Climate Change Roundtable


 

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color:black”>Red Pepper: In international negotiations it is widely accepted that a global temperature increase of 2oC above pre-industrial levels will trigger dangerous climate change. However, in his book ‘Requiem for a species. Why we resist the truth about climate change’ Clive Hamilton notes “most leading climate scientists now believe that 2oC of warming would pose a substantial risk.” What do you consider to be a safe temperature increase after which dangerous climate change occurs?

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"Times New Roman";mso-bidi-font-family:Arial;color:black”> I think 2oC is the limit that we should not exceed. This is because 2oC is the highest temperature that we can infer occurred on Earth at least in the past 2 million years. Thus we know that warming of 2oC is stable enough for humans to live, even though we would have a lot of adjustments to make to adapt to a 2oC warmer world, particularly for producing food and for ensuring the availability of water. Above 2oC the risk is very high that the Earth's natural feedbacks would destabilise climate well beyond warming itself, and that it could become technically difficult, costly, and even impossible to adapt, particularly in the poorest regions of the world.

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color:black”>We are already living with the adverse effects of anthropogenic climate change in many parts of the world with changes in both biological and physical systems. Hence, in an ideal world we would keep the climate as close to today’s climate as possible. As the magnitude and rate of climate change increases the effects become increasingly detrimental, with poor people and poor countries being the most adversely affected. People living in low-lying areas are particularly vulnerable to sea level rise, while others are vulnerable to threats to food security and water security, loss of critical ecosystem services, and increased health threats. While I do not like the term “dangerous” because different groups of individuals and sectors are affected differently, there is little doubt that more people, and more natural ecosystems, will be adversely affected by changes in temperature above 1.5oC relative to pre-industrial levels. The political goal of limiting the change in global mean surface temperature to no more than 2oC above pre-industrial levels will not be realized without immediate significant global reductions in global greenhouse gas emissions.

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"Times New Roman";mso-bidi-font-family:Arial;color:black”> A safe average global temperature increase is impossible to state objectively. For some people climate change-related impacts are already dangerous, even deadly. The victims, who we rarely hear from, are overwhelmingly very young, old or poor. It is important to recognise that some people and countries, and species and ecosystems, are more vulnerable than others. These types of calculations explain why some of the more vulnerable countries advocate a limit of 1.5oC in international negotiations. Of course, deciding what outcomes and risks are an acceptable price for the use of fossil fuels is in the realm of politics, not science. Looking only at the likely negative impacts on crop yields under sustained warming and an increase in climatic extremes, coupled with the known impacts of recent food prices rises, such the 2007 and 2008 food protests and riots spanning three continents, and food prices being widely considered to have been a contributory factor explaining the timing of the Arab Spring, I consider 2oC warming to not just be environmentally world-changing, but it may be socially explosive too.

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color:black”> It is not the role of climate scientists to define the appropriate threshold between acceptable and dangerous climate change. This is properly the decision of civil society – through an iterative and open dialogue, coalesced through the unavoidably messy process of politics and international negotiations. Science enlightens the discussion, but scientists are no more suitably equipped to give a definitive answer than are other engaged individuals. However, once civil society has defined a ‘dangerous’ threshold – it is the role of scientists to explore what this means in terms of carbon budgets, emission reductions, etc. As a citizen, I rightfully have a view as to what constitutes ‘dangerous climate change’. For a range of reasons, informed by my moral compass and personal framing of values, I judge we should aim for below 2°C, limited, in the end, by the emissions we have already locked into the system (so probably around 1.5°C). Ultimately, my choice as to the appropriate threshold is made from an expert knowledge of carbon budgets, mitigation rates etc., combined with a moral interpretation of the world and my personal approach towards risk and uncertainty. Consequently, I have to acknowledge that my value-laden choice of the appropriate threshold has no more veracity than does that of others who have given the issues serious thought. What does lend authority to the various positions held, is the internal consistency of the arguments.
 

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mso-bidi-font-family:Arial;color:black”>RP: 

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mso-bidi-font-family:Arial;color:black”> The Earth has now warmed by about 0.8oC, so we can limit warming to 2oC, but we need to act now and make drastic actions so that growth, wealth and development do not continue to rely on burning fossil fuels. Socio-economic models tell us that a peak in emissions needs to occur before 2020 to limit warming to 2oC. This is a matter of choice for society and governments.

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mso-bidi-font-family:Arial;color:black”> In spite of the recent economic recession in many parts of the world and stated Government commitments to limit greenhouse gas emissions recent global emissions of carbon dioxide are at an all-time high, hence little possibility of even achieving the stated 2oC goal. The world’s current commitments to reduce emissions are consistent with at least a 3oC rise (50:50 chance) in temperature: a temperature not seen on the planet for around 3 million years, with serious risks of 5oC rise: a temperature not seen on the planet for around 30 million years.

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mso-bidi-font-family:Arial;color:black”>It is the cumulative emissions of greenhouse gases that count for the long-term. However, emissions continue to rise, with little serious effort to reduce them. There is almost no discussion about how to keep most fossil carbon out of the atmosphere. When even the wealthiest of countries discover they have billions of dollars of fossil carbon buried underground, they extract it: tar sands in Canada, fracked oil and gas in the US and UK. There is very little chance of staying below 2oC. The rare positive news is the slower increase in global surface air temperature in the 2000’s suggests that it may take a decade longer to reach 2oC than many scientists previously thought.

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mso-bidi-font-family:Arial;color:black”>Unless we are very fortunate on climate sensitivity, the chances of not exceeding even the 2°C threshold are extremely slim! However, if we don’t try the chance slips from very little to effectively zero. For the wealthier parts of the world, I concur with the broad thrust of the International Energy Agency’s conclusions. To be serious about the 2°C threshold, we have about five years to mobilise a radical transition to a zero-carbon energy system (note ‘energy’ and  ‘system’; i.e. it’s not just about electricity, and it is as much about energy demand as it is about energy supply).
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mso-bidi-font-family:Arial;color:black”>RP: If adequate action is not taken on climate change, what will the world look like in 50, 100 years in terms of global temperatures, environmental, social and economic impacts?

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mso-bidi-font-family:Arial;color:black”> Emissions at or above current rates could increase global mean surface temperatures by over 3oC inducing changes in all components in the climate system, some of which would be unprecedented in hundreds to thousands of years, and many of these changes would persist for many centuries. Changes would occur in all regions of the globe, and include changes in land and ocean temperatures, the water cycle, the cryosphere, sea level, some extreme events and in ocean acidification. These changes would reduce agricultural productivity, water quantity and quality in many parts of the world, undermine efforts to reduce poverty, displace large numbers of people, and cause significant losses of biodiversity and degrade critical ecosystem services.

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mso-bidi-font-family:Arial;color:black”> If today’s emission rates continue (and currently I see no significant policies or reasons as to why they are likely to reduce) – then I concur with the IEA’s analysis that 4°C to 6°C by the end of the century looks likely. And with emissions remaining unabated, 4°C by 2050-70 does not appear too unreasonable.

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mso-bidi-font-family:Arial;color:black”> Carbon emissions are currently following the most carbon-intensive scenarios used to project climate change, leading to warming levels of about 2oC already around 2050, and 4-6oC in 2100. This is not only very high warming levels, but also very rapid warming, limiting the capacity to adapt for much of our ecosystems and for society. At 2oC you would expect the Arctic to be ice-free in the summer, and large and systematic melting of the snow and ice cover in the Northern hemisphere, including the permafrost that contains large quantities of carbon. You would also expect changes in weather patterns particularly in the Northern Hemisphere, and large changes in the water cycle, with generally dry regions becoming dryer and wet regions wetter, and with an increase in the intensity and severity of floods, droughts, and heat waves (i.e. more extreme events). At 4oC you expect a transformation of the environment, including of the vegetation at all latitudes, of the weather, seasons, and climatic patterns (e.g. the Monsoon and North Atlantic Oscillation that controls weather in Europe). Implications for the biosphere are enormous, as common plants and animals loose over 50% of their niche ranges. The costs of adaptation, in particular to sea level rise and protecting against increasing storm surges in coastal regions, will be very large. 

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mso-bidi-font-family:Arial;color:black”> The world of 2100 will be shaped by numerous responses to the challenges facing humanity. We will need to innovate to remain ahead of the evolution of antibiotic resistant bacteria; we will need to conserve soil and its health to maintain agricultural productivity, to name but two neglected long-term problems that may limit human welfare this century. In terms of mean annual surface temperature, I suspect we will see warming of 3-4oC. This would transform the physical world our descendants would see. Many ecosystems will be entirely novel assemblages of species. Biodiversity will have dramatically declined. Sea levels will be higher; some city and island populations will have relocated. Global agricultural productivity will struggle as rainfall regimes shift. Huge amounts of resources will have been expended on adaptation to the new conditions. I would not wager the condition of humanity. It is entirely unclear to me what the dominant response will be to confronting – when many people experience the negative impacts of fossil fuel use – the fact that the way the economy is run is undercutting the environmental conditions required to sustain billions of people on planet Earth.

 

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mso-bidi-font-family:Arial;color:black”>RW:

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mso-bidi-font-family:Arial;color:black”>CLQ:
 

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mso-bidi-font-family:Arial;color:black”>SL:
 

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mso-bidi-font-family:Arial;color:black”>KA:
 

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mso-bidi-font-family:Arial;color:black”>RP: As someone whose job gives them a deep understanding of the bleak future facing the planet and humanity, how do you personally deal with this on an emotional and psychological level?
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mso-bidi-font-family:Arial;color:black”>RW:
 

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mso-bidi-font-family:Arial;color:black”>CLQ: 

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mso-bidi-font-family:Arial;color:black”>KA: 

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mso-bidi-font-family:Arial;color:black”>SL: 

The March That Shook Blair: An Oral History of 15 February 2003ian_js@hotmail.comhttps://twitter.com/IanJSinclair 

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