Climate Science for the public – The IPCC report on Ocean and Cryosphere

Hari VishnuArctic, Climate, climate change

Figure 6: Options for risk reduction through adaptation. Taken from Fig. TS4 of the Technical summary [3].

A quick gist of the message of the IPCC report on climate change and its impact.

Jan 26, 2020

by Hari Vishnu

The global Ocean covers 71% of the Earth's surface and contain 97% of the Earth's water [1]. All people on Earth depend directly or indirectly on the Ocean and the cryosphere.

Most of us are familiar with the Ocean. But if you are suddenly wondering: cryo-WHAT?...

The cryosphere is the frozen water part of the Earth system [2]. It includes land ice (ice caps, glaciers, and snow areas, sea ice, frozen rivers, lakes, and mountain ice. It is one of the components of Earth that is facing drastic changes due to climate change. Human communities near coastal environments, small islands, polar areas and high mountains are particularly exposed to impacts from this, such as sea-level rise, extreme sea level events and shrinking cryosphere [1].

Another report ?
By now, you're probably thinking - Oh no, not another long list of climate change related facts to read !

What if there was a way to view the big picture on climate change all together in one place ? No bad science, no exaggerated facts, just plain scientific numbers put together into a single message ?

While a large number of scientific studies are showing the drastic level of change impacting the Ocean and cryosphere, the message often stays stuck in scientific literature, and is too slow to reach the public.

This is in part due to the fact that there is a large deluge of information out there, a lot of it is only available in purely scientific terms, adding to the public's hesitation to try and understand this information  and crunch it down in simple terms.

Story Index
  • Ocean and the Cryosphere
  • Another report?
  • Enter - the IPCC
  • How reliable/conclusive is the science ?
  • Town hall on IPCC SROCC
  • Polar regions (Chapter 3)
  • Sea level rise (Chapter 4)
  • Impacts of changing Ocean on Marine Ecosystems & Dependent Communities (chapter 5)
  • Extremes, Abrupt Changes and Managing Risks (chapter 6)
  • Questions and discussions
  • Conclusion
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  • Figure 2: Schematic of the IPCC usage of calibrated language (taken from Figure TS.1 in the technical summary <a title=

    Figure 1: IPCC usage of language on uncertainty (taken from Figure TS.1 in the technical summary [5]).

    How can the public understand these studies as a whole - the simple message and takeaway from them ?
  • Can policy-makers pin-point the right facts and summaries they need for making important decisions, from this huge mountain of studies ?
  • Can we summarize the message on the amount of climate change and its impacts, in numbers ?
  • How certain are we of these numbers?

Enter - the IPCC

The Intergovernmental Panel on Climate Change (IPCC), an international body for climate-change assessment, is trying to bridge this gap. IPCC is bringing together scientists around the world to review and assess the most recent scientific, technical and socio-economic information produced worldwide relevant to understanding climate change. It does not conduct any research or monitor climate data. IPCC was established by the United Nations Environment Programme and World Meteorological Organization.

The Ocean Sciences meeting held in San Diego in Feb, 2020 held a town hall to discuss the IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC). The IPCC report is the latest and most comprehensive assessment of how climate changes are affecting the ocean and cryosphere, the impacts and risks of those changes for ecosystems and humans as well as adaptation options and capacities.

(Video on the IPCC report: https://www.youtube.com/watch?v=rVjp3TO_juI&feature=emb_logo)

How reliable/conclusive is the science ?

The SROCC report was prepared by scientists from over 40 countries around the world. It was released in September 2019, and had 104 lead authors and 294 contributing authors. It spanned 6981 studies and 31176 comments that were ironed out over 4 days.

One of the most striking aspects of the report to me -

The authors made every attempt to quantify not only what they know about climate change, but also the level of certainty or uncertainty they associate with each statement.

This is important, considering that a natural question in anyone's mind would be "How certain can I be of these statements?". From this point-of-view, the authors have made an attempt to homogenize the language used throughout the report based on their level of confidence shown by the data (see Figure 1).

Town hall on IPCC SROCC

Structure of IPCC report

Structure of IPCC report

The town hall introduced the report and the assessment procedure, highlighted new knowledge and its relevance for supporting policy-makers. There was a Q&A session discussing interpretation of the report, and how to get involved and contribute to IPCC reports. The Town Hall also invited feedback on the report. People working in related areas of climate change can get involved in several ways, including through peer-reviewed publications, and signing up as authors, review-editors or reviewers. Coordinating Lead Authors, Lead Authors and Review Editors for each report chapter are nominated by IPCC Focal Points, Observer Organizations and/or IPCC Bureau Members. If you are interested in becoming an IPCC author or review editor, look out for calls for nominations and contact the relevant IPCC government or Observer Organization focal points for more information.

The panel moderator was Nathaniel Bindoff from University of Tasmania, and the panel featured lead authors involved in various chapters of the report (totally 6 - see Figure 2):

  • Mônica Muelbert, Institute of Marine and Antarctic Studies (IMAS), University of Tasmania (author of Ch. 3)
  • Erwin Lambert, Institute for Marine and Atmospheric Research Utrecht (Ch. 4)
  • Robert Hallberg, Geophysical Fluid Dynamics Laboratory, NOAA  (Ch. 5)
  • Lisa Levin, Scripps Institution of Oceanography (Ch. 5)
  • Matthew Collins, University of Exeter (Ch. 6)

There were no panelists representing chapter 2 (High-mountain areas) because there were no Lead authors of that chapter (usually land experts) present at the Ocean Sciences meeting.

A point that was repeatedly raised at the townhall was:

This was not meant to be a report for scientists alone. It was meant to be communicated to the world, and it was requested by the IPCC countries, amongst other similar reports. Available apart from the detailed chapters is a Summary for policymakers[1] - a key chapter aimed at summarizing the findings into a language understandable for policymakers and the public.

SROCC take on Polar regions (chapter 3): The discussion continued with Monica Muelbert summarizing Chapter 3 on Polar regions [6]. The key takeaways she mentioned include that:

  • Scientific observations show a decline in low-elevation snow cover (high confidence), glaciers (very high confidence) and permafrost (high confidence) due to climate change in recent decades.
  • Snow cover, glaciers and permafrost are projected to continue to decline in almost all regions throughout 21st century (high confidence).

Figure 4: Impacts and risks to ocean ecosystems based on observed and projected climate impacts. (reproduced from Figure TS8 of the Technical summary <a title=

Figure 3: Impacts and risks to ocean ecosystems based on observed and projected climate impacts. (reproduced from Figure TS8 of the Technical summary [5])

Sea level rise (chapter 4): Erwin Lambert discussed some takeaways from Chapter 4. The observations show that

  • Scientists are virtually certain that the mean sea level is rising, and can say with high confidence that it is accelerating [7]
  • The sum of glacier and ice sheet contributions is now the dominant source of sea level rise (very high confidence)
  • Human-induced activities have played an important role in increasing low-lying coastal communities’ vulnerability to sea level rise and extreme events (very high confidence)
  • Coastal ecosystems are already impacted by the combination of sea level rise, other climate-related Ocean changes, and adverse effects from human activities on Ocean and land (high confidence)
  • Widespread adaptation will be necessary by mid century to cope with sea level rise, though effective mitigation may still prevent multi-meter sea level rise.

Impacts of the changing Ocean on Marine Ecosystems and Dependent Communities (chapter 5): Robert Hallberg, in his discussion on Chapter 5, pointed out that 

  • Changes are already observed in the Ocean in physical and ecological systems and have impacted human life even upto the present-day (eg. Figure 5.16 in Chapter 5). 
  • Carbon emissions from human activities are causing ocean warming, acidification and oxygen loss [8].
  • The warming ocean is affecting marine organisms at multiple levels, impacting fisheries with implications for food production. 
  • Concerns regarding the effectiveness of existing Ocean and fisheries governance are already reported, highlighting the need for timely mitigation and adaptation responses.

Locations where extreme events with a link to ocean changes have been identified. Taken from Fig. 6.2 of Chapter 6 of SROCC

Figure 4: World locations where extreme events with a link to ocean changes have been identified. Taken from Fig. 6.2 of Chapter 6 of SROCC [9]

Lisa Levin continued the discussion on Chapter 5 [8]: (burning ember diagram reproduced here in Figure 3) All marine ecosystems will be altered to some degree by climate change as the Ocean warms, with widespread consequences for humans that rely on these ecosystems. The impact is felt more or less in the descending order shown below:

  • Most impacted: Warm water corals (high-risk)
  • Seagrass beds and kelp forests experiencing (moderate risk)
  • Salt marshes and rocky shores
  • Cold-water corals and deep-sea systems

Marine systems such as estuaries, sandy beaches, seamounts, canyons, abyssal plains, vents and seeps and mangroves (coastal) are at lesser risk than the above-mentioned, but they can be at severe risk by the end of the century too. All of them are expected to be affected to some degree.

Extremes, Abrupt Changes and Managing Risks (chapter 6): Mathew Collins discussed Chapter 6[9]. He mentioned that extreme events such as tropical cyclones, marine heatwaves and El Nino events are becoming stronger and more frequent. He also mentioned excerpts from the chapter [9]:

  • climate change has increased rain (medium confidence), winds (low confidence), and extreme sea level events (high confidence) associated with some tropical cyclones, which has increased intensity of multiple extreme events and associated cascading impacts (high confidence).
  • Extreme wave heights which contribute to flooding and coastal erosion have increased in the Southern and North Atlantic Ocean by 0.8-1.0 cm/year over 1985–2018 (medium confidence). 
  • The strongest El Niño and La Niña events since the pre-industrial have occurred during the last fifty years (medium confidence)
  • For high levels of warming, extremes will become more severe and the chance of abrupt change increases.

Figure 5 Past and future changes in the ocean and cryosphere (taken from TS3 of the technical summary <a title=

Figure 5: Past and future changes in the ocean and cryosphere (taken from Fig. 1.2 of the technical summary [5])

In response to a question, Collins mentioned that while there is no real estimate of a single so-called climate ‘tipping point’ where everything would go awry, Table 6.2 in Chapter 6 tells you close to that for different subsystems of the Ocean and cryosphere. It discusses potential abrupt changes in these subsystems, whether they are reversible, their impacts on human life and their chances of happening in the 21st century. I shall not reproduce the table, but a short summary would be:

  • Almost all the changes discussed in each subsystem are abrupt changes.
  • About half of them are irreversible.
  • Changes such as Marine heatwave increase, Arctic sea-ice retreat and Greenland Ice-sheet decay are expected to happen with high or very high confidence, whereas Ocean acidification has already taken place. Ocean acidification is a phenomenon whereby the Ocean turns more acidic (rather than neutral, as water is) over a period of time caused primarily by the uptake of carbon dioxide [10](read more on acidification here).

The abrupt changes and extreme events that have already happened are also summarized in Fig. 6.2 in the SROCC (reproduced here in Figure 4). For example, there is a drastic change shown in Ocean acidification that happened in the recent past, and the report gives expected trends for the future. But when one looks at details, there is no fully clear picture yet due to the complexity of the problem  (read more articles on hurricanes here).

Questions and discussion session

The panel also opened up for questions from the audience, and there were quite a few asked. A few of them are reported here.

Q: How possible is the RCP2.6 possibility ? Is there any hope for us not to hit that level ?  (In context of Fig. TS 3 reproduced here in Figure 5)

For context to the reader: Representative Concentration Pathways (RCPs) describe different 21st century ‘pathways’ of greenhouse-gas emissions, air pollutant emissions and land use - think of them as possible eventualities informed by the trajectory taken by human activities so far. The RCPs include a stringent mitigation scenario (RCP2.6), two intermediate scenarios (RCP4.5 and RCP6.0) and one scenario with very high GHG emissions (RCP8.5).

Reply: The RCP2.6 eventuality was considered by assuming there would be a way to mitigate the carbon (in the Earth's atmosphere and Ocean) by 2050 (IPCC AR5 report [3], see Figures 6 and 7). I.em RCP2.6 may be ‘optimistic enough’ to assume that some ‘negative emissions’ (or additional carbon removal) will happen by 2050. Currently, we don't even have such a technology. (Mathew) So at this point, it seems like it's hard to avoid the RCP2.6 eventuality. The moderator (Nathaniel) mentioned that he’s a little more optimistic than that - an increase of 2°C (3.6°F) seems to have a 66% probability of happening. But the panel re-iterated that they did not want to advocate anything, and are just laying out the facts clearly for everyone to see. The plots shown post-2019 are not predictions, but projections based on the emission levels assumed. The plot was included because it can help understand the potential projections of the impacts in the future, and the IPCC member countries felt it was necessary.

Annual anthropogenic CO2 emissions for different RCPs

Figure 6: Annual anthropogenic CO2 emissions for different RCPs [4]

Human activities are estimated to have caused approximately 1.0°C (1.8°F) of global warming above pre-industrial levels. Global warming is likely to reach 1.5°C (2.7°F) between 2030 and 2052 if it continues to increase at the current rate. (high confidence) [5]

Q: Is there a role for everyone here in spreading the message ? Do you think everyone should try and advocate so that we can, as humans, jointly hit that target ?

Reply: (Panel) As scientists, our role primarily lies in giving the facts out there. (Lisa Levin) My personal opinion here is: Yes, everyone should try and reach out to others and spread the message on climate change. For a scientist, there is a very blurry line between being a scientist and knowing, suggesting, and being an advocate. But yes, everyone needs to advocate in their own way. The first step would be to start from each one’s personal circle - start by talking to friends and family about it.

The audience also brought up the point that a lot of the report discusses impacts on a global scale.

 But the messaging to local communities has to be on a local scale - we need to reach out to communities by informing them how specifically they may be impacted. The panel and audience interacted on how we could customize the message of the IPCC to reach out to local people in an area. One aspect of this depends on whether the data behind the plots is easily available, and whether it can be scaled down and interpreted in local areas easily. The panel mentioned that the data is available, but it should be made more accessible. They mentioned that efforts were on to make the data more transparent to reach.

Cumulative emissions of CO and future non-CO radiative forcing determine the probability of limiting warming to 1.5°C

Figure 7: The probability of limiting warming to 1.5°C (2.7°F), taken from [4]

Conclusion

If you’ve read till this point, you've hopefully realized that this is not a conclusion, but just the beginning. While the good climate science keeps happening, advancing and updating the numbers, we cannot afford the message being stuck in only the scientific literature and failing to reach the public and the policy-makers. What’s the point of all this excellent science if the information does not get across ? Bridging this information gap is the need of the hour - it can help address inertia that arises due to lack of simple clear facts.

In this regard, the IPCC reports provide an excellent go-to source for gathering summary messages on climate change for the common man. Ofcourse, IPCC report summaries are only scratching the surface, but they are comprehensive. For any reader who just wants to understand what is the latest update on climate change, for people looking to organize awareness campaigns, or for those consulting on policy decisions, this is one good source to start with. And this is just the next step in promoting humanity to incorporate adaptations in their lifestyle to reduce the risk due to climate change (see Figure 8).

Figure 6: Options for risk reduction through adaptation. Taken from Fig. TS4 of the Technical summary <a title=

Figure 8: Options for risk reduction through adaptation. Taken from Fig. TS4 of the Technical summary [5].

The IPCC is preparing more reports that regularly capturing updates on this front. The next one, Annual Report 6, Climate Change 2021: The Physical Science Basis, is expected to come out in April 2021. Stay tuned for more updates on these reports and our coverage on them !

If you have any feedback on how we can make these better, of if you have any questions you want us to bring up at IPCC panels, email us at earthzineeditor@ieee.org

 

References

[1] Summary for Policymakers - Special Report on the Ocean and Cryosphere in a Changing Climate In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)]. In press.

[2] NOAA, What is the cryosphere? , Accessed March 8th 2020

[3] R.K. Pachauri, L. A. M. and C. W. T. (2014). Climate Change 2013 - The Physical Science Basis. In Intergovernmental Panel on Climate Change (Ed.), Ipcc. https://doi.org/10.1017/CBO9781107415324

[4] Masson-Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P. R. S., A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M. I. G., & E. Lonnoy, T. Maycock, M. Tignor, and T. W. (eds. ). (2018). IPCC, 2018: Summary for Policymakers. In: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global.

[5] Technical Summary — Special Report on the Ocean and Cryosphere in a Changing Climate IPCC, 2019: Technical Summary [H.-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, E. Poloczanska, K. Mintenbeck, M. Tignor, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)]. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.- O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)]. In press.

[6] Chapter 3: Polar regions — Special Report on the Ocean and Cryosphere in a Changing Climate Meredith, M., M. Sommerkorn, S. Cassotta, C. Derksen, A. Ekaykin, A. Hollowed, G. Kofinas, A. Mackintosh, J. Melbourne-Thomas, M.M.C. Muelbert, G. Ottersen, H. Pritchard, and E.A.G. Schuur, 2019: Polar Regions. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)]. In press.

[7] Chapter 4: Sea Level Rise and Implications for Low-Lying Islands, Coasts and Communities — Special Report on the Ocean and Cryosphere in a Changing Climate, Oppenheimer, M., B.C. Glavovic , J. Hinkel, R. van de Wal, A.K. Magnan, A. Abd-Elgawad, R. Cai, M. Cifuentes-Jara, R.M. DeConto, T. Ghosh, J. Hay, F. Isla, B. Marzeion, B. Meyssignac, and Z. Sebesvari, 2019. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)]. In press.

[8] Chapter 5: Changing Ocean, Marine Ecosystems, and Dependent Communities - Special Report on the Ocean and Cryosphere in a Changing Climate, Bindoff, N.L., W.W.L. Cheung, J.G. Kairo, J. Arístegui, V.A. Guinder, R. Hallberg, N. Hilmi, N. Jiao, M.S. Karim, L. Levin, S. O’Donoghue, S.R. Purca Cuicapusa, B. Rinkevich, T. Suga, A. Tagliabue, and P. Williamson, 2019. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)].

[9] Chapter 6: Extremes, Abrupt Changes and managing risks, Collins M., M. Sutherland, L. Bouwer, S.-M. Cheong, T. Frölicher, H. Jacot Des Combes, M. Koll Roxy, I. Losada, K. McInnes, B. Ratter, E. Rivera-Arriaga, R.D. Susanto, D. Swingedouw, and L. Tibig, 2019, In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)].

[10] NOAA, What is Ocean acidification? Accessed March 21st, 2020.