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Event details

20 June 2023
16:00 - 17:30
Alumni, Public, Staff

Are carbon credits worthless?

The Centre for Climate Finance & Investment and the Centre for Environmental Policy invites you to a discussion on Voluntary Carbon Markets. We will explore the current challenges of VCMs, including the integrity of carbon credits.

In January 2023, a joint investigation by the Guardian, Die Zeit and Source Material found that the forest carbon offsets approved by the world’s leading certifier and used by major corporations for climate claims are largely worthless. Patrick Greenfield, one of the reporters on the investigation, will present the story of their investigation and discuss its wider implications.

Unraveling the Voluntary Carbon Market (VCM): Challenges, Improvements and the Way Forward

The voluntary carbon market (VCM), currently estimated to turn around $2 billion a year, has experienced an impressive upsurge in recent years. This rapid growth, however, has not been without some challenges.  What does "good" look like in the Voluntary Carbon Market (VCM)? And, how can we ensure that we are practicing it? The industry’s focus should be on upholding the quality of credits that successfully divert capital into decarbonization efforts and holding accountable those who remain inactive, set no concrete targets, and continue to pollute.

At a recent seminar hosted by the Centre for Climate Finance & Investment and the Centre for Environmental Policy at Imperial College London. Pernille Holtedahl, a Research Fellow at CCFI, steered a robust discussion between Patrick Greenfield, a journalist at The Guardian, Guy Turner - CEO and founder of Trove Research, and Tommy Ricketts -CEO and co-founder of BeZero Carbon.
The discussion focused on concerns regarding the integrity and value of carbon credits which have been reignited following investigations by The Guardian, the German weekly, Die Zeit, and Source Material, a non-profit investigative journalism organization.
The investigation primarily questioned the quality of rainforest credits –whether carbon was being sequestered at the rate and scale claimed. But it also underscored several problems within the offsetting industry, including the close association with the oil and gas industry and unclear benefits to local people.   

Part of the criticism against the voluntary carbon market has been the perception that it amounts to giving companies the right to pollute. There is now widespread agreement that offsets should not replace mitigation efforts, rather they are intended to compensate for those emissions that are impossible – within the current system – to avoid. Interestingly, according to recent research by Trove, companies that use carbon credits to a material extent decarbonize at twice the rate of those that do not use them. More research on this topic is needed, to back up or refute claims which inevitably will continue to emerge.

The Stewardship of “Good Carbon Credits”

Assessing the quality of carbon credits is a complex and multidimensional task. In addition to existing registry-led methodologies and verification systems, independent quality guidelines are emerging:-notably the Integrity Council on the Voluntary Carbon Market (ICVCM)’s Core Carbon Principles (CCPs) which is positioning itself as a global benchmark for high-integrity carbon credits. Rating agencies – such as BeZero - offer another tool. According to these third-party providers, quality is not binary and rating tools can contribute to educating the market. The last word has not been said on the voluntary carbon market. But that’s how it should be – unprecedented challenges such as climate change and nature loss require responses which are continuously refined and improved. The CCFI will host more of these discussions: where science meets finance, and real-life experiences are brought in to ensure the discussion remains grounded.


Patrick Greenfield
Reporter for the Guardian and the Observer

He writes about biodiversity loss and the climate crisis.Patrick Greenfield is a biodiversity and environment reporter with the Guardian newspaper covering the loss of nature and the climate crisis. Alongside his work investigating carbon markets and nature based solutions, he was part of the Guardian's climate COP26 and COP27 reporting teams, and helped lead their biodiversity COP15 coverage in Montreal last year.

He was previously a TV producer with CNN and holds a masters in international and development economics from Yale University.

Recent work (published by The Guardian):

Biggest carbon credit certifier to replace its rainforest offsets scheme

Revealed: more than 90% of rainforest carbon offsets by biggest certifier are worthless, analysis shows

Guy Turner 
Founder and CEO of Trove Research Limited

He has 30 years’ experience in research and strategy in sustainability and the energy transition. He spent his first 15 years in consulting advising companies and governments on a wide range of sustainability issues. In 2006 he joined New Energy Finance (NEF) to create the carbon market research business (New Carbon Finance) which was integrated into NEF. After the sale to Bloomberg, Guy continued as Head of Commodities and Chief Economist of BNEF, building out power and gas market analysis and renewables economics.

In 2017 Guy joined BP Economics where he was responsible for global oil supply analysis and worked on BP's Energy Outlook. From 2018 to 2020 Guy was the Strategy and Analysis Manager at EDF Renewables, overseeing market and financial analysis to support investments in offshore and onshore wind, solar, battery storage and hydrogen. Guy has undergraduate degrees in Mechanical Engineering and Economics, a Masters in Environmental Technology and is a graduate of London Business School Corporate Finance Evening Programme.

Tommy Ricketts
CEO and Co-Founder, BeZero Carbon

Tommy Ricketts is the CEO and co-founder of BeZero Carbon, a global ratings agency for the voluntary carbon market. BeZero was founded in 2020, its global team combines expertise within climate and earth science, financial research, data science, and public policy. Prior to founding BeZero Carbon, Tommy was a VP in Global Research at Bank of America and worked as a political strategist in London and Brussels.


Pernille Holtedahl is a Research Fellow at the Centre for Climate Finance and Investment, part of Imperial College Business School. Pernille’s primary research interests are models and incentive systems for increasing private investments in nature. Her expertise lies in nature investing, green finance and green bonds – with particular exposure to the forestry, land-use and agriculture sectors. She has worked to promote jurisdictional approaches to forest protection and restoration through ART (Architecture for REDD+ Transactions) and advised philanthropic foundations on impact investment strategies in the forest sector in developing countries.

In addition to her research activities at CCFI, she is a senior consultant to CICERO Shades of Green (now a part of S&P Global), founder of Blue Maia Ltd. (an advisory firm), and on the European advisory board of the Hawthorn Club. She has worked on issues related to climate change, green finance and sustainable development for over 20 years and holds a PhD in environmental economics from George Washington University.

16:00  Welcome and Presentation

16:30 Panel discussion

17:00 Q&A

Event details

20 June 2023
16:00 - 17:30
Alumni, Public, Staff


A birds eye view of a pine forest, showing dense green trees in abundance

Centre for Environmental Policy

The CEP provides a unique and interdisciplinary research interface between science and technology, and the economic and policy context in which it is developed and applied.

Event details

Date: 20 June 2023
Time: 16:00 - 17:30
Audience: Alumni, Public, Staff