Tag: global warming

In defence of science: Making facts great again

Posted on by janet.crompton

“We must not let rhetoric or vested interests divert us from what we know is the right course of action.”

From across the Atlantic, the European scientific community is watching warily as our American colleagues endure increasingly politicised attacks on their work and on the very foundation of evidence-based science.

President Donald Trump‘s decision earlier this month to withdraw the United States from the historic Paris Agreement on Climate Change – a decision condemned by heads of state, businesses, mayors and ordinary people in the US and the world over – epitomised this contempt for the facts from some within the political sphere.

We can, to some degree, relate, as many European scientists – and particularly those who research climate change and its impacts, as I do – have been forced to confront the politicisation of their disciplines, the distortion of their research and the promotion of “alternative facts” and vested-interest propaganda.

In fact, just two months ago at the annual General Assembly of the European Geosciences Union, for the first time in the body’s history, we debated issues around existential threats to science in general, the integrity of the scientific community, trust in science and what we can do to ensure that evidence-based science forms the basis for informed decisions and debate by policymakers and the public.

Later this month, we’ll watch as some of our American colleagues gather for the annual Broadcast Meteorology Conference of the American Meteorological Society, which will include in its programme a short course explicitly focused on the communication of climate science.

Never has accurate, fact-based communication of climate science been more urgently needed, and in modern history, it has rarely been so compromised. There is a clear trend, particularly evident in the US, of a growing distrust of “experts” who are branded as intellectual elites, rooted in a populist backlash towards the establishment.

This goes all the way up the rungs of government to the American president himself, who has called climate change a “hoax” and in his first 100 days in office has moved to curb spending on climate and earth science research and is overseeing an agency-wide scrubbing of climate science out of federal websites and publications.

As he announced the US withdrawal from the Paris Agreement on June 1, Trump also left himself open to accusations of misrepresenting climate science to suit his own political objectives: after the US president quoted a figure from a Massachusetts Institute of Technology (MIT) study to support his argument that the Paris Agreement is ineffectual, MIT officials – including one of the study’s authors – declared that Trump had misunderstood their work and that they did not support a US withdrawal from the agreement.

The science of climate change, however, is clearer than ever. We see the fingerprints of human-induced global warming on more and more long-term climate trends. In the US and throughout the world, for instance, warmer temperatures are amplifying the intensity, duration and frequency of many weather events, none more evident than extreme heat. Western states have suffered through record numbers of heat waves since the turn of the century, with overnight temperatures often at historical highs. This is particularly dangerous as it doesn’t give the human body the necessary relief. Already, these heat waves are costing lives, and the scientific link between human-induced global warming and heat waves is crystal clear. The European heat wave of 2003 is estimated to have caused 35,000 premature deaths and was very likely a consequence of human interference with the climate system.

By listening to the best available science on climate change, we can better prepare for its impacts. By ignoring, censoring, or shunning our scientists, we put more Americans at risk. The alternative to informed decision-making is uninformed decision-making. Without evidence-based science, decisions of vital importance to humanity will be made founded in prejudice, emotion and ignorance. That is no way to run the planet. It is no way to plan our future.

Besides helping prepare for the impacts of climate change, science should guide our efforts to minimise them. For these mitigation efforts, the science is telling us that we don’t have much time. In fact, it’s saying that 2020 must be the target for peaking global carbon emissions. We must bend the curve of global greenhouse gas emissions towards a steady decline by the next US presidential election. If emissions continue to rise beyond 2020, the world stands very little chance of limiting global warming below 1.5 degrees Celsius, the threshold set by the Paris Agreement, and a temperature limit that many of the world’s most vulnerable communities consider a threshold for survival.

The world has four short years to reverse our emissions trends to avoid the very real risk of dangerous and irreversible climate change, but we won’t get the policies we need without trusting and relying on the science that tells us that’s so. Science has no political affiliation, nor can it be bent to your will. You don’t renegotiate with physics and you aren’t about to “win” a deal with chemistry. We must not let rhetoric, vested interests or the blind dismissal of the overwhelming scientific consensus divert us from what we know is the right course of action ethically, scientifically and economically.

By Jonathan Bamber, professor of polar science at the University of Bristol and president of the European Geosciences Union. Blog originally posted on Al Jazeera.

A response to Trump’s withdrawal from the Paris Agreement

Posted on by janet.crompton

The decision by President Trump to withdraw from the Paris Agreement on Climate Change puts the United States at odds with both science and global geopolitical norms.  The fundamentals of climate change remain unambiguous: greenhouse gas concentrations are increasing, they are increasing because of human action, the increase will cause warming, and that warming creates risks of extreme weather, food crises and sea level rise. That does not mean that scientists can predict all of the consequences of global warming, much work needs to be done, but the risks are both profound and clear. Nor do we know what the best solutions will be – there is need for a robust debate about the nature, fairness and efficacy of different decarbonisation policies and technologies as well as the balance of responsibility; the Paris Agreement, despite its faults with respect to obligation and enforcement, allowed great flexibility in that regard, which is why nearly every nation on Earth is a signatory.

Moreover, although climate change affects us all, it will affect the poorest and most vulnerable the most. They, despite being least responsible, bear the greatest risks and the greatest burdens. For the President of the world’s second largest carbon polluter to blatantly disregard such evidence and injustice, to refuse to even acknowledge the consequences of its actions and to disengage with this relatively modest and non-binding agreement puts it odds with the norms of global partnership and human rights. This abrogation of responsibility is particularly profound because President Trump has also withdrawn the United States from the Green Climate Fund, which helps the poorest of the world adapt to the climate change that his actions make more likely.

And to what end?  Other nations will now assume global leadership, politically, morally and technologically.  It will likely cost American businesses money, hinder innovation in one of the world’s most dynamic sectors, and ultimately cost jobs. It will likely undermine the United States’ global stature and diplomatic reach. It is hard to imagine a decision so blatantly motivated by self-interest while being so profoundly self-harming.

The crucial question now is how we respond.  China and the EU have stepped forward, increasing their voluntary commitments, repudiating President Trump’s decision and assuming the mantle of leadership.  Nations around the world are following suit, as are cities and states across the United States.  Businesses have re-stated their commitment to decarbonisation – ironically, the day before Trump’s decision, shareholders voted that Exxon develop plans compliant with the Paris Agreement’s targets.  In the UK, in the midst of a general election, parties from across the political spectrum have responded to Trump’s decision with reactions ranging from disappointment to outrage. The UK has always provided leadership in this arena, recognising that climate change is a non-partisan issue, and it is one of the few nations with a cross party Climate Change Act.  It is vital for both the planet and the UK that these initial comments are followed by bolder actions and stronger leadership.

Across the world and in the University of Bristol, we are frustrated with the symbolism of Trump’s actions, his speech’s misrepresentation of facts, and his decision’s potential to slow climate action.  But we also recognise that these actions will not stop climate action. The responses of local, national and international leaders, in politics, community groups and businesses, across sectors and across society show that no person, regardless of his position or his nation, can stop the energy revolution. It is too deeply embedded in our politics, economy and ambitions, borne of out of multiple necessities.

Here, in the University of Bristol Cabot Institute, we remain committed to this challenge.  Our University is committed to carbon neutrality, ethical and low-carbon procurement and divestment from fossil fuel-intensive businesses. We have foregrounded Sustainable Futures in our undergraduate teaching.  And in our research, we are investigating improved energy efficiency in everything from computer software, to our homes and our cities.  We are exploring how smart technology enables new forms of transport, community energy and individual action. We are converting nuclear waste into diamond batteries with 5000-year lifetimes, we are leading one of the projects under the Natural Environment Research Council’s Greenhouse Gas Reduction programme and we have just launched new initiatives in wind, tidal, solar and nuclear energy.

Our ambitions are at all scales, from the local to the global.  We continue to work with our Green Capital partners, with a focus on building an informed, diverse, inclusive and powerful movement to become a more sustainable city and region, exemplified by the Green and Black Ambassadors Initiative.  Globally, our projects have been exploring the impact of conflict, climate change and geological hazards on development and the environment; the potential for micro-grids to deliver electricity to isolated communities; new forms of parasite resistance for subsistence farmers; and how geothermal energy can be harnessed in Ethiopia.

This commitment to sustainability builds on five decades of research on our environmental challenges and how to manage them.  The Atmospheric Chemistry Research Group makes among the world’s most accurate measurements of atmospheric concentrations of greenhouse gases, and they have shown how rapidly these compounds are accumulating. They are committed to refining those measurements and the modelling methods that allow us to understand why global emissions change. The Bristol Initiative for the Dynamic Global Environment reconstructs past climates and uses those insights to better understand our future; recent projects are building global collaborations to explore the controls on Earth’s temperature and monsoons.  Our glaciologists study sea level rise; our hydrologists study floods and drought; our social scientists study the injustice of climate change and its impact on migration and conflict; and our vets and life scientists are exploring how to improve animal welfare and crop yields on a climate disrupted planet.

Our commitment includes appointing the best and the brightest at understanding these challenges, including Dr Dann Mitchell who joined the University in November.  As co-ordinator of the largest dedicated project in the world on the climate impacts of the Paris Agreement (www.happimip.org), he sums up the Cabot Institute’s collective commitment: “The news of Trump wanting to pull out is incredibly frustrating. Our results are already suggesting more extreme events, such as droughts and heat waves, and serious impacts on society, such as increased human and animal health issues, failures in global crop distributions and bleaching of our coral reefs. I am frustrated that Trump continues to ignore the scientific evidence that has been recognised by his global peers, but that will not dissuade us from doing all we can to understand climate risks… and prevent them.’

 

 

Article by Professor Rich Pancost
Director of the University of Bristol Cabot Institute
Professor of Biogeochemistry
Royal Society Wolfson Research Merit Scholar

COP21 daily report: Can we limit global warming to 1.5C?

Posted on by janet.crompton
abot 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 and other Cabot Institute members 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.  All blogs in the series are linked to at the bottom of this blog.

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One of the most stunning developments in the climate negotiations of COP21 – perhaps of the entire 20 years of negotiations – has been the emergence of major push to raise the accord’s ambitions.

After years of watering down language and creating flexible and non-binding targets, many of us anticipated that the pressure of compromise would weaken the COP21 accord. It might still be weakened in many respects.  And yet, in the past 72 hours, a group of 100 nations, including the European Union, the United States and dozens of developing nations, has emerged to propose the nearly unimaginable: to reduce the acceptable limit to human-caused global warming from 2C to 1.5C.

This has, for lack of a better word, stunned the scientific community.  Here in Paris, these raised ambitions resulted in applause and celebration – especially when they remained in place in the second draft circulated Wednesday.  But those of us who study climate change wonder whether this is possible.  Already this year, global warming reached 1C, and several more decimal places of warming are already baked into the system due to the slow response of the climate system. In short, there is some chance that our current 400 ppm CO2 is already enough to push the globe past 1.5C.

Ensuring even a 50:50 chance of staying below 1.5C will require urgent action – far more urgent than what nations have committed through their INDCs which will only limit warming to 2.7 to 3C.  In fact, it will almost certainly require achieving zero emissions, a complete cessation of all fossil fuel use, in the next several decades – and then negative emissions. We will have to capture and store carbon dioxide (CCS) either through biology  or technology; and as I mentioned in yesterday’s blog, the UK has actually cancelled potential CCS projects.

It is laudable that countries want to push for a stronger global warming limit, but they must be honest about the distance between their ambitions and their policies.  By policies I mean not only the insufficient INDCs to which they are committing, but the actual policies back home to achieve them.  Many nations’ policies will help achieve 40% reductions – the low-hanging fruit – but are they really investing in the innovation and infrastructure to achieve a 100% reduction in any timeframe, let alone a timeframe to limit warming to 1.5C?  If 1.5C requires an almost complete decarbonisation with the next several decades, how can that be achieved when global shipping and aviation are not even in the current draft of the accord?

Consequently, many of my colleagues around the globe are as stunned and confused about the political agenda as I am.  Are the politicians idealistic and naïve?  Out of touch with the science? Grandstanding?

I am cautious about jumping to conclusions.

The underlying politics are complex. Maybe the leaders are caught up in the moment.  More likely, they are caught up in their needs; this initiative has been led by small island states – especially Tony de Brum, Foreign Minister of the Marshall Islands – and these nations do face an existential threat from 2C warming, and some even from 1.5C warming.  They have been demanding this increased ambition for over a decade; they are living on the sharp end of climate uncertainty (as we learned when hosting many of them last summer) and they know what is coming.

It is surprising that others have joined them.

If I had to guess, I think this change is designed to strengthen post-COP21 policy both internationally and domestically.  It could be related to putting stronger pressure on the ratcheting up process of the accord, the mechanism by which nations will impose more demanding targets on themselves.  It could also be related to enshrining more robust compensation for those nations that will be most impacted by climate change. Or it could also be the confidence-building statement that investors and businesses have been demanding all week long. It is too soon to say.

Nonetheless, there is a large disconnection between these targets and our commitments and between our commitments and our policies. I’d be more comfortable about a step-up in our targets, if these gaps were being more openly discussed.

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Prof Rich Pancost

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

COP21 daily report: Reflecting on the science of climate change

Posted on by janet.crompton
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.

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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.

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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:

Global warming ‘pause’ was a myth all along, says new study

Posted on by janet.crompton

The idea that global warming has “stopped” is a contrarian talking point that dates back to at least 2006. This framing was first created on blogs, then picked up by segments of the media – and it ultimately found entry into the scientific literature itself. There are now numerous peer-reviewed articles that address a presumed recent “pause” or “hiatus” in global warming, including the latest IPCC report.

So did global warming really pause, stop, or enter a hiatus? At least six academic studies have been published in 2015 that argue against the existence of a pause or hiatus, including three that were authored by me and colleagues James Risbey of CSIRO in Hobart, Tasmania, and Naomi Oreskes of Harvard University.

Our most recent paper has just been published in Nature’s open-access journal Scientific Reports and provides further evidence against the pause.

Pause not backed up by data

First, we analysed the research literature on global temperature variation over the recent period. This turns out to be crucial because research on the pause has addressed – and often conflated – several distinct questions: some asked whether there is a pause or hiatus in warming, others asked whether it slowed compared to the long-term trend and yet others have examined whether warming has lagged behind expectations derived from climate models.

These are all distinct questions and involve different data and different statistical hypotheses. Unnecessary confusion has resulted because they were frequently conflated under the blanket labels of pause or hiatus.

 

New NOAA data released earlier this year confirmed there had been no pause. The author’s latest study used NASA’s GISTEMP data and obtained the same conclusions.
NOAA

To reduce the confusion, we were exclusively concerned with the first question: is there, or has there recently been, a pause or hiatus in warming? It is this question – and only this question – that we answer with a clear and unambiguous “no”.

No one can agree when the pause started

We considered 40 recent peer-reviewed articles on the so-called pause and inferred what the authors considered to be its onset year. There was a spread of about a decade (1993-2003) between the various papers. Thus, rather than being consensually defined, the pause appears to be a diffuse phenomenon whose presumed onset is anywhere during a ten-year window.

Given that the average presumed duration of the pause in the same set of articles is only 13.5 years, this is of concern: it is difficult to see how scientists could be talking about the same phenomenon when they talked about short trends that commenced up to a decade apart.

This concern was amplified in our third point: the pauses in the literature are by no means consistently extreme or unusual, when compared to all possible trends. If we take the past three decades, during which temperatures increased by 0.6℃, we would have been in a pause between 30% and 40% of the time using the definition in the literature.

In other words, academic research on the pause is typically not talking about an actual pause but, at best, about a fluctuation in warming rate that is towards the lower end of the various temperature trends over recent decades.

How the pause became a meme

If there has been no pause, why then did the recent period attract so much research attention?
One reason is a matter of semantics. Many academic studies addressed not the absence of warming but a presumed discrepancy between climate models and observations. Those articles were scientifically valuable (we even wrote one ourselves), but we do not believe that those articles should have been framed in the language of a pause: the relationship between models (what was expected to happen) and observations (what actually happened) is a completely different issue from the question about whether or not global warming has paused.

A second reason is that the incessant challenge of climate science by highly vocal contrarians and Merchants of Doubt may have amplified scientists’ natural tendency to be reticent over reporting the most dramatic risks they are concerned about.

We explored the possible underlying mechanisms for this in an article earlier this year, which suggested climate denial had seeped into the scientific community. Scientists have unwittingly been influenced by a linguistic frame that originated outside the scientific community and by accepting the word pause they have subtly reframed their own research.

Research directed towards the pause has clearly yielded interesting insights into medium-term climate variability. My colleagues and I do not fault that research at all. Except that the research was not about a (non-existent) pause – it was about a routine fluctuation in warming rate. With 2015 being virtually certain to be another hottest year on record, this routine fluctuation has likely already come to an end.
The Conversation

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This article was originally published on The Conversation. Read the original article.

This blog is by Cabot Institute member Prof Stephan Lewandowsky, University of Bristol.

Prof Steve Lewandowsky



Read the official press release.

Michael E Mann: The climate wars

Posted on by janet.crompton
Michael E Mann at the Cabot Institute, 23 September 2014.
Image credit: Amanda Patterson.

As Professor Michael E Mann said at his Cabot Institute Lecture on Tuesday 23 September, you won’t find scientists at conferences or in peer-reviewed publications debating whether or not global warming is happening. Professor John Cook’s recent talk highlighted the scientific consensus; 97% of climate scientists agree that global warming is mostly man made. Despite this, Mann’s talk focussed on his experiences in the centre of “the climate wars”.

Mann is well-known in climate science for producing the “hockey stick” graph, depicting the mean annual temperatures over the past 1000 years. The graph is pretty flat until 1900, followed by a very sharp increase in global temperatures to a peak in the late 1990s when the report was published. The recent IPCC findings suggest that if we carry on as we are, we’re looking at a ~4°C increase in global temperature, which could have devastating effects all over the world. As Mann said, that describes a very different planet to the one we know today.

We need to act now, but what Mann calls the “scientisation of politics” is holding back policymakers around the world. He has personally been the target of a few politicians and other groups hoping to discredit the science by casting doubt on his work. In the 2009 ‘Climategate’ scandal, over 1000 e-mails from the University of East Anglia climate scientists were hacked and published online, just before the important UN Climate Change Conference in Copenhagen. Words and specific quotes were taken out of context and spread through the media, which Mann believes was timed to distract delegates in Copenhagen from the major issue of mitigating global warming. In total, 17 climate scientists were caught up in Climategate, but several investigations found that their science was sound and none of the scientists had been fudging their data or misleading anyone about their findings.

Mann has been under attack for many years, which scares me as a scientist. Calls from politicians and other groups have led to him being investigated several times, however he has always been found innocent and his science is sound. Several scientific groups have criticised this intimidation tactic of climate researchers. I cannot imagine spending several years having my name dragged through the mud for no reason just to further someone else’s political agenda, but I am grateful to Professor Mann for standing up to the climate bullies and continuing to push the important findings of his work. The planet is warming and a big part of it is our fault. The sooner the public comes to a climate consensus, the sooner we can move forward, and if we want to keep the temperature increase to below 2°C, we’d better act now.

Please watch the recording of the lecture to learn more about the Climate Wars.

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This blog is written by Sarah Jose, Cabot Institute, Biological Sciences, University of Bristol

 
Sarah Jose

 

John Cook in Bristol: The consensus gap

Posted on by janet.crompton

As a biologist, the fact that anthropogenic climate change is occurring has been explained to me throughout my education. We are interested in how crops might respond to global warming or what might happen to bees or coral reefs, not the basic question of whether or not it is happening at all.  So that is why I was keen to attend John Cook’s talk at the Cabot Institute and learn a bit more about climate science and how it is perceived both within and outside the climate change science community

John Cook is the Climate Communication Fellow for the Global Change Institute at the University of Queensland, Australia. He runs the popular Skeptical Science blog, with the aim of explaining the scientific consensus on global warming. As he pointed out, his website has received a lot of criticism from people who do not agree that climate change is significantly driven by human effects.

The climate consensus

97% of climate scientists agree that humans are responsible
for climate change. Image credit: Skeptical Science

Several studies, including John’s own (Cook et al., 2013), have shown that 97% of climate scientists agree that humans are significantly contributing to global warming. Doran and Zimmermann (2009) asked earth and climate scientists whether they thought that humans are significantly impacting global climate change and found that 97.4% agreed we are, while Anderegg and colleagues (2010) found that 97-98% of climate scientists agreed with the Intergovernmental Panel on Climate Change finding that anthropogenic greenhouse gases have been responsible for most of the Earth’s global warming.

 

Public perception of consensus

John described how the public does not seem to realise the extent of scientific agreement. When asked to estimate “how many climate experts agree that the global warming we are witnessing is a direct consequence of the burning of fossil fuels by humans”, the average response was 55%, a marked underestimate of the 97% consensus.

John
is working to improve public understanding of
the scientific consensus around global
climate change.
Image credit: Skeptical Science 

John showed a video from comedian John Oliver, who insisted that the only reason there was still an ongoing debate about climate change is because it is always portrayed with an “inherently misleading” 50:50 divide in representation. He goes on to hold a “mathematically fair” debate with three sceptics and 97 climate scientists, which ends with the immortal line, “I can’t hear you over the weight of scientific evidence”.

John Cook tried to bridge the consensus gap with a more balanced approach in his latest project, entitled “97 hours of consensus”. A total of 97 experts were asked to address the topic of humans causing global warming. Cabot’s own director, Professor Rich Pancost, was one of the scientists included.

Cabot Institute Director Professor Rich Pancost was a featured
climate expert in the 97 Hours
of Consensus project.
Image credit: Skeptical Science 

John said that there is a lot of misinformation out there, causing confusion for the public who put their trust in scientific experts. He highlighted one particular website, the Global Warming Petition Project, which as of today [10 February 2014] had been signed by 31,487 American scientists urging their government to reject any limits on greenhouse gas emissions. As John pointed out, only 39 of these people are actually climatologists, therefore 99.9% of them are simply people with science degrees. As I mentioned earlier, I’m a biologist, but that doesn’t give me the expertise needed to decide whether anthropogenic climate change is occurring or what the causes are. I leave that to the experts. Instead, I focus my intellectual energy on ecosystems and how global warming (and other factors) will affect them.

Dr. Tamsin Edwards is a climate scientist who actively engages with people who differ in their opinions on what the science shows. In her blog, she states, “We can’t avoid scientific uncertainty, because we can’t perfectly measure or understand the universe. So we need to be very clear about what we know, what we don’t know, and the surprises we might face”. It can be tempting to avoid discussing difficult topics, but Tamsin inspires me (and hopefully her fellow climate scientists) to explain the science behind the conclusions and hopefully enable the public to make informed decisions too.

Do we need to close the consensus gap?

John said that he fears that if people don’t realise there is 97% scientific consensus about anthropogenic climate change, they won’t accept that it is happening and/or care enough to do anything about it. In the video abstract for his 2013 paper, John states that, “This misperception has real world consequences. When people correctly understand that the scientists agree, they are more likely to support policy that mitigates climate change”.

In the UK, several polls over the past five years have looked at what people consider the main cause of global climate change. Where two options (humans versus natural causes) were given, 43-71% of respondents chose humans as the main driver of global warming. These results were diluted when a third option (both human and natural causes) was given, however it is encouraging to note that only around 10-15% blamed natural processes alone.

Carbon
Brief compared UK participants’ opinions on what
causes climate change. Image
credit: Carbon Brief

The weekend following John’s talk was a perfect example of a possible change in public opinion of climate change globally. Hundreds of thousands of people marched in cities across the world in the People’s Climate March, including a couple thousand locally in Bristol.  This was the largest climate march in history. The biggest turnout was in New York, where over 300,000 people called for action from the UN climate summit, which convened in the city on Tuesday 23 September 2014. UN Secretary General Ban Ki-moon marched with the crowd, an unusual move highlighting the importance of the event. He said, “Action on climate change is urgent. The more we delay, the more we will pay in lives and in money”.

I think Joel Pett’s cartoon sums up my thoughts pretty well on the subject of climate change…
Joel Pett, USA Today and Kentucky.com 


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This blog is written by Sarah Jose, Cabot Institute, Biological Sciences, University of Bristol
Sarah Jose

Climate lessons from the past: Are we already committed to a warmer and wetter planet?

Posted on by janet.crompton

Last September, the Cabot Institute and the University of Bristol hosted the 2nd International Workshop on Pliocene Climate.   Following on from that, we have just  released a short video describing what the Pliocene is and its relevance for understanding climate change.

The Pliocene is a geological time interval that occurred from 5.3 to 2.6 million years ago.  This interval of Earth history is interesting for many reasons, but one of the most profound is that the Earth’s atmosphere apparently contained elevated concentrations of carbon dioxide – in fact, our best estimates suggest concentrations were about 300 to 400  ppm, which is much higher than concentrations of 100 years ago but lower than those of today after a century of intensive fossil fuel combustion.

Image by NASA

Consequently, the Pliocene could provide valuable insight into the type of planet we are creating via global warming.  Our video release happens to coincide with pronounced flooding across the UK and focussed attention on our weather and climate.  There is little doubt that increased carbon dioxide concentrations will cause global warming; instead, the key questions are: how much warming will there be and what are the consequences of that warming? One way to study that is to examine previous intervals of Earth history also characterised by high carbon dioxide concentrations. The comparisons are not perfect, of course; for example, during the Pliocene the continents were in roughly but not exactly the same positions that they are in today.  But it can serve as another piece of the puzzle in predicting future climate.

One of the key lessons from Earth history is climate sensitivity.  Climate sensitivity can be expressed in various ways, but in its simplest sense it is a measure of how much warmer the Earth becomes for a given doubling of atmospheric carbon dioxide concentrations.  This is well known for the Pleistocene, and especially the past 800,000 years of Earth history, an interval with detailed temperature reconstructions and carbon dioxide records from ice core gas bubbles.  During that time, and through multiple ice ages, climate sensitivity was about 2.5 to 3°C warming for a doubling of carbon dioxide, which is in the middle of the model-based range of predictions.

Ice core sampling.
Image by NASA ICE (Ice Core Vitals) [CC-BY-2.0]
Wikimedia Commons

Ice core records, however, extend back no more than a million years, and this time period is generally characterised by colder climates than those of today.  If we want to explore climate sensitivity on a warmer planet, we must look further back into Earth history, to times such as the Pliocene.  Reconstructing atmospheric carbon dioxide concentrations in the absence of ice cores is admittedly more challenging.  Instead of directly measuring the concentration of carbon dioxide in gas bubbles, we must rely on indirect records – proxies.  For example, carbon dioxide concentration influences the number of stomata on plant leaves, and this can be measured on ancient leaf fossils. Alternatively, there are a number of geochemical tools based on how carbon dioxide impacts the pH of seawater or how algae assimilate carbon dioxide during photosynthesis; these are recorded by the chemical composition of ancient fossils.

These estimates come with larger error bars, but they provide key insights into climate sensitivity on a warmer Earth.  Recent research indicates a convergence of Pliocene carbon dioxide estimates from these various proxies and gives us more confidence in deriving climate sensitivity estimates.  In particular, it appears that an increase of carbon dioxide from about 280 parts per million (the modern value before the industrial revolution) to about 400 parts per million in the Pliocene results in a 2°C warmer Earth. Accounting for other controls, this suggests a climate sensitivity of about 3°C, which confirms both the Pleistocene and model-based estimates.

It also suggests that we have yet to experience the full consequences of the greenhouse gases already added to the atmosphere.

So then, what was this much warmer world like?  First of all, it was not an inhospitable planet – plants and animals thrived.  This should not be a surprise; in fact, the Earth was much warmer even deeper into the past. The climate change we are inducing is a problem for humans and society, not our planet.

However, the Pliocene was a rather different world.  For example – and importantly, given current events in the UK –  these higher global temperatures were associated with a climate that was also wetter* than present.  That provides important corroborating evidence for models that predict a warmer and wetter future.

 Image by w:en:User:Ivan and licensed as GFDL

Perhaps most striking, sea level appears to have been between 10 to 40 metres  higher than today, indicating that both the Greenland Ice Sheet and  Antarctic Ice Sheet were markedly smaller.  To put that into context, the Met Office has already commented on how flooding in the UK has been and will be exacerbated by sea level rise of 12 centimetres over the last 100 years and a further 5 to 7 centimetres by 2030.

We must be careful in how we extract climate lessons from the geological record, and that is particularly true when we consider ice sheet behaviour.  One widely discussed concept is ice sheet hysteresis.  This is a fancy way of saying that due to feedback mechanisms, it could be easier to build an ice sheet on Greenland or Antarctica than it is to melt one.  If such hysteresis does stabilise our current ice sheets, then we should not assume a planet with 400 ppm of carbon dioxide will necessarily have sea level 20 metres higher than that of today. But if hysteresis is rather weak, then the question is not whether we will see massive sea level change but rather how long it will take (Note: It is likely to take centuries or millennia!).

Most importantly, the collective research into Earth history, including the Pliocene, reveals that Earth’s climate can change.  It also reveals that climate does not just change randomly: it changes when forced in relatively well understood ways.  One of these is the concentration of carbon dioxide in our atmosphere. And consequently, there is little doubt from Earth history that transforming fossil carbon into carbon dioxide – as we are doing today – will significantly impact the Earth’s climate system.

* See Brigham-Grette, J., Melles, M., Minyuk, P., Andreev, A., Tarasov, P., DeConto, R., Koenig, S., et al., 2013. Pliocene Warmth, Polar Amplification, and Stepped Pleistocene Cooling Recorded in NE Arctic Russia. Science 340 (6139), 1421-1427. doi: 10.1126/science.1233137 and Salzmann, U., Haywood, A.M., Lunt, D.J., 2009. The past is a guide to the future? Comparing Middle Pliocene vegetation with predicted biome distributions for the twenty-first century. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 367 (1886), 189-204.

This blog is by Prof Rich Pancost, Director of the Cabot Institute.  Rich will be giving a public lecture on how biogeochemical cycles have regulated the global climate system throughout Earth’s history on 25 February in Bristol.  The event is free and open to all, do come along to learn more.

To learn more about the Pliocene – and palaeoclimate research, in general – you can watch Professor Gerald Haug’s public lecture, Climate and Societies, recorded at the Cabot Institute as part of the 2nd International Workshop on Pliocene Climate.

Prof Rich Pancost

Unprecedented melting of the Greenland Ice Sheet

Posted on by janet.crompton

Three Cabot Institute researchers provide their own insights on the highly publicised news story about the extent of melting observed on the Greenland Ice Sheet.

 

Chris Vernon, Ph.D student in the Bristol Glaciology Centre, studying the mass balance of the Greenland Ice Sheet

Last week NASA released new images of the Greenland ice sheet generated from satellite data showing that between the 8th and 12th of July 2012 the area of the ice sheet’s surface that was melting had increased from about 40 percent to an estimated 97 percent.  On average during the summer approximately half of the ice sheet experiences such surface melting and this expansion of the melt area to include the highest altitude and coldest regions was described as “unprecedented” by the scientists at NASA.  Such widespread melting has not been seen before during the past 34 years of satellite observations and melting at Summit Station, near the highest point on the ice sheet, has not occurred since 1889 based on ice core records.

The Greenland ice sheet gains mass from rain and snowfall and loses mass by solid ice discharge to the ocean (iceberg calving) and runoff of surface melt water.  During the period 1961-1990 these processes are thought to have been in balance with the ice sheet’s mass stable (Rignot et al., 2008).  During the last two decades, however, both ice discharge and liquid runoff have increased resulting in the ice sheet losing mass over this period at an accelerating rate (Velicogna, 2009, Rignot et al., 2011). Changes to these two processes have contributed approximately equally to recent mass loss (van den Broeke et al., 2009).  Whilst these NASA images do not provide data about how much snow and ice have melted or the direct effect on mass balance, they do indicate a significantly larger area of the ice sheet has been melting.

While this melting is an extreme weather event, associated with a series of unusually warm fronts passing over Greenland this summer, new research on the ice sheet’s albedo from Jason Box, a researcher with Ohio State University’s Byrd Polar Research Center, shows summer albedo has been decreasing over the last decade.  This reduced reflectivity, particularly at high elevations, is associated with warming related feedbacks and means more energy is absorbed at the surface for melting leading Box to suggest earlier this year that it is reasonable to expect 100% melt extent within another decade of warming (Box et al., 2012).  His latest albedo data are available here: http://bprc.osu.edu/wiki/Latest_Greenland_ice_sheet_albedo.

 

References (some behind paywall)

BOX, J. E., FETTWEIS, X., STROEVE, J. C., TEDESCO, M., HALL, D. K. & STEFFEN, K. 2012. Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers. The Cryosphere Discuss, 6, 593-634.

RIGNOT, E., BOX, J. E., BURGESS, E. & HANNA, E. 2008. Mass balance of the Greenland ice sheet from 1958 to 2007. Geophysical Research Letters, 35.

RIGNOT, E., VELICOGNA, I., VAN DEN BROEKE, M. R., MONAGHAN, A. & LENAERTS, J. 2011. Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise. Geophysical Research Letters, 38.

VAN DEN BROEKE, M., BAMBER, J., ETTEMA, J., RIGNOT, E., SCHRAMA, E., VAN DE BERG, W. J., VAN MEIJGAARD, E., VELICOGNA, I. & WOUTERS, B. 2009. Partitioning Recent Greenland Mass Loss. Science, 326, 984-986.

VELICOGNA, I. 2009. Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE. Geophysical Research Letters, 36.

 

Liz Stephens, Research Assistant in flood risk and co-author of article: ‘Communicating probabilistic information from climate model ensembles-lessons from numerical weather prediction’ soon to be published in WIRES Climate Change

The story of the unprecedented extent of melting of the Greenland ice sheet no doubt forms an important discussion point amongst scientists and those concerned about future climate change in the Arctic. However, for me it demonstrated the problems of clumsy communication; causing confusion that led some to think that the entire ice sheet had melted, and accusations of sensationalism from climate change sceptics (see http://sfy.co/a1AS for examples).

My main grievance is in the use of colour in the images. This may be the standard colour bar used by the NASA scientists, but it is too emotive for those not used to what is being referred to. At first glance the white area suggests ‘this is ice’, and the red, ‘we should be really scared that this is no longer white’.  In my opinion the colour white should not be used because it is evocative of what is ice rather than what is freezing ice, and so more neutral colours should be used to distinguish areas of melting from areas of freezing ice.

Additionally, I think that some of the language used is problematic; scientists need to be careful not to assume that people understand what is meant by the terms ‘ice sheet’, ‘area’, ‘surface’ etc., so that people don’t think that the entire volume of the ice sheet has disappeared.  Further, the subheading of the Guardian article – 97% surface melt over four days – is misleading, because the images refer to the area of the ice sheet that is undergoing melting and not the rate of melting itself, and so is not a direct indication of any volume of ice lost.

I also don’t like some of the phrasing used, particularly, ‘had thawed’. This is perhaps misleading, because if 97% of the ice sheet surface ‘had thawed’, then perhaps some might think that only 3% of the ice sheet surface would be left. I would probably go for an image caption of:

“The area of the Greenland ice sheet surface that was melting on July 8, left, compared to July 12th on the right.”

Subtle changes to the language can make it clear that this is an unusual weather event that could be indicative of climate change, rather than the ice sheet starting to disappear for good.

 

Jon Hawkings, Ph.D student in the Bristol Glaciology Centre, studies the chemistry of glacial meltwaters

During the course of my stay at the University of Bristol-led field site near Leverett glacier in south-west Greenland, I witnessed the start of what has since been identified as one of the most significant Greenland melt years over the past century. Over that time Leverett glacier’s subglacial drainage river, fed by the melting ice sheet surface together with stored meltwater from the bed, had altered from a small stream to a raging torrent. Although this is usual for a glacial river during a melt season in Greenland, the scale of change was unprecedented. Temperatures around camp far exceeded my expectations. I packed expedition gear expecting Arctic summer temperatures of around 10°C – a little higher than I had previously experienced in the northerly island archipelago of Svalbard. What I experienced were temperatures sometimes reaching 20°C. In our camp mess tent where we cooked and ate our meals the temperature would sometimes exceed 30°C – shorts and t-shirt weather – were it not for the thousands of mosquitoes that were thriving in the warmer weather. In June I often found myself processing samples in the science tent with beads of sweat on my brow.

When the discharge of the river exiting the margin of Leverett glacier hit around 500 m3/s in late June (over six times that of the average River Thames discharge when flowing through London), it was evident to all of the camp that the 2012 melt season was going to be much larger than in previous years. Over the period that Leverett catchment has been studied (2009-), river discharge usually reaches a high of 405 m3/s, and that was in early August – more than a month after this high (and therefore after a month’s more melt). At that time a bridge crossing the glacial meltwater river in the nearest town, Kangerlussuaq, approximately 25 km downstream (Watson River, fed by Leverett glacier and two other large glaciers in the area), had to be closed as the amount of water deemed it unsafe. I’ve recently been informed that discharge of Leverett river has subsequently hit more than 800 m3/s since I left camp – nearly twice that of the previous high. At the same time Watson River discharge at Kangerlussuaq was nearly double its previous high (3500 m3/s – more than the average discharge of the Nile), and in dramatic fashion has washed away the same bridge that was closed in 2010 (see http://www.guardian.co.uk/environment/picture/2012/jul/27/glaciers-flooding?newsfeed=true# and http://www.guardian.co.uk/environment/2012/jul/25/greenland-glacier-bridge-destroyed-video?newsfeed=true). Although a trend for higher melt season discharge has been observed, locals and scientists in the Kangerlussuaq area have all been taken aback by the magnitude of change experienced this year (http://www.ouramazingplanet.com/3254-greenland-flooding.html).

As this was my first field season in Greenland it was difficult for me to grasp the scale of change from previous years. Ben Linhoff, an isoptope geochemist from Woods Hole Oceanographic Institute in Massachusetts, USA, has been in camp during the 2011 and 2012 melt seasons, and was surprised by the difference in temperature and river size between the two years. He has documented the scale of change on his Scientific American blog (http://blogs.scientificamerican.com/expeditions/tag/following-the-ice/), and in a short video with Andrew Tedstone of the University of Edinburgh (http://www.whoi.edu/page.do?pid=80757&cl=82073&tid=5122). Ben comments that air temperatures in camp are substantially warmer than in 2011 and that glacial moraine deposited by Leverett glacial hundreds of years ago (possibly during the Little Ice Age) was being eroded by Leverett river – likely for the first time in decades. Dave Chandler, a University of Bristol researcher, camped within the ice sheet interior, 40km from the margin, has also been surprised by the warm temperatures. During the 2011 melt season he found that the temperature on the ice very rarely exceeded freezing at night. In contrast, the temperature has stayed above freezing throughout most of June and July at a similar point on the ice this year. Higher temperatures and the lack of freezing conditions on the ice sheet interior mean that more glacial ice has melted on the surface. This water is then thought to be routed to the bed through conduits know as moulins. At the bed the meltwater joins a large subglacial channel that flows under the ice and exits the glacier via a portal such as that which exists on Leverett glacier. The discharge of these subglacial rivers is thus indicative of the amount of ice melt.

 

 

 
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