Skip to main content

COP21 daily report: Reflecting on the science of climate change

Cabot Institute Director Professor Rich Pancost will be attending COP21 in Paris as part of the Bristol city-wide team, including the Mayor of Bristol, representatives from Bristol City Council and the Bristol Green Capital Partnership. He will be writing blogs during COP21, reflecting on what is happening in Paris, especially in the Paris and Bristol co-hosted Cities and Regions Pavilion, and also on the conclusion to Bristol’s year as the European Green Capital.  Follow #UoBGreen and #COP21 for live updates from the University of Bristol.
---------------------------------
Image credit: ICLEI
Bristol’s presence at COP21 started with a bang, with some of its most important contributions being showcased as it opened  the Bristol/Paris/ICLEI Cities and Regions Pavilion.  There is a lot to digest from that and that will be the focus of tomorrow’s or Friday’s blog.  Today, however, I am going to take a step back and revisit the climate science that is the basis for the political, entrepreneurial and social actions currently being discussed in Paris.

When I started by PhD in 1992, the concentration of carbon dioxide in the Earth’s atmosphere was about 355 ppm and already a huge source of concern to climate scientists.

About one year ago, depending on the station or the season, CO2 levels passed 400 ppm for the first time in human history.  And for the first time in ice core history, extending back nearly 1 million years.  And – based on our recent work using chemical proxies to reconstruct atmospheric carbon dioxide – probably for the first time in about 3 million years

If we continue burning fossil fuel, even with reduced emissions, we will reach 550 to 700 ppm by the end of this century. Our work and that of others reveals that these are values that the Earth has not experienced for at least 10 million and maybe even 30 million years.

This is causing the Earth to warm.  That relationship is derived from fundamental physics and first articulated by Svante Arrhenius over a century ago.  Our climate models elaborate and clarify this relationship.  Earth history validates and confirms it - when CO2 was higher, the planet was warmer.  And consistent with that, this year is on track to be the warmest in recorded history, with human-induced warming now thought to have warmed our planet by 1C.
This is half of our agreed limit of 2C; and due to the slow response of the climate system, more warming will come.

These are some of the truly eye-opening facts surrounding climate change, the challenge we face and the need for this week’s negotiations. 

There are many who will argue that the science of climate change is too uncertain to act upon.  The observations listed above, and many others, reveal that to be a manipulative half-truth.  There is an astonishing amount of knowledge about climate change – and global warming in particular.

Moreover, as Steve Lewandowksy (and Tim Ballard and myself) discussed in an article in the Guardian yesterday, the uncertainty that does exist in our understanding of climate change impacts is cause for mitigative action not complacency.  This was based on our recent volume in the Proceedings of the Royal Society, in which a great diversity of researchers highlight the impact of uncertainty on the economy, cooperation, action and creativity.

This has long been a focus of the Cabot Institute; Living with Environmental Uncertainty is a central tenet of our mission. ]We have hosted consultations and workshops on understanding, constraining and communicating uncertainty; advised decision makers and leaders; produced papers, reports and even handbooks. This year as part of the Green Capital, we framed much of our own activity, as well as our contributions to the Summits, Arts Programme and Festivals, around this theme: The Uncertain World.
A great example of this research is that of the Bristol Glaciology Centre.  Tony Payne was a Lead Author on the IPCC report on ice sheets and sea level rise.  Glacial biogeochemists, Martyn Tranter, Jemma Wadham and Alex Anesio, are studying how surface melting can create dark patches of algal growth which could absorb light and accelerate melting.  Jonathan Bamber led a fascinating expert elicitation study which suggested a wider range of potential sea level rise than previously thought.

All in all, this work is consistent with the most recent IPCC report that sea level rise will likely range from 0.7 to 1.1 m by the end of the century.  However, that range belies deeper and more frightening uncertainty. Professor Bamber spoke about this yesterday at COP21 as part of the International Cryosphere Climate Initiative and Scientific Committee on Antarctic Research session on Irreversible Impacts of Climate Change on Antarctica.  Their presentation highlighted that the IPCC range of potential sea level rise is largely a function of the 2100 time frame applied.  Longer timescales reveal the true magnitude of this threat. The projected ~1m of sea level rise is probably already inevitable. It will be even higher – perhaps several metres higher – if we warm our planet by 2C, and even more so if it warms by the 2.7C that current Paris commitments yield. The geological record suggests even more dramatic potential for sea level rise: 3 million years ago, when CO2 concentrations were last ~400 ppm, sea level might have been 20 m higher.  These changes almost certainly would take place over hundreds of years rather than by 2100.  But their consequences will be vast and irreversible.
Flooding in Clifton, Bristol 2012. Events like these are likely to
become more common. Image credit Jim Freer
This uncertainty is not limited to warming and sea level rise.  Uncertainty is deeply dependent in rainfall forecasts for a warmer world; we know that warmer air can hold more water such that rainfall events are likely to become more extreme.  However, how will that change regionally?  Which areas will become wetter and which drier?  How will that affect food production?  Or soil erosion? 

Of course, climate change is about more than just warming, sea level rise and extreme weather.  It is also about the chemistry of our atmosphere, soils and oceans.  Again profound concern and uncertainty is associated with the impact of coastal hypoxia and ocean acidification on marine ecosystems. In fact, it is the biological response to climate change, especially when coupled with all of the other ways we impact nature, that is most uncertain. Unfortunately, Earth history is less useful here.  Even the most rapid global warming events of the past seem to have occurred over thousands of years, far far slower than the change occurring now, a point that emerges again and again in our research and frequently emphasised by the Head of our Global Change Theme Dani Schmidt.

What is happening today appears to be unprecedented in Earth history.

We are creating an Uncertain – but also volatile, extreme and largely unknown world.  Some of that is inevitable.  But much of it is not.   How much will be largely decided in Paris. 

But not just by nations.  Also by mayors and councils and LEPs, NGOs, citizens, businesses and other innovation and transformation leaders.  This is why the actions being proposed in the Cities and Regions Pavilion, not just by Bristol but by hundreds of cities and local authorities across the globe, are so very exciting.

-----------------------------------------
This blog is by Prof Rich Pancost, Director of the Cabot Institute at the University of Bristol.  For more information about the University of Bristol at COP21, please visit bristol.ac.uk/green-capital
Prof Rich Pancost

This blog is part of a COP21 daily report series. View other blogs in the series below:

Popular posts from this blog

Powering the economy through the engine of Smart Local Energy Systems

How can the Government best retain key skills and re-skill and up-skill the UK workforce to support the recovery and sustainable growth? This summer the UK’s Department for Business, Energy and Industrial Strategy (BEIS) requested submission of inputs on Post-Pandemic Economic Growth. The below thoughts were submitted to the BEIS inquiry as part of input under the EnergyREV project . However, there are points raised here that, in the editing and summing up process of the submission, were cut out, hence, this blog on how the UK could power economic recovery through Smart Local Energy Systems (SLES). 1. Introduction: Factors, principles, and implications In order to transition to a sustainable and flourishing economy from our (post-)COVID reality, we must acknowledge and address the factors that shape the current economic conditions. I suggest to state the impact of such factors through a set of driving principles for the UK’s post-COVID strategy. These factors are briefly explained belo

Farming in the Páramos of Boyacá: industrialisation and delimitation in Aquitania

Labourers harvest ‘cebolla larga’ onion in Aquitania. Image credit: Lauren Blake. In October and November 2019 Caboteer  Dr Lauren Blake  spent time in Boyacá, Colombia, on a six-week fieldtrip to find out about key socio-environmental conflicts and the impacts on the inhabitants of the páramos, as part of the historical and cultural component of her research project, POR EL Páramo . Background information about the research can be found in the earlier blog on the project website . Descending down the hill in the bus from El Crucero, the pungent smell of cebolla larga onion begins to invade my nose. The surrounding land transforms into plots of uniform rows of onion tops at various stages of growth, some mostly brown soil with shoots poking out along the ridges, others long, bushy and green. Sandwiched between the cloud settled atop the mountainous páramos and the vast, dark blue-green Lake Tota, all I can see and all I can smell is onion production. Sprinklers are scattered around, dr

IncrEdible! How to save money and reduce waste

The new academic year is a chance to get to grips with managing your student loan and kitchen cupboards. Over lockdown the UK wasted a third less food than we usually would. This is brilliant, as normally over 4.5 million tonnes of edible food is wasted from UK homes every year. For students, it’s even higher. The average cost of food waste per student per week is approximately £5.25 - that's about £273 per year !  It’s not just our bank accounts that are affected by food waste – it’s our planet too. The process of growing, making, distributing, storing and cooking our food uses masses of energy, fuel and water. It generates 30% of the world’s CO₂ greenhouse gas emissions. The same amount of CO₂ as 4.6 million return flights from London to Perth, Australia! So it makes sense to keep as much food out of the bin as possible, start wasting less and saving more.  Start the new term with some food waste busting, budget cutting, environment loving habits! Here’s five easy ways to reduce