Monday 1 April 2013

Our Choice: Rocket to a Warming Catastrophe or Turn Down the Jets?

The Future is Certain, Unless...

We live in an astonishing times.  We can predict the future.  In one ever-increasingly certain area of knowledge – the overall global trend of climate and its relation to carbon emissions – we now know what is happening and where we are headed.  More emissions will lead to more global warming, a warming to temperatures beyond anything humans have experienced in our species' entire existence.

What is more, the most up-to-the-minute science, reconstructing the Earth's average surface temperature over the past 20,000 years, shows how massively humanity's recent intensive use of fossil fuels has disturbed the world's climate.

If we do act fast to lower global emissions radically, by beginning massive and immediate actions now, by altering personal behaviour, and rapidly decarbonising energy, goods and services, we really can have a limiting effect on future temperatures.  If humanity does not act and emissions continue unabated, the climate will pass through temperature level "trapdoors" that will be irreversible for a thousand years or more.

The Past as Guide to the Future

Marcott et al, authors of the most recent past temperature reconstruction, in summarising their results, state:
[T]he decade 2000-2009 has probably not exceeded the warmest temperatures of the early Holocene, but is warmer than ~75% of all temperatures during the Holocene. In contrast, the decade 1900-1909 was cooler than~95% of the Holocene. Therefore, we conclude that global temperature has risen from near the coldest to the warmest levels of the Holocene in the past century.

Jos Hagelaars, here, has combined temperature reconstructions for the past 22,000 years, including the recent one from Marcott et al., with temperature records for the past 120 years, and with the emission path that humanity is now following – which is tracking the very worst emissions scenario envisaged by the Intergovernmental Panel on Climate Change.  

Holgaars' presentation is as below and makes the recent century's change compared to the past very clear indeed.  The extraordinary rate of change now being seen is unprecedented in tens of thousands of years of human history and pre-history.

Jos Holgaars' presentation of temperature reconstructions, recent temperature, and IPCC forecast.

After a long slow cooling in temperature from about five thousand years ago, the recent increased use of fossil fuels, especially from 1900 onward, has launched global temperature upward at an unprecedented rate (as shown at the most recent part of the blue line), a rate that will continue (as shown in red) if emissions continue.  This warming will not be continuous and warming will not occur evenly around the world, but it will happen.  It has already begun to show the first damaging effects in the increasing weather extremes and weather event intensities.

To give a sense of where humanity's rocket launch into higher temperatures is taking us we can look to the past.  In the Permian extinction of 251 million years ago, 95% of all species on Earth were eliminated due to a global warming of 6ºC, in that case naturally caused, probably by volcanic eruptions.  Corresponding to the currently forecast 'business-as-usual' emissions, our current path, the resultant amount of warming by the end of this century is very likely to be around 6ºC in only ninety years from now.  This warming is a result of human interference in Earth's biosphere, the sudden addition of massive amounts of carbon dioxide and methane from burning of fossil fuels with additions from agriculture and clearing forests.  

If ever there was a time for precautionary action it is now,  while it is still possible to act.  Science also shows that urgent reductions in emissions could limit warming to a far safer, though still dangerous, level of 2º to 3ºC.  "Dangerous" is far preferable to catastrophic.

Only the choices we, as an intelligent species, make right now in the light of this information, will determine the level at which warming stops.  Humanity, collectively, will have to act fast but it is still possible to limit the warming, if and only if we can reduce emissions very rapidly.  Mitigating (reducing) emissions is a far safer and more certain course than geoengineering which has very unpredictable and very uncertain, often short-lived outcomes.

Below, I have added temperature bands to Holgaars' temperature anomaly versus time graph, to emphasise how different the future is likely to be compared to the past.  I have added date markers for agriculture to show how all of recent human history has occurred within a very narrow temperature (with a constant CO2 level close to 280 ppm).  By the end of this century the CO2 level is likely to be three times as great pushing temperatures ever upward.

The Choice: Delay Action or Act Now

We are heading up to higher temperatures than mankind has ever experienced as a species or as a global civilisation.  We now know this with certainty.  In sum, the remaining uncertainties are not reassuring and many of them such as methane from melting permafrost are likely to add to the warming once they begin in earnest as global temperatures reach tipping points.  Therefore, the humans who live now, we ourselves, can choose to add greenhouse gases to the atmosphere, at current, large and also increasing future rates, thereby knowingly choosing an apocalyptic future of climate extremes outside anything we have known before.  Or we can choose to act.

Either way, humanity and we individually are making a decision right now by our actions: to do nothing or to do something.  To date, despite much talk, nothing has been achieved.  Global emissions have doubled since 1990 and they continue to increase because nation states have not peaked emissions, quite the reverse.  They have been dishonest brokers in addressing the problem (see previous post).  

Starting this year every nation has to start by being honest about the warning our science is giving us.  At this point we have to peak emissions urgently, even if it costs economic growth.  Whatever fossil fuelled, economic growth could be achieved over the next few decades will be undermined by economic decay and possible collapse due to climate damage caused by fossil fuelled, economic growth that could be achieved over the next few decades.  We are loading the dice and nature will keep on rolling them.

Apologies for the necessary shouting on the next line:
It is our emissions now that are adding to warming.  By lowering emissions now – rapidly, globally, politically, corporately, nationally, regionally, locally, personally – we can still change the future to limit warming. Anyone unaware of this needs to become aware of it.  Anyone aware of the warnings needs to act on them.

Currently, rich nations, businesses and individuals are acting as though their own future is not in doubt and that 'business as usual' is possible into the far future.  The rich need to finally realise that we really are all in this together.  The futures of their nations, their businesses, their shareholdings, and their children are also in doubt if they do not choose to act for a safer long-term outcome by lowering emissions urgently and radically.

We really do have a choice.  We can still make the right one.

No comments:

Post a Comment

Comments welcome, observing etiquette of course.