Natürlicher Klimazyklus in der Antarktis aktiv

IOP Publishing:

Cost of climate change: 2°C global warming target not economically reasonable unless we make major changes, says study

Climate change goals set out in the Paris Agreement are only economically reasonable if non-market factors such as human health and loss of biodiversity are prioritized, according to a new study published by Dr. Taikan Oki, former Senior Vice-Rector of United Nations University headquartered in Japan, in Environmental Research Letters.

A multi-disciplinary, collaborative effort from researchers at 23 institutions including The University of Tokyo, National Institute for Environmental Studies, and Kyoto University, the new study provides a cost-benefit analysis of climate change including previously neglected non-market factors such as biodiversity loss and the impact on human health. The team calculated the cost of climate change for varying priority systems, estimating the total cost including mitigation between 2010 and 2099 to be 46–230 trillion US dollars.

The results show that the financial benefits of reducing climate change are often similar to the cost of mitigation efforts. The research team estimate the cost of additional mitigation efforts to be 45 to 130 trillion US dollars, while the financial benefits of these reduction efforts range from 23 to 145 trillion US dollars. They found that for the 2°C temperature goal to be economically feasible there must be a greater emphasis placed on the future impact of biodiversity and health factors, arguing that these factors will become ever more pressing in the future.



University of Aberdeen:

Study highlights carbon capture, utilization and storage potential for North Sea ‘super basin’

A research study led by the University of Aberdeen has identified areas of a North Sea gas ‘super basin’ with the greatest potential for storing industrial carbon emissions, a key aim of the energy transition.

Scientists from the University’s Center for Energy Transition used subsurface data and techniques usually employed in oil and gas exploration, to produce a detailed technical study of the Anglo-Polish Super Basin in the Southern North Sea to determine its suitability for carbon capture, utilization and storage (CCUS).

Their results confirm the huge potential of the area—a globally important hydrocarbon basin—as a future CCUS hub where industrial emissions can be safely stored in former gasfields and other geological formations.

If used in this way, the basin could play a major role in helping European nations sequester carbon emissions and meet net zero targets while promoting energy security, protecting industrial activity and prolonging the life of North Sea basin infrastructure.

As well as showing the geological criteria that determine the areas with the greatest potential, the study also highlights the need to assess non-geological risks—such as the potential for leaks along legacy wells and the need to avoid co-location conflicts with other stakeholders such as windfarm operators or the fishing industry.

The research provides a framework that can be used to determine CCUS suitability in other major basins around the world, as part of global efforts to safely store billions of metric tons of CO2 in geological formations.

The two-year study was led by Professor John Underhill, Director of the University’s Center for Energy Transition, along with colleagues from Heriot Watt University in Edinburgh. It was published in the AAPG Bulletin.

Professor Underhill said, “The study highlights the areas where the best carbon stores are located and provides a basis to evaluate and rank sites.

“Perhaps just as importantly, it also demonstrates the urgent need for regulators and stakeholders to work together to resolve any issues that may arise from the co-location and overlap of technologies to avoid competition for the offshore real estate. This is vital in ensuring that the UK remains on track to retain energy security and meet its net zero emission targets.

“The study also has global relevance and application, and the workflow we have used has already been adopted by other countries. We have also used it to undertake studies in other parts of the UK as well as in Malaysia, Egypt and Brazil.”

Dr. Nick Richardson, Head of Exploration & New Ventures at the UK’s regulator for Carbon Storage activities, the North Sea Transition Authority, said, “The Aberdeen University-led team has made a timely and incisive contribution with this world-class research that puts the UK’s storage resource capability on the map as a leading destination for the sequestration of industrial emissions from across Europe.

“By establishing a consistent regional geological framework, this work will assist the evaluation of storage sites within the Southern North Sea, allowing the optimization of their exploitation and supporting assessments of risk and uncertainty. It will also aid regulatory and marine planning bodies in their ongoing efforts to identify synergies between offshore activities, and maximize opportunities for innovation and collaboration on the pathway to net zero.”

Graeme Davies, Harbor Energy’s Project Director of Viking CCS said, “The UK Continental Shelf, and in particular the Southern North Sea Gas Basin, provides world-class CO2 storage opportunities as we look to decarbonize our industrial and power sectors.

“This leading independent academic study into the basin’s geology and structured approach to risk segment analysis provides a robust platform for the long-term development of CO2 storage opportunities and provides further insight into how we are well positioned to use our existing oil and gas sector’s skills, data and infrastructure to help develop the burgeoning CCS industry in the UK.”

Paper: Use of exploration methods to repurpose and extend the life of a super basin as a carbon storage hub for the energy transition. AAPG BulletinDOI: 10.1306/ … le/107/8/1419/627234


Ari Plachta, The Sacramento Bee (via

California’s ambitious 2030 climate target faces serious obstacles, acknowledges regulator

For the first time, California’s leading air regulator acknowledged major roadblocks to meeting its ambitious carbon emissions target for 2030, a goal the agency set just months ago in a sweeping plan to tackle climate change.

The hurdles revolve around the feasibility of carbon capture technologies and the state’s flagship climate program, known as cap-and-trade. It’s a tension poised to intensify as the California Air Resources Board navigates a transformation of the energy economy. Central to the debate is the question of whether California should tighten the reins on industrial emitters by strengthening its cap-and-trade program, which established an emissions trading system aimed at cutting emissions while providing flexibility for industry. In its 2022 climate change roadmap, the agency placed heavy bets on emerging technologies to remove carbon pollution from the atmosphere, setting a target to reduce emissions across the economy to 48% below 1990 levels by 2030—an increase from the previous 40%.

But Air Board staff now say those technologies may not be widely available in time. As a result, they say relying solely on cap-and-trade could drive carbon prices to unmanageable heights and push industrial polluters out of California. Dave Clegern, an Air Board spokesman, emphasized the need to overcome carbon removal infrastructure challenges to attain the ambitious 48% reduction goal. “If those tools are not widely available by 2030 with a 48% target, then prices get very high in the program and that leads to leakage—production moving out of state to reduce emissions in state and comply with the program,” Clegern said in a statement.



Alessandro Silvano et al. 2023 auf The Conversation:

Slowing deep Southern Ocean current may be linked to natural climate cycle – but that’s no reason to stop worrying about melting Antarctic ice

Our new research in the Antarctic suggests that the vital layer of cold water on the sea bed, which circulates the globe and influences the ocean’s ability to continue absorbing much of the rise in atmospheric heat and greenhouse gas emissions, is heating up and shrinking.

Much of this is a result of human-made climate change, which is melting Antarctic ice shelves and disrupting the complex system that controls this circulation. But it appears, as far as the past 30 years are concerned, a natural cycle may have been partly responsible for the changes observed.

The ocean has absorbed more than 90% of the excess heat and around 30% of the extra carbon dioxide humans have generated since the start of the industrial age. This has greatly reduced the impact of climate change at the Earth’s surface where we live.

Most of this exchange of gases and heat between the atmosphere and the ocean happens in the Southern Ocean around Antarctica through the complex vertical movement of water. One of the biggest drivers of this vertical movement is the production of what oceanographers call Antarctic bottom water.

Around the Antarctic coastline, seawater near freezing point contacts the much colder air and freezes into sea ice, expelling salt and consuming freshwater to leave cold, salty and dense water.

The vast majority of this dense water is produced at only a few locations around Antarctica. In these places, wind blowing off the frigid continent continually pushes newly formed sea ice away from the surrounding ice shelves to create areas of open water known as polynyas.

These polynya ice factories produce great volumes of cold and salty water which cascade down Antarctica’s continental slope like a submarine waterfall to the ocean bottom. Once there, Antarctic bottom water, the world’s deepest and densest water mass and the biggest of its kind spreads around the globe, storing carbon from the atmosphere for hundreds or even thousands of years.

As Antarctic bottom water moves north along the sea floor it drives the great ocean conveyor, also known as the overturning circulation: currents that redistribute heat, carbon and nutrients around ocean basins and regulate the global climate.

Our new research used observations from ships and satellites to reveal that the bottom water volume in the Weddell Sea, the Atlantic sector of the Southern Ocean and one of the biggest producers of this water mass, has decreased by more than 20% over the past 30 years, causing the deep Weddell Sea to warm four times faster than the global average.

Our evidence suggests weakening offshore winds in the region are to blame for polynyas shrinking and making less of the cold, dense, salty water which feeds Antarctic bottom water and drives the global ocean conveyor. This could slow down the deep overturning circulation, with profound implications for the climate system.

Previous studies have linked the slowing global ocean conveyor with less cold, dense water forming in the Southern Ocean due to increasing meltwater from ice shelves. While man-made climate change is significant, our new research suggests that natural variability in wind and sea ice are also important.

What’s up with the wind in the Weddell Sea?

Weaker winds blowing offshore in the southern Weddell Sea over the past 30 years have limited the size of the coastal polynya, which in turn has produced less sea ice.

We found that this change in the wind seems to be linked to surface temperature changes over the tropical Pacific during the same period, part of a natural cycle similar to El Niño, known as the Interdecadal Pacific Oscillation.

Oscillating sea surface temperatures in the tropical Pacific are strong enough to affect the local air pressure and even influence the wind on both sides of the Antarctic peninsula. This means that the trend in Weddell Sea winds and consequent Antarctic bottom water formation over the past 30 years may also be part of a longer natural cycle.

If it is natural, should we stop worrying?

Ship-based observations have helped us show that the bottom water layer has been warming and thinning everywhere around Antarctica for decades. In regions other than the Weddell Sea, both recent model predictions and observations suggest that this can be explained by increasing freshwater from melting Antarctic ice shelves, which disrupts the formation of salty and dense water that would otherwise sink.

A similar change was found in the bottom water layer of the Weddell Sea, although the ice shelves here are not melting nearly as rapidly as elsewhere in the Antarctic. This is mainly because the polynya sea ice factory near the coast usually keeps warmer Southern Ocean water at bay.

Although our study suggests that changes in the Weddell Sea are a result of natural variability in the Earth system, they are also part of an Antarctic-wide trend that is not as clearly explained by natural causes. In fact, freshening and shrinking bottom water is consistent with scientific predictions about the melting ice sheet. Satellite observations have shown a steady loss in ice sheet mass since 2002.

Models are one of the best tools for translating current knowledge of physics and present and past conditions into an understanding of the future climate. But their representation of many important processes, such as Antarctic bottom water formation, is often incomplete. And so it takes ongoing research to advance our understanding of how the Earth system works and refine projections of the future.

More and more evidence indicates that the Antarctic ice sheet is vulnerable to the warming climate and that the melting of this great reservoir of ice will disrupt the overturning circulation that extends throughout the global ocean. This will disrupt the climate and accelerate sea-level rise globally.

As scientists who study the complex interaction between the ocean, ice sheet and atmosphere around Antarctica, we hope that continuing to refine our understanding of the Earth system and future climate projections will help inform decision makers. Systematic efforts are needed to immediately reduce greenhouse gas emissions and slow the pace of global warming.