IPCC AR6 WG2: 8 Dire Impact Facts You Must Know

By Chien Tat Low 23 March, 2022

What's at stake amid the current trends of climate change? CWR brings you our round-up on 8 key dire facts from the recent IPCC report & why we must act now

Water is how we will feel climate change - all 7 impact chapters in the AR6 WG2 are water-related; 3 - 4bn people could face a thirsty future, then there are impacts on rain, snowmelt, glaciers groundwater & it goes on; so, central to adapting, is dealing with water
Impacts are worse than expected than in AR5 - they are escalating, cascading & reach to points of no return from loss of species & food production to sea level rise; impacts will be worse even if 1.5C is breached, which is >50% to happen by 2040
Window of opportunity to build resilience closing fast yet current pledges to cut emission still lag; climate impacts are wide-ranging & interlinked - from water, food, energy to health plus making the earth more dangerous to live if we don't adapt now

It cannot be more clear  – the recently published IPCC AR6 Working Group 2 Report (WG2) drives the message home again –climate impacts are hitting the planet faster than we thought and we need act now or loose the option to act later.

“ The cumulative scientific evidence is unequivocal: Climate change is a threat to human well-being and planetary health. Any further delay in concerted anticipatory global action on adaptation and mitigation will miss a brief and rapidly closing window of opportunity to secure a liveable and sustainable future for all.”

IPCC AR6 WG2, 2022

It’s not just small island states, everyone will be impacted. As the report warns, climate threats are escalating, irreversible, and reaching points of no return. Check out 8 dire facts you must know to increase our chance for survival.

1. Water is how we will feel climate change – 3 to 4bn people could face a thirsty future

Climate change is caused by greenhouse gases (GHGs) but how it manifests is actually through various forms of water. The IPCC AR6 Working Group 1 Report (WG1) has already made clear that 25 out of 36 climate impact drivers are water-related, be they freshwater or saltwater like coastal threats. It is even clearer in the AR6 WG2 that water is the central theme of climate impacts.

All 7 impact chapters in the AR6 WG2 are water-related

Of all seven major chapters about impacts, three chapters are very explicitly water-related including “Terrestrial and Freshwater Ecosystems and their Services”, “Ocean and Coastal Ecosystems and Their Services”, and of course Water”; while the remaining four chapters are how water underpins the success and failure of “Food, Fibre, and other Ecosystem Products”, “Cities, Settlements and Key Infrastructure”, “Health, Wellbeing, and the Changing Structure of Communities”, and “Poverty, Livelihoods and Sustainable Development”. Clearly, water impacts are wide ranging and influence all aspects of our life.

Roughly 1/2 of the global population currently experience severe water scarcity at least one month per year

One of the direst impacts is on water scarcity. Currently, roughly half of the global population (~4bn out of 7.8bn people) are estimated to experience severe water scarcity for at least one month per year due to climatic and non-climatic factors. If we don’t rein in carbon emission, 3bn and 4bn people could face chronic water scarcity at 2°C and 4°C of warming, respectively.

Some of the projected impacts on physical water availability include:

  • Rainfall: Annual mean precipitation is projected to increase or decrease by up to 40% or more at 4°C;
  • Snowmelt: At ~2°C, snowmelt water availability for irrigation is projected to decline in some snowmelt dependent river basins by up to 20%;
  • Glacier: In the mid-to long-term, global glacier mass loss of 18 ± 13% is projected to diminish water availability for agriculture, hydropower, and human settlements; these impacts will double at 4°C;
  • Groundwater: Projected groundwater recharge could either increase or decrease by region and the results are often uncertain. However, global total and non-renewable groundwater withdrawals are projected to increase from 952 km3/year (2010) to 1,621 km3/year (2099) and from 304 km3 /year (2010) to 597 km3 /year (2099), respectively. At the same time, groundwater depletion is projected to increase from approximately 204 (±30) km3/year (2000) to 427 (±56) km3/year (2099); and
  • Streamflow/ Runoff: By 2050, environmentally critical streamflow is projected to be affected in 42% to 79% of the world’s watersheds, causing negative impacts on freshwater ecosystems. By 2100, 1/3rd of the 56 large-scale glacierized catchments are projected to experience a mean annual run-off decline by over 10%, with the most significant reductions in Central Asia and Andes.

Clearly, the centre of adapting to climate change is to deal with water

Water-related hazards such as droughts, floods, and marine heatwaves have affected the productivity of all agricultural and fishery sectors, with negative consequences for food security and livelihoods. These climate-related extremes also increased deaths and occurrence of food-, water- and vector-borne diseases.

Since the 1970s, 44% of all disaster events have been flood-related. A large share of adaptation interventions (~60%) is about adapting to water-related hazards like droughts, floods, and rainfall variability. Clearly, the centre of adapting to climate change is to deal with water. Most of the strategies in AR6 WG2 also have a focus on water, which is interlinked and pervasive in our lives. Therefore, adapting to water equals to dealing with the core issue of climate impacts. See how China is dealing with water in their national plan here.

2. Impacts are worse than expected – escalating & compounding

The AR6 WG2 sounds more alarming than ever. The extent and magnitude of climate change impacts are evidently becoming “larger than estimated in previous assessments”, and “increasingly complex and more difficult to manage”. Even at current levels of warming, the observed impacts are already worse and some cannot be undone.

“Levels of risk for all Reasons for Concern (RFC) are assessed to become high to very high at lower global warming levels than in AR5″…

…significant increased risks from SLR

The report says levels of risk for all Reasons for Concern (RFC) are assessed to become high to very high at lower global warming levels than in AR5”. “Between 1.2°C and 4.5°C global warming level, very high risks emerge in all five RFCs compared to just two RFCs in AR5”. This is worrying because some key risks contributing to the RFCs are projected to lead to widespread, pervasive, and potentially irreversible impactsat 1.5–2°C if exposure and vulnerability are high and adaptation is low. Also, all 127 identified key risks are up to multiple times higher than currently observed in the mid and long-term future.

One of the escalating impacts and risks is sea level rise (SLR) as the report highlights the following:

  • By 2050, the number of the affected population who lived within low-lying coastal areas would increase from 896mn to 1bn people by 2050;
  • The current 1-100-year extreme sea level is also projected to increase by a median 20-30 times across tide gauge sites by 2050 regardless of emission scenario;
  • Risks from SLR for coastal ecosystems and people are very likely to increase 10x by 2100 without adaptation and mitigation action as agreed by Parties to the Paris Agreement; and
  • By 2100 the value of global assets within the future 1-in-100 year coastal floodplains is projected to be between US$7.9-12.7trn (2011 value) under RCP4.5, rising to between US$8.8-14.2trn under RCP8.5.

The report also warns against complex, compound cascading risk ahead –  “multiple climate hazards will occur simultaneously, and multiple climatic and non-climatic risks will interact, resulting in compounding overall risk and risks cascading across sectors and regions”.

Compound & cascading climate hazards (e.g. SLR & storm surges) complicate risks across multiple sectors including water, food, etc…

…and trigger tipping points

For instance, increasing concurrent of heat and drought events are causing crop production losses and tree mortality. In cities, climate extremes such as SLR combined with storm surges and heavy rainfall are leading to losses and damages across water, food and energy sectors, as well as affect economic activity, with impacts extending beyond the area directly impacted by the climate hazard. Compound climate hazards and cascading risks also trigger tipping points in sensitive ecosystems including ice melt, permafrost thaw, and changing hydrology in polar regions.

Given that we have underestimated the projected climate impacts from the past, we must not underestimate them again in the future despite deep uncertainties in the current risk projections. After all, it’s better to be safe than sorry.

3. It’s irreversible! Points of no returns from loss of species and food production to rising seas

Some climate impacts have already reached or nearly reaching “irreversibility” in AR6 WG2, from loss of species and food production disruption to rising seas.

Some climate impacts have already reached or nearly reaching “irreversibility”…

…food production has been compromised & could get worse with future extreme events

The report says that climate change could have played a role in the extinction or near extinction of at least three species including the white ringtail possum in Australia. Intensifying heat extremes have also caused losses of hundreds of local species, as well as mass mortality events on land and in the ocean and loss of kelp forests. In particular, the report cited a study that found 47% of 976 plants and animals had suffered local extinctions as a result of the climate-induced change.

Extreme events have also compromised our food production from agriculture, aquaculture, forestry and fisheries. The report says that the frequency of “sudden food production losses” due to extreme weather events has increased since at least mid-20th century on land and sea. Ocean warming and acidification not only have decreased sustainable yields of some wild fish populations but also farmed aquatic species. A lot of fish and marine mammals are also being pushed poleward because of warming waters. Going forward, we could even face the risk of losing farming areas permanently because of extreme weather events… more on this in point 6.

Other irreversible impacts caused by global warming include ocean extreme heat, melting of mountain glaciers, sea ice and polar ice sheets, as well as sea level rise. If we trigger further tipping points, all of these impacts will continue to escalate and cause disastrous consequences. For example, ice sheets collapse will cause rapid multi-meter sea level rise, as already warned in the AR6 WG1.

Click on the right picture to see how close we are reaching further tipping points especially on SLR. It’s certainly faster than you think as extreme heats in ocean has already passed “point of no return” plus, summer in Arctic already reached 38°C last year. Even more terrifying is that the Thwaites Glacier Ice Shelf could shatter in 5 years and accelerate SLR. Further warming only means that more systems will reach their limits as discussed in the next point.

4. We must avoid to trigger further tipping points that will cause disastrous impacts

There certainly are some “large-scale singular events” that we must avoid triggering at all cost, as they would cause “abrupt, drastic, and sometimes irreversible changes in physical, ecological, or social systems”. The consequences will be too great for us to adapt and survive.

Must avoid triggering some events as the consequences will too great for us to survive…

These events include the change of cryosphere, slowdown of Atlantic Ocean current, El-Nino Southern Oscillation as a global mode of climate variability, and the role of the Southern Ocean in the global carbon cycle. At current warming level, these events are at “moderate risk” but will be transitioning to “high risk” at 1.5°C-2°C.

Indeed, a report released by cryosphere scientists after the COP26 meeting has already warned that “we cannot negotiate with the melting point of ice” and must remain close to 1.5°C because most of the permanent changes such as irreversible melt of mountain glaciers would be triggered even by 2°C. To know more about the ice tipping points and the state of the cryosphere, click here. Below are some of the key highlights from the cryosphere report.

  • Once 2°C is passed, the Himalayas, which are the water towers of Asia that provide water supplies for 1 in 2 Asians,  may halve or shrink to a third of its current size by 2300.
  • At 3°C, the Atlantic Ocean current will shut down and cause “severe and unpredictable disturbances to global weather pattern”.
  • Our current emissions path to 4°C-5°C will drive us to “cryosphere collapse” causing extreme losses and significant damages for many generations. West Antarctic Ice Sheet will collapse with 2m of sea level rise possible by 2100 and 5m by 2150. Our oceans will become extremely corrosive and cause a mass extinction of marine species such as wild cod, herring and salmon, which will negatively impact our food security…more on this in point 7.

Some tipping points already triggered – can only be slowed down & to prevent other worse impacts if we decarbonise fast enough…

To be clear, some of the above impacts such as the melt of mountain glaciers and polar ice sheets are already happening. Further deteriorating impacts can only be slowed down and prevented (e.g. shutdown of Atlantic Ocean current and ice sheet collapse) if we decarbonise deeply and rapidly. Even temporarily overshooting 1.5°C is not an option, as explained in the next point.


5. Cannot overshoot 1.5C – the impacts are even worse with every incremental degree

The AR6 WG2 has made it clear that we must keep global warming below 1.5°C as every degree counts. Already we may not be able to adapt to some of the changes that have already happened, but with every incremental degree, the impacts will be worse.

“If global warming transiently exceeds 1.5°C in the coming decades or later (overshoot) human and natural systems will face additional severe risks, compared to remaining below 1.5°C. Depending on the magnitude and duration of overshoot, some impacts will cause the release of additional

IPCC AR6 WG2, 2022

No matter what we do, there’s a >50% chance to reach 1.5°C before 2040 & cause irreversible impacts e.g. ice melts & sea level rise…


…& become worse with every incremental degree

Unfortunately, the IPCC also says that no matter what we do, there’s a greater than 50% chance that we will reach 1.5°C before 2040. Overshooting 1.5°C will also result in “irreversible impacts on certain ecosystems with low resilience, such as polar, mountain, and coastal ecosystems, impacted by ice-sheet, glacier melt, or by accelerating and higher committed sea level rise”, which will bring increased risks to infrastructure, low-lying coastal settlements, and some ecosystem-based adaptation measures. If we breach 1.5°C, “limited freshwater resources pose potential hard limits for Small Islands and for regions dependent on glacier and snow-melt”.

The report also says with high confidence that “risk of severe impacts increase with every additional increment of global warming during overshoot”, such as wildfires, tree mortality, drying of peatlands, and permafrost thaw. Also, it would weaken natural land carbon sinks and results in releasing more greenhouse gases that further amplify global warming.

Below are some of the reasons why we should stay below 1.5°C to reduce further water-related risks:

  • Flood damages: Projected increases in direct flood damages are higher by 1.4-2x at 2°C and 2.5-3.9x at 3°C compared to 1.5°C global warming without adaptation; and
  • Agricultural drought: Over large areas of northern South America, the Mediterranean, western China and high latitudes in North America and Eurasia, extreme agricultural drought are projected to be at least 2x as likely at 1.5C; 150%-200% more likely at 2C; and >200% at 4°C. Due to the combined effects of water and temperature changes, risks to agricultural yields could be 3x higher at 3°C compared to 2°C

If we don’t act now and act fast, the window of opportunity to build climate resilience will be closed; it’s closing fast. Sadly, it’s getting more and more challenging as global strategies in decarbonisation are still lagging behind yet, the clock is clicking…

6. Window of opportunity to build resilience closing fast, yet current pledges to cut emissions lag…

There is a rapidly narrowing window of opportunity to enable climate resilient development and it is more urgent than previously thought, the report warns. If current carbon emissions do not rapidly decline and we overshoot 1.5°C in the near future, options for climate resilient development are “progressively constrained by every increment of warming”.

Our current policies & actions pathway will get us to 2.7C, far exceeding the 1.5C Paris target

There is still a long way to go because the COP26 climate pledges still fall short of the 1.5°C target. Even the most “optimistic scenario” will keep the end-of-century warming to 1.8°C (range: 1.5°C-2.4°C). And this “optimistic scenario” is only achievable only IF all the net zero targets are fully implemented. Our 2030 targets could still lead to 2.4°C of warming by 2100; but if we don’t stick to our targets, the world could head to 2.7°C on our current policies and actions pathway, which would be disastrous to both nature and people, as highlighted in previous points above.

According to the UN Emissions Gap Report 2021, to stay within 1.5°C, global CO2 emissions must reach net zero around 2050 with global GHGs reaching net zero 15-20 years later. A delay of 15-20 years in either net zero CO2 or net zero GHGs will drive us to 2°C rather than 1.5°C.

This means that we must cut all GHGs – it’s not just CO2 from coal, but we must also end methane from oil and gas. Globally, the oil and gas sector is responsible for 32% of human-caused methane and methane is responsible for 0.5°C of warming. Sadly, while the world is relying on the G20 to lead the pathway to achieve the 1.5°C goal but they are still dominating and subsidising fossil fuels production. Don’t believe us? See for yourself here.

By the way, the world’s richest 10% were also responsible for nearly half of global emissions against 7% produced by the poorest half. Clearly reducing the carbon footprint of the richest may be the fastest way to net zero?

Atmospheric methane is growing ‘dangerously fast’ – worrying new feedback loop

There are also other sources of methane such as livestock, agricultural waste, and landfill, which accounted for about 62% of total methane emissions from 2007 to 2016, including those from fossil-fuel extraction. A recent study showed that atmospheric methane is growing “dangerously fast”, tripling the levels of the pre-industrial period and we could be in a new methane feedback loop because of wetland.

Sure, the global outlook for carbon emissions is not promising, but we still have time and transformational changes must start right away. The possibility of a prolonged war in Europe certainly is not helping this. Not only it will lower the chances of near-term actions that would deliver 1.5°C andsubstantially reduce projected losses and damagescompared to higher warming levels, it would also disrupt the food security that is already threatened by climate change.

7. Impacts are all interlinked: water-food-energy

Water, food and energy are the most basic resources that support our daily lives. They are strongly interlinked. Agriculture is the largest user of water especially in Asia; while power needs water to generate and water needs power to be cleaned and delivered from source to tap. This is why the AR6 WG2 discussed the climate impacts on each of these sectors extensively as losing one of the links will jeopardise the whole system that supports our lives.

As discussed and obvious in previous points, water is the most vulnerable resource to climate change. The report found that climate change’s impacts on water availability such as increased drought events combined with limited access to irrigation are constraining agricultural production. Globally, droughts caused yield reduction in about three-quarters of harvested areas (~454mn hectares), with production losses corresponding to US$66bn between 1983 and 2009.

Under a high emission scenario, we will lose 10%-30% of global crop & livestock areas by 2050 & 2100, respectively…

… & extremely hot days will up to 250 workdays/year by 2100

The report also warns that extreme weather eventswill make some current food production areas unsuitable”. Under a high emission scenario, we will lose 10%-30% of global crop and livestock areas by 2050 and 2100, respectively. Though these impacts will be reduced to 8% under low emission scenario.

Meanwhile, outdoor workers and animals are severely exposed to heat stress which further reduces labour capacity, animal health, and dairy and meat production. The number of days with heat extremes will increase up to 250 workdays/year by 2100 in under high emission scenario. In addition to the threat of agricultural production on land, climate change will also significantly alter aquatic food provisioning services and water security with regional variances” due to ocean warming, acidification, declining oxygen levels, loss of habitat, and SLR.

Power is also thirsty for water. Climate impacts on water availability are limiting thermal power and hydropower generation. The report says droughts jeopardised thermoelectric and hydropower production with a 4%-5% reduction in plant utilisation rate during drought years since the 1980s.

Some parts of Europe could see hydropower reduction by 40% at 3C…

Going forward, climate impacts on water availability will be a huge challenge for the transition to renewable energy like hydropower. Some parts of Europe such as the Mediterranean could see the potential for hydropower reduction by 40% at 3°C, compared to 10% at 2°C and 5% at 1.5°C. At the same time, we will also get a double whammy when hotter summer increases energy demand and there’s not enough water.

Therefore, we need to adapt as well as start planning holistically to balance and control water use between agriculture and power generation to ensure food and energy security. Otherwise, water scarcity willincrease the risk of planned infrastructure projects, such as hydropower in some regions, having reduced productivity for food and energy sectors including across countries that share river basins”. To know more about the nexus between water-food-energy, please see our big picture.

8. An atlas of human suffering

The report also details the adverse impacts on livelihoods and social issues in its chapter 7 & 8 – including public health, conflicts, and migrations. It’s not just hotter, our world is also getting sicker, hungrier, more miserable and more dangerous to live in.

The report says in either high or very high confidence that climate change is increasing a range of diseases such as food-, water-, and vector-borne diseases. Greater evidence has also emerged of the detrimental impacts of climate change on mental health such as anxiety, depression and acute stress. Hot extremes not only have aggravated air pollution but also limits the functioning of key infrastructure including transportation, water, sanitation and energy system with “resulting in economic losses, disruptions of services and impacts to wellbeing”. Climate impacts on food insecurity can also lead to malnutrition and disease susceptibility in low- and middle-income countries.

Water scarcity & inadequate WASH have aggravated the COVID-19

In addition, the report also highlights that water insecurity and inadequate WASH have aggravated the COVID-19 pandemic and compound vulnerabilities and inequities. On the other hand, the COVID-19 pandemic is also a compounding risk factor to climate risks as it constrained evacuation plans due to social distancing.

For every degree of warming, the global risk of involuntary displacement due to flooding will increase by 50%

Climate change is also causing “humanitarian crises where climate hazards interact with high vulnerability” and “increasingly driving displacement in all regions, with small islands states “disproportionately affected”. Since 2008, an average of more than 20mn people have been internally displaced annually by weather-related events with storms and floods the most common drivers. For every degree of warming, the global risk of involuntary displacement due to flooding will increase by 50%.

The report also suggests climate extremes affect violent conflict due to reduced food and water security, loss of income and livelihoods. These conflicts are also associated with increased violence against women, girls and vulnerable groups.

~1/2 of the global population lives in areas highly vulnerable to climate change

Today, already nearly half of the global population between 3.3 and 3.6 billion people lives in areas highly vulnerable to climate change. Countries that don’t manage their resources well will suffer even more.


Adapt or die – transformational changes must start now

It’s clear that climate change has changed the world we are living with more complex and compound extreme events. Some damages are already irreversible no matter what we do or how much we adapt and we are slowly losing the resources supporting our basic needs.

Yet, most of our efforts to tackle climate change are not enough as they are either “fragmented” or “small in scale”. We need a transformational change and must start immediately if we want to be able to survive in the future. Check out the 8 things you must know on how to build a resilience roadmap here.

As an individual, we still can help to slow climate change and cut carbon emissions with only small changes to our lifestyles. Don’t know how? Check out our new report “Together We Can: 8 Habit changes for below 2°C”.

Further Reading

  • Code Red: 8 things you need to know about water in IPCC AR6 IPCC AR6 is a code red for water too! CWR’s Debra Tan shares 8 things you may have missed on water and urges to delay no more
  • Where Are We On Ice Tipping Points Post COP26? – If we are not careful, we could change weather as we know it – what are these tipping points? How high will seas rise? What will happen to mountain glaciers? See our review of the report State of Cryosphere 2021 for answers
  • Risks Rising: 5 Reports You May Have Missed – Water & climate risks are rising and it’s not just us saying it. CWR’s Dawn McGregor sums up key findings from 5 reports on rising risks released in the last four months from the World Economic Forum to the Hong Kong Monetary Authority
  • 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
  • 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
  • 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

Chien Tat Low
Author: Chien Tat Low
Low has extensive inter-disciplinary research experience, which although wide-ranging, focuses on identifying hotspots to facilitate better planning. At CWR, Low uses spatial modelling and statistical analysis as well as remote sensing, cartography, and geo-statistics to map and assess water risks. In addition, he helps manage CWR’s extensive network of contributors and partners. CWR is Low’s first foray outside academia and he hopes to apply his 12 years of scientific know-how toward enhancing the understanding of water risk in Asia, including spatial temporal variabilities of anthropogenic and natural factors on water resources. Previously, Low was a postdoctoral fellow at the University of Hong Kong where he devised methodologies to measure and benchmark the quality of urban life in an Asian context. As a certified GIS Professional, he also taught GIS and spatial analysis modules there. Low’s research on urban, human and environmental health is published in 11 prominent international peer-reviewed journals; he has also written a chapter in a book on managing environmental hazards. His PhD thesis on place effect on human well-being was prize-winning. Low is currently the reviewer editor for the journal “Frontiers in Environmental Informatics” and also reviews other international journals such as “Applied Geography”.
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