Code Red: 8 Things You Need To Know About Water In IPCC AR6

By Debra Tan 24 August, 2021

IPCC AR6 is a code red for water too! CWR's Tan shares 8 things you may have missed & urges to delay no more

26/35 CIDs in IPCC's AR6 are water-related and no region will be unaffected; with water & climate risks undervalued, we can’t build resilience or bounce back after disasters
Having likely blown our chances of 1.5°C, we must try for 2°C; must plan for the worst & adjust if we manage to stay on track, especially with compounding climate events
2m SLR by 2100 cannot be ruled out - but it’s not too late to do better; we have a once-in-a-lifetime opportunity to re-imagine and build a climate-ready and resilient world

The IPCC AR6’s stark warnings came as no surprise to those in the space, but it does help others focus on key existential threats ahead and what to prioritise. There has since been a lot of news voicing frustration over the slow pace of decarbonisation and rightly so; the need to fast track low carbon economies is indeed now more urgent than ever.

But you may have missed what the IPCC AR6 said about water. Here are 8 key points on why we can no longer delay putting water risks at the forefront of our climate fight.

1. Impacts are all about water – 26 out of 35 Climatic Impact Drivers (CIDs) in AR6 are water-related

The IPCC AR6 Summary for Policymakers (AR6-SPM) has a dedicated section on “Climate Information for Risk Assessment & Regional Adaptation” where it sets out the future projections of 35 CIDs across various categories from ‘Heat & Cold’. ‘Wet & Dry’ to ‘Coastal’ –  26 of these are water-related be they freshwater or saltwater – including River Flood, Fire Weather, Relative Sea Levels to Snow, Glaciers & Ice Sheet melt. See for yourself … click to expand

“Water is the primary vehicle through which we feel the impacts of climate change. To effectively address both water and climate challenges, we must bring climate change and water to the same table – into the same conversation: Tackling them as one” urged the World Meteorological Organisation. We couldn’t have said it better.

Water is the primary vehicle through which we feel the impacts of climate change…

…26/35 CIDs are water-related & no region will be left untouched

The 26 water-related CIDs are interlinked. One triggers another causing cascading risks likely replete with feedback loops. If you are not on top of these, not only have you undervalued them but how can you build resilience against water & climate risks or bounce back after disasters you didn’t even know were coming.

The AR6-SPM warned that multiple CIDs are projected to change in all regions of the world – almost all regions (96%) are projected to experience changes in at least 10 CIDs and half in at least 15 CIDs. Nevertheless, no region is left unscathed with all regions around the world projected to experience changes in at least 5 CIDs.

Yes, it’s dire. BTW, water also dominates the disaster roster over the past 50 years and it is about to get worse as we continue to warm…

2. Increasing likelihood that extreme events will become more extreme & more frequent

“Many changes in the climate system become larger in direct relation to increasing global warming. They include increases in the frequency and intensity of hot extremes, marine heatwaves, and heavy precipitation, agricultural and ecological droughts in some regions, and proportion of intense tropical cyclones, as well as reductions in Arctic sea ice, snow cover and permafrost”  


“Continued global warming is projected to further intensify the global water cycle, including its variability, global monsoon precipitation and the severity of wet and dry events.


Let’s take a moment here to digest the info in the above box.

We are already seeing more emissions = more warming = larger changes in CIDs…

…& we are far from prepared

More emissions = more warming = larger changes in CIDs. We are already seeing this today – events are becoming more extreme with new records set year-on-year. The rate at which records have been broken this year is frightening yet the AR6 is saying that all these extreme events will get worse if we don’t manage to rein in emissions.

It is clear from the damage this summer that we are far from prepared – our current infrastructure is simply not designed to cope with these new levels of climate threats.

What’s more worrying is that we are only at 1.1-1.2°C of warming, imagine what will happen when we reach 2°C or 3°C.

Can we cope with even more extreme events? See our concerns over new extremes on flooding from Europe to China

River floods, mega-fires & droughts – we need to get ready come hell or high water

Worst still, one-off events occurring more often could become chronic or ‘the norm’ – we will just have to learn to live with this. Already, we are seeing this with the fires in the US where 100+ mega-fires are burning at the same time over an extended fire season which is likely to continue due to the dry condition. (FYI – the AR6 has “Fire weather” grouped under the category of “Wet & Dry” CIDs). More droughts in the future will also hamper the ability to fight such fires.

And when global scientists say there is “medium to high confidence” that both fire weather and river floods are set to increase, we need to get ready come hell or high water.

3. Now they could all happen at the same time – “compound extreme events” debut in AR6

Even more depressing is the arrival of “compounding events”, making its debut in the AR6-SPM (it was not mentioned in the AR5-SPM). “Human influence has likely increased the chance of compound extreme events” it warned.

Lethal combo of more extreme + more frequent + compounding event = worst is yet to come

Again the IPCC warned that the worst is yet to come “Many regions are projected to experience an increase in the probability of compound events with higher global warming”

This lethal combo of more extreme + more frequent + compounding events has serious implications for policymakers, corporates and the financial sector. More on this in our review on rising clustered & cascading risks.

Other worrying compound events worth highlighting are front ice sheet collapse and abrupt ocean circulation changes. Although the AR6 has classified these as low-likelihood events, they would bring about devastating impacts including multimeter levels of rapid sea level rise (SLR) by 2100, bringing us on to the next point …

4. 2m SLR by 2100 and 5 m SLR by 2150 cannot be ruled out under the worst-case scenario

Last year, when we said that the latest science pointed to plausible worst-case SLR of 2.9m by 2100 in our 5-report series on APAC coastal threats, many thought we were way too doom-and-gloom. But apparently not – the AR6-SPM warned that these multi-meter levels “cannot be ruled out due to deep uncertainty in ice sheet processes”.

We wish we were wrong but IPCC says up to 2.9m SLR possible…

Sadly, “I told you so” doesn’t bring any satisfaction – this is one area where we wish we were wrong. At around 3m of SLR, our analysis showed that just in 20 APAC capitals and coastal hubs,  urban real estate equivalent to 22 Singapores will be underwater. It’s worth noting here that the extent of the impact is conservative as we did not factor in regional tides.

Coastal impacts on critical infrastructure from ports, airports to CBDs vary from Tokyo to Sydney, as do the cities’ readiness – see how the 20 cities rank in the CWR APACCT 20 Index or check out the individual city factsheets.

Here, it is important to note that whilst the AR6 ascribes “low confidence” to this range, the IPCC has included this in the AR6-SPM indicating its importance as consideration for adaptation planning today. It is classified as “low confidence” because climate science behind ice sheet dynamics, although fast-evolving, is relatively new with limited evidence gathered so far.

Unfortunately, all the latest research/observations published this year point to a grim future so we agree with the IPCC – 2-5m of SLR “cannot be ruled out”. We won’t go into this in detail now but we will reconcile the SLR projections in the AR6 with our coastal threat reports later this year … so do sign up now for our next newsletter, if you haven’t already!

…2m of SLR +  2.5m tides in HK would mean that K11 in Kowloon & Cheung Kong Center will be seafront properties

It’s not just island that will be lost within the century, 2m of SLR with high tides of 2.5m in Hong Kong would reshape its coastlines. At these levels, Hong Kong’s K11 in Kowloon, Cheung Kong Center, and Regal Hotel in Causeway Bay will be seafront properties.

The question Hong Kongers must ask is not ‘will seas rise to these levels?’ but can Hong Kong survive this level of impact?

If the answer is no, no-regret adaptation planning needs to start now – on this front, everyone can take a page out of Singapore’s resilience playbook and check out expert advice on dealing with SLR deep uncertainty. 

5. Other terrifying news about our oceans: from heatwaves, thermal expansion to deoxygenation

The AR6 is more assertive than the AR5 – there are many more projections/ causal relationships that are now “virtually certain”,  “extremely likely” or have “high confidence”. Many of these are related to our oceans. We had covered these in “ but here are a few worrying updates affirming the trends we highlighted:

  • We made our oceans warmer: We now have high confidence that GHG emissions have committed the global ocean to future warming – even for low emission scenarios this is 2-4x the 1971–2018 change. At high emission scenarios, this doubles to 4–8x. Indeed, ocean warming accounted for 91% of the heating in the climate system.
  • Ocean warming = thermal expansion + ice sheet loss = SLR: Thermal expansion explained 50% of sea level rise during 1971–2018, while ice loss from glaciers contributed 22%, ice sheets 20% and changes in land water storage 8%. The rate of ice sheet loss had already increased by a factor of four between 1992–1999 and 2010–2019. Continued ice loss over the 21st century is virtually certain for the Greenland Ice Sheet and likely for the Antarctic Ice Sheet.
  • Ocean acidification: It is now “virtually certain” that human-caused CO2 emissions are the main driver of current global acidification of the surface open ocean. This has serious implications for marine biodiversity.
  • Less oxygen: There’s now high confidence that oxygen levels have dropped in many upper ocean regions since the mid-20th century and will continue to drop at rates dependent on future emissions. Our oceans are the lungs of the planet – we must look after them.

It’s bad is an understatement. And we’ve not even started with the rubbish, microplastics, antibiotics, endocrine-disrupting chemicals that have ended up in our oceans. Surely losing our “oxygen maker” should get us racing towards net zero?

6. Timing matters – decarbonising sooner increases the likelihood of staying within 2°C = better for water

Given imminent existential threats, cutting carbon is a brainer yet there is a tendency to procrastinate with actual deep cuts in carbon emissions in favour of waiting for tech/biotech/nature-based innovations in offsetting or large scale carbon sequestration to get to net zero. But they are not here today and we cannot wait because when we get to net zero also matters:

  • The ‘best estimate’ ECS is now at 3°C, there is no time to waste. The window of time we have to get to net zero for 1.5-2°C is collapsing as low-end equilibrium climate sensitivity (ECS) is now ruled out. ECS measures climate sensitivity to carbon emissions – the lower the number, the more time we have to tackle climate change. However, the AR6 narrowed the ECS range from the AR5 – it is now 2.5°C to 4°C (high confidence), compared to 1.5°C to 4.5°C in AR5.
  • Our remaining 1.5-2°C carbon budget is very tight. Having already released around 2,390GtCO2 between 1850 and 2019, our carbon budget for an 85% chance of staying within 1.5°C by 2100 stands at 300GtCO2. We currently emit around 50GtCO2 per annum which means we will blow this budget in 6 years time if we continue at this rate. So it’s not surprising that the AR6’s “best estimate” of warming between 2021-2040 is at least 1.5°C across all 5 core IPCC SSP scenarios.

With 1.5°C unlikely, must try to stay within 2°C, our carbon budget is 900GtCO2 – it’s going to be difficult

Having likely blown our chances of 1.5°C, we must try to stay within 2°C. For an 85% chance of doing this, our carbon budget is 900GtCO2; or 18 years at the current rate of emissions. It is going to be difficult, COVID only managed to reduce 2020 emissions by around 2.3GtCO2 and 2021 emissions so far are back up despite increasing noise around climate change.

Why urgently decarbonise to stay within 1.5-2°C by 2100? Because there is high confidence that “More CIDs across more regions are projected to change at 2°C and above compared to 1.5°C global warming” says the AR6-SPM.

  • Picking a later net zero date could trigger faster Antarctica melt & rapid SLR earlier. The latest research cited in the IPCC AR6 showed that 1.5-2°C will likely result in Antarctica ice loss at a rate similar to that today whereas a current policies path of 3°C could trigger “an abrupt jump” in ice loss after around 2060 due to the destabilisation of the West Antarctic Ice Sheet caused by the retreat of the Thwaites Glacier. This abrupt jump could deliver multimeter SLR by 2100.

Given the clear red card on emissions, we need to concurrently cut all emissions, offset and sequester carbon. We should be throwing everything at the wall (including lots of capital) to deliver innovations in carbon capture (tech/nature-based) plus delivering emission cuts by transitioning away from all fossil fuels.

On fossil fuels, there’s a lot of noise on cutting coal emissions but less so on oil & gas. We don’t see why this should be the case – there should be equal if not more pressure on the oil & gas sectors – after all oil & gas emissions are 42% greater than that of coal; plus they account for a sizeable chunk of methane emissions.

Need to tackle oil & gas, not just coal

With over 60% of global oil & gas production controlled by the G20, why just try to end coal when you can deliver deep cuts in oil & gas. See why we think the G20 can take the lead – here.

The other sector we need to seriously shine a light on is agriculture and rethink our GHG-intensive diet. Incidentally, the fossil fuels & agriculture industries are also big users of water and will be impacted by a variety of water risks so a holistic rethink of these is inevitable.

7. If we are not on track, we need to step up adaptation

The AR6 has 5 core IPCC scenarios:

  • SSP1-1.9 & SSP1-2.6; these two scenarios give us the best chance of staying below 2.5°C and require year-on-year carbon emission reductions from today both reaching net zero before 2100 followed by net negative emissions thereafter – one scenario reaches net zero at around mid-century; the other reaches it in the second half of the century
  • SSP2-4.5; this has carbon emissions staying at current levels until 2050 and falling year on year thereafter; this takes us to a very likely range of 2.1-3.5°C
  • SSP3-7.0 & SSP5-8.5; these two scenarios represent high emission scenarios – one scenario has emissions roughly doubling by 2050 and another doubling by 2100. These take us to a very likely range of 2.8- 5.7°C

As impacts vary dramatically across scenarios, DO NOT tie your adaptation plans to your/our decarbonisation targets. Saying and doing are two different things, plan for the worst and adjust if we manage to stay on track with decarbonisation.

Plan for the worst & adjust if we manage to stay on track with decarbonisation

Also, remember that net zero requires collective effort – if some are carbon neutral whilst others are not (especially big emitters) then you had better also revise up your adaptation plans.

So far we only have commitments for 1.9 – 3°C and many are behind on their commitments and there is only so much offsetting you can do. Don’t forget also to keep an eye out on carbon sequestration – projects here are also falling behind.

8. Locked-in! Changes in the ocean, ice sheet and SLR are already irreversible

Even by some miracle and if we reach zero emissions TODAY, the AR6-SPM states that Many changes due to past and future greenhouse gas emissions are irreversible for centuries to millennia, especially changes in the ocean, ice sheets and global sea level.”

This means that it is “virtually certain that global mean sea level will continue to rise over the 21st century.” Asia is particularly vulnerable with multiple coastal economies. The AR6 also stated with high confidence that extreme sea-level events that occurred once per century in the recent past are now projected to occur at least annually at more than half of all tide gauge locations by 2100.

While it’s too late to dial back the impacts we have baked in, it’s not too late to do better on adapting to survive

We have literally no choice but to prepare for this onslaught. The bad news is that there’s now “unequivocal” evidence that we caused this; the good news is that if we caused it we can fix it so it doesn’t get worse. And while it’s too late to dial back the impacts we have baked in, it’s not too late to do better on adapting to survive imminent threats ahead.

Recent events and the IPCC AR6 have given us a fair warning of what’s to come. It’s now up to us to be brave; embrace the risks and embark on a visionary re-think and re-design of our future. We have a once-in-a-lifetime opportunity to re-imagine and build a climate-ready and resilient world. Squandering this has unthinkable consequences.

Further Reading

  • It’s Time To Prioritise Sea Level Rise – CWR’s Debra Tan says it’s time to be FOMO about our rising seas. From emission accelerants to accelerated impacts she runs through three reasons to rethink our attitudes towards sea level rise – it’s a big deal, sea level rise is worse than you think. This time, even she’s depressed
  • 3 Ways To Deal With The Deep Uncertainty Of Sea Level Rise – SLR uncertainty is here to stay but it can be minimised as discussed at SIWW 2021. CWR’s Ronald Leung & Dawn McGregor share what the climate & planning experts advised
  • Existential Coastal Threats: 8 Things You Must Know – Rapid SLR will happen sooner than we think, yet we are still driving investments to vulnerable locations. CWR’s Debra Tan shares 8 things you need to know about the existential threat from SLR – from glaciers in the mountains to ice sheets in our poles, permafrost + more
  • Sea Level Rise – What The Science Tells Us – What’s the latest on sea level rise projections? HKU’s Dr. Nicole Khan shares key findings from her survey of 100+ sea level experts, as well as talks risks to Hong Kong and what we should take away from COVID-19
  • Future SLR Projections & Biggest Worries – In this follow up interview, HKU’s Dr. Nicole Khan shares her biggest concerns on how future SLR projections are rising higher & faster than thought & shares the best approach for building realistic scenarios
  • Sovereigns At Risk: Lots Of Capital In Vulnerable Spots – Clustered nature of rising coastal threats plus lax govt action put APAC sovereigns at risk. CWR’s analysis of GDP, trade, markets & bank loans reveal intense concentration of risks. As no-sense strategies pervade, see who’s in CWR’s watchlist

More on Latest

Debra Tan
Author: Debra Tan
Debra heads the CWR team and has steered the CWR brand from idea to a leader in the water risk conversation globally. Reports she has written for and with financial institutions analyzing the impact of water risks on the Power, Mining, Agricultural and Textiles industries have been considered groundbreaking and instrumental in understanding not just China’s but future global water challenges. One of these led the fashion industry to nominate CWR as a finalist for the Global Leadership Awards in Sustainable Apparel; another is helping to build consensus toward water risk valuation. Debra is a prolific speaker on water risk delivering keynotes, participating in panel discussions at water prize seminars, numerous investor & industry conferences as well as G2G and academic forums. Before venturing into “water”, she worked in finance, spending over a decade as a chartered accountant and investment banker specializing in M&A and strategic advisory. Debra left banking to pursue her interest in photography and also ran and organized philanthropic and luxury holidays for a small but global private members travel network She has lived and worked in Beijing, HK, KL, London, New York and Singapore and spends her spare time exploring glaciers in Asia.
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