Andy Lyford – Cabot Institute for the Environment blog

IPCC blog series – Working Group 3 – Mitigation of climate change

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

This blog is part of a series on the Intergovernmental Panel on Climate Change’s recent 6th Assessment Report, with this post covering the output of Working Group III and the proposed solutions and mitigations for the climate crisis. This article also features a chat with IPCC Lead Author Dr Jo House and contributor Viola Heinrich, researchers at the University of Bristol and Cabot Institute for the Environment.

Of the three Working Groups, the third makes for the most positive reading. As the title suggests, this one is all about the mitigation of climate change and preventing the disastrous climate futures explained by Working Groups I and II. Whilst remaining focussed on the impending nature of the climate crisis, this report spells out that we have the solutions.

As discussed in the previous posts, massive behavioural changes are needed at government and societal levels. When I spoke to academics, they were positive that we were well past the point of whether climate change is real or has an impact on humanity and that economically minded leaders are starting to see the benefits of sustainable practice and the economic security it brings. Governments and states are listening and looking at policy to mitigate the crisis.

Let’s look at some of the solutions and mitigations proposed:

The quicker we act, the less economic impact

This follows on nicely from previous reports that stated the effects of warming increase with each incremental global average temperature increase. That is to say, a +1.5 degrees C future will see less devastation than a +2 degrees C or even a +1.7 degrees C rise in temperature. Such disasters (drought, extreme weather, flooding) require huge amounts of money resources to sort out. From an economic security point of view, it makes complete sense to act with great urgency. The climate crisis is already here, and therefore already having an economic impact. Action immediately will mitigate against the future potential costs of a climate disaster.

Relative to the economic impact of climate disaster in the future, the investment of reducing the impact of the crisis and securing a liveable planet is small.

The immediate reduction of fossil fuel production and limitation of greenhouse gases in the pursuit of Net Zero

As discussed before, the greatest culprit of the climate crisis is unequivocally greenhouse gas (GHG) emissions from fossil fuels. Therefore, in an ideal world, the immediate halt of fossil fuel extraction, production and consumption would be enough to prevent an overshoot +1.5 degrees C (as discussed in the first report, there is a lag between emissions and warming). Unfortunately, this is not an ideal world, so significant policy to pursue a Net-Zero will be needed.

Going further, carbon must also be removed from the atmosphere somehow, to allow the planet to return to preindustrial atmospheric carbon levels.

Carbon removal, naturally and technologically

A key aspect to the third Working Group is its arguments for carbon capture. This could be either through natural carbon removal through plants and trees, or by using carbon removal technology through direct air capture.

Carbon capture will be essential to solving the climate crisis, as carbon needs to be removed in order to return to the pre-industrial levels of atmospheric carbon. As well as this, proposed tech allows for carbon to be captured at the source of emissions. The issue is that carbon capture could lead to a dependence on the technology.

Companies, understandably, are drawn to the idea of “planting trees” to offset their emissions. It’s visible, tangible, and easy for the public to grasp. However, it’s not always the most efficient use of land and resources, and some worry that these methods will be exploited as a crutch to not reduce emissions output. While an extremely important step in mitigating climate change, some worry that there may be a resultant reliance on carbon removal over carbon emission reduction, allowing the world’s most prolific polluters to continue maintain their carbon output.

One of the most cost-effective mitigation techniques is simply the protection of existing forests and natural sites. The IPCC also stresses that decisions of protection like these must involve the input of the indigenous communities living there.

From the policy level to the personal level

It’s brilliant to be making the personal decisions to limit your own carbon impact, but individuals have limited impact on the climate system. What these reports suggest is wide reaching policy at state level to incentivise populations to make better climate conscious choices, by making things easier through improved infrastructure and methods of “demand management”, reducing the consumption of resource intensive products like meat and dairy. Diet changes at a population scale will be needed to combat the emissions of methane (another greenhouse gas) in particular.

In urban environments, investment in public transportation and cycling infrastructure would go a long way to reduce emissions. As would policy that makes retrofitting buildings to be more energy efficient and building new infrastructure with energy efficiency in mind.

For a great bit of further reading, the IPCC Special report on Climate Change and Land goes into much further detail about the impact of changing diets and consumption habits at scale.

Read the IPCC Special Report on Climate Change and Land

As previously discussed in the blog post on the WGII report, the impacts of climate change are not equal or in proportion to climate impact of the nation affected. Therefore, much of the mitigation will need to take the form of humanitarian aid, improving infrastructure for nations without the resources to do so themselves.

The IPCC reports end on a poignant note: “International cooperation is a critical enabler for achieving ambitious climate change mitigation goals”.

Insight from IPCC Lead Author Dr Jo House and contributor Viola Heinrich

Dr Jo House

Dr Jo House is Reader in Environmental Science and Policy, Research Lead of Cabot Institute for the Environment’s Environmental Change theme and a Lead Author on the IPCC’s AR6 Working Group III report.

Viola Heinrich is a Physical Geography PhD Candidate at the University of Bristol, studying the emissions and climate mitigation potential within the land use sector in the tropics, especially the Brazilian Amazon. Viola assisted Dr House in her AR6 work, producing figures for WG III.

How did you get involved with the IPCC and WGIII?

Dr Jo House – “I have been working on IPCC reports for 20 years. I was first employed as a chapter scientist to support the chapter team for working group I, 3rd assessment report carbon cycle chapter. I was then made a lead author for the synthesis report for AR3. Since then, I have been a lead author or contributing author on all three Working Groups, as well a lead author for the Special Report on Climate Change and Land. I am also a lead author twice for the IPCC Task Force on Inventories, who provide methodological guidance to countries on how to produce their greenhouse gas inventories, for reporting to the UNFCCC, as well as accounting under the Kyoto Protocol.

Viola Heinrich

Despite the long hours and the many thousands of comments we must respond to, I do IPCC because I care about climate change, and IPCC gets the science into the hands of people who can do something about it.”

Viola Heinrich – “I’m a PhD student working on understanding the emissions and climate mitigation potential within the land use sector in the tropics, especially the Brazilian Amazon. Jo, as my supervisor, approached me in 2019 to help produce some figures for her work on AR6 and WGIII.

It was a great learning experience seeing how these report cycles work and one bonus was that the work I produced for the IPCC reports was able used in the introduction to my PhD thesis”

What’s one key message you’d like to highlight from WGIII?

Dr Jo House – “We are nearly already too late to stay within 2 degrees, so we need to reduce fossil fuels usage drastically and rapidly to avoid even worse impacts.

Also specifically from a land perspective: The land has potential for mitigation, but it cannot do it all, planting trees is not a get out of jail free card for continuing to burn fossil fuels.”

Viola Heinrich – “This report has followed nicely on form previous cycles in that it has reaffirmed what we know about the land use component and the mitigation potential of the land use sector (20% to 30% by 2050). The big caveat of course is that the land can’t do it all and we need to be actively reducing emissions rather than relying in capture methods from trees for example.

Another interesting factor about the report is that it stresses the importance of considering the local communities in places where solutions and mitigations take place, seeking their expertise in protection, and understanding how these actions will affect them.”

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As always, 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.

That wraps up the blog series, I hope that it was enjoyable and informative.

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

Andy Lyford

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.”

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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