan to generate Europe's energy from solar farms in the Sahara a reality, while there is growing evidence that such investments would actually deliver a net increase in GDP.
The upfront costs might sound large, but they are miniscule compared to the amount governments have spent propping up failing banks. Many of the stimulus packages being rolled out around the world already have a green hue, but if we made them greener still we really could deliver deep cuts in emissions while restoring economic growth.
Finally, while the change in the climate might be terrifyingly fast, rapid cultural and economic changes are possible too.
Speaking at the conference, Lord Nicholas Stern noted that his generation had in just a few decades moved from a position where drink driving was widely seen as a basic right to an acceptance that it was the height of irresponsibility and should be severely punished.
A session at the conference on green cities, featured two photographs of a road in Dubai taken from the same point. One of the photographs was taken 13 years ago and featured a vast expanse of desert; the other was taken this year and showed a teeming metropolis dominated by skyscrapers and highways. It might be an example of the kind of unsustainable growth that has contributed to the current climate crisis, but it also serves as a reminder of how quickly societies can change if the ambition and will is there.
And that is the only good news we have left.
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