climate – Page 2 – Cabot Institute for the Environment blog

Arctic Ocean could be ice-free in summer by 2030s, say scientists – this would have global, damaging and dangerous consequences

Posted on June 8, 2023 by amanda.woodman-hardy

Ice in the Chukchi Sea, north of Alaska and Siberia.
NASA Goddard Space Flight Center

The Arctic Ocean could be ice-free in summer by the 2030s, even if we do a good job of reducing emissions between now and then. That’s the worrying conclusion of a new study in Nature Communications.

Predictions of an ice-free Arctic Ocean have a long and complicated history, and the 2030s is sooner than most scientists had thought possible (though it is later than some had wrongly forecast). What we know for sure is the disappearance of sea ice at the top of the world would not only be an emblematic sign of climate breakdown, but it would have global, damaging and dangerous consequences.

The Arctic has been experiencing climate heating faster than any other part of the planet. As it is at the frontline of climate change, the eyes of many scientists and local indigenous people have been on the sea ice that covers much of the Arctic Ocean in winter. This thin film of frozen seawater expands and contracts with the seasons, reaching a minimum area in September each year.

Animation of Arctic sea ice from space — Arctic sea ice grows until March and then shrinks until September.
NASA

The ice which remains at the end of summer is called multiyear sea ice and is considerably thicker than its seasonal counterpart. It acts as barrier to the transfer of both moisture and heat between the ocean and atmosphere. Over the past 40 years this multiyear sea ice has shrunk from around 7 million sq km to 4 million. That is a loss equivalent to roughly the size of India or 12 UKs. In other words, it’s a big signal, one of the most stark and dramatic signs of fundamental change to the climate system anywhere in the world.

As a consequence, there has been considerable effort invested in determining when the Arctic Ocean might first become ice-free in summer, sometimes called a “blue ocean event” and defined as when the sea ice area drops below 1 million sq kms. This threshold is used mainly because older, thicker ice along parts of Canada and northern Greenland is expected to remain long after the rest of the Arctic Ocean is ice-free. We can’t put an exact date on the last blue ocean event, but one in the near future would likely mean open water at the North Pole for the first time in thousands of years.

Annotated map of Arctic — The thickest ice (highlighted in pink) is likely to remain even if the North Pole is ice-free.
NERC Center for Polar Observation and Modelling, CC BY-SA

One problem with predicting when this might occur is that sea ice is notoriously difficult to model because it is influenced by both atmospheric and oceanic circulation as well as the flow of heat between these two parts of the climate system. That means that the climate models – powerful computer programs used to simulate the environment – need to get all of these components right to be able to accurately predict changes in sea ice extent.

Melting faster than models predicted

Back in the 2000s, an assessment of early generations of climate models found they generally underpredicted the loss of sea ice when compared to satellite data showing what actually happened. The models predicted a loss of about 2.5% per decade, while the observations were closer to 8%.

The next generation of models did better but were still not matching observations which, at that time were suggesting a blue ocean event would happen by mid-century. Indeed, the latest IPCC climate science report, published in 2021, reaches a similar conclusion about the timing of an ice-free Arctic Ocean.

As a consequence of the problems with the climate models, some scientists have attempted to extrapolate the observational record resulting in the controversial and, ultimately, incorrect assertion that this would happen during the mid 2010s. This did not help the credibility of the scientific community and its ability to make reliable projections.

Ice-free by 2030?

The scientists behind the latest study have taken a different approach by, in effect, calibrating the models with the observations and then using this calibrated solution to project sea ice decline. This makes a lot of sense, because it reduces the effect of small biases in the climate models that can in turn bias the sea ice projections. They call these “observationally constrained” projections and find that the Arctic could become ice-free in summer as early as 2030, even if we do a good job of reducing emissions between now and then.

Walruses on ice floe — Walruses depend on sea ice. As it melts, they’re being forced onto land.
outdoorsman / shutterstock

There is still plenty of uncertainty around the exact date – about 20 years or so – because of natural chaotic fluctuations in the climate system. But compared to previous research, the new study still brings forward the most likely timing of a blue ocean event by about a decade.

Why this matters

You might be asking the question: so what? Other than some polar bears not being able to hunt in the same way, why does it matter? Perhaps there are even benefits as the previous US secretary of state, Mike Pompeo, once declared – it means ships from Asia can potentially save around 3,000 miles of journey to European ports in summer at least.

But Arctic sea ice is an important component of the climate system. As it dramatically reduces the amount of sunlight absorbed by the ocean, removing this ice is predicted to further accelerate warming, through a process known as a positive feedback. This, in turn, will make the Greenland ice sheet melt faster, which is already a major contributor to sea level rise.

The loss of sea ice in summer would also mean changes in atmospheric circulation and storm tracks, and fundamental shifts in ocean biological activity. These are just some of the highly undesirable consequences and it is fair to say that the disadvantages will far outweigh the slender benefits.

This blog is written by Cabot Institute for the Environment member Jonathan Bamber, Professor of Physical Geography, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Intense downpours in the UK will increase due to climate change – new study

Posted on March 8, 2023March 8, 2023 by amanda.woodman-hardy

A flash flood in London in October 2019.
D MacDonald/Shutterstock

Elizabeth Kendon, University of Bristol

In July 2021, Kew in London experienced a month’s rain in just three hours. Across the city, tube lines were suspended and stations closed as London experienced its wettest day in decades and flash floods broke out. Just under two weeks later, it happened again: intense downpours led to widespread disruption, including the flooding of two London hospitals.

Colleagues and I have created a new set of 100-year climate projections to more accurately assess the likelihood of heavy rain downpours like these over the coming years and decades. The short answer is climate change means these extreme downpours will happen more often in the UK – and be even more intense.

To generate these projections, we used the Met Office operational weather forecast model, but run on long climate timescales. This provided very detailed climate projections – for every 2.2km grid box over the UK, for every hour, for 100 years from 1981 to 2080. These are much more detailed than traditional climate projections and needed to be run as a series of 20-year simulations that were then stitched together. Even on the Met Office supercomputer, these still took about six months to run.

We ran 12 such 100-year projections. We are not interested in the weather on a given day but rather how the occurrence of local weather extremes varies year by year. By starting the model runs in the past, it is also possible to verify the output against observations to assess the model’s performance.

At this level of detail – the “k-scale” – it is possible to more accurately assess how the most extreme downpours will change. This is because k-scale simulations better represent the small-scale atmospheric processes, such as convection, that can lead to destructive flash flooding.

The fire service attending to a vehicle stuck in floodwater. — Flash flooding can be destructive.
Ceri Breeze/Shutterstock

More emissions, more rain

Our results are now published in Nature Communications. We found that under a high emissions scenario downpours in the UK exceeding 20mm per hour could be four times as frequent by the year 2080 compared with the 1980s. This level of rainfall can potentially produce serious damage through flash flooding, with thresholds like 20mm/hr used by planners to estimate the risk of flooding when water overwhelms the usual drainage channels. Previous less detailed climate models project a much lower increase of around two and a half times over the same period.

We note that these changes are assuming that greenhouse gas emissions continue to rise at current rates. This is therefore a plausible but upper estimate. If global carbon emissions follow a lower emissions scenario, extreme rain will still increase in the UK – though at a slower rate. However, the changes are not inevitable, and if we emit less carbon in the coming decades, extreme downpours will be less frequent.

The increases are significantly greater in certain regions. For example, extreme rainfall in north-west Scotland could be almost ten times more common, while it’s closer to three times more frequent in the south of the UK. The greater future increases in the number of extreme rainfall events in the higher resolution model compared with more traditional lower resolution climate models shows the importance of having k-scale projections to enable society to adapt to climate change.

As the atmosphere warms, it can hold more moisture, at a rate of 7% more moisture for every degree of warming. On a simple level, this explains why in many regions of the world projections show an increase in precipitation as a consequence of human-induced climate change. This new study has shown that, in the UK, the intensity of downpours could increase by about 5% in the south and up to about 15% in the north for every degree of regional warming.

Group of girls with an umbrella walking through a city. — The projected increase in the intensity of rainfall is significantly greater in certain regions.
NotarYES/Shutterstock

However, it is far from a simple picture of more extreme events, decade by decade, as a steadily increasing trend. Instead, we expect periods of rapid change – with records being broken, some by a considerable margin – and periods when there is a pause, with no new records set.

This is simply a reflection of the complex interplay between natural variability and the underlying climate change signal. An analogy for this is waves coming up a beach on an incoming tide. The tide is the long-term rising trend, but there are periods when there are larger waves, followed by lulls.

Despite the underlying trend, the time between record-breaking events at the local scale can be surprisingly long – even several decades.

Our research marks the first time that such a high-resolution data set has spanned over a century. As well as being a valuable asset for planners and policymakers to prepare for the future, it can also be used by climate attribution scientists to examine current extreme rainfall events to see how much more likely they will have been because of human greenhouse gas emissions. The research highlights the importance of meeting carbon emissions targets and also planning for increasingly prevalent extreme rainfall events, which to varying degrees of intensity, look highly likely in all greenhouse gas emissions scenarios.

The tendency for extreme years to cluster poses challenges for communities trying to adapt to intense downpours and risks infrastructure being unprepared, since climate information based on several decades of past observations may not be representative of the following decades.

This blog is written by Cabot Institute for the Environment member Elizabeth Kendon, Professor of Climate Science, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Towards urban climate resilience: learning from Lusaka

Posted on November 29, 2022March 29, 2023 by janet.crompton

“This is a long shot!”

These were the words used by Richard Jones (Science Fellow, Met Office) in August 2021 when he asked if I would consider leading a NERC proposal for a rapid six-month collaborative international research and scoping project, aligned to the COP26 Adaptation and Resilience theme. The deadline was incredibly tight but the opportunity was too good to pass up – we set to work!

Background to Lusaka and FRACTAL

Zambia’s capital city, Lusaka, is one of Africa’s fastest growing cities, with around 100,000 people in the early 1960s to more than 3 million people today. 70% of residents live in informal settlements and some areas are highly prone to flooding due to the low topography and highly permeable limestone sitting on impermeable bedrock, which gets easily saturated. When coupled with poor drainage and ineffective waste management, heavy rainfall events during the wet season (November to March) can lead to severe localised flooding impacting communities and creating serious health risks, such as cholera outbreaks. Evidence from climate change studies shows that heavy rainfall events are, in general, projected to increase in intensity over the coming decades (IPCC AR6, Libanda and Ngonga 2018). Addressing flood resilience in Lusaka is therefore a priority for communities and city authorities, and it became the focus of our proposal.

Lusaka was a focal city in the Future Resilience for African CiTies and Lands (FRACTAL) project funded jointly by NERC and DFID from 2015 to 2021. Led by the Climate System Analysis Group (CSAG) at the University of Cape Town, FRACTAL helped to improve scientific knowledge about regional climate in southern Africa and advance innovative engagement processes amongst researchers, practitioners, decision-makers and communities, to enhance the resilience of southern African cities in a changing climate. I was lucky enough to contribute to FRACTAL, exploring new approaches to climate data analysis (Daron et al., 2019) and climate risk communication (Jack et al., 2020), as well as taking part in engagements in Maputo, Mozambique – another focal city. At the end of FRACTAL there was a strong desire amongst partners to sustain relationships and continue collaborative research.

I joined the University of Bristol in April 2021 with a joint position through the Met Office Academic Partnership (MOAP). Motivated by the potential to grow my network, work across disciplines, and engage with experts at Bristol in climate impacts and risk research, I was excited about the opportunities ahead. So when Richard alerted me to the NERC call, it felt like an amazing opportunity to continue the work of FRACTAL and bring colleagues at the University of Bristol into the “FRACTAL family” – an affectionate term we use for the research team, which really has become a family from many years of working together.

Advancing understanding of flood risk through participatory processes

Working closely with colleagues at Bristol, University of Zambia, University of Cape Town, Stockholm Environment Institute (SEI – Oxford), Red Cross Climate Centre, and the Met Office, we honed a concept building on an idea from Chris Jack at CSAG to take a “deep dive” into the issues of flooding in Lusaka – an issue only partly explored in FRACTAL. Having already established effective relationships amongst those involved, and with high levels of trust and buy-in from key institutions in Lusaka (e.g., Lusaka City Council, Lusaka Water Security Initiative – LuWSI), it was far easier to work together and co-design the project; indeed the project conceived wouldn’t have been possible if starting from scratch. Our aim was to advance understanding of flood risk and solutions from different perspectives, and co-explore climate resilient development pathways that address the complex issue of flood risk in Lusaka, particularly in George and Kanyama compounds (informal settlements). The proposal centred on the use of participatory processes that enable different communities (researchers, local residents, city decision makers) to share and interrogate different types of knowledge, from scientific model datasets to lived experiences of flooding in vulnerable communities.

The proposal was well received and the FRACTAL-PLUS project started in October 2021, shortly before COP26; PLUS conveys how the project built upon FRACTAL but also stands for “Participatory climate information distillation for urban flood resilience in LUSaka”. The central concept of climate information distillation refers to the process of extracting meaning from multiple sources of information, through careful and open consideration of the assumptions, strengths and limitations in constructing the information.

The “Learning Lab” approach

Following an initial evidence gathering and dialogue phase at the end of 2021, we conducted two collaborative “Learning Labs” held in Lusaka in January and March 2022. Due to Covid-19, the first Learning Lab was held as a hybrid event on 26-27 January 2022. It was facilitated by the University of Zambia team with 20 in-person attendees including city stakeholders, the local project team and Richard Jones who was able to travel at short notice. The remainder of the project team joined via Zoom. Using interactive exercises, games (a great way to promote trust and exchange of ideas), presentations, and discussions on key challenges, the Lab helped unite participants to work together. I was amazed at the way participants threw themselves into the activities with such enthusiasm – in my experience, this kind of thing never happens when first engaging with people from different institutions and backgrounds. Yet because trust and relationships were already established, there was no apparent barrier to the engagement and dialogue. The Lab helped to further articulate the complexities of addressing flood risks in the city, and showed that past efforts – including expensive infrastructure investments – had done little to reduce the risks faced by many residents.

One of the highlights of the Labs, and the project overall, was the involvement of cartoon artist Bethuel Mangena, who developed a number of cartoons to support the process and extract meaning (in effect, distilling) the complicated and sensitive issues being discussed. The cartoon below was used to illustrate the purpose of the Lab, as a meeting place for ideas and conversations drawing on different sources of information (e.g., climate data, city plans and policies) and experiences of people from flood-affected communities. All of the cartoons generated in the project, including the feature image for this blog, are available in a Flickr cartoon gallery – well worth a look!

Image: Cartoon highlighting role of Learning Labs in FRACTAL-PLUS by Bethuel Mangena

Integrating scientific and experiential knowledge of flood risk

In addition to the Labs, desk-based work was completed to support the aims of the project. This included work by colleagues in Geographical Sciences at Bristol, Tom O’Shea and Jeff Neal, to generate high-resolution flood maps for Lusaka based on historic rainfall information and for future climate scenarios. In addition, Mary Zhang, now at the University of Oxford but in the School of Policy Studies at Bristol during the project, collaborated with colleagues at SEI-Oxford and the University of Zambia to design and conduct online and in-person surveys and interviews to elicit the lived experiences of flooding from residents in George and Kanyama, as well as experiences of those managing flood risks in the city authorities. This work resulted in new information and knowledge, such as the relative perceived roles of climate change and flood management approaches in the levels of risk faced, that was further interrogated in the second Learning Lab.

Thanks to a reduction in covid risk, the second lab was able to take place entirely in person. Sadly I was unable to travel to Lusaka for the Lab, but the decision to remove the virtual element and focus on in-person interactions helped further promote active engagement amongst city decision-makers, researchers and other participants, and ultimately better achieve the goals of the Lab. Indeed the project helped us learn the limits of hybrid events. Whilst I remain a big advocate for remote technology, the project showed it can be far more productive to have solely in-person events where everyone is truly present.

The second Lab took place at the end of March 2022. In addition to Lusaka participants and members of the project team, we were also joined by the Mayor of Lusaka, Ms. Chilando Chitangala. As well as demonstrating how trusted and respected our partners in Lusaka are, the attendance of the mayor showed the commitment of the city government to addressing climate risks in Lusaka. We were extremely grateful for her time engaging in the discussions and sharing her perspectives.

During the lab the team focused on interrogating all of the evidence available, including the new understanding gained through the project from surveys, interviews, climate and flood data analysis, towards collaboratively mapping climate resilient development pathways for the city. The richness and openness in the discussions allowed progress to be made, though it remains clear that addressing flood risk in informal settlements in Lusaka is an incredibly challenging endeavour.

Photo: Participants at March 2022 Learning Lab in Lusaka

What did we achieve?

The main outcomes from the project include:

Enabling co-exploration of knowledge and information to guide city officials (including the mayor – see quote below) in developing Lusaka’s new integrated development plan.
Demonstrating that flooding will be an ongoing issue even if current drainage plans are implemented, with projections of more intense rainfall over the 21st century pointing to the need for more holistic, long-term and potentially radical solutions.
A plan to integrate flood modelling outputs into the Lusaka Water Security Initiative (LuWSI) digital flood atlas for Lusaka.
Sustaining relationships between FRACTAL partners and building new links with researchers at Bristol to enable future collaborations, including input to a new proposal in development for a multi-year follow-on to FRACTAL.
A range of outputs, including contributing to a FRACTAL “principles” paper (McClure et al., 2022) supporting future participatory projects.

It has been such a privilege to lead the FRACTAL-PLUS project. I’m extremely grateful to the FRACTAL family for trusting me to lead the project, and for the input from colleagues at Bristol – Jeff Neal, Tom O’Shea, Rachel James, Mary Zhang, and especially Lauren Brown who expertly managed the project and guided me throughout.

I really hope I can visit Lusaka in the future. The city has a special place in my heart, even if I have only been there via Zoom!

“FRACTAL-PLUS has done well to zero in on the issue of urban floods and how climate change pressures are making it worse. The people of Lusaka have continually experienced floods in various parts of the city. While the problem is widespread, the most affected people remain to be those in informal settlements such as George and Kanyama where climate change challenges interact with poor infrastructure, poor quality housing and poorly managed solid waste.” Mayor Ms. Chilando Chitangala, 29 March 2022

————————————————————————————-

This blog is written by Dr Joe Daron, Senior Research Fellow, Faculty of Science, University of Bristol;

Science Manager, International Climate Services, Met Office; and Cabot Institute for the Environment member.

Find out more about Joe’s research at https://research-information.bris.ac.uk/en/persons/joe-daron.

Are you a journalist looking for climate experts? We’ve got you covered

Posted on October 25, 2022April 16, 2023 by janet.crompton

We’ve got lots of media trained climate change experts. If you need an expert for an interview, here is a list of Caboteers you can approach. All media enquiries should be made via Victoria Tagg, our dedicated Media and PR Manager at the University of Bristol. Email victoria.tagg@bristol.ac.uk or call +44 (0)117 428 2489.

Climate change / climate emergency / climate science / climate-induced disasters

Dr Eunice Lo – expert in changes in extreme weather events such as heatwaves and cold spells, and how these changes translate to negative health outcomes including illnesses and deaths. Follow on Twitter @EuniceLoClimate.

Professor Daniela Schmidt – expert in the causes and effects of climate change on marine systems. Dani is also a Lead Author on the IPCC reports.

Dr Vikki Thompson – expert on climate extremes, particularly heat extremes. Follow on Twitter @ClimateVikki

Dr Katerina Michalides – expert in drylands, drought and desertification and helping East African rural communities to adapt to droughts and future climate change. Follow on Twitter @_kmichaelides.

Professor Dann Mitchell – expert in how climate change alters the atmospheric circulation, extreme events, and impacts on human health. Dann is also a Met Office Chair. Follow on Twitter @ClimateDann.

Professor Dan Lunt – expert on past climate change, with a focus on understanding how and why climate has changed in the past and what we can learn about the future from the past. Dan is also a Lead Author on IPCC AR6. Follow on Twitter @ClimateSamwell.

Professor Jonathan Bamber – expert on the impact of melting land ice on sea level rise (SLR) and the response of the ocean to changes in freshwater forcing. Follow on Twitter @jlbamber

Professor Paul Bates CBE – expert in the science of flooding, risk and reducing threats to life and economic losses worldwide. Follow on Twitter @paul_d_bates

Professor Tony Payne – expert in the effects of climate change on earth systems and glaciers.

Dr Matt Palmer – expert in sea level and ocean heat content research at the Met Office Hadley Centre and University of Bristol. Follow on Twitter @mpclimate.

Net Zero / Energy / Renewables

Professor Valeska Ting – Engineer and expert in net zero, low carbon technologies, low carbon energy and flying. Also an accomplished STEM communicator, is an BAME Expert Voice for the BBC Academy. Follow on Twitter @ProfValeskaTing.

Professor Philip Taylor – Expert in net zero, energy systems, energy storage, utilities, electric power distribution. Also Pro-Vice Chancellor at the University of Bristol. Follow on Twitter @rolyatlihp.

Dr Colin Nolden – expert in sustainable energy policy, regulation and business models and interactions with secondary markets such as carbon markets and other sectors such as mobility. Colin will be at COP27. Colin will be in attendance in the Blue Zone at COP27.

Professor Charl Faul – expert in novel functional materials for sustainable energy applications e.g. in CO2 capture and conversion and energy storage devices. Follow on Twitter @Charl_FJ_Faul.

Climate finance

Dr Rachel James – Expert in climate finance, damage, loss and decision making. Also has expertise in African climate systems and contemporary and future climate change. Follow on Twitter @_RachelJames. Rachel will be in attendance in the Blue Zone at COP27.

Climate justice

Dr Alix Dietzel – climate justice and climate policy expert. Focusing on the global and local scale and interested in how just the response to climate change is and how we can ensure a just transition. Alix will be at COP27. Follow on Twitter @alixdietzel. Alix will be in attendance in the Blue Zone at COP27.

Dr Ed Atkins – expert on environmental and energy policy, politics and governance and how they must be equitable and inclusive. Also interested in local politics of climate change policies and energy generation and consumption. Follow on Twitter @edatkins_.

Climate activism / Extinction Rebellion

Dr Oscar Berglund – expert on climate change activism and particularly Extinction Rebellion (XR) and the use of civil disobedience. Follow on Twitter @berglund_oscar.

Air pollution / Greenhouse gases

Dr Aoife Grant – expert in greenhouse gases and methane. Set up a monitoring station at Glasgow for COP26 to record emissions.

Professor Matt Rigby – expert on sources and sinks of greenhouse gases and ozone depleting substances. Follow on Twitter @TheOtherMRigby.

Land, nature and food

Viola Heinrich – expert in emissions and climate mitiagion potential within the land use sector in the tropics, especially the Brazilian Amazon. IPCC author. Follow on Twitter @vh_trees.

Dr Jo House – expert on land and climate interactions, including emissions of carbon dioxide from land use change (e.g. deforestation), climate mitigation potential from the land (e.g. afforestation, bioenergy), and implications of science for policy. Previously Government Office for Science’s Head of Climate Advice. Follow on Twitter @Drjohouse.

Dr Taro Takahashi – expert on farming, livestock production systems as well as progamme evaluation and general equilibrium modelling of pasture and livestock-based economies.

Dr Maria Paula Escobar-Tello – expert on tensions and intersections between livestock farming and the environment.

Climate change and infrastructure

Dr Maria Pregnolato – expert on effects of climate change and flooding on infrastructure. Follow on Twitter @MariaPregnolat1.

Plastic and the environment

Dr Charlotte Lloyd – expert on the fate of chemicals in the terrestrial environment, including plastics, bioplastics and agricultural wastes. Follow on Twitter @DrCharlLloyd.

Climate change and health

Dr Dan O’Hare – expert in climate anxiety and educational psychologist. Follow on Twitter @edpsydan.

Cabot Institute for the Environment at COP27

We will have three academics in attendance at the Blue Zone at COP27. These are:

Dr Alix Dietzel, Dr Rachel James and Dr Colin Nolden. All are media-trained and feature in the list above.

Read more about COP on our website at https://bristol.ac.uk/cabot/what-we-do/projects/cop/

Watch our Cabot Conversations – 10 conversations between 2 experts on a climate change issue, all whilst an artist listens in the background and interprets the conversation into a beautiful piece of art in real time. Find out more at bristol.ac.uk/cabot/conversations.

——————————

This blog was written by Amanda Woodman-Hardy, Communications and Engagement Officer at the Cabot Institute for the Environment. Follow on Twitter @Enviro_Mand and @cabotinstitute.

IPCC blog series: Working Group 1 – The Physical Science Basis

Posted on July 27, 2022March 29, 2023 by janet.crompton

This blog is part of a series from the Cabot Institute for the Environment on the Intergovernmental Panel on Climate Change’s recent AR6 report (IPCC, AR6), with this post covering the output of Working Group 1 and the physical scientific basis of climate change. This article also features a chat with Professor Dan Lunt, a Climate Scientist at the University of Bristol who focusses on paleoclimates and climate modelling, and a Lead Author on the IPCC’s AR6 report. For links to the rest of the series, see the bottom of the post.

The IPCC begins their 6th Assessment Report by explaining the physical science basis and publishing the finding of Working Group 1 (WG1) in August 2021. This means that, rather than considering the impact on humans, ecosystems and societies covered by later working groups, this report only looks at the effects on the planet from a physical standpoint. Consider this part of the report to be describing the problem, where later reports describe the impacts and then the possible solutions.

Here are the key points from WG1, detailing the physical science basis:

Human activity has unequivocally caused a change in the global climate.

If you were in any doubt before, let this be the sole key message you take away from this report.

Human activity has caused widespread warming of the land, ocean an atmosphere, affecting weather systems, ecosystems, and the cryosphere (areas covered by ice such as mountain glaciers and the polar regions).

One of the main drivers of this change has been Greenhouse Gases (GHGs), which have been observed to be increasing in atmospheric concentration since as far back as 1750 and the beginning. These gases, such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), come from human processes that burn fossil fuels – transport, energy production, intense cattle farming for example.

Greenhouse gases in the atmosphere act like blanket, trapping rather than heart from the sun, warming the Earth. We also know from studying past climates that the Earth will get warmer with greater atmospheric CO2 levels.

Changes to the climate are happening at an unprecedented rate.

Figure 1: Graph from AR6-WG1 showing the unprecedented levels of warming seen in the last 2000 years.

You may have heard that the Earth’s climate has naturally ebbed between periods of hot and cold. This is completely true, however it can be a misleading statement that completely undersells the issue. Human activity has caused the planet to warm at an unprecedented rate. We are currently undergoing thousands of years of warming in just a few decades (fig.1) – much to fast for adaptation from the world’s ecosystems.

As such, the Earth will take millions of years to recover and reach an equilibrium. I highly encourage you to check out climatearchive.org’s simulations of the next million years using cutting edge modelling data – created by the Cabot Institute for the Environment’s Sebastian Steinig.

Climate change is ALREADY affecting every inhabited region on Earth, with observed increases in extreme weather and climate extremes.

Many people believe that the climate crisis is far off in the future, a problem to prevent before it arrives. However, this is not the case. It’s already happening under our noses. And everywhere. Every inhabited region in the world currently experiences an increased likelihood of an extreme weather event, extreme heat drought, or extreme precipitation. This summer for example, temperatures in the UK have been modelled and subsequently measured to creep above 40°C, unprecedented for a region with a usually temperate climate and setting national records.

Increased warming leads to an increase in effect and creeps towards a tipping point from which recovery is impossible.

You might have heard phrases like “2 degree C future” or “1.5 degree C rise” in the news, but what do these really mean? These numbers refer to the global mean temperature rise using a rolling average of the previous 20 years, relative to the temperature measured between 1850-1900 when climate change started to begin. Currently, the average global temperature anomaly sits above 1 degree C of warming (fig.1).

The Earth system is remarkably robust, but not quite robust enough to maintain an equilibrium with such rapid warming in a short space of time. One place where this is most stark is the cryosphere – parts of the Earth usually covered by ice all year round (glaciers, polar regions for example).

Melting has already begun and will continue to happen for decades even if emissions magically ended tomorrow. This is incredibly troubling, since the cryosphere also happens to be huge carbon store in the form of methane trapped in the ice. This creates what’s known as a feedback loop, where the effects of warming lead to greater warming in themselves.

Through studying paleoclimates, the IPCC reports that climate sensitivity and therefore “tipping point” sits at around 3 degree C, resulting in total climate breakdown.

Significant and immediate action limiting Greenhouse Gas emissions will be a major key in fighting climate change.

The one silver lining the report alludes to is that IPCC scientists are confident that the climate crisis is caused primarily by greenhouse gas concentrations, therefore we know the solution – reducing emissions quickly and effectively will mitigate against the worst warming in a big way. Pursuing a net-zero CO2 strategy and limiting other GHG emissions will be absolutely necessary. Working Group 3’s report on the Mitigation of Climate Change goes into greater detail on how governments can work together to go about this. This will be published on 29 August 2022.

Insight from IPCC WG1 author Professor Dan Lunt

Professor Dan Lunt is a Professor of Climate Science, Cabot Institute member and a key author on the IPCC’s WGI report.

How did you get involved with IPCC AR6?

Dan Lunt

“I was involved with the previous IPCC report, AR5, providing some data and graphs for a section on polar amplification in past and future climates (the disproportionate warming of the polar regions relative to the rest of the Earth system). This time round, a call went out around four or five years ago for authors to work on the upcoming Sixth Assessment Report. I applied for and was chosen to be a Lead Author on Chapter 7 of the AR6 report – a section focussed the Earth’s radiation budget and Climate Sensitivity, as well as on paleoclimates as evidence for the patterns of global warming, such as polar amplification.”

What’s one key point you’d like to get across from the work of Working Group 1?

“For me, what I would interpret as the key message would be climate change is already happening, and it’s happening all over the globe. It’s unprecedented in terms of its magnitude and its speed of change, relative to the past tens of thousands of years. It’s unequivocally caused by human activity.”

“One of the new key points in this assessment report is that there’s a lot more evidence now that there are changes in the frequency of extreme events. We now have enough data to say that this increased frequency is human induced. So that’s more droughts, floods, extreme heat events etc.”

———————————–

We recommend taking a look at the IPCC’s full reports and report summaries for yourself if you seek to further understand the evidence and reasoning behind their headline statements.

As we’ve discussed the scientific basis for climate change, you may be wondering what the real-world impacts. The specific impacts on ecosystems, global health and on human society will be covered in greater detail in our summary of WG2’s report titled “Impacts, Adaption and Vulnerability”, publishing tomorrow (Thursday, 28th of August).

This blog was written by Cabot Communications Assistant Andy Lyford, an MScR Student studying Paleoclimates and Climate modelling on the Cabot Institute Master’s by Research in Global Environmental Challenges at the University of Bristol.

Andy Lyford

What protections are available to people displaced by climate change?

Posted on June 20, 2022April 16, 2023 by janet.crompton

Climate change will impact all our lives in the coming years and many people will experience extreme events due to climate change resulting in displacement, both internally and across international borders. This has become the reality for some already within low-lying archipelago islands within the South Pacific, such as Tuvalu and Kiribati. Despite the certainty of increased climate change-related displacement, there is still no specific frameworks which protect those moving for climate related reasons (see a detailed discussion here).

The site of the village of Tebunginako, Kiribati – relocated due to severe coastal erosion and saltwater intrusion (image: Department of Foreign Affairs and Trade, Australia)

Are people displaced by climate change refugees?

Under Article 1(A) of the 1951 Refugee Convention, climate-related displacement does not constitute grounds for international protection. I will take the essential elements of Article 1(A) in turn. First, a refugee must have crossed an international border, whereas climate-related displacement is expected to be predominantly internal.

Second, a refugee must have a well-founded fear of persecution. Persecution requires an egregious violation of human rights, which is assessed in light of the nature of the right and the severity of the violation (see here for further discussion). It also requires that the fear of persecution must be well-founded – this does not require certainty – but it must not be far-fetched and should be based upon both an objective assessment of the likelihood of persecution and the subjective nature of the individual’s fear (see Chan v Minister for Immigration and Ethnic Affairs, 1989). Climate change is unlikely to fulfil this requirement despite the detriment it can have on an individual’s access to human rights. It is unlikely to meet the severity threshold even in relation to socio-economic rights and, as McAdam (2016) highlights, it is difficult to identify a ‘persecutor’ that the refugee fears; instead, many refugees are likely to be moving to states that are major greenhouse gas contributors.

Third, persecution must be related to a reason given by the Convention of ‘race, religion, nationality, membership of a particular social group or political opinion…’ The impacts of climate change do not discriminate. Even if an individual did establish persecution based upon an egregious socio-economic rights violation caused by climate change, they would need to argue that this affected them because of their membership of one of these groups. At best, an individual could argue that a government had consciously withheld assistance to address the impacts of climate change to a specific group, amounting to persecution (see here) but the group must be connected by an immutable characteristic (Applicant A v Minister for Immigration and Ethnic Affairs, 1997), not just the impact of the climate change.

Courts have firmly established that the Refugee Convention does not protect victims of natural disasters, slow-onset degradation, poor economic conditions or famine – even when the country of origin is unable or unwilling to provide protection (Canada (Attorney General) v Ward, 1993; Horvath v Secretary of State for the Home Department, 2001). UNHCR has echoed this in its own discussions of how to respond to climate-related displacement (see here and here).

What protections are available to people displaced by climate change?

A response to climate-change related displacement must therefore be sought through other international legal mechanisms. In 2009, the UN Human Rights Council recognised under resolution 10/4 that there is a ‘core inter-linkage between human rights and climate change’ such that those displaced by climate change would be able to rely on the obligations outlined in the ICCPR and the ICESCR. In particular, this would include state’s non-refoulment obligations as the cumulative effect of socio-economic harms can amount to inhumane and degrading treatment such that an individual cannot be returned to such conditions (see Sufi v Elmi, 2011). However, courts may require an immediacy to the rights violation such that future fear of climate-related impacts is insufficient grounds to provide protection from return (see AF(Kiribati), 2013).

In the specific situation of small island states whose territory is threatened by climate change, the law relating to statelessness may also be able to provide some protection and a remedy (see the 1954 Statelessness Convention; Rayfuse 2009). UNHCR has a mandate to prevent and reduce statelessness enabling them to work with states to respond, including coordinating international cooperation, providing protection and resettlement. However, issues concerning when a state will have ceased to exist under international law remains unsettled. For example, for a state to be recognised by international law, Article 1 of the Montevideo Convention requires a permanent population, territory, government and capacity to enter international relations (see Lauterpacht, 1944, and Crawford, 2007, for further discussion). However, there is a lack of clarity on when these criteria will cease to be fulfilled. The problem that international law has grappled with until now has been when new states are formed, not when existing ones have disappeared. As a result, it is unclear when protection for stateless persons of ‘disappeared’ states will be triggered.

There are also regional frameworks that provide broader protections to displaced people, beyond the narrow 1951 definition. In particular, the 1969 OAU Convention Governing the Specific Aspects of Refugee Problems and the 1984 Cartagena Declaration both contain provisions relating to ‘events seriously disturbing public order’, which could be taken to include the events resulting from the effects of climate change. These are both non-binding instruments, whereas Article 5(4) of the Kampala Convention is within a binding instrument and explicitly includes protection for those affected by climate change:

States parties shall take measures to protect and assist persons who have been internally displaced due to natural or human made disasters, including climate change.

This focusses protection on internally displaced individuals and ensures that signatory states are required to provides protection and assist those displaced by climate change.

The Kampala Convention is largely based upon the UN Guiding Principles on internal displacement which, under Principle 6(d), outlines that internal displacement is prohibited including in the context of disasters. The principles then provide a framework for states to respond to internal displacement, including that resulting from disasters. The extension of human rights protections to those fleeing climate change is echoed in the Global Compact on Migration, which calls for humanitarian visas for people migrating due to natural disasters and climate change (see objective 2 and 5), as well as similar commitments in the Sustainable Development Goals. Such a response to climate-change related displacement is required under the commitments of Article 14(f) of the Cancun Adaptation of the United Nations Framework Convention on Climate Change (UNFCCC). This aims to enhance understanding, coordination and cooperation with regard to climate change induced displacement…’ These instruments represent moves by the international community to consolidate existing legal frameworks to respond to climate-change related displacement. However, they are not binding treaty law. They demonstrate political commitments not legal obligations. It is evident that, outside the Africa region, mechanisms for protecting individuals from climate-change related displacement are often non-binding and ad-hoc.

The future of climate-related displacement

The term ‘climate refugee’ is conceptually flawed. Such individuals will not constitute refugees for the term ignores the complex causation involved in any displacement, let alone that related to climate change, which in itself is a multi-causal phenomenon. Whilst human rights law, the law relating to statelessness and regional arrangements do provide for some protections to individuals displaced by climate change, these approaches remain disparate and uncoordinated. A lack of clarity can lead to legal loopholes that are abused by states to limit protections.

To respond to this complexity, there are calls for a separate framework for cross-border climate migrants. Commitments within the Global Compact on Migration and the Sustainable Development Goals, as well as the Cancun Agreement, represent attempts by the international community to start to coordinate and elucidate protection for climate-related displacement. However, much more must be done to ensure clarity on the personal, material and temporal scope of protections and obligations for climate change-related displacement.

—————————–

This blog is written by Dr Kathryn Allinson, a Lecturer in Law, University of Bristol Law School. Her research concerns the establishment of state responsibility for breaches of international law focussing on the interaction of human rights and humanitarian law in relation to displacement, and the protection of socio-economic human rights during conflict.

Kathryn Allinson

A previous MMB blog by Ignacio Odriozola looked at a landmark decision by the United Nations Human Rights Committee on people seeking international protection due to the effects of climate change: Climate-change displacement: a step closer to human rights protection.

Stockholm+50: No way to have a conversation about climate change

Posted on June 13, 2022April 16, 2023 by janet.crompton

I’m just back from Stockholm+50, the summit convened to mark 50 years since the first UN conference on ‘the human environment’ that led to the founding of the UN Environment Programme. Could the participants then have imagined that half a century later we would be living through mass extinctions and still be trying to work out how to stop (some) humans creating a hothouse world?

Perhaps they would, if they’d seen what these conferences have become. While ‘jaw jaw’ remains better than ‘war war’, there is no doubt that these climate conferences have become a parody performance of international negotiations. Children sang and presented flowers; the UN Secretary General Antonio Gutierrez restated the ‘code red’ call he’s been making for a while now; John Kerry stated publicly that world leaders were on a ‘collective suicide mission’, which, given that he’s the United States Ambassador on Climate Change, should have made more headlines, but was instead greeted with a collective ‘meh’. ‘Interactive’ dialogue sessions promised to open up the agenda, but invited only pre-selected agencies all of whom said, again, what they’d been saying for years.

This is no way to have a conversation.

Over two days, ministers and civil servants from every UN country and associated organisations make five minute speeches on the main stage designed to appeal to the media back home rather than make any breakthroughs in the room. There are the usual obligatory selfie walls and hordes of professional sustainability experts in suits taking advantage of them to burnish their green international network credentials. Civil society groups have to fight discriminatory visa systems and lack of funds to even get to the summit, only to find out that there is no access to the processes by which the summit decisions and texts are being made. The youth delegations express their now familiar (and understandable) frustration with the older generation and demand of tired, under-funded UN representatives that they ‘use their privilege’ and power to make the changes needed. It resembles nothing so much as a pyramid selling scheme, with everyone fighting to get closer and closer to a centre of power which, in the end, turns out to be illusory.

As an outsider, watching this process in Stockholm, just as I watched COP last year in Glasgow, was like watching an old world dying. You could see old institutions struggle and fail to deal with state capture by fossil fuel interests, observe exponential natural changes meet incremental policy negotiations, feel the chaotic speed of ecosystem transformations meet lock-in and predatory delay of social systems.

And yet, where there is death there is also, always, life.

All around the official event were people using the summit as an excuse to gather, as a way of using the old systems to create something new. A new generation of policy actors, youth movements, academics, unions and civil society, energised by lessons learned from COP26, gathered in informal associated events and activities. This is where the energy was, where dialogue was taking place, where people were learning from each other and naming the obstacles that needed to be overcome.

You could feel the energy in the work of the Fossil Fuel Non Proliferation Treaty movement which is creating serious alliances across countries and interests and is beginning to exert enough pressure to get commitments to fossil fuel phase-out on the formal agenda; you could see it in the brilliant legal escapades of the ‘Stop Ecocide’ movement making the case for the rights of nature and getting faith leaders around the world signed up to protecting nature. And more than energy, you could see serious, feasible new ideas emerging in the hard economic thinking mobilised by the Stockholm Resilience Centre in their new Earth4all report, which outlines concrete steps towards non-ecocidal and non-suicidal economic arrangements; and in the principled and practical work of the Rainforest Coalition demonstrating what real carbon capture actually looks like and tracing routes towards sustaining it.

What characterises many of these activities is a commitment to a different sort of conversation – to processes of unlearning, of listening, of deep attention to others in the room, of naming the hard problems and working together on them. They point the way to a new sort of conversation – one from which the organisers of future UN conferences might learn. And one which we can all begin to model and practice in each country, network or community that we are part of back home.

————————————-

This blog is written by Cabot Institute for the Environment member Keri Facer, Professor of Social and Educational Futures at the University of Bristol.

Hydrological hazards across timescales

Posted on June 6, 2022March 29, 2023 by janet.crompton

University of Bristol – Met Office Academic Partnership Meeting

From droughts and floods to water quality and water resource management, researchers at the University of Bristol and the Met Office are world-leaders in climate and hydrological research. Building on the new academic partnership between Bristol and the Met Office, the goal of this meeting was to foster new collaborations and strengthen existing partnerships between Bristol and the Met Office on the topic of weather, climate and hydrology.

In total, we had 29 attendees attend the workshop, with 10 from the Met Office, 17 from the University of Bristol and 2 from Fathom including weather and climate scientists, catchment hydrologists and flood modellers at a wide range of career stages.

The meeting explored two key themes, the first half of the meeting focused on ‘Exploiting convection permitting weather and climate models for flood and drought prediction’, while the second half focused on ‘Quantifying uncertainty in hydrological projections’. For each theme, there were two short plenary talks that highlighted existing research across the Met Office and University of Bristol and then a presentation focused on an exciting piece of research covering topics on exploiting convection permitting models for flood and drought prediction (Lizzie Kendon) and towards large ensembles of km-scale precipitation simulations using AI (Peter Watson and Henry Addison). We also had eight lighting talks on topics ranging from tropical cyclones to pan-tropics convection-permitting climate simulations to compound wind and flood risk.

Alongside the talks, there was time for attendees to discuss ideas and opportunities focused around five key discussion topics; uncertainty estimation, compound events and multi-hazard coupling, evaluation of weather and climate driving information for hydrology, exploiting higher resolution capabilities for hydrology and from hydrological predictions to ‘services’.

Overall, the meeting was a success and we appreciated an in person meeting fuelled by coffee, cake and cheese! Tangible outputs from the day included contributions on a NERC proposal, making new connections, ideas for future collaborations, sharing of data and methodologies and the foundations for a collaborative climate and hydrology community.

Further details from the meeting can be requested from Gemma Coxon (gemma.coxon@bristol.ac.uk).

Mock COP26: Convincing, Cooperating and Collaborating

Posted on May 26, 2022April 16, 2023 by janet.crompton

Glasgow COP26 presentation, preliminary discussion, and negotiation rounds 1 & 2

On 11th November at 10am around 60 A-level students from schools across Bristol gathered to participate in this year’s Mock COP26, hosted by Jack Nicholls, Emilia Melville, and Camille Straatman from the Cabot Institute for the Environment. After a resounding success from the first Mock COP, which took place online in March 2021, there was real excitement and anticipation building for the in-person event which would be held in the Great Hall of the Wills Memorial Building.

The morning kicked off with an engaging presentation by Jack, Emilia, and Camille, outlining the objectives of the upcoming COP26 in Glasgow. There had been much discussion surrounding the COP in the public sphere in the prior weeks, so it was interesting to see a summary of where things stand in the time since the Paris Agreement and what the potential outcomes of this COP may be.

The negotiations began with preliminary intra-group discussions, facilitated by a group of 12 postgraduate students. Each group defined their stance on each of the COP resolutions, ranging from option A, the most radical response, to C, the most conservative. It was evident from the off that these students were highly knowledgeable and passionate about the environmental, sociological, and economic impacts of each resolution, and as a result, each group wasted no time in prioritising the resolutions that would benefit their actor the most. Brazil factored in its current economic and development situation, as well as the Amazon’s critical role in the ecosystem balance, choosing to prioritise climate finance, natural protection and conservation and protecting climate refugees. For the International Indigenous Peoples Forum on Climate Change (IIFPCC), giving protected status to 50% of Earth’s natural areas by 2050 was defined as the most important resolution, whereas Shell chose to focus on phasing out coal, with the understanding that this would take the onus off the oil industry. Each group presented their ideal resolutions in a clear and concise manner.

The atmosphere really started to build in the hall when the first round of negotiations began. China faced Greenpeace in a heated discussion on coal usage while the IIFPCC negotiated with the USA on protecting indigenous populations. The United Nations High Commissioner for Refugees found alignment with Brazil on many of the resolutions, namely achieving net-zero emissions by 2050, natural protection and conservation to 30% of Earth’s natural areas and protecting climate refugees. In round two of negotiations, we saw Shell and the International Monetary Fund categorically disagree on the timeline for transition to Zero Emissions Vehicles, eventually compromising on a B resolution to have all new vehicle sales as zero-emission by 2040. Brazil was happy in supporting the IIPFCC in resolution 7a. (All countries must allow people fleeing from natural disasters, environmental degradation, and sea level rise to enter their countries and make their new homes there). Brazil and IIPFCC made an alliance to encourage USA toward resolution 7a, instead of their preferred 7b (Countries at risk of extinction from sea level rise should be provided with new land to settle and move their people to OR be provided with financial help to buy land in other nations). China and the Alliance of Small Island States (AOSIS) clash on coal usage, with AOSIS pushing back with a suggestion of image control, but ultimately China held strong on their decision.

Negotiation rounds 3 & 4, voting, and deputy mayor’s speech

The UK showed their tactical abilities and their knowledge in the negotiations with Greenpeace, but Greenpeace did not cede to their demands and manage to agree to a deal. The IIPFCC was determined to protect indigenous land and communities, but their quest was heavily challenged by Shell. There was no common ground in the negotiation with this petrol giant, so the IIPFCC had to ensure an allyship with Brazil if they wanted to ensure the protection of the indigenous. On round four, Shell tried to sway some votes from China and Sweden, but while agreements were found with the former, the latter country was not going to let Shell influence their values. The tête-à-tête became lively as neither Shell nor Sweden were willing to compromise, resulting in a rather unsuccessful attempt of finding complicity.

After four intense rounds of negotiating, the voting began. Were all parties going to remain faithful to the agreements established during the negotiations? Or would some throw a curve ball, changing their minds at the last minute? The pondered tactics of the IIPFCC were successful, as they managed to lock Brazil’s and the USA’s support on their most valued resolutions. All parties pondered thoroughly on how to best use their votes, and it seemed that this meant that some agreements had been silently retracted, when some astonished reactions followed the raise of hands here and there.

The conference was finally over and many parties, including Brazil and Greenpeace, could celebrate the victory of the resolutions agreed upon. Yet, it was clear that a bittersweet aftertaste was left in the mouths of some parties, who did not manage to persuade enough. The heated debate had ended, and what was done was done, but one more surprise was awaiting our participants. Deputy Mayor Asher Craig had been sitting on the sidelines for a few instances already, assisting in the final yet most heated rounds of the conference. She was there, observing our pupils in awe as they got into character and avidly fought for their beliefs. The Deputy Mayor was impressed by the passion of these young minds and how much they are invested in the cause; she was proud to see that young generations care about the environment and our planet, as they came up with ideas for change that they would like to see more in the Bristol. The innovativeness and creativity of the students was remarkable in her eyes, as she proceeded to give an inspiring and uplifting speech on the efforts currently being made by the City Council to respond to the climate emergency. The mock COP26 was a more than a successful event, and as everyone waited for the results of the conference in Glasgow, we all wished that our simulation had been real.

Watch the students in action in this short video created by Particle Productions and funded by Bristol City Council.

————————————–

This blog is written by Sonia Pighini and Jennifer Malone, who are students on the Cabot Institute for the Environment Master’s by Research.

Jennifer Malone

Currently studying for a Master’s by Research in Global Environmental Challenges from the Cabot Institute for the Environment, Jennifer’s research is centred on food system decarbonisation within the scope of UK food policy and community practice.

Sonia Pigini

Sonia is an international student in the MscR programme Global Environmental Challenges. Their research focuses on people-centred sustainable food system transitions in Bristol. They are particularly interested in exploring the potential for a more decentralised food system in the city, which empowers local producers, engages consumers and that keeps aspects such as justice and inclusion at its heart.

Image credit (image at top of blog): Jack Pitts

India heatwave: why the region should prepare for even more extreme heat in the near future

Posted on May 13, 2022March 29, 2023 by janet.crompton

An extreme heatwave in India and Pakistan has left more than a billion people in one of the most densely populated parts of the world facing temperatures well above 40℃. Although this has not broken all-time records for the regions, the hottest part of the year is yet to come.

Though the heatwave is already testing people’s ability to survive, and has led to crop failures and power blackouts, the really scary thing is that it could be worse: based on what has happened elsewhere at some point India is “due” an even more intense heatwave.

Together with a few other climate scientists, we recently looked for the most extreme heatwaves globally over the past 60 years – based on the greatest difference from expected temperature variability in that area, rather than by maximum heat alone. India and Pakistan do not feature in our results, now published in the journal Science Advances. Despite regularly having extremely high temperatures and levels of heat stress in absolute terms, when defined in terms of deviation from the local normal, heatwaves in India and Pakistan to date have not been all that extreme.

In fact, we highlighted India as a region with a particularly low greatest historical extreme. In the data we assessed, we didn’t find any heatwaves in India or Pakistan outside three standard deviations from the mean, when statistically such an event would be expected once every 30 or so years. The most severe heatwave we identified, in southeast Asia in 1998, was five standard deviations from the mean. An equivalent outlier heatwave in India today would mean temperatures of over 50℃ across large swaths of the country – such temperatures have only been seen at localised points so far.

Our work therefore suggests India may experience even more extreme heat. Assuming the statistical distribution of daily maximum temperatures is broadly the same across the world, statistically a record-breaking heatwave is likely to occur in India at some point. The region has not yet had reason to adapt to such temperatures, so may be particularly vulnerable.

Harvests and health

Although the current heatwave has not broken any all-time records, it is still exceptional. Many parts of India have experienced their hottest April on record. Such heat this early in the year will have devastating impacts on crops in a region where many rely on the wheat harvest both to eat and to earn a living. Usually, extreme heat in this area is closely followed by cooling monsoons – but these are still months away.

It is not just crop harvests that will bear the brunt, as heatwaves affect infrastructure, ecosystems and human health. The impacts on human health are complex as both meteorological factors (how hot and humid it is) and socioeconomic factors (how people live and how they are able to adapt) come into play. We do know that heat stress can lead to long-term health issues such as cardiovascular diseases, kidney failure, respiratory distress and liver failure, though we will be unable to know exactly how many people will die in this heatwave due to the lack of necessary health data from India and Pakistan.

What the future holds

To consider the impact of extreme heat over the next few decades, we have to look at both climate change and population growth, since it is a combination of the two that will amplify the human-health impacts of heat extremes in the Indian subcontinent.

world map with some countries shaded yellow — Hotspots of population increases over the next 50 years (red circles), all coincide with locations where no daily mortality data exists (yellow).
Mitchell, Nature Climate Change (2021), CC BY-SA

In our new study, we investigated how extremes are projected to increase in the future. We used a large ensemble of climate model simulations, which gave us many times more data than is available for the real world. We found that the statistical distribution of extremes, relative to a shift in the underlying climate as it generally gets warmer, does not change. In the climate models the daily temperature extremes increase at the same rate as the shift in the mean climate. The IPCC’s latest report stated that heat waves will become more intense and more frequent in south Asia this century. Our results support this.

The current heatwave is affecting over 1.5 billion people and over the next 50 years the population of the Indian subcontinent is projected to increase by a further 30%. That means hundreds of millions more people will be born into a region that is likely to experience more frequent and more severe heatwaves. With even larger numbers of people being affected by even greater heat extremes in the future, measures to adapt to climate change must be accelerated – urgently.

————————-

This blog is written by Cabot Institute for the Environment members Dr Vikki Thompson, Senior Research Associate in Geographical Sciences, University of Bristol and Dr Alan Thomas Kennedy-Asser, Research Associate in Climate Science, University of Bristol.

This article is republished from The Conversation under a Creative Commons license. Read the original article.