The ocean remembers – the new dimension of climate legacy
The IPCC Special Report on Global Warming of 1.5°C sent a message of urgency. The IPCC Special Report on the Ocean and Cryosphere in a Changing Climate re-emphasises it and adds the dimensions of legacy of our actions. It shows how changes in ocean and cryosphere will continue for centuries and millennia even after emissions have seized. Sea levels in 2300 might exceed 3.5m under very high emission scenarios, and only achieving the Paris Agreement temperature goal would give a good chance to hold 2300 sea level rise below 1m.
The climate reality to date
Impacts of climate change on ocean and cryosphere are already unequivocal today; marine heatwaves’ frequency has doubled in forty years and caused irreversible loss, such as for the Great Barrier Reef that has already lost 50% of its shallow-water corals. Limiting warming to 1.5°C would lead to a decline by a further 70-90% at 1.5°C with larger losses (>99%) at 2°C at the end of the century, emphasizing the need for urgent action but also the loss and damage inferred by climate change to these unique and precious systems already.
Changes are pervasive and observed from high mountains, to the polar regions, to coasts, and into the deep ocean, strongly exposing communities who live in connection to these environments. Loss and damage is already a reality for vulnerable coastal communities, some of them being forced to migrate.
Achieving the goals of the Paris Agreement would substantial reduce climate change impacts
The IPCC assessment reveals the benefits of ambitious mitigation and effective adaptation for sustainable development and, conversely, the escalating costs and risks of delayed action. It also establishes how adaptation can only delay impacts in ocean and cryosphere, and not be a ‘solution’. Limits to adaptation can be reached and exceeded if warming exceeds 1.5°C; adaption costs for coastal adaptation alone for some small island states can amount to several percent of GDP.
Under a high greenhouse gas emission scenario (RCP8.51 ), at the end of the century, the ocean will have taken up 5-7 times more heat compared to the observed accumulated ocean heat uptake since 1970; marine heatwaves will be 50 times more frequent; sea level rise will reach around 0.84 m with respect to 1986-2005; the global-scale biomass of marine animals across the food-web will decrease by 15%, the maximum catch potential of fisheries by 20%. Millions of people are and will continue to be threatened by sea-level rise, even under a low emission scenario (RCP2.62 ).
Post-IPCC science re-emphasizes the importance of limiting warming to below 2°C to avoid tipping points
Recent science has found that at 2°C warming, the West Antarctic Ice Sheet would reach a tipping point. In addition, emissions implied by present day NDCs would commit the world to sea level rise above 1m in 2300 with the NDCs of the biggest five emitters (China, US, EU, India, Russia) alone contributing about 12cm. In addition, new elevation data has revealed that three times more people might be vulnerable to sea-level rise and coastal flooding than previously thought.
New science on permafrost release reveals how abrupt permafrost thaw can lead to increased rates of greenhouse gas emissions.
Impacts on the marine biosphere continue to emerge. In 2020, the Great Barrier Reef has experienced its worst mass bleaching event since 1998 and this in a year without an El Niño. February 2020 had the highest monthly sea surface temperatures ever recorded on the Great Barrier Reef, and for the first time, severe bleaching has struck all three regions of the Great Barrier Reef – the northern, central and now large parts of the southern sectors.
Coastal loss and damage for small islands
This commentary on a paper in Nature Sustainability reviews how the study quantifies the impacts of sea-level rise on small island states and estimates the impacts in terms of cost, land loss and population exposure across all small islands worldwide.
Risks of synchronised low yields are underestimated in climate and crop model projections
This study finds that the jet stream – air currents in the upper atmosphere – can synchronise extreme weather caused by climate change, resulting in crop failures in multiple countries at the same time.
The deployment length of solar radiation modification: an interplay of mitigation, net-negative emissions and climate uncertainty
Here, we investigate the deployment timescales of solar radiation modification and how they are affected by different levels of mitigation, net-negative emissions and climate uncertainty.
Solar radiation modification: a dangerous distraction from required emissions reductions
Investing precious time and resources in this critical decade to explore SRM technologies distracts from the urgent need to step up mitigation efforts to halve emissions by 2030.
Emissions as usual: implications for the Safeguard Mechanism of LNG and coal mine projects
This report examines the implications of committed and proposed developments in the LNG and coal mining sectors for reform of Australia's Safeguard Mechanism.
Only halving emissions by 2030 can minimise risks of crossing cryosphere thresholds
Institutional decarbonisation scenarios evaluated against the Paris Agreement 1.5°C goal
This study analyses six institutional decarbonisation scenarios published between 2020 and mid 2021 (including four from the oil majors and two from the International Energy Agency. It finds that most of the scenarios would be classified as inconsistent with the Paris Agreement as they fail to limit warming to ‘well below 2 ̊C, let alone 1.5 ̊C, and would exceed the 1.5 ̊C warming limit by a significant margin.
Uncertainty in near-term temperature evolution must not obscure assessments of climate mitigation benefits
This work comments on a study by Samset et al. that found the effects of emission mitigation will only be perceived through global temperature with a multi-decadal delay. This paper provides additional context and expresses concerns with the approach.
An emission pathway classification reflecting the Paris Agreement climate objectives
When categorising pathways in line with the Paris Agreement, the focus has been put on the temperature outcome. Here we propose a pathway based on emission reduction objectives that reflect the climate criteria set out in the Paris Agreement.
No time for complacency: without closing the 2030 gap, net zero targets cannot prevent severe climate impacts
Fossil gas: a bridge to nowhere
This report assesses how fast fossil gas power generation must be phased out in different parts of the world to keep the Paris Agreement’s 1.5°C temperature goal in reach.
Managing climate change risks to world heritage using the In Danger List: Griffith climate action beacon policy discussion paper
This paper considers how the World Heritage Convention’s ‘List of World Heritage in Danger’ could be used more effectively for managing sites threatened by climate change or where climate change has already caused significant degradation.