Cryosphere Call to Action – COP28: 2°C is Too High

View the Full List of Signatures

The below Open Letter asks the 28th Conference of Parties (COP28), meeting under the UN Framework Convention on Climate Change (UNFCCC) in Dubai, to move forward both urgency and ambition in mitigation of climate change due to the response of the various components of the Cryosphere — ice sheets, glaciers, snow, permafrost, sea ice and also polar oceans — already today, but far worse at 2°C. In essence, it requests that the COP28 Cover Decision expand on the Glasgow Pact by not just emphasizing 1.5°C as the “lower” Paris limit, but defining the “upper” Paris limit (“well below 2°C”) as 1.5°C alone; since global impacts and damage for each tenth of a degree higher, especially for longer periods of time, will grow well beyond the limits of adaptation.

It is open for signature by all cryosphere scientists globally; as well as those working on emissions pathways: and those in the social sciences with research on adaptation, loss and damage and health impacts. This includes research and field associates, as well as doctoral students — because you are the future, and will be dealing with the impacts of climate change in the global cryosphere throughout your lives, as well as your professional careers.

Signers do so in a personal capacity, not representing their university or other institution; but there is the opportunity to check whether you wish an institutional or other affiliation to be shown together with your signature. For a twice-daily updated list of signatures, see the List of Signatories spreadsheet (). A full list of the original signatories can be found at the bottom of this page.

Signing will close at midnight on the final day of COP28, Tuesday December 12, 2023. Questions may be directed to Dr. Julie Brigham-Grette at and Dr. Twila Moon at For administrative assistance and additional media inquiries, please contact ICCI Outreach Director Amy Imdieke at

The Cryosphere Call to Action:

This has been a year of climate disasters and ice loss. A glacial lake outburst flood devastated Sikkim in India. Swiss glaciers lost 10% of their remaining ice over just two years. Sea ice around Antarctica hit all-time-low summer and winter records. Unprecedented fires raged across Canadian permafrost. Parts of the Arctic and North Atlantic saw water temperatures 4-6°C higher than normal. It rained far inland on Antarctica, and Greenland saw its second-highest surface melt ever.

None of these tragic events surprised us, members of the global Cryosphere scientific community, because – despite all the climate pledges from Paris in 2015, to Egypt in 2022 – greenhouse gas concentrations in the air have continued their steady march upwards. This year, 2023, atmospheric carbon dioxide (CO2) concentrations officially hit 50% above pre-industrial levels: 424ppm, higher than at any point in at least 3 million years. 2023 will be the warmest year on record, probably by the largest margin ever.

Our message – the message of the Cryosphere – is that this insanity cannot and must not continue. COP28, and December 2023 must be when we correct course. Some degree of planetary-wide damage from Cryosphere loss is already locked in. We must prevent even worse impacts from a collapsing Cryosphere for each additional tenth of a degree temperatures rise, especially past the “lower” Paris Agreement limit of 1.5°C.

The Cryosphere – Earth’s ice sheets, sea ice, permafrost, polar oceans, glaciers and snow – is ground zero for climate change. This is because of the simple physical reality of the melting point of ice; or in the case of our rapidly acidifying polar oceans, the amount of CO2 in the atmosphere absorbed and turned to carbonic acid.

The warming impact of CO2, around 80% from fossil fuel use, already has led to steep glacier and ice sheet loss causing global sea-level rise; reduction of water resources from snowpack; growing CO2 and methane emissions from thawing permafrost; dramatic reduction of sea ice, now alarmingly low in both polar oceans; and growing evidence of stress on keystone polar marine species, such as krill, salmon and cod, from polar ocean acidification, warming and freshening.

Enough. It is time to carve a line in the snow: because of what we have learned about the Cryosphere since the Paris Agreement was signed in 2015, 1.5°C is not merely preferable to 2°C. It is the only option.

At COP28, we call on global leaders to enshrine this reality in the Cover Decision: because of the Cryosphere response, even 2°C is too high. The Paris Agreement’s “well below 2°C” can mean just one thing: 1.5°C alone. We therefore need a Stocktake with clear guidelines to make 1.5°C a reality; a path to phase out fossil fuels; and financial mechanisms to support climate action, as well as the adaptation, and loss and damage – most of it ultimately tied to irreversible Cryosphere loss – now inevitable even below 1.5°C; but far worse above that.

Otherwise, world leaders are de facto deciding to burden humanity for centuries to millennia by displacing hundreds of millions of people from flooding coastal settlements; depriving societies of life-giving freshwater resources, disrupting delicately-balanced polar ocean and mountain ecosystems; and forcing future generations to offset long-term permafrost emissions.

This continued rise in CO2 is unacceptable.

The melting point of ice pays no attention to rhetoric, only to our actions.

For more information on the research underlying this call, please see the State of the Cryosphere Report 2023, which will be released in mid-November before COP28.

View the Full List of Signatures

Original Signatories

Dr. Julie Brigham-Grette
Former Chair, U.S. Polar Research Board
Dept of Earth, Geographic and Climate Sciences, University of Massachusetts-Amherst

Dr. Georg Kaser
Retired Professor for Climate and Cryospheric Research, University of Innsbruck
Vice President for Natural Sciences and Technology of the Austrian Science Fund FWF
IPCC Lead Author in AR4 and AR5, WGI, Review Editor in AR6 SROCC and WGII

Dr. Carolina Adler
Executive Director, Mountain Research Initiative
IPCC Lead Author SROCC and AR6 WGII, Co-Lead AR6 WGII Cross-Chapter Paper Mountains

Dr. Pema Gyamtsho
Director General
International Centre for Integrated Mountain Development (ICIMOD), Nepal

Dr. Julienne Stroeve
University of Manitoba
National Snow and Ice Data Center (NSIDC)
IPCC Contributing Author

Dr. Jonathan Bamber
Director Bristol Glaciology Centre, University of Bristol
IPCC Review Editor AR5, Contributing Author AR6

Dr. Chris Stokes
Durham University, UK

Dr. Helen Findlay
Senior Scientist, Plymouth Marine Laboratory
Honorary Professor University of Exeter, UK

Srabani Roy (M.S.)
Strategic Group Lead, Resilient Mountain Economies and Landscapes
International Centre for Integrated Mountain Development (ICIMOD)

Dr. Mandira Singh Shrestha
Senior Water Resources Specialist
International Centre for Integrated Mountain Development (ICIMOD)

Dr. Neera Shrestha Pradhan
Action Area Coordinator, Managing Cryosphere and Water Risks
International Centre for Integrated Mountain Development (ICIMOD)

Dr. Garee Khan
Department of Earth Sciences, Karakoram International University, Gilgit, Pakistan


Dr. Twila Moon
National Snow and Ice Data Center (NSIDC)
Cooperative Institute for Research in Environmental Sciences (CIRES)
University of Colorado Boulder

Dr. Ron Kwok
Principal Scientist, Polar Science Center, Applied Physics Laboratory, University of Washington
IPCC Lead Author AR5 WG1, Contributing Author AR4/AR6 WG1

Dr. Heïdi Sevestre
Deputy Secretary, Arctic Monitoring and Assessment Programme (AMAP)
Working Group to the Arctic Council

Dr. Miriam Jackson
Senior Cryosphere Specialist and Cryosphere Intervention Manager
International Centre for Integrated Mountain Development (ICIMOD)
IPCC Lead Author SROCC

Dr. Regine Hock
Department of Geoscience, University of Oslo
Geophysical Institute, University of Alaska Fairbanks
IPCC Coordinating Lead Author SROCC

Dr. Martin Siegert
Vice President and Professor of Geoscience
University of Exeter, Cornwall, UK

Dr. Gustaf Hugelius
Vice Director
Bolin Centre for Climate Research, Stockholm University

Dr. Babar Khan
Senior Specialist Ecosystem Management, Ecosystem Services Theme
International Centre for Integrated Mountain Development (ICIMOD)

Dr. Amina Maharjan
Senior Livelihood and Migration Specialist
International Centre for Integrated Mountain Development (ICIMOD)

Dr. Madhav Dhakal
Watershed and Springshed Analyst
International Centre for Integrated Mountain Development (ICIMOD)