Living in an Uncertain World

Posted in: Comment, Talks and Presentations

This was the title of last Tuesday night's I-SEE lecture by Richard Pancost, Director of the University of Bristol's Cabot Institute.

His seminar abstract was that:

"Our future Uncertain World (sic) is not one of which we have no knowledge – we have high confidence that temperatures and sea level will rise – but there is uncertainty in the magnitude and speed of change.  Nor should we view The Uncertain World with existential fear – we know that warm worlds have existed in the past.  

However, crucial details remain difficult to predict: we do not know whether many regions of the world will become wetter or dryer. Moreover, the consequences of these rapid changes on the wider and complex biological and chemical systems, and the people dependent upon them, are poorly understood. How do we better understand such issues?  What are their implications in terms of policy decisions being made today?  And how do we become a resilient city – both to the changes that are likely to come but also those that are difficult to forecast?"

Pancost conducts research on how organisms adapt to environmental conditions, how they mediate our planet’s chemical environment and how their molecular signatures can be used to reconstruct the history of our planet’s climate and environment.  Three major themes have emerged from his research:

1) the past record of climate broadly confirms our first order understanding of the climate system: a doubling of CO2 will bring about 2-4C of warming;

2) current rates of environmental change are essentially without precedent in geological history creating deep uncertainty in predicting biotic responses to rapid global warming; and

3) it is very difficult to predict how complex biogeochemical systems respond to rapid global warming, revealing the deep uncertainty associated with climate change, especially with respect to the sustainability of ecosystems on which we depend.

This was an enjoyable event: an engaging speaker with lots of data (some of it from rocks so old it was almost venerable), uncertainties galore, and good graphs.  I learned a lot, but one thing remained fixed: my conviction that we have no hope of restricting Earth temperature rise to 2 degrees Celsius.  But yet we pretend that we can, although COP21 is not even trying to do that.

Here are a few highlights:

  • If we burn all the Carbon, there will be a 5 to 6 degree Celsius rise (over 18th century levels)
  • Doubling the atmospheric CO2 gives a 2.5 degree increase
  • There will be between 0.7 to 1.3 m of sea level rise by 2100
  • Wet areas will get wetter with more intense rain; dry ones will probably get drier
  • Change now is very fast compared to past times
  • Adaption is not as good as mitigation in the short term as it's never quite clear what we're adapting to
  • The poorest will be the hardest hit as they tend to be the most vulnerable and least resilient
  • An ability to migrate is a key factor in survival (for every body / thing)
  • We should think about energy, the nhs and education (etc) at the same time.
  • Go for a 100% cut in emissions as quickly as possible – if not faster
  • Methane has a low atmospheric half life, and it will contribute 0.5 of the 2.5 degree temperature rise
  • All the Earth system models underestimate polar temperature rise
  • We need an ability to reimagine things
  • We need an education system that develops the ability to reimagine things

All very stimulating and ever so slightly depressing.  Future I-SEE events are listed here.

Posted in: Comment, Talks and Presentations


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  • Thanks for this pithy and helpful summary and checklist which I will send to my sceptical friends. Professors of biogeochemistry surely have to be taken seriously, especially when they highlight the complexities and uncertainties that sceptics always use to undermine the application of the precautionary principle. Unfortunately the corporate advance over state power represented by the emerging so-called secretly negotiated 'trade agreements' (the 3 Ts) does not encourage optimism re your desire for 100% cut in emissions, nor does the continuing blind eye of educators that I encounter (your good self excepted) to the urgency of these and other sustainability issues.