Sean

5 posts
An image visually contrasting carbon-intensive industry with climate-resilient development. A central river flowing from distant mountains divides the scene into two distinct halves. The left side depicts a polluted, grey environment featuring factory smokestacks emitting dark clouds of smog, an active oil beam pump, heavy motor vehicle traffic, bare dead trees, red warning signs, and an outflow pipe discharging brown toxic waste into the left half of the river. In sharp contrast, the right side displays a clean, sustainable environment rendered in vibrant greens and blues. This side features tall wind turbines, ground-mounted solar panels, modern green buildings integrated with nature, electric vehicle charging stations, bicycles, and lush leafy trees. The right half of the river runs a clear blue, contrasting directly with the polluted water on the left, while the sky transitions from dark and smoggy on the industrial side to bright with crisp white clouds on the sustainable side. Source: Adobe Stock 714565142.
Decarbonisation

Mitigation options

“All global modelled pathways that limit warming to 1.5°C (>50%) with no or limited overshoot, and those that limit warming to 2°C (>67%), involve rapid and deep and in most cases immediate GHG emission reductions in all sectors. Modelled mitigation strategies to achieve these reductions include transitioning from fossil fuels without CCS to very low- or zero-carbon energy sources, such as renewables or fossil fuels with CCS, demand side measures and improving efficiency, reducing non-CO2 emissions, and deploying carbon dioxide removal (CDR) methods to counterbalance residual GHG emissions.” [IPCC (2022) AR6 WGIII, Summary for Policymakers, C.3, pg. 24]

A photograph of Earth viewed from space, showing the bright blue curve of the atmosphere against the black void. Swirling white clouds cover much of the planet below, while golden sunlight reflects off the ocean surface, casting long dark shadows from towering cloud formations. Source: ISS/NASA (downloaded 24 Aug. 2018) from https://www.theguardian.com/environment/2017/aug/18/climate-scientist-clouds-climate-change-interview-kate-marvel
Decarbonisation

A growing imbalance: carbon, ocean heat, and rising seas

Key ideas Our collective greenhouse gas (GHG) emissions are disrupting the Earth’s energy balance. This enhanced greenhouse effect is driving up global mean temperatures and pushing us out of the Holocene sweet spot, the stable climate window where civilisation developed. Due to the huge thermal inertia of the Earth’s oceans, […]

A floating step bar chart set against a photographic background of a bright blue sky and white clouds, comparing historic carbon dioxide emissions against future carbon budgets. The vertical axis measures CO2 emissions in gigatonnes, scaling from 0 to 4000 in increments of 1000. The chart uses blue rectangular blocks to stack cumulative emissions over time, with black vertical whiskers on each block indicating uncertainty ranges. The historical sequence begins with a block for 1850 to 1989 adding 1400 plus or minus 195 gigatonnes. Floating directly above this, the 1990 to 2009 block adds 620 plus or minus 60 gigatonnes. Floating above that, the 2010 to 2019 block adds 410 plus or minus 30 gigatonnes. This creates a cumulative historical baseline of 2430 gigatonnes by the end of 2019. From this identical 2019 baseline level, two alternative future budget blocks are plotted side-by-side. The 1.5 degrees Celsius budget block adds 500 plus or minus 220 gigatonnes. Next to it, the 2 degrees Celsius budget block adds 1200 plus or minus 220 gigatonnes. Visually, the chart emphasises that the remaining budget for 1.5 degrees Celsius is exceptionally small, representing less than the emissions produced in just the single 1990 to 2009 historical time block.
Decarbonisation

Carbon budgets

“Cumulative net CO2 emissions over the last decade (2010–2019) are about the same size as the remaining carbon budget to limit warming to 1.5°C (>67%) (medium confidence). 62% of total cumulative CO2 emissions from 1850 to 2019 occurred since 1970 (1500 ± 140 GtCO2), about 43% since 1990 (1000 ± 90 GtCO2), and about 17% since 2010 (410 ± 30 GtCO2). For comparison, the remaining carbon budget for keeping warming to 1.5°C with a 67% (50%) probability is about 400 (500) ± 220 GtCO2” [IPCC (2022) AR6 WGIII Technical Summary, pg. 61]

Decarbonisation

Carbon dioxide removal & solar radiation modification

Carbon dioxide removal (CDR) is defined as “Anthropogenic activities removing carbon dioxide (CO2) from the atmosphere and durably storing it in geological, terrestrial, or ocean reservoirs, or in products.” [IPCC (2021) AR6 WGI Annex VII, Glossary, pg. 2221]
Solar radiation modification (SRM) “contrasts with climate change mitigation activities, such as emissions reductions and CDR, as it introduces a ‘mask’ to the climate change problem by altering Earth’s radiation budget, rather than attempting to address the root cause of the problem, which is the increase in GHGs in the atmosphere. By masking only the climate effects of GHG emissions, SRM does not address other issues related to atmospheric CO2 increase, such as ocean acidification.” [IPCC (2021) AR6 WGI, Technical Summary, Box TS.8, pg. 105]

A two-panel line and area graph, comparing global carbon dioxide emissions from 2010 to 2100 across two different pathways: the Low Energy Demand, or LED, scenario on the left and a scenario labelled SSP2-2.6 on the right. A legend at the top explains the visual elements. A thick black line tracks the total amount of CO2 produced in the economy, a dashed purple line indicates gross CO2 emissions emitted into the atmosphere, and a solid light blue line tracks net CO2 emissions emitted into the atmosphere. Shaded areas represent specific sources and sinks: solid grey for gross fossil fuel and industry emissions, a hatched pattern for fossil fuel and industry emissions captured with carbon capture and storage (CCS), brown for net CO2 emissions from agriculture, forestry and other land use (AFOLU), and yellow for gross CO2 removal by bioenergy combined with CCS (BECCS). Both panels share a vertical axis measuring annual global CO2 emissions in gigatonnes per year, scaling from negative 20 to 50. The left panel for the LED scenario shows the thick black line for total CO2 produced dropping rapidly and steeply towards near zero, closely matched by the purple dashed line. It contains no hatched or yellow areas, relying solely on rapid fossil fuel emissions reduction and a small brown land-use sink to push the light blue net emissions line below zero around 2050. In contrast, the right panel for the SSP2-2.6 scenario shows the black total emissions line remaining much higher throughout the century. To achieve net-zero emissions, this scenario requires a massive hatched area emerging after 2030, representing extreme deployment of carbon capture to offset the delayed fossil fuel phase-out, alongside a deep yellow area appearing below the zero line representing heavy reliance on BECCS technologies. Consequently, the light blue net emissions line takes decades longer to reach zero, finally crossing the threshold around 2070. Source: a presentation by Arnulf Grubler on a Low Energy Demand scenario (downloaded in 2019).
Decarbonisation

Global decarbonisation scenarios

“Scenarios with very low or low GHG emissions (SSP1-1.9 and SSP1-2.6) lead within years to discernible effects on greenhouse gas and aerosol concentrations and air quality, relative to high and very high GHG emissions scenarios (SSP3-7.0 or SSP5-8.5). Under these contrasting scenarios, discernible differences in trends of global surface temperature would begin to emerge from natural variability within around 20 years, and over longer time periods for many other climatic impact-drivers (high confidence).” [IPCC (2021) AR6 WGI Summary for Policymakers, D.2, pg. 30]