Category: Climate Science

Articles about climate science

What does recent temperature data mean for the Paris Agreement 1.5°C goal?

October 19, 2023

In mid-2019 I posted a global temperature analysis that showed how we might have a first 1.5°C year sooner than many were imagining. This built on a 2016 story I posted. My 2016 analysis was catalysed by the significant jump in temperature the world experienced that year as a very strong El Niño event took hold. In February of 2016 the world had experienced the first month in which the global temperature anomaly was over 1.5°C higher than pre-industrial times (represented by the 1850-1900 baseline and as reported by NASA/GISS). As the El Niño subsided the elevated warming also reduced, but it left me thinking that the next strong El Niño might deliver a first 1.5°C year rather than just a single month. With El Niño emerging again in 2023, are we now at that point?

In recent weeks and months we have seen a number of media stories about the global temperature reaching unprecedented levels with societal alarm bells ringing about the situation. The current El Niño event started in about April of this year with the Oceanic Nino Index (ONI) crossing from negative (La Niña conditions) to positive and rising since then. It is now at 1.3° and continuing to rise, but is not yet at the point of being a Strong or Very Strong event; the ONI has to be around 2.0° for that to be declared. According to a NOAA report on October 16th El Niño is favoured through to Northern Hemisphere spring 2024, with chances exceeding 95% through January-March 2024. Thereafter, chances of El Niño gradually decrease, with a possible return of ENSO-neutral (El Niño Southern Oscillation) in May-July 2024. So could 2023 be a 1.5°C year on the back of this?

Here is what we know.

  1. The underlying global temperature anomaly (i.e. global average surface temperature vs. 1850-1900) is rising at about 0.2°C per decade (in fact 0.0197 per year from 1975 to 2023 according to the most recent Berkeley Earth data) as more and more CO2 is added to the atmosphere.
  1. The recorded temperature anomaly (which the Paris Agreement is attempting to keep below 1.5°C) for a specific year is highly variable depending on annual climatic shifts, most notable being the El Niño Southern Oscillation (ENSO).
  2. ENSO has two distinct phases, El Niño when the mid-Pacific warms and we tend to see higher global temperatures and La Niña when there is cooling and we tend to see lower global temperatures.
  3. We have recently moved from a La Niña condition to an El Niño condition and that condition is growing.
  4. Based on years in the last half century when we had a similarly strong to very strong El Niño (1966, 1973, 1983, 1998, 2016) and a consequent anomalously high global average surface temperature, we can see that in the near term if we move into Strong El Niño conditions, we will likely see the first 1.5°C year. In the chart below, this would be any time after about 2021.
  1. While 2023 isn’t a Strong El Niño year yet, we are heading in that direction (but that doesn’t mean we get there). The ONI continues to rise and for each year after 2021, the height that it needs to rise to for a first 1.5°C year will become progressively lower due to the underlying warming trend.

With all that in mind, what can we say about the temperature so far this year and the possibility of 2023 exceeding 1.5°?

If we draw a chart that removes the underlying 0.2°C per decade warming, then we are left with the variation in annual temperature as a function of other factors, including the ONI. The latter typically varies between -2° (strong La Niña) to +2° (strong El Niño).

The chart below shows two annual trends. At the bottom in grey is the Oceanic Niño Index, which is now at about 1.3°, but during the Very Strong El Niño of 2015/2016 reached 2.6°. The orange line at the top is the ‘warming removed’ variation in global average surface temperature variation vs. 1850-1900. This appears to be just a very noisy chart, but the trend through it is flat which is important (meaning that the warming has been cleanly removed).

Eyeballing the chart might lead to the view that the variation is more positive in El Niño years and more negative in La Niña years, which it should be given this is a shorter term cooling and warming cycle. However, plotting the ONI vs. the anomaly variation (see the chart in blue below) doesn’t yield a strong trend. A regression of the data points with the intercept at zero gives a slope of around 0.1°C (actually 0.0731) of global temperature variation for each point of Oceanic Niño Index change. But a visual inspection of the data range (orange dotted lines) perhaps points to something more aggressive, possibly around 0.2°C for each point of Oceanic Niño variation. A more detailed statistical analysis of this is almost certainly required, which is beyond my university statistics. This may be challenging though as the data includes all possible reasons for short term variations, besides the ENSO. There’s volcanoes (e.g. Mt. Pinatubo in 1991), solar variances, sea ice cycles and perhaps even events like very major forest fires, to name a few.

If we were to assume a factor of around 0.15°C warming for each point in the ONI, then the temperature excursions seen over recent months are not surprising (although the very last month of the trend has really concerned the science community). Using the Berkeley Earth monthly time series, the monthly average temperature anomaly in 2018 was 1.2°C, in a year when ONI averaged very close to zero, i.e. neutral. Compared to 2018, then today which is five years later we would be at:

1.2 (2018 data)  + 0.1 (underlying warming over five years) + 0.2 (1.3° * 0.15, current El Niño impact) = 1.5°C

The calculation above uses the current ONI of 1.3°, which is above the year to date average of around 0.5°, but it does show that we are in 1.5°C territory for 2023, which is concerning. There’s also a great deal of annual variability in the numbers. For example, starting with 2020 data (instead of 2018) when ONI averaged -0.4 (i.e. cooler La Niña period), but with the Berkeley monthly average anomaly at 1.35°C, then the same calculation comes out above 1.5°C.

Nevertheless, please note that the above analysis uses only the Berkeley Earth Data Set, which is one of several. In the World Meteorological Organisation (WMO) State of the Global Climate 2022 Report they included six datasets, of which Berkeley was one. Further, the IPCC use a ten year moving average temperature to assess the longer term state of the climate, which is still tracking well below 1.5°C but clearly rising. And if the world was back in a La Niña phase by 2025 the temperature in that year would likely be back below 1.5°C as well. As such, the recent temperature data and the possibility of 2023 or 2024 crossing the 1.5°C threshold serve as an important warning for the future.

As has been the case in recent COPs, we may see the WMO  announce a final estimate for 2023 at COP28, before the complete data set is available in early 2024. Should an announcement point to 2023 being the first 1.5°C year it will certainly focus the minds of the negotiators in attendance as they contemplate the Global Stock Take and the COP28 declaration of action, expected to be finalised on December 12th.

A chat with ChatGPT about emissions mitigation

January 12, 2023

In a recent article from the World Economic Forum the authors made the point that artificial intelligence (AI) systems will be essential for the emissions mitigation task that society faces. In fact they go so far as to say that “without AI, we won’t meet ESG goals and address climate change”. In the article they refer to specific systems now coming into use, with different systems tasked with managing particular tasks within the overall mitigation journey. They conclude by noting;

Corporations that connect all their relevant data within a unified AI platform — not just ESG and financial data streams — will benefit the most. When corporations can see the entire picture and understand all the ESG metrics, only then will we produce goals that provide meaningful change and avoid the worst effects of climate change.

At the societal level, AI platforms are also starting to emerge and they are being designed to tackle a broad range of issues and questions by being introduced to huge amounts of data, such as you and I might come across if we sit all day and trawl through hundreds of internet sites and pages. The skill of the AI platform will be to integrate this data and use it to derive clear answers to questions and offer proposals for change so that progress can be made. Ideally the systems should develop insights that are not obvious to humans looking at the same data, perhaps because of the amount of data presented, which the AI system can easily handle.

Late last year one of the newest versions of such a system was made available for public testing. It is called ChatGPT and can be accessed here. To be fair this is a system that is designed more to engage in a conversation than to solve the world’s problems, but it does still draw on an immense data resource in compiling its responses. As such, I thought it would be interesting to engage with the system over the Christmas break and see what conclusions it might draw from a discussion on emissions mitigation. Note that the answers below are abbreviated, simply to limit the length of the blog post.

I started with posing a simple question;

Q: Atmospheric CO2 is now over 420 ppm. Why is this a problem?

A: Rising temperatures, changing climate, ocean acidification and therefore overall negative impacts on human health. Overall, it is important to reduce our greenhouse gas emissions and limit the concentration of CO2 in the atmosphere in order to mitigate the negative impacts of climate change and protect the health of people and ecosystems.

Q: So how might carbon dioxide emissions be reduced very quickly, say halved by 2030?

A: Increasing the use of renewable energy, improving energy efficiency, planting trees, electrifying transportation and making use of carbon capture and storage: Carbon capture and storage (CCS) is a technology that captures CO2 emissions from power plants and other industrial facilities and stores them underground. CCS has the potential to significantly reduce CO2 emissions from these sources, but it is not yet widely deployed.

So ChatGPT certainly understands the issue and is clear on the direction of travel. It also sees the importance of CCS without any prior reference to the technology by me (other than it may have read my blog posts as part of its learning), so that’s a good start. But getting it to be specific on how quickly these technologies could be scaled and how much difference they might make by 2030 turned out to be much more difficult.

Q: How quickly would these steps need to be scaled to cut emissions in half by 2030?

A: The rate at which these measures would need to be scaled up in order to cut carbon dioxide (CO2) emissions in half by 2030 would depend on the current level of emissions and the specific measures being implemented. For example, transitioning to electric vehicles (EVs) and public transportation could make a significant dent in transportation-related CO2 emissions, but it would require a rapid expansion of charging infrastructure and a significant shift in consumer behavior towards EVs. Improving energy efficiency in buildings and appliances and increasing the use of renewable energy sources could also make a significant impact on CO2 emissions, but again, it would require policy changes, infrastructure investments, and the deployment of new technologies. Planting trees and implementing carbon capture and storage (CCS) could also contribute to reducing CO2 emissions, but these measures alone are unlikely to be sufficient to achieve a 50% reduction by 2030. Overall, reducing CO2 emissions by 50% by 2030 would require a rapid and concerted effort across multiple sectors, including transportation, energy, and industry, and would likely involve significant policy and infrastructure changes, as well as the deployment of new technologies.

From this point the conversation became rather circular, with the system continually rephrasing the answer it had already given in different ways, depending on how I asked the question. More than once it said;

A: However, it is generally understood that the increased deployment of low-carbon technologies, such as EVs, solar PV, and advanced nuclear technologies, can make a significant contribution to reducing CO2 emissions.

A: However, if these technologies were widely deployed and powered by low-carbon energy sources, they could make a significant contribution to reducing CO2 emissions.

But the system was reluctant to offer a numerical assessment even when asked, although eventually it offered a number:

Q: By how much would global emissions fall if EV production, solar PV module production and nuclear power deployment all  quintupled by 2030.

A: It is difficult to estimate by exactly how much global carbon dioxide (CO2) emissions would fall if electric vehicle (EV) production, solar PV module production, and nuclear power deployment all quintupled by 2030, as it would depend on a number of factors, including the current level of emissions, the specific technologies being deployed, and the mix of energy sources used to power these technologies.

Q: Can you make a numerical estimate of the likely reduction in emissions?

A: It is difficult to make a numerical estimate of the likely reduction in carbon dioxide (CO2) emissions that would result from quintupling electric vehicle (EV) production, solar PV module production, and nuclear power deployment by 2030, as it would depend on a number of factors, including the current level of emissions, the specific technologies being deployed, and the mix of energy sources used to power these technologies.

Q: Can’t you make an estimate based on some simple assumptions?

A: It is possible to make a rough estimate of the likely reduction in carbon dioxide (CO2) emissions that could result from quintupling electric vehicle (EV) production, solar PV module production, and nuclear power deployment by 2030 based on some simple assumptions. However, it is important to note that such an estimate would be highly speculative and would not take into account a number of important factors that could affect the actual reduction in CO2 emissions. For example, if we assume that:

  • All EVs are powered by electricity from low-carbon sources and replace gasoline-powered vehicles
  • All solar PV modules are used to displace coal-fired power plants
  • All nuclear power is used to displace coal-fired power plants

. . . . and we further assume that these technologies are able to completely displace the higher-emitting technologies they are replacing, we can estimate the potential reduction in CO2 emissions that could result from these measures. Under these assumptions, if EV production, solar PV module production, and nuclear power deployment were all quintupled by 2030, it is possible that CO2 emissions could be reduced by a rough estimate of around 15-20%. However, it is important to note that this is a highly speculative estimate and the actual reduction in CO2 emissions could be higher or lower depending on a range of factors.

Q: Do you mean 15-20% of total global anthropogenic CO2 emissions?

A: Yes, the estimate of a 15-20% reduction in carbon dioxide (CO2) emissions that I provided is based on total global anthropogenic CO2 emissions, which are emissions that are produced by human activities, such as the burning of fossil fuels and deforestation.

There we have it; after some pushing the AI system was able to determine that quintupling (5x) the current deployment of solar PV, EVs and nuclear power generation would give us a 15-20% reduction in emissions by 2030, although this is still along way from the 45% goal of the Glasgow Climate pact. With that in mind I asked a follow-up question.

Q: So what extra steps would need to be taken to get a 45-50% reduction in global emissions?

A: Increasing the use of renewable energy, improving energy efficiency, planting trees, electrifying transportation and making use of carbon capture and storage: Carbon capture and storage (CCS) is a technology that captures CO2 emissions from power plants and other industrial facilities and stores them underground. CCS has the potential to significantly reduce CO2 emissions from these sources, but it is not yet widely deployed.

I was back in the same loop I had started with in that ChatGPT didn’t want to be specific on the measures. After  some additional pushing I hadn’t progressed out of the loop, but one extra important insight emerged.

A: Implementing carbon pricing: Establishing a price on carbon, through mechanisms such as a carbon tax or cap-and-trade system, can provide incentives for businesses and individuals to reduce their CO2 emissions.

At least as a set of basic insights and discussion points, ChatGPT seems to have a grip on the climate issue, but it is far from making clear recommendations on what needs to happen, when and at what scale. That still seems to be a job for the energy modelling community . . . . . at least for now!!

ChatGPT is an open system to try and use, which is what I have done. This post isn’t meant as a recommendation or a criticism of ChatGPT, but just a look at how AI is developing.

Happy New Year!

Back to Antarctica

April 22, 2022

As those familiar with this blog may recall, I have been fortunate to visit the Antarctic Peninsula on more than one occasion. These visits have been part of a long standing relationship between Shell and the 2041 Foundation. The 2041 Foundation is named for the point in time that countries may begin to consider reopening the Antarctic Treaty, or 50 years on from its agreement (2041) and eventual ratification (2048). The treaty currently prevents any use of Antarctica for commercial and development purposes, other than limited tourism and scientific research. The preservation of Antarctica has become 2041’s raison d’être, which also broadens into the subject of climate change given that surface temperature warming represents a direct threat to Antarctica.

In mid-March, after two years of COVID-19 deferments, a group of 170 people set off from Ushuaia in southern Argentina on board the Ocean Victory, headed for the Antarctic Peninsula. The group came from many backgrounds and countries, including entrepreneurs, venture capitalists, YouTube influencers, corporate staff, students, artists and academics and led by Robert Swan, the founder of the 2041 Foundation and the first man to trek on foot to both the North and South Poles. I was there, along with others, to give some talks on climate change and the energy transition to the broader group. Much of the material from various blogs I have posted over the last two years featured in the sessions.

The Ocean Victory in Antarctica

While the learning opportunity is excellent and the group of people were outstanding in so many respects, the scenery, wildlife and conditions of Antarctica loom large over everything. The continent, and noting that we saw just a tiny fraction of it, is majestic and presents itself on a scale that is unmatched anywhere else I have ever been. Having crossed the infamous Drakes Passage and experienced 7+ metre waves, the relative calm of the Peninsula and its accompanying archipelago awaits. The sights are astounding, from vast ice formations slowly edging their way into the sea where they end their days as haunting sculptures on the shore line, to penguins in colonies going about their business preparing for the winter. Whales can be seen on a regular basis, although on this trip it was primarily humpbacks that were spotted. We even managed a very quick dip in the ocean at Deception Island, the site of a long abandoned whaling station in the caldera of a dormant volcano. The water was at 2°C, so when I say “very quick”, I mean it.

A particular highlight for me was to travel with my son, who took the spectacular sunset photograph below. It was good to see him relaxing after a long two years of COVID tension as an NHS Junior Doctor.

As someone who has been to Antarctica several times over the space of more than a decade, I am often asked if I have noticed a change in the environment. The honest answer is no, but on this trip we did experience something that nobody on board had ever experienced before in Antarctica, rain. That was highly unusual, even for Robert Swan who has been to Antarctica many times over a near 40 year time span. But perhaps we shouldn’t have been surprised as while we were there the deeper continent experienced the largest temperature anomaly ever recorded, a swing from -50°C to -10°C (see below). These anomalous readings are becoming more common as the global surface temperature rises, which could ultimately threaten the stability of ice shelves and lead to faster and earlier rises in global sea level. During my visit in 2015 we were passing by an Argentine weather station on the day and at the time it measured and reported the highest ever recorded temperature on the Peninsula.

Image from Climate Reanalyzer (https://ClimateReanalyzer.org), Climate Change Institute, University of Maine, USA.

For now, Antarctica remains a pristine and largely untouched wilderness, still looking the same as when explorers first sighted the continent and when intrepid expeditions led by the likes of Scott, Amundsen and Shackleton trekked across the continent. It’s important for the sake of all of us that we ensure this remains the case.

For additional photographs from the expedition, click here.

The last chance COP? Some more carbon budget maths!

November 1, 2021

With world leaders and thousands of delegates and observers meeting in Glasgow for COP26, there is much talk of this being the last chance to save 1.5°C. It wouldn’t be the first time a COP has been described as the last chance we have, but in the case of COP26 and 1.5°C, it is a fair assessment of the situation. It all rests on the available carbon budget which I discussed in a recent post.

In the August 2021 6th Assessment Report from IPCC WGI, the carbon budget analysis for 1.5°C was published, as shown in the table below. 

Estimates of historical CO2 emissions and remaining carbon budgets (Source: IPCC)

In its recent NZE 2050 scenario, the IEA used the mid range figure of 500 Gt from 1.1.2020 as the carbon budget for the analysis, although we should recognise that for a greater degree of certainty of not exceeding 1.5°C a lower number is more desirable. But we are two years on from the baseline of 1.1.2020 with cumulative carbon dioxide emissions since that time of some 80 Gt, so from 1.1.2022 which is now just a few weeks away, the carbon budget for 1.5°C is closer to 400 Gt. This sits against global annual carbon dioxide emissions of over 40 Gt, comprising 33 Gt from fossil fuel use, 3 Gt from the calcination of limestone for cement manufacture and 6 Gt as a result of land use change practices, which includes ongoing deforestation.

So with at most 400 Gt of remaining budget and it diminishing by 1 Gt every 9 days (so 1.5 Gt while COP26 is on), the challenge facing the conference is huge. 2021 (originally 2020 in the Paris Agreement but delayed due to COVID-19) is the year in which countries are asked through the Paris Agreement to reassess their initial Nationally Determined Contributions and to increase ambition in light of the prevailing science. Indeed, that process is well underway and a quick look at the UNFCCC NDC Registry will show many new submissions, with more appearing each day. 

A quick analysis of the NDCs reveals that in the 2020s global society is likely to consume much of the remaining carbon budget for 1.5°C, which implies that the temperature goal is breached soon after the decade is over (although it may be some years after that the IPCC and WMO confirm this). Just ten medium to large emitting countries account for some 200 Gt in the 2020s, based on the emissions pathways they have announced through their existing or revised NDCs and assuming that these are delivered. That list includes China, the USA, India, the EU, Australia, the UK, Canada, Korea, Japan and Russia. These ten make up about two thirds of current global energy system emissions. China is the largest, with emissions currently around 10 Gt per year. Their revised NDC was submitted last week and brings forward their peaking of emissions to ‘before 2030’. I have assumed that their emissions plateau now, then being falling in 2027 and drop to 9 Gt per year by 2030.

Most of the countries outside my ten, albeit not all, either have modest current emissions and are therefore likely to see short term increases as development continues, or at best will plateau at their current levels. This includes Brazil, Indonesia and all of the African (1.3 Gt energy emissions in 2019) and Middle East (2.1 Gt energy emissions in 2019) countries. The 10+ Gt per year for nine years that these countries represent is around 100+ Gt, so that takes the total to 300+ Gt. Add to this international aviation and marine bunkers over a decade and another 15-20 Gt of the budget is consumed. The total by 2030 is therefore becoming perilously close to 400 Gt and will certainly exceed the tighter 67% and 83% numbers in the table above. At best the NDCs might see carbon dioxide emissions at around 30 Gt per year by 2030, with a remaining budget of 60-80 Gt going into the 2030s and beyond.

While there is a very strong focus at COP26 on net-zero emissions in 2050, the real challenge for 1.5°C is within this decade. The next round of NDCs won’t be submitted until 2025 if the Paris schedule is maintained, by which time another 160-200 Gt of carbon dioxide could have been emitted based on a global plateau at current levels. This really will be too late to make changes for 1.5°C, so it has to be in 2021 with COP26 acting as the catalyst for change.

The simple climate maths the IPCC didn’t fully explain

August 19, 2021

When I first started delving into the issue of climate change about 20 years ago, the clarion call of the day was to reduce emissions by 50% by 2050. Today, as we all know, the call is for net-zero emissions by 2050. Last week we also heard again from the Intergovernmental Panel on Climate Change (IPCC) with the release of the first part of the 6th Assessment Report (AR6), which the United Nations Secretary General called a ‘code-red for humanity’. But both the call in 2001 and again in 2021 are entirely consistent. It’s not the climate science that has changed, just the carbon maths associated with it.

As the IPCC clearly state in Part D of the Summary for Policymakers of AR6-WG I;

  • This Report reaffirms with high confidence the AR5 finding that there is a near-linear relationship between cumulative anthropogenic CO2 emissions and the global warming they cause. Each 1000 GtCO2 of cumulative CO2 emissions is assessed to likely cause a 0.27°C to 0.63°C increase in global surface temperature with a best estimate of 0.45°C. This is a narrower range compared to AR5 and SR1.5. This quantity is referred to as the transient climate response to cumulative CO2 emissions (TCRE). This relationship implies that reaching net zero anthropogenic CO2 emissions is a requirement to stabilize human-induced global temperature increase at any level, but that limiting global temperature increase to a specific level would imply limiting cumulative CO2 emissions to within a carbon budget.

While the biggest difference between now and 2001 is the shift in the goal from below 2°C to 1.5°C which in turn has contributed to the change in required emissions trajectory, this is not enough to explain the shift in the required outcome by 2050. That change is more a function of the cumulative carbon math associated with any level of warming.

To limit the temperature rise to 1.5°C, the notional carbon budget based on the above best estimate of TCRE is 1.5/0.45*1000 =  3330 Gt CO2 and for 2°C it is 4440 Gt. This is effectively targeting the central estimate in a range and is a calculation you might do before emissions start. However, we already know from IPCC AR6 that cumulative emissions of 2390 Gt correspond to a 1.07°C temperature rise in 2010-2019 vs. 1850-1900. They also indicate that the remaining carbon budget from 1.1.2020 for 1.5°C is 400 Gt and 2°C is 700 Gt for a 67% likelihood, which implies an overall carbon budget of 2790 Gt for 1.5°C and 3090 for 2°C with a good degree of certainty.

In the following calculations and accompanying charts I will work on the basis of a simple linear reduction in emissions to net-zero from a particular point in time to calculate the overall cumulative emissions. Returning to 2001, the annual CO2 emissions (from energy, cement and land use) were approximately 30 Gt, the cumulative emissions from 1850 at that time were about 1700 Gt and a linear reduction pathway from 2001 for 2790 Gt final cumulative emissions (1.5°C) means net-zero emissions in about 2073. This is illustrated in the chart below.

As noted for 2001, cumulative carbon dioxide emissions since 1850 were at 1715 Gt (Source: Our World in Data), which means net-zero emissions in 2073 for 1.5°C and 2123 for 2°C. Back in 2001 the focus was more on 2°C, so targeting well below 2°C, to completely avoid the 2°C threshold, would mean net-zero emissions around 2100 and therefore a 50% reduction in emissions by 2050 assuming a linear decline.

But twenty years later the story is very different. At the time of the IPCC Special report on 1.5°C cumulative carbon dioxide emissions had reached 2300 Gt, so a linear reduction to net-zero had a target date of 2040. For 2°C it was 2077. In fact the IPCC opted for scenarios with a steeper early reduction pathway, and therefore targeted 2050 for net-zero emissions, but that means a very steep early reduction of over 50% by 2030 to balance the longer tail to 2050. With twenty further years of rising emissions, a considerable portion of the 2001 carbon budget had been consumed and therefore the date for net-zero emissions had moved forward in time dramatically.

In fact, for each year that emissions don’t reduce, the requirement for net-zero emissions comes towards us by a year, effectively narrowing the gap for action by two years. The IPCC Special Report on 1.5°C was baselined from 1.1.2018, so another four years has passed (or will soon pass). Even the recent IPCC AR6 is two years out of date now in terms of its carbon budget baseline. This rapidly shifting picture is shown below. In 2015 the target year for 1.5°C is shown to be 2042, a gap of 27 years, but by 2019 the target year is 2038, a gap of only 19 years.

Should carbon dioxide emissions remain at 40 Gt (below the pre-COVID high) for the coming few years, the available carbon budget for 1.5°C is rapidly consumed, as illustrated in the chart below. By 2025 net-zero emissions would be required by about 2033 and by 2029 net-zero emissions would be required before 2030, in other words the available carbon budget will have been consumed.

All the above presupposes that emissions cannot go below zero in the future, thereby drawing carbon dioxide out of the atmosphere and eventually correcting any overshoot of the carbon budget and its associated temperature goal. But negative emissions are a possibility, through the implementation of large scale air capture systems with geological storage (BECCS or DACCS) and enhancement of natural carbon uptake in the biosphere via programmes such as those that increase global forest cover and improve soil carbon management in agriculture.

Today, the carbon budget is still a rather arcane subject, well understood by a few but not widely appreciated in terms of relevance to managing surface temperature. That understanding will need to improve rapidly so policymakers can develop better mechanisms to manage it, also ensuring large scale deployment of atmospheric drawdown practices and technologies.

Are we now range bound on temperature?

July 6, 2021

In my last post I discussed the recent IEA 1.5°C Scenario that sets out what is required to reach net-zero emissions by 2050 and manage the transition within a carbon budget of 500 Gt CO2. The IEA have shown that while this is a relatively straightforward calculation to do (and last year I presented a similar one), the resulting energy transition pathway is extraordinarily difficult to imagine, let alone achieve. While such a pathway might be technically possible, is it actually plausible? Is society socially ready to embark on such a journey and inflict such large scale change upon itself?

A new report coordinated through the University of Hamburg’s Center for Earth System Research and Sustainability (CEN) in close collaboration with multiple partner institutions and funded by the Deutsche Forschungsgemeinschaft (DFG) attempts to answer the question of plausibility. In the annual Hamburg Climate Futures Outlook, researchers make the first systematic attempt to assess which climate futures are plausible, by combining multidisciplinary assessments of plausibility. The inaugural 2021 Hamburg Climate Futures Outlook addresses the question: Is it plausible that the world will reach deep decarbonization by 2050? The authors discuss the outcome in their own blog post, found here.

The methodology employed isn’t a direct technical analysis of the pathway steps, but rather an assessment of a number of social drivers that would be required to underpin such a transition. The authors conclude that deep decarbonisation by 2050 isn’t currently plausible, meaning that warming will exceed 1.5°C. None of the drivers show enough momentum to bring about deep decarbonisation by 2050 and they find that some drivers are currently inhibiting progress.

The authors combined their assessment of social plausibility with the latest set of socioeconomic future emissions scenarios (SSPs) and the latest physical science research on climate sensitivity to show that warming lower than 1.7°C and higher than 4.9°C by the end of the century as currently not plausible. The lower figure of 1.7°C relative to pre-industrial levels corresponds to the lower bound of the 90% uncertainty range in a low emissions IPCC scenario (SSP1-2.6) and  the higher figure of 4.9°C corresponds to the upper bound of the 90% uncertainty range of a higher emissions IPCC scenario (SSP3).

Source: Hamburg Climate Futures Outlook 2021

Reframing this around central estimates for the scenarios gives a plausible range of 1.8°C to 3.8°C for warming by the end of the century. The original Shell Sky 2018 scenario also had a central estimate of about 1.8°C.

While the lower end of the range was analysed by the Hamburg team in terms of social plausibility, the upper end was not (see chart below); presumably that is a task still to be done.

Source: Hamburg Climate Futures Outlook 2021

However, the upper end of the range has been the subject of social plausibility analysis in a recent paper released by the MIT Joint Program on the Science and Policy of Global Change and discussed in this blog. That analysis was led by MIT, with me and my colleague Martin Haigh as contributing authors. A scenario called Growing Pressures was developed to illustrate how and why there is now an inevitable trend towards near zero emissions, catalysed by the physical reality of a rising average surface temperature. Near (net) zero emissions means that warming will stop and the temperature will plateau, but only a rapid shift to near (net) zero emissions will deliver the 1.5°C. The question the analysis sought to answer was what the highest plausible warming outcome might be given that an energy transition is clearly underway and there is real concern growing across society around the issue of climate change.

While political trends, such as populism or leaning to the left or right, tend to come and go over time and social norms shift around as the decades pass, the temperature trend is essentially a monotonic increasing function. As such, the influence it has on our consciousness will only grow over time.  The cascade can be simplified as follows;

  • Climate changes;
    • Global surface temperature continues to rise, and impacts become more apparent.
    • Sea level keeps rising with visible consequences.
  • Concern rises;
    • Voter pressure on cities, states and countries to develop ‘green’ policies.
    • Shareholders pushing companies to take on net-zero emission goals and targets.
  • Local and national governments pursue (piecemeal) interventions;
    • Ongoing actions under the UNFCC under the banner of the Paris Agreement and the emergence of net-zero emissions (NZE) as a framing concept.
    • Incentives and mandates drive down the cost of new energy technologies and lead to further uptake.
    • Large established NZE policy frameworks continue to operate (e.g. EU, California) and some new NZE policy frameworks emerge (e.g. China by 2060).
  • Technology marches on;
    • Renewable energy access becomes cheaper.
    • Developments in physics, chemistry and materials sciences (e.g. PV, storage).
    • Rapid and broadening digitalization of society.
  • Markets rule;
    • Financial markets distance themselves from fossil fuel investments, but particularly coal, and climate-related financial disclosures bring increasing transparency.
    • Demands by businesses and consumers for lower carbon footprint products and some preparedness to pay for this.
    • Development of markets to support low-carbon investment (e.g. nature-based solutions).
    • Alternatives to coal, oil and gas becoming increasingly competitive.

While each of these will undoubtedly vary over time, their ongoing combined effect gives rise to a scenario of continuous change and transition. The central estimate temperature outcome for Growing Pressures is 2.7°C in 2100 leading to a 2.8°C plateau in 2150, well below the 3.8°C central estimate upper threshold discussed above.

Source: MIT Joint Program

Combining the findings of the these two separate analyses indicates that at the current stage of the energy transition, the warming outcome is now range bound between 1.8°C and 2.7°C in 2100, based on central estimates. That range is partly dictated by the development and availability of energy technologies, but is perhaps overwhelmingly driven by social plausibility, as discussed by the Hamburg team and in the MIT report.

The range may well narrow as time goes by. In the short term, if emissions don’t fall quickly, society will rapidly consume the available carbon budget for 1.5°C and then upwards. As was shown in the IPCC 2018 Special Report on 1.5°C (SR15) report and again by the IEA in their own NZE2050 scenario, that budget is less than 500 Gt CO2 for 1.5°C of warming and is currently being consumed at the rate of over a gigaton every ten days (41 Gt per year). However, as the temperature rises and it becomes apparent to society critical thresholds are being passed, that in turn increases the drivers in the Growing Pressures scenario, as well as opening the social plausibility for nearer term reductions. Under such circumstances, repeating the two analyses in 2030 could well see a much narrower range, perhaps 2.0°C to 2.5°C.

None of the above is meant to argue that such a range is a good thing; the IPCC made it plain in their SR15 that we need to stay as close to 1.5°C as possible. However, the analyses are nevertheless important as they act as a signpost to help guide us forwards and they demonstrate that the energy transition is having an impact.

You can read the MIT report here.

Featured image courtesy of the UK Met Office.

Note: Scenarios don’t describe what will happen, or what should happen, rather they explore what could happen. Scenarios are not predictions, strategies or business plans. Please read the full Disclaimer here.

Pathways to 1.5°C

June 11, 2021

In 2018 when the IPCC released their Special Report on 1.5°C, they presented four archetype scenarios to help readers understand that there were fundamentally different approaches to limit long term warming to 1.5°C or below. The scenario pathways are shown below and vary significantly in their approach, time horizon and use of sinks.

Source: IPCC SR15

All four scenarios (P1, P2, P3, P4) are based around the same carbon budget, or total cumulative emissions of 420 Gt from 1.1.2018 consistent with providing a 66% chance of limiting warming to 1.5°C. Whether the carbon budget is aligned with 420 Gt (67th percentile) or 580 Gt (50th percentile), it represents a very limited amount given that annual CO2 emissions are in excess of 40 Gt, so these represent 10-15 years of emissions at current levels. Since this IPCC publication, a further 160 Gt will have been emitted by society by the end of 2021, meaning that the budget is reduced to 260 – 420 Gt.

Source: IPCC SR15

In attempting to align with a very limited carbon budget, the P1 scenario imagines a world of falling overall energy use and a very rapid shift away from fossil fuels. There is no use of geological storage of CO2 and a modest reliance on natural sinks, although in doing so the world must shift away from net-deforestation by the 2040s. By contrast, the P4 scenario sees increasing demand for energy and as a consequence, a much more difficult decarbonisation journey that involves considerable use of sinks in the second half of the century. Notably, the P4 scenario exceeds the carbon budget by quite some amount with peak emissions to the atmosphere of 900 Gt, before reining in the amount to 200 Gt by 2100. This results in P4 being a so-called overshoot scenario, in that the world exceeds 1.5°C during the century before returning to 1.5°C and below by the end of the century.

Source: IPCC SR15

All the above might seem a bit academic, but it became very real recently when the IEA released their 1.5°C scenario and some commentators began comparing it to one of the very few other 1.5°C scenarios, notably Sky 1.5 from Shell.

In fact, the two scenarios are at near opposite ends of the P1 to P4 spectrum.

The IEA 1.5°C scenario looks at the period from 2020 to 2050 and presents a proposal for the problem of containing emissions to a 500 Gt carbon budget (the 580 Gt IPCC number less 80 Gt for the years 2018 and 2019). Apart from recognising that the land based system is likely to reduce this budget by a further 40 Gt over the period (i.e. reducing it to 460 Gt), the analysis limits itself to the energy system and the changes that would be required to meet a 460 Gt cumulative emissions constraint within a 30 year time frame. As is the case in similar scenarios, including Sky 1.5, their analysis assumes rapid electrification of final energy (e.g. electric cars instead of gasoline) and makes use of renewables  and nuclear power generation to produce the electricity. They introduce hydrogen as an energy carrier, make use of bioenergy and include carbon capture and storage (CCS) where fossil fuel remains in use. For the latter, the IEA deploy CCS directly on facilities that use fossil fuels and indirectly through direct air capture for fossil fuel use in applications such as aviation.

All the above steps are well understood, but even given rapid and stretching deployment rates of all technologies, these steps are unlikely to contain emissions to less than 500 Gt in under thirty years. This is because of the expected increase in overall energy use, a consequence of economic growth, the general rise in population and the shift of billions of people from very low energy use lifestyles to at least modest energy use, a simple outcome of development and the provision of basic services like lighting, clean water, food refrigeration and some mobility.

As such, energy modelers looking at a very constrained time frame of 30 years must make the assumption that energy growth can be contained or even fall, as in the IPCC P1 scenario. This is exactly what the IEA have done to meet the carbon constraint. In the 1.5°C Scenario primary energy demand falls from 612 EJ in 2019 to 543 EJ in 2050, a drop of over 10%. Efficiency will certainly help deliver such an outcome and the use of renewable electricity gives the story a big boost as the thermal losses in power stations vanish, although new losses emerge through the use of transmission and storage. But the big story is the widespread assumption of behavioural change across society to reduce energy demand. The chosen measures include steps such as;

  • Ride-sharing in all urban car trips
  • Reducing motorway / freeway speeds to below 100 kph / 60 mph.
  • Increasing temperatures in air conditioned vehicles and buildings.
  • Lowering temperatures in heated buildings.
  • Replacing short flights with high speed rail.
  • Limiting long haul air travel to 2019 levels.

With low energy demand and high deployment rates of new energy technologies it then becomes possible to resolve the carbon budget within a 30 year time frame.

At the other end of the spectrum is the Sky 1.5 scenario, which tackles the problem of a limited carbon budget in a very different way. Sky 1.5 looks at the period from 2020 to 2100, an 80 year time frame, and starts with an expectation of rising global energy demand, even assuming significant energy efficiency improvements across society. The growth in population and the demand for energy services, including significant new demand from developing countries for basic services, cannot be contained and energy demand rises. This immediately poses a challenge in that rising demand more quickly consumes the available carbon budget at the front end, when alternative energy technologies and sinks have not been deployed.

Sky 1.5 also recognises that for many energy technologies, the 2020s still remain a period of development and limited deployment and even for more mature technologies such as solar and wind, a period of early growth where change on a global scale will remain limited.

The solution to this approach is to accept that, at least in the short term, the carbon budget may be consumed and the temperature it is linked to (1.5°C in this case) potentially surpassed for a period of time. The subsequent rapid deployment of sink capacity, both manmade in the form of air capture with geological storage and natural as reforestation, then offers the possibility of a period of net-negative emissions later in the century, to redress the imbalance and reduce cumulative carbon dioxide emissions and therefore temperature. This is the approach that Sky 1.5 takes, as do the IPCC P3 and P4 scenarios. Sky 1.5 takes this approach out of necessity, in that the scenario reaches a limit on energy technology deployment and does not foresee a fall in energy demand.

The end carbon budget for both the IEA 1.5°C scenario and Sky 1.5 are similar, but the IEA restricts itself to a thirty year time-frame, whereas Sky 1.5 operates over an eighty year time-frame. Sky 1.5 is also remodeled by MIT within their integrated assessment model to give a temperature outcome, rather than simply using the IPCC central estimate for a carbon budget. The two scenarios are attempting to answer the same question, but take very different approaches to doing so. There is no right or wrong here, just different ways of solving a tough problem.

Note: Scenarios don’t describe what will happen, or what should happen, rather they explore what could happen. Scenarios are not predictions, strategies or business plans. Please read the full Disclaimer here.

Growing pressures

March 18, 2021

The task of getting to net-zero emissions by 2050 has become the rallying cry behind COP 26 and considerable diplomatic effort is now being applied to the push to get countries to sign up to such an outcome. But plans and outcomes aren’t always aligned, however plans often set the scene for outcomes that at least align with the intention.

Thinking back even a decade, the concept of net-zero emissions barely registered in the political consciousness. In the Copenhagen Accord of 2009, there is only mention of ‘deep cuts in global emissions are required according to science, and as documented by the IPCC Fourth Assessment Report with a view to reduce global emissions so as . . . . ‘ and in the IPCC 4AR, while some of the scenarios show emissions falling to zero late in the second half of the century, this wasn’t a key message for policymakers. Rather, the key message in 2007 in relation to mitigation in the long term, i.e. after 2030, was;

  • In order to stabilize the concentration of GHGs in the atmosphere, emissions would need to peak and decline thereafter. The lower the stabilization level, the more quickly this peak and decline would need to occur. Mitigation efforts over the next two to three decades will have a large impact on opportunities to achieve lower stabilization levels.

By the time the IPCC Special Report on 1.5°C (SR15) appeared in 2018, the key mitigation message was very different.

  • Reaching and sustaining net zero global anthropogenic CO2 emissions and declining net non-CO2 radiative forcing would halt anthropogenic global warming on multi-decadal time scales. The maximum temperature reached is then determined by cumulative net global anthropogenic CO2 emissions up to the time of net zero CO2 emissions and the level of non-CO2 radiative forcing in the decades prior to the time that maximum temperatures are reached.

Moreover, a timeline to 2050 was proposed in SR15 for reaching net-zero emissions.

The history for this change is a separate discussion, but it perhaps started with the simple recognition that climate change is a stock problem and that the stock will only stop growing (and therefore stop the problem getting worse) when the flow into the atmosphere is the same as the flow out, i.e. net-zero. The science community has always known this, but the concept has taken some time to register more widely. I first discussed this in a blog post and made mention of net-zero emissions in 2009.

Today, with society having done little to arrest the flow of carbon dioxide into the atmosphere, the timing for net zero has been brought forward from late in the century to around 2050, based simply on the relationship between temperature and cumulative emissions, or stock. Both companies and policymakers are now focused on the actions required for net zero as 2050 is, in many cases, within their long term planning horizon window for major capital investment.There is growing pressure on all parties to do something, which leads to the declarations of net-zero emissions goals from many countries, with presumably many more to come.

The effort required to achieve an outcome of net-zero emissions by 2050 will be extraordinary, which might raise the question of why countries are being so ambitious (apart from the fact that it is necessary). One answer is perhaps because now, versus just a few years ago, we are heading there anyway; it is just a question of when the goal is reached.

One of the key observations that emerges from the recently released Shell Energy Transformation Scenarios is that within the course of about a century all three scenarios (namely Waves, Islands and Sky 1.5) reach net-zero emissions. In Sky 1.5 is it in in the late 2050s, in Waves around 2100 and Islands perhaps the 2120s (by extrapolation as the Shell World Energy Model doesn’t extend past 2100). The recognition of net-zero emissions as a possible inevitable outcome has been on my mind for some time now and I felt that it needed further analysis. To that end, Shell supported a project by the MIT Joint Program on the Science and Policy of Global Change to look at the implications of where the energy transition is taking society.

The analysis MIT did recognises that there is now a cascade of growing pressures operating in society, starting with the physical reality of a rising average surface temperature. While political trends, such as populism or leaning to the left or right, tend to come and go over time and social norms shift around as the decades pass, the temperature trend is essentially a monotonic increasing function. As such, the influence it has on our consciousness will only grow over time.  The cascade can be simplified as follows;

  • Climate changes;
    • Global surface temperature continues to rise, and impacts become more apparent.
    • Sea level keeps rising with visible consequences.
  • Concern rises;
    • Voter pressure on cities, states and countries to develop ‘green’ policies.
    • Shareholders pushing companies to take on net-zero emission goals and targets.
  • Local and national governments pursue (piecemeal) interventions;
    • Ongoing actions under the UNFCC under the banner of the Paris Agreement and the emergence of net-zero emissions (NZE) as a framing concept.
    • Incentives and mandates drive down the cost of new energy technologies and lead to further uptake.
    • Large established NZE policy frameworks continue to operate (e.g. EU, California) and some new NZE policy frameworks emerge (e.g. China by 2060).
  • Technology marches on;
    • Renewable energy access becomes cheaper.
    • Developments in physics, chemistry and materials sciences (e.g. PV, storage).
    • Rapid and broadening digitalization of society.
  • Markets rule;
    • Financial markets distance themselves from fossil fuel investments, but particularly coal, and climate-related financial disclosures bring increasing transparency.
    • Demands by businesses and consumers for lower carbon footprint products and some preparedness to pay for this.
    • Development of markets to support low-carbon investment (e.g. nature-based solutions).
    • Alternatives to coal, oil and gas becoming increasingly competitive.

While each of these will undoubtedly vary over time, their ongoing combined effect gives rise to a scenario of continuous change and transition. The resultant MIT ‘Growing Pressures’ scenario is built on a series of simple premises; for example, if by 2050 the push-back by financial markets in combination with the falling cost of renewables means that new coal fired power station development ceases globally, then by about 2100 at the latest coal fired generation of electricity will have ceased (because the power stations built up to 2050 would have been largely decommissioned by then). An overview of the premises is shown below, set against the Growing Pressures emissions trajectory.

Progression towards net-zero emissions in the Growing Pressures scenario (Source: MIT Joint Program)

The premises are not meant to be the fast pace changes needed to limit warming to 1.5°C, but an assessment of events that are now seemingly locked into our collective energy system future as a result of the growing pressures. This then establishes a new baseline from which to think about mitigation actions and to assess the progress that is being  made towards a better outcome.

With net-zero emissions looking more like an inevitable outcome than an aspiration, the framing of the climate issue may also change. Looking at the IPCC 5th Assessment Report, readers were presented with a series of impact risk tables that gave the impression of a binary outcome, i.e. society could take action and limit warming to 2°C or accept the consequences of 4°C of warming.

Risk assessment example in IPCC 5th Assessment Report (Source: IPCC)

But the Growing Pressures scenario limits warming to around 2.8°C (central estimate), effectively eliminating the IPCC central outcome of 4°C. In less than a decade the framing of the climate issue has moved from being somewhat unbounded in terms of temperature rise, to one that is bounded between central estimates of 1.5°C and 2.8°C. Both the Shell Waves and Islands scenarios fall within this range and of course Sky 1.5 is at the low end of the range (i.e. 1.5°C).

MIT assessed scenario outcomes (Source: MIT Joint Program)

This finding is not an argument for just letting events play out; 2.8°C would have serious consequences in terms of adaptation. Rather, the finding illustrates that change is underway and highlights the steps needed to accelerate that change. It also strengthens the hand of policymakers as they encourage adoption of a net-zero emissions goal by as many countries as possible.

Returning to this analysis in a decade hence might see the boundaries contract further. Scenarios that continue historical trends of unfettered fossil fuel use no longer seem relevant when a shift toward a low-carbon society is already under way. The task in front of society is now about the pace of change, not whether change can happen.

You can read the MIT report here.

Note: Scenarios don’t describe what will happen, or what should happen, rather they explore what could happen. Scenarios are not predictions, strategies or business plans. Please read the full Disclaimer here.

Featured image courtesy of the UK Met Office.

Carbon budgets, CCS and the energy transition

November 4, 2019

One of the key talking points of the recent Climate Summit in New York was the carbon budget available for a transition that could limit surface temperature warming to 1.5°C. In her speech to the UN, Greta Thunberg made note of the numbers;

“To have a 67% chance of staying below a 1.5 degrees global temperature rise – the best odds given by the [Intergovernmental Panel on Climate Change] – the world had 420 gigatons of CO2 left to emit back on Jan. 1st, 2018. Today that figure is already down to less than 350 gigatons . . . . . . . . . . With today’s emissions levels, that remaining CO2 budget will be entirely gone within less than 8 1/2 years.”

The physics and chemistry of the atmosphere tell us that the currently observed surface temperature warming can only be brought to a halt when society stops adding carbon dioxide to the atmosphere from long sequestered sources (fossil fuels, limestone for cement, global forests). Further, we also know that there are only two pathways forward for doing this – one is to stop the current practice of deforestation and using oil, coal, gas and limestone and the other is to at least remove an equivalent amount of carbon dioxide from the atmosphere for as long as these practices continue.

With this in mind, society has set out on a journey of energy transition, which involves reducing its use of fossil fuels as quickly as possible and reversing forest loss. The goals of the journey are based on our understanding of how much more warming will take place for a given amount of cumulative ongoing emissions; the data was published in the IPCC Special Report on 1.5°C released just over a year ago. It is also clear that the so-called ‘carbon budget’ for 1.5°C of warming (about 0.4°C above current levels) is very small and vanishing rapidly as emissions continue.

Carbon Budget IPCC SR15

For a 2°C goal at 50%, the notional carbon budget of 1500 Gt CO2 looks achievable. While it represents only 35 years of emissions at current levels, on a 0.54 Gt per year linear declining emissions basis to net-zero it could extend to the 2090s, but that means emissions need to start falling from 2020. If there would be a ten year period of flat emissions prior to a fall, then the rate shifts to about 0.75 Gt per year. A fall of 0.54 Gt in the coming year would be about 1.4%, below the rises of the last two years.

Most published strategies that address the carbon budget problem make use of a set of technologies that are well understood and available at scale today, namely various applications of carbon dioxide capture and geological storage. Carbon capture and storage (CCS) can be used today to prevent emissions of carbon dioxide in the first instance when fossil fuels are used, but also offers the potential for removal of carbon dioxide from the atmosphere. But progress in actual scaling and deployment of CCS is essentially moribund, while other energy related technologies are moving ahead. In a world of growing climate anxiety, why is this?

In some cases, there is the belief that CCS is experimental and untested, yet this couldn’t be further from the truth. For starters, the technologies involved have been used in the oil and gas industry for decades, just not in the precise configuration that CCS requires. For example, separating carbon dioxide from other gases is a common practice in the natural gas sector where the gas coming from the well typically contains a low concentration of carbon dioxide, but it must be removed before the product is sent through pipelines and sold to customers. Furthermore, nineteen large scale CCS facilities are in operation around the world, including a Shell operated facility in Canada capturing and storing one million tonnes of carbon dioxide per annum. CCS technology may well improve, but it certainly isn’t experimental or untested, nor does it require pilot plant testing or demonstration – that phase is well and truly over. New CCS technologies will undoubtedly emerge and they will be subject to demonstration, but that is true for any technology pathway.

For others there is a belief that alternative technologies will emerge, be deployed very rapidly and effectively do away with the need for CCS. This is based on a view that the world can quickly move on from using fossil fuels, but is very unlikely to be the case. While there are clearly a set of technologies now available to generate electricity without fossil fuels, we are still very distant from a society based entirely on electricity using solar PV, wind turbines and nuclear reactors. Electricity makes up just 20% of the energy we use to provide services and historically that has shifted at a rate of two percentage points per decade. But even doubling or quadrupling the rate of change would still mean a century or more of transition and likely exceeding the desired carbon budget along the way. Further to this, there are many applications for combustion based energy provision where an electricity pathway doesn’t exist (e.g. cement manufacture, aviation). Some ideas are out there, but moving from concept to full scale commercial deployment is a multi-decade programme in itself.

We shouldn’t underestimate the time it takes to move from one system to another or build whole new systems. Even the internet has taken 25 years to deploy at scale, but that was on the back of an existing telephony system and was based on technologies that were first tested 25 years prior, in the late 1960s. In the field of energy transition, even longer time-frames are likely. The first Liquefied Natural Gas (LNG) carrier commenced operation 60 years ago, with the current market now reaching around 350 million tons per year; that’s about 17 EJ, or less than 5% of global energy demand. In the Shell Sky scenario we imagine a global hydrogen industry in 2100 that is four times this size and yet still only provides about 10% of final energy. Building a significant hydrogen and electricity based energy system (or any other system) to replace the current fossil fuel system is quite possible, but the time-span to do so will be measured in decades.

Finally, there are those who just claim that CCS costs too much, but usually without a reference to compare it with. Mitigating carbon dioxide won’t come at no cost, so the costs we do incur are all relative. Depending on the application, CCS projects can cover a range from as little as $30 per ton of carbon dioxide (e.g. in ethanol plants in the USA) to over $100 per ton in power stations. But as infrastructure develops costs will come down, as has been the case for many other technologies. Building a new electricity system based on renewable energy or deploying electric vehicles (EV) will also come at a cost, in some cases in excess of the cost of utilizing CCS, but the option to use CCS instead may not be available due to policy choices. This happens in instances where governments have given preference to certain energy technologies, rather than looking more broadly at the full range of opportunities for managing emissions. A challenge often faced by CCS is that its cost in CO2 terms is very transparent, against other technologies where costs on a CO2 basis are often not published or even used.

So we are left with the dilemma of a vanishing carbon budget and the eventual deployment of an alternative fossil fuel free energy system that will likely mean breaching that budget. Technologies and approaches that seek to remove carbon dioxide from the atmosphere or prevent emissions in the first instance can bridge this gap. This includes the full range of application of CCS technologies, but also the use of nature based solutions such as large scale afforestation. In the Shell Sky scenario the use of CCS in industry ramps up rapidly from the 2030s as this is an immediately available technology. It peaks in the 2070s and then starts to decline, as new technologies begin to deploy at scale, for example hydrogen based smelting of iron ore. This forty year gap is successfully bridged with CCS. We could imagine that by the middle of the 22nd century there is no further need for CCS in industry as a complete transition away from fossil fuels has taken place. But for 50 to 100 years, CCS has offered the possibility of no net addition of carbon dioxide to the atmosphere, even as fossil fuel use continues in legacy industrial processes.

Sky Heavy Industry