Menu

causes

dairy cows are methane producing machines

, , , , , , , , , , , ,

Authors: Milena Bojovic, PhD Candidate, Macquarie University


This article is republished from The Conversation under a Creative Commons license. Read the original article.

Milena Bojovic, Macquarie University

New Zealand’s dairy sector faces an uncertain future due to several challenges, including water pollution, high emissions, animal welfare concerns and market volatility.

All of these issues are building tensions and changing public perceptions of dairy farming.

In my new research, I argue the time has come for the dairy sector to adopt a “just transition” framework to achieve a fair and more sustainable food future and to navigate the disruptions from alternative protein industries.

The concept of a just transition is typically applied to the energy sector in shifting from fossil fuels to renewable energy sources.

But a growing body of research and advocacy is calling for the same principles to be applied to food systems, especially for shifting away from intensive animal agriculture.

Aotearoa New Zealand’s dairy sector is an exemplary case study for examining the possibilities of a just transition because it is so interconnected in the global production and trade of dairy, with 95% of domestic milk production exported as whole-milk powder to more than 130 countries.

Environmental and economic challenges

New Zealand’s dairy sector faces significant threats. This includes environmental challenges such as alarming levels of nitrate pollution in waterways caused by intensive agriculture.

The sector is also a major source of emissions of biogenic methane from the burps of almost six million cows in the national dairy herd.

Debates about how to account for these emissions have gone on for many years in New Zealand. But last month, the coalition government passed legislation to keep agriculture out of the Emissions Trading Scheme.

This means livestock farmers, agricultural processors, fertiliser importers and manufacturers won’t have to pay for on-farm emissions. Instead, the government intends to implement a pricing system outside the Emissions Trading Scheme by 2030. To meet emissions targets, it relies on the development of technologies such as methane inhibitors.

A cheese board with soem bread and a cheese made from cashews
The development of plant-based and fermentation proteins poses another threat to the dairy sector. Getty Images

In addition to environmental challenges, global growth and domestic initiatives in the development of alternative dairy products are changing the future of milk production and consumption.

New Zealand dairy giant Fonterra is pursuing the growth of alternative dairy with significant investments in a partnership with Dutch multinational corporation Royal-DSM. This supports precision fermentation start-up Vivici, which already has market-ready products such as whey protein powder and protein water.

Fonterra’s annual report states it anticipates a rise in customer preference towards dairy alternatives (plant-based or precision-fermentation dairy) due to climate-related concerns. The company says these shifting preferences could pose significant business risks for future dairy production if sustainability expectations cannot be met.

Pathways to a just transition for dairy

What happens when one the pillars of the economy becomes a major contributor to environmental degradation and undermines its own sustainability? Nitrate pollution and methane emissions threaten the quality of the land and waterways the dairy sector depends on.

In my recent study which draws on interviews with people across New Zealand’s dairy sector, three key transition pathways are identified, which address future challenges and opportunities.

  • Deintensification: reducing the number of dairy cows per farm.

  • Diversification: introducing a broader range of farming practices, landuse options and market opportunities.

  • Dairy alternatives: government and industry support to help farmers participate in emerging plant-based and precision-fermentation industries.

While the pathways are not mutually exclusive, they highlight the socioeconomic and environmental implications of rural change which require active participation and engagement between the farming community and policy makers.

The Ministry of Business, Innovation and Employment recently published a guide to just transitions. It maps out general principles such as social justice and job security.

But the guide is light on advice for agricultural transitions. My work puts forward recommendations to shape future policy for a more just and sustainable dairy future. This includes issues such as navigating intensification pressures, supporting the development of alternative proteins and fundamentally supporting farmer agency in the transition process.

For the dairy transition to be fair and sustainable, we need buy-in from leadership and support from government, the dairy sector and the emerging alternative dairy industry to help primary producers and rural communities. This needs to be specific to different regions and farming methods.

The future of New Zealand’s dairy industry depends on its ability to adapt. Climate adaptation demands balancing social license, sustainable practices and disruptions from novel protein technologies.The Conversation

Milena Bojovic, PhD Candidate, Macquarie University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

carbon dioxide emissions

, , , , , , , , ,


This article is republished from The Conversation under a Creative Commons license. Read the original article.
___________________________________________________________________________________

The COP28 climate summit in Dubai has adjourned. The result is “The UAE consensus” on fossil fuels.

This text, agreed upon by delegates from nearly 200 countries, calls for the world to move “away from fossil fuels in energy systems in a just, orderly and equitable manner”. Stronger demands to “phase out” fossil fuels were ultimately unsuccessful.

The agreement also acknowledges the need to phase down “unabated” coal burning and transition towards energy systems consistent with net zero emissions by 2050, while accelerating action in “the critical decade” of the 2020s.

As engineers and scientists who research the necessary changes to pull off this energy system transition, we believe this agreement falls short in addressing the use of fossil fuels at the heart of the climate crisis.

Such an approach is inconsistent with the scientific consensus on the urgency of drastically reducing fossil fuel consumption to limit global warming to 1.5°C.


‘Abated’ v ‘unabated’

The combustion of coal, oil and gas accounts for 75% of all global warming to date – and 90% of CO₂ emissions.

So what does the text actually ask countries to do with these fuels – and what loopholes might they exploit to continue using them well into the future?

Those countries advocating for the ongoing use of fossil fuels made every effort to add the term “unabated” whenever a fossil fuel phase-down or phase-out was proposed during negotiations.

“Abatement” in this context typically means using capture capture and storage technology to stop CO₂ emissions from engines and furnaces reaching the atmosphere.

However, there is no clear definition of what abatement would entail in the text. This ambiguity allows for a broad and and easily abused interpretation of what constitutes “abated” fossil fuel use.

Will capturing 30% or 60% of CO₂ emissions from burning a quantity of coal, oil or gas be sufficient? Or will fossil fuel use only be considered “abated” if 90% or more of these emissions are captured and stored permanently along with low leakage of “fugitive” emissions of the potent greenhouse gas methane, which can escape from oil and gas infrastructure?

This is important. Despite the agreement supposedly honouring “the science” on climate change, low capture rates with high residual and fugitive emissions are inconsistent with what research has shown is necessary to limit global warming to the internationally agreed guardrails of 1.5°C and 2°C above pre-industrial temperatures.

In a 2022 report, the Intergovernmental Panel on Climate Change (IPCC) indicated that almost all coal emissions and 33%-66% of natural gas emissions must be captured to be compatible with the 2015 Paris agreement.

That’s assuming that the world will have substantial means of sucking carbon (at least several billion tonnes a year) from the air in future decades. If these miracle machines fail to materialise, our research indicates that carbon capture would need to be near total on all fuels.

The fact that the distinction between “abated” and “unabated” fossil fuels has not been clarified is a missed opportunity to ensure the effectiveness of the Dubai agreement. This lack of clarity can prolong fossil fuel dependence under the guise of “abated” usage.

This would cause wider harm to the transition by allowing continued investment in fossil fuel infrastructure – new coal plants, for instance, as long as some of the carbon they emit is captured (abated) – thereby diverting resources from more sustainable power sources. This could hobble COP28’s other goal: to triple renewable energy capacity by 2030.

By not explicitly defining these terms, COP28 missed the chance to set a firm, scientifically-backed benchmark for future fossil fuel use.

The coming age of carbon dioxide removal

Since the world is increasingly likely to overshoot the temperature goals of the Paris agreement, we must actively remove more CO₂ from the atmosphere – with reforestation and direct air capture (DAC), among other methods – than is emitted in future.

Some carbon removal technologies, such as DAC, are very early in their development and scaling them up to remove the necessary quantity of CO₂ will be difficult. And this effort should not detract from the urgent need to reduce emissions in the first place. This balanced approach is vital to not only halt but reverse the trajectory of warming, aligning with the ambitious goals of the Paris agreement.

There has only really been one unambiguously successful UN climate summit: Paris 2015, when negotiations for a top-down agreement were ended and the era of collectively and voluntarily raising emissions cuts began.

A common commitment to “phase down and then out” clearly defined unabated fossil fuels was not reached at COP28, but it came close with many parties strongly in favour of it. It would not be surprising if coalitions of like-minded governments proceed with climate clubs to implement it.

Polar stratospheric clouds: Night Lights Films - Adrien Mauduit

, , , , , , , , , ,


This article is republished from The Conversation under a Creative Commons license. Read the original article.

Our planet has warmed by about 1.2°C since 1850. But this warming is not uniform. Warming at the poles, especially the Arctic, has been three to four times faster than the rest of the globe. It’s a phenomenon known as “polar amplification”.

Climate models simulate this effect, but when tested against the past 40 years of warming, these models fall short. The situation is even worse when it comes to modelling past climates with very high levels of greenhouse gases.

This is a problem because these are the same models used to project into the future and forecast how the climate will change. They are likely to underestimate what will happen later this century, including risks such as ice sheet melting or permafrost thawing.

In our new research published today in Nature Geoscience we used a high-resolution model of the atmosphere that includes the stratosphere. We found a special type of cloud appears over polar regions when greenhouse gas concentrations are very high. The role of this type of cloud has been overlooked so far. This is one of the reasons why our models are too cold at the poles.

Polar Stratospheric Clouds over Norway (Night Lights Films – Adrien Mauduit)


Back to the future

Looking into past climates can give us glimpses of possible futures for a range of extreme conditions. For us, this means we can use Earth’s history to find out how well our climate models perform. We can test our models by simulating episodes in the past when Earth was much warmer. The advantage of this is that we have temperature reconstructions for these episodes to evaluate the models, as opposed to the future, for which measurements are not available.

If we go back 50 million years or so, our planet was very hot. Carbon dioxide (CO₂) concentrations ranged between 900 and 1,900 parts per million (ppm), compared with 415 ppm today. Methane (CH₄) concentrations were likely also much higher.

Canada’s arctic archipelago was covered in lush rainforests inhabited by alligators, turtles, lizards and mammals.

For these plants and animals to survive, conditions must have been warm and ice-free year-round. Indeed, surface ocean temperatures exceeded 20°C near the north pole (at about 87°N) and 25°C in the Southern Ocean (at about 67°S).

This period called the early Eocene is a perfect test bed for our models, because it was globally very warm, and the poles were even warmer, meaning it was a climate with extreme polar amplification. In addition, the Eocene is recent enough for temperature reconstructions to be available.

But as it turns out, the models fail again. They are much too cold at high latitudes. What are our models missing?

Polar stratospheric clouds

In 1992 American paleoclimatologist Lisa Sloan suggested polar stratospheric clouds might have caused extreme warming at high latitudes in the past.

These clouds are a rare and beautiful sight today. They are also called nacreous or mother-of-pearl clouds for their vivid and sometimes luminous colours.

They form at very high altitudes (in the stratosphere) and at very low temperatures (over the poles). In the present day climate, they appear mainly over Antarctica, but have also been observed during winter months over Scotland, Scandinavia and Alaska, at times when the stratosphere was particularly cold.

Just like greenhouse gases, they absorb infrared radiation emitted by the Earth’s surface and re-emit a portion of this energy back to the surface. This suggests polar stratospheric clouds could be one of the missing puzzle pieces.

They warm the surface. And their effect could be significant, especially in winter, when the sun does not rise. But they are difficult to simulate in a climate model, so most models ignore them. This omission could explain why climate models miss some of the polar warming, because they miss a process that warms the poles.

Three decades after Sloan’s paper, a few atmosphere models are finally complex enough to allow us to test her hypothesis. In our research we use one of them and find that under certain conditions, the additional warming due to these polar stratospheric clouds exceeds 7°C during the winter months. This significantly reduces the gap between climate models and temperature evidence from the early Eocene. Sloan was right.

Implications for future projections

Our research explains why climate models don’t work so well for past climates when greenhouse gas levels were much higher than they are today. But what about the future? Should we be concerned?

There is some good news. While polar stratospheric clouds do warm the poles, they won’t be as common in the future as they were in the distant past, even if both CO₂ and CH₄ reach very high levels.

This is due to another difference between the Eocene and today: the position of continents and mountains, which were different back then and which also influence the formation of polar stratospheric clouds. So even if we hit early Eocene levels of CH₄ and CO₂ in the future, we would expect less polar stratospheric cloud to be formed. This suggests the standard climate models are better at predicting the future than the past.

It’s therefore unlikely the Arctic and Antarctica will be covered by these beautiful clouds anytime soon. But our research shows evidence from past climates can reveal processes that only become important when greenhouse gas concentrations are high. Some of these processes are not included in our models because models are tested against present day observations and other processes simply seemed more important to include. Looking into the past is a way of broadening our horizon and learning for the future.

Antarctica image: James Eades

, , , ,

Authors: Kaitlin Naughten, Ocean-Ice Modeller, British Antarctic Survey; Jan De Rydt, Associate Professor of Polar Glaciology and Oceanography, Northumbria University, Newcastle, and Paul Holland, Ocean and Ice Scientist, British Antarctic Survey

This article is republished from The Conversation under a Creative Commons license. Read the original article.


The rate at which the warming Southern Ocean melts the West Antarctic ice sheet will speed up rapidly over the course of this century, regardless of how much emissions fall in coming decades, our new research suggests. This ocean-driven melting is expected to increase sea-level rise, with consequences for coastal communities around the world.

The Antarctic ice sheet, the world’s largest volume of land-based ice, is a system of interconnected glaciers comprised of snowfall that remains year-round. Coastal ice shelves are the floating edges of this ice sheet which stabilise the glaciers behind them. The ocean melts these ice shelves from below, and if melting increases and an ice shelf thins, the speed at which these glaciers discharge fresh water into the ocean increases too and sea levels rise.

In West Antarctica, particularly the Amundsen Sea, this process has been underway for decades. Ice shelves are thinning, glaciers are flowing faster towards the ocean and the ice sheet is shrinking. While ocean temperature measurements in this region are limited, modelling suggests it may have warmed as a result of climate change.

We chose to model the Amundsen Sea because it is the most vulnerable sector of the ice sheet. We used a regional ocean model to find out how ice-shelf melting will change here between now and 2100. How much melting can be prevented by reducing carbon emissions and slowing the rate of climate change – and how much is now unavoidable, no matter what we do?

Rapid change is locked in

We used the UK’s national supercomputer ARCHER2 to run many different simulations of the 21st century, totalling over 4,000 years of ocean warming and ice-shelf melting in the Amundsen Sea.

We considered different trajectories for fossil fuel burning, from the best-case scenario where global warming is limited to 1.5°C in line with the Paris Agreement, to the worst, in which coal, oil and gas use is uncontrolled. We also considered the influence of natural variations in the climate, such as the timing of events such as El Niño.

The results are worrying. In all simulations there is a rapid increase over the course of this century in the rate of ocean warming and ice-shelf melting. Even the best-case scenario in which warming halts at 1.5°C, something that is considered ambitious by many experts, entails a threefold increase in the historical rate of warming and melting.

What’s more, there is little to no difference between the scenarios up to 2045. Ocean warming and ice-shelf melting in the 1.5°C scenario is statistically the same as in a mid-range scenario, which is closer to what existing pledges to reduce fossil fuel use over the coming decades would produce.

The worst-case scenario shows more melting than the others, but only from around mid-century onwards, and many experts think this amount of future fossil fuel burning is unrealistic anyway.

The results imply that we are now committed to rapid ocean warming in the Amundsen Sea until at least 2100, regardless of international policies on fossil fuels.

The increases in warming and melting are the result of ocean currents strengthening and driving more warm water from the deep ocean towards the shallower ice shelves along the coast. Other studies have suggested this process is behind the ice shelf thinning measured by satellites.

How much will the sea level rise?

Melting ice shelves are a major cause of sea-level rise, but not the whole story. We can’t put a number on how much sea levels will rise without also simulating the flow of Antarctic glaciers and the rate of snow accumulating on the ice sheet, which our model didn’t include.

But we have every reason to believe that increased ice-shelf melting in this region will cause the rate at which sea levels are rising to speed up.

The West Antarctic ice sheet is already contributing substantially to global sea-level rise and is losing about 80 billion tonnes of ice a year. It contains enough ice to cause up to 5 metres of sea-level rise, but we don’t know how much of it will melt, and how quickly. Our colleagues around the world are working hard to answer this question.

Courage and hope

There are some consequences of climate change that can no longer be avoided, no matter how much fossil fuel use falls. Substantial melting of West Antarctica up to 2100 may now be one of them.

How do you tell a bad news story? The conventional wisdom is that you’re supposed to give people hope: to say that there’s a disaster behind one door, but we can avoid it if only we choose a different one. What do you do when your science tells you that all doors lead to the same disaster?

Kate Marvel, an atmospheric scientist, said that when it comes to climate change, “we need courage, not hope … Courage is the resolve to do well without the assurance of a happy ending”. In this case, courage means shifting our attention to the longer term.

The future will not end in 2100, even if most people reading this will no longer be around. Our simulations of the 1.5°C scenario show ice-shelf melting starting to plateau by the end of the century, suggesting that further changes in the 22nd century and beyond may still be preventable. Reducing sea-level rise after 2100, or even slowing it down, could save many coastal cities.

Courage means accepting the need to adapt, protecting coastal communities where it’s possible to do so, and rebuilding or abandoning them where it’s not. By predicting future sea-level rise in advance, we’ll have time to plan for it – rather than wait until the ocean is on our doorstep.


Kaitlin Naughten, Ocean-Ice Modeller, British Antarctic Survey; Jan De Rydt, Associate Professor of Polar Glaciology and Oceanography, Northumbria University, Newcastle, and Paul Holland, Ocean and Ice Scientist, British Antarctic Survey

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Climate change event attribution - wildfire: image Mike Newbry

, , , , ,

Podcast hosted by: Joelle Gergis, Australian National University and Michael Green, The Conversation

Interviewed: Honorary Professor, The University of Melbourne;  Senior Lecturer in Climate Science, Imperial College London, Tannecia Stephenson Physics Professor, University of the West Indies, Mona Campus

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Last month the United Nations’ Intergovernmental Panel on Climate Change (IPCC) released its Synthesis Report of the Sixth Assessment Report.

It showed global temperatures are now 1.1℃ above pre-industrial levels. This warming has driven widespread and rapid global changes, including more frequent and intense weather extremes that are now impacting people and ecosystems all over the world.

But when an extreme weather event hits, how certain can we be that it was made more likely by climate change? How do we know it wasn’t just a rare, naturally-occuring event that might have happened anyway?

Fear & Wonder is a new podcast from The Conversation that takes you inside the UN’s era-defining climate report via the hearts and minds of the scientists who wrote it.

The show is hosted by Dr Joëlle Gergis – a climate scientist and IPCC lead author – and award-winning journalist Michael Green.

In this episode, we’re delving into one of the major shifts in the public communication of climate change – the attribution of extreme weather events to climate change.

Although in the past we knew climate change was making extreme weather more likely, advances in climate modelling now allow scientists to pinpoint the influence of natural and human-caused factors on individual weather extremes.

We speak to climatologist Dr Friederike Otto about a rapid attribution study of a heatwave in Toulouse, France, as it unfolded in 2019. We also hear from climatologist Professor David Karoly to help us understand how climate models actually work, while Professor Tannecia Stephenson explains how global models are then used to develop regional climate change projections over the Caribbean island of Jamaica.

To listen and subscribe, click here, or click the icon for your favourite podcast app in the graphic above.

Fear and Wonder is sponsored by the Climate Council, an independent, evidence-based organisation working on climate science, impacts and solutions.The Conversation

, , , , , , , , ,

By: Matthew England, Scientia Professor and Deputy Director of the ARC Australian Centre for Excellence in Antarctic Science (ACEAS), UNSW Sydney; Adele Morrison Research Fellow, Australian National University; Andy Hogg Professor, Australian National University; Qian Li Massachusetts Institute of Technology (MIT); Steve Rintoul CSIRO Fellow, CSIRO.

 Republished in full from The Conversation under a Creative Commons license. See the original article: March 3, 2023

Off the coast of Antarctica, trillions of tonnes of cold salty water sink to great depths. As the water sinks, it drives the deepest flows of the “overturning” circulation – a network of strong currents spanning the world’s oceans. The overturning circulation carries heat, carbon, oxygen and nutrients around the globe, and fundamentally influences climate, sea level and the productivity of marine ecosystems.

But there are worrying signs these currents are slowing down. They may even collapse. If this happens, it would deprive the deep ocean of oxygen, limit the return of nutrients back to the sea surface, and potentially cause further melt back of ice as water near the ice shelves warms in response. There would be major global ramifications for ocean ecosystems, climate, and sea-level rise.

Conveyer overturning schematic showing the pathways of flow in the upper, deep and bottom layers of the ocean.

Our new research, published today in the journal Nature, uses new ocean model projections to look at changes in the deep ocean out to the year 2050. Our projections show a slowing of the Antarctic overturning circulation and deep ocean warming over the next few decades. Physical measurements confirm these changes are already well underway.

Climate change is to blame. As Antarctica melts, more freshwater flows into the oceans. This disrupts the sinking of cold, salty, oxygen-rich water to the bottom of the ocean. From there this water normally spreads northwards to ventilate the far reaches of the deep Indian, Pacific and Atlantic Oceans. But that could all come to an end soon. In our lifetimes.

The authors explain the results of their landmark paper: Is the Southern Ocean about to have its own ‘Day After Tomorrow’ moment? Fact-checked by experts, the video explains how these changes would profoundly alter the ocean’s overturning of heat, freshwater, oxygen, carbon and nutrients, with impacts felt throughout the global ocean for centuries to come.

Why does this matter?

As part of this overturning, about 250 trillion tonnes of icy cold Antarctic surface water sinks to the ocean abyss each year. The sinking near Antarctica is balanced by upwelling at other latitudes. The resulting overturning circulation carries oxygen to the deep ocean and eventually returns nutrients to the sea surface, where they are available to support marine life.

If the Antarctic overturning slows down, nutrient-rich seawater will build up on the seafloor, five kilometres below the surface. These nutrients will be lost to marine ecosystems at or near the surface, damaging fisheries.

Changes in the overturning circulation could also mean more heat gets to the ice, particularly around West Antarctica, the area with the greatest rate of ice mass loss over the past few decades. This would accelerate global sea-level rise.

An overturning slowdown would also reduce the ocean’s ability to take up carbon dioxide, leaving more greenhouse gas emissions in the atmosphere. And more greenhouse gases means more warming, making matters worse.

Meltwater-induced weakening of the Antarctic overturning circulation could also shift tropical rainfall bands around a thousand kilometres to the north.

Put simply, a slowing or collapse of the overturning circulation would change our climate and marine environment in profound and potentially irreversible ways.

Signs of worrying change

The remote reaches of the oceans that surround Antarctica are some of the toughest regions to plan and undertake field campaigns. Voyages are long, weather can be brutal, and sea ice limits access for much of the year.

This means there are few measurements to track how the Antarctic margin is changing. But where sufficient data exist, we can see clear signs of increased transport of warm waters toward Antarctica, which in turn causes ice melt at key locations.

Indeed, the signs of melting around the edges of Antarctica are very clear, with increasingly large volumes of freshwater flowing into the ocean and making nearby waters less salty and therefore less dense. And that’s all that’s needed to slow the overturning circulation. Denser water sinks, lighter water does not.

How did we find this out?

Apart from sparse measurements, incomplete models have limited our understanding of ocean circulation around Antarctica.

For example, the latest set of global coupled model projections analysed by the Intergovernmental Panel on Climate Change exhibit biases in the region. This limits the ability of these models in projecting the future fate of the Antarctic overturning circulation.

To explore future changes, we took a high resolution global ocean model that realistically represents the formation and sinking of dense water near Antarctica.

We ran three different experiments, one where conditions remained unchanged from the 1990s; a second forced by projected changes in temperature and wind; and a third run also including projected changes in meltwater from Antarctica and Greenland.

In this way we could separate the effects of changes in winds and warming, from changes due to ice melt.

The findings were striking. The model projects the overturning circulation around Antarctica will slow by more than 40% over the next three decades, driven almost entirely by pulses of meltwater.

Abyssal ocean warming driven by Antarctic overturning slowdown, Credit: Matthew England and Qian Li.

Over the same period, our modelling also predicts a 20% weakening of the famous North Atlantic overturning circulation which keeps Europe’s climate mild. Both changes would dramatically reduce the renewal and overturning of the ocean interior.

We’ve long known the North Atlantic overturning currents are vulnerable, with observations suggesting a slowdown is already well underway, and projections of a tipping point coming soon. Our results suggest Antarctica looks poised to match its northern hemisphere counterpart – and then some.

What next?

Much of the abyssal ocean has warmed in recent decades, with the most rapid trends detected near Antarctica, in a pattern very similar to our model simulations.

Our projections extend out only to 2050. Beyond 2050, in the absence of strong emissions reductions, the climate will continue to warm and the ice sheets will continue to melt. If so, we anticipate the Southern Ocean overturning will continue to slow to the end of the century and beyond.

The projected slowdown of Antarctic overturning is a direct response to input of freshwater from melting ice. Meltwater flows are directly linked to how much the planet warms, which in turn depends on the greenhouse gases we emit.

Our study shows continuing ice melt will not only raise sea-levels, but also change the massive overturning circulation currents which can drive further ice melt and hence more sea level rise, and damage climate and ecosystems worldwide. It’s yet another reason to address the
climate crisis – and fast.

wildfire

, , , , , , , , , , , , , , , , , ,

By: Professor of Energy and Climate Change, University of Manchester. Republished in full from The Conversation under a Creative Commons license. See the original article: March 25, 2023

The Intergovernmental Panel on Climate Change’s (IPCC) synthesis report recently landed with an authoritative thump, giving voice to hundreds of scientists endeavouring to understand the unfolding calamity of global heating. What’s changed since the last one in 2014? Well, we’ve dumped an additional third of a trillion tonnes of CO₂ into the atmosphere, primarily from burning fossil fuels. While world leaders promised to cut global emissions, they have presided over a 5% rise.

The new report evokes a mild sense of urgency, calling on governments to mobilise finance to accelerate the uptake of green technology. But its conclusions are far removed from a direct interpretation of the IPCC’s own carbon budgets (the total amount of CO₂ scientists estimate can be put into the atmosphere for a given temperature rise).

The report claims that, to maintain a 50:50 chance of warming not exceeding 1.5°C above pre-industrial levels, CO₂ emissions must be cut to “net-zero” by the “early 2050s”. Yet, updating the IPCC’s estimate of the 1.5°C carbon budget, from 2020 to 2023, and then drawing a straight line down from today’s total emissions to the point where all carbon emissions must cease, and without exceeding this budget, gives a zero CO₂ date of 2040.

Graph with lines
 A full description of the above chart is available here.
 
If emissions stay at their current levels, we will exhaust the 50% chance of 1.5°C in 9 years. If we begin to immediately cut emissions following the blue line, then to stay within the carbon budget for 50:50 chance of not exceeding 1.5°C we need zero global emissions by 2040. The vertical axis represents how much carbon is emitted each year – note the pandemic-related blip in 2020.
 

Given it will take a few years to organise the necessary political structures and technical deployment, the date for eliminating all CO₂ emissions to remain within 1.5°C of warming comes closer still, to around the mid-2030s. This is a strikingly different level of urgency to that evoked by the IPCC’s “early 2050s”. Similar smoke and mirrors lie behind the “early 2070s” timeline the IPCC conjures for limiting global heating to 2°C.

IPCC science embeds colonial attitudes

For over two decades, the IPCC’s work on cutting emissions (what experts call “mitigation”) has been dominated by a particular group of modellers who use huge computer models to simulate what may happen to emissions under different assumptions, primarily related to price and technology. I’ve raised concerns before about how this select cadre, almost entirely based in wealthy, high-emitting nations, has undermined the necessary scale of emission reductions.

In 2023, I can no longer tiptoe around the sensibilities of those overseeing this bias. In my view, they have been as damaging to the agenda of cutting emissions as Exxon was in misleading the public about climate science. The IPCC’s mitigation report in 2022 did include a chapter on “demand, services and social aspects” as a repository for alternative voices, but these were reduced to an inaudible whisper in the latest report’s influential summary for policymakers.

The specialist modelling groups (referred to as Integrated Assessment Modelling, or IAMs) have successfully crowded out competing voices, reducing the task of mitigation to price-induced shifts in technology – some of the most important of which, like so-called “negative emissions technologies”, are barely out of the laboratory.

The IPCC offers many “scenarios” of future low-carbon energy systems and how we might get there from here. But as the work of academic Tejal Kanitkar and others has made clear, not only do these scenarios prefer speculative technology tomorrow over deeply challenging policies today (effectively a greenwashed business-as-usual), they also systematically embed colonial attitudes towards “developing nations”.

With few if any exceptions, they maintain current levels of inequality between developed and developing nations, with several scenarios actually increasing the levels of inequality. Granted, many IAM modellers strive to work objectively, but they do so within deeply subjective boundaries established and preserved by those leading such groups.

Four people in formal attire converse on a stage behind a
March 2023’s synthesis report capped eight years of research. IISD/ENB/Anastasia Rodopoulou

 

What happened to equity?

If we step outside the rarefied realm of IAM scenarios that leading climate scientist Johan Rockström describes as “academic gymnastics that have nothing to do with reality”, it’s clear that not exceeding 1.5°C or 2°C will require fundamental changes to most facets of modern life.

Starting now, to not exceed 1.5°C of warming requires 11% year-on-year cuts in emissions, falling to nearer 5% for 2°C. However, these global average rates ignore the core concept of equity, central to all UN climate negotiations, which gives “developing country parties” a little longer to decarbonise.

Include equity and most “developed” nations need to reach zero CO₂ emissions between 2030 and 2035, with developing nations following suit up to a decade later. Any delay will shrink these timelines still further.

Most IAM models ignore and often even exacerbate the obscene inequality in energy use and emissions, both within nations and between individuals. As the International Energy Agency recently reported, the top 10% of emitters accounted for nearly half of global CO₂ emissions from energy use in 2021, compared with 0.2% for the bottom 10%. More disturbingly, the greenhouse gas emissions of the top 1% are 1.5 times those of the bottom half of the world’s population.

So where does this leave us? In wealthier nations, any hope of arresting global heating at 1.5 or 2°C demands a technical revolution on the scale of the post-war Marshall Plan. Rather than relying on technologies such as direct air capture of CO₂ to mature in the near future, countries like the UK must rapidly deploy tried-and-tested technologies.

Retrofit housing stock, shift from mass ownership of combustion-engine cars to expanded zero-carbon public transport, electrify industries, build new homes to Passivhaus standard, roll-out a zero-carbon energy supply and, crucially, phase out fossil fuel production.

Three decades of complacency has meant technology on its own cannot now cut emissions fast enough. A second, accompanying phase, must be the rapid reduction of energy and material consumption.

Given deep inequalities, this, and deploying zero-carbon infrastructure, is only possible by re-allocating society’s productive capacity away from enabling the private luxury of a few and austerity for everyone else, and towards wider public prosperity and private sufficiency.

For most people, tackling climate change will bring multiple benefits, from affordable housing to secure employment. But for those few of us who have disproportionately benefited from the status quo, it means a profound reduction in how much energy we use and stuff we accumulate.

The question now is, will we high-consuming few make (voluntarily or by force) the fundamental changes needed for decarbonisation in a timely and organised manner? Or will we fight to maintain our privileges and let the rapidly changing climate do it, chaotically and brutally, for us?

Un Gap Report 2022

, , , , , , , , ,

It comes as no surprise. Following COP 26, in December last year it was evident that the carbon budget to stay under 1.5C already was bankrupt. Some simple arithmetic clearly demonstrated that.

Since COP26, the ‘Don’t-Look-Up’ mentality, or perhaps the ‘war-in-Ukraine’ and ‘post-Covid-economy’ have become diversionary topics. The latest UN GAP Report begins with a clear admission, and an admonition. Nations have shaved just 1% off their projected greenhouse gas emissions for 2030, at a time when reductions need to be 45% to have even a chance to keep temperatures under 1.5C. In short, there is no credible no credible pathway in which global temperatures under that 2.8C, and “...uncertainties in the climate system mean that warming of up to 4C cannot be fully ruled out.”

These uncertainties are the dangerous tipping points explained in more detail on this website.

If you’re not up to reading the full report, Carbon Brief has an in depth analysis. While the report also offers solutions, the window is closing on fingernails barely clinging to the sill.

Look up.
 
Please.
 

“Every year, the negative impacts of climate change become more intense. Every year, they bring more misery and pain to hundreds of millions of people across the globe. Every year, they become more a problem of the here and now, as well as a warning of tougher consequences to come. We are in a climate emergency.

“And still, as UNEP’s Emissions Gap Report 2022 shows, nations procrastinate. Since COP26 in Glasgow in 2021, new and updated nationally determined contributions (NDCs) have barely impacted the temperatures we can expect to see at the end of this century.

“This year’s report tells us that unconditional NDCs point to a 2.6°C increase in temperatures by 2100, far beyond the goals of the Paris Agreement. Existing policies point to a 2.8°C increase, highlighting a gap between national commitments and the efforts to enact those commitments. In the best- case scenario, full implementation of conditional NDCs, plus additional net zero commitments, point to a 1.8°C rise. However, this scenario is currently not credible.

“To get on track to limiting global warming to 1.5°C, we would need to cut 45 per cent off current greenhouse gas emissions by 2030. For 2°C, we would need to cut 30 per cent. A stepwise approach is no longer an option. We need system-wide transformation. This report tells us how to go about such a transformation. It looks in-depth at the changes needed in electricity supply, industry, transport, buildings and food systems. It looks at how to reform financial systems so that these urgent transformations can be adequately financed.

“Is it a tall order to transform our systems in just eight years? Yes. Can we reduce greenhouse gas emissions by so much in that timeframe? Perhaps not. But we must try. Every fraction of a degree matters: to vulnerable communities, to species and ecosystems, and to every one of us. Most importantly, we will still be setting up a carbon-neutral future: one that will allow us to bring down temperature overshoots and deliver other benefits, like clean air.

“The world is facing other crises. We must deal with them. But let us remember that they also offer opportunities to reform our global economy. We have missed the opportunity to invest in a low-carbon recovery from the COVID-19 pandemic. Now, we are in danger of missing the opportunity to boost clean and efficient energy as a response to the energy crisis. Instead of missing such opportunities, we must capitalize on them with confidence.

“I urge every nation and every community to pore over the solutions offered in this report, build them into their NDCs and implement them. I urge everyone in the private sector to start reworking their practices. I urge every investor to put their capital towards a net-zero world. The transformation begins now. ”

– Inger Anderson, Executive Director, UNEP, Emissions Gap Report 2022

Antarctica image: James Eades

, , , , , , , ,

By: Maurice Huguenin, PhD Candidate, UNSW Sydney; Matthew England, Scientia Professor and Deputy Director of the ARC Australian Centre for Excellence in Antarctic Science (ACEAS), UNSW Sydney, and Ryan Holmes, Research fellow, University of Sydney

Republished in full from The Conversation under a Creative Commons license. See the original article: September 7, 2022

Over the last 50 years, the oceans have been working in overdrive to slow global warming, absorbing about 40% of our carbon dioxide emissions, and over 90% of the excess heat trapped in the atmosphere.

But as our research published today in Nature Communications has found, some oceans work harder than others.

We used a computational global ocean circulation model to examine exactly how ocean warming has played out over the last 50 years. And we found the Southern Ocean has dominated the global absorption of heat. In fact, Southern Ocean heat uptake accounts for almost all the planet’s ocean warming, thereby controlling the rate of climate change.

This Southern Ocean warming and its associated impacts are effectively irreversible on human time scales, because it takes millennia for heat trapped deep in the ocean to be released back into the atmosphere.

This means changes happening now will be felt for generations to come – and those changes are only set to get worse, unless we can stop carbon dioxide emissions and achieve net zero.


It’s important yet difficult to measure ocean heating

Ocean warming buffers the worst impacts of climate change, but it’s not without cost. Sea levels are rising because heat causes water to expand and ice to melt. Marine ecosystems are experiencing unprecedented heat stress, and the frequency and intensity of extreme weather events is changing.

Yet, we still don’t know enough about exactly when, where and how ocean warming occurs. This is because of three factors.

First, temperature changes at the ocean surface and in the atmosphere just above track each other closely. This makes it difficult to know exactly where excess heat is entering the ocean.

Second, we don’t have measurements tracking temperatures over all of the ocean. In particular, we have very sparse observations in the deep ocean, in remote locations around Antarctica and under sea ice.

Last, the observations we do have don’t go back very far in time. Reliable data from deeper than 700 metres depth is virtually non-existent prior to the 1990s, apart from observations along specific research cruise tracks.

Earth’s heat inventory since 1960 (ZJ = 10²¹ J). Credit: von Schuckmann et al. (2020).


Our modelling approach

To work out the intricacies of how ocean warming has played out, we first ran an ocean model with atmospheric conditions perpetually stuck in the 1960s, prior to any significant human-caused climate change.

Then, we separately allowed each ocean basin to move forward in time and experience climate change, while all other basins were held back to experience the climate of the 1960s.

We also separated out the effects of atmospheric warming from surface wind-driven changes to see how much each factor contributes to the observed ocean warming.

By taking this modelling approach, we could isolate that the Southern Ocean is the most important absorber of this heat, despite only covering about 15% of the total ocean’s surface area.

In fact, the Southern Ocean alone could account for virtually all global ocean heat uptake, with the Pacific and Atlantic basins losing any heat gained back into the atmosphere.

One significant ecological impact of strong Southern Ocean warming is on Antarctic krill. When ocean warming occurs beyond temperatures they can tolerate, the krill’s habitat contracts and they move even further south to cooler waters.

As krill is a key component of the food web, this will also change the distribution and population of larger predators, such as commercially viable tooth and ice fish. It will also further increase stress for penguins and whales already under threat today.

So why is the Southern Ocean absorbing so much heat?

This largely comes down to the geographic set-up of the region, with strong westerly winds surrounding Antarctica exerting their influence over an ocean that’s uninterrupted by land masses.

This means the Southern Ocean winds blow over a vast distance, continuously bringing masses of cold water to the surface. The cold water is pushed northward, readily absorbing vast quantities of heat from the warmer atmosphere, before the excess heat is pumped into the ocean’s interior around 45-55°S (a latitude band just south of Tasmania, New Zealand, and the southern regions of South America).

This warming uptake is facilitated by both the warmer atmosphere caused by our greenhouse gas emissions, as well as wind-driven circulation which is important for getting heat into the ocean interior.

And when we combine the warming and wind effects only over the Southern Ocean, with the remaining oceans held back to the climate of the 1960s, we can explain almost all of the global ocean heat uptake.

But that’s not to say the other ocean basins aren’t warming. They are, it’s just that the heat they gain locally from the atmosphere cannot account for this warming. Instead, the massive heat uptake in the Southern Ocean is what has driven changes in total ocean heat content worldwide over the past half century.

We have much to learn

While this discovery sheds new light on the Southern Ocean as a key driver of global ocean warming, we still have a lot to learn, particularly about ocean warming beyond the 50 years we highlight in our study. All future projections, including even the most optimistic scenarios, predict an even warmer ocean in future.

And if the Southern Ocean continues to account for the vast majority of ocean heat uptake until 2100, we might see its heat content increase by as much as seven times more than what we have already seen up to today.

This will have enormous impacts around the globe: including further disturbances to the Southern Ocean food web, rapid melting of Antarctic ice shelves, and changes in the ocean conveyor belt.

To capture all of these changes, it’s vital we continue and expand our observations taken in the Southern Ocean.

One of the most important new data streams will be new ocean floats that can measure deeper ocean temperatures, as well as small temperature sensors on elephant seals, which give us essential data of oceanic conditions in winter under Antarctic sea ice.

Even more important is the recognition that the less carbon dioxide we emit, the less ocean change we will lock in. This will ultimately limit the disruption of livelihoods for the billions of people living near the coast worldwide.The Conversation

Healthy native dune system with wetlands

, , , , , , , , , , , , ,

Top image: healthy coastal wetlands

The Environmental Defence Society has filed its submission on the Ministry for the Environment’s regulations on coastal wetlands and says that the Ministry’s approach undermines the original intent of the regulations and leaves coastal wetlands vulnerable to future degradation.

This is a classic case of maladaptation, the exact opposite to adaptation that the Government itself warned against in its National adaptation plan.

“The Resource Management (National Environmental Standards for Freshwater) Regulations 2020 (NES-F) set national direction to protect and improve wetlands and put a stop to further loss of their values”, said EDS COO Shay Schlaepfer.

“The NES-F was clearly intended to apply to both inland and coastal wetlands. The Ministry is now proposing a policy U-turn and wants to exclude coastal wetlands from the regulations.

“This approach is totally unjustified. Coastal wetlands are capable of being mapped so there is no reason why they should not be included. The NES-F is a rules framework that integrates national policy relating to wetlands and provides a consistent approach to wetland management across all domains.

“Removing coastal wetlands from the NES-F will leave a gap in their management and protection at the national level and leave too much discretion with regional councils.

“The Ministry also seeks to exempt certain activities from the consenting pathways set out in the NES-F. These activities have the potential to adversely affect coastal wetlands and should be subject to the regulations.

“Wetlands are one of the country’s most valuable ecosystems. They have undergone extensive loss with over 90% of them destroyed since human occupation. Many of those that remain are in a severely degraded state. The Ministry’s proposed approach will only serve to further continue this decline.

“This cannot be allowed to occur and we urge the Ministry to think again,” Ms Schlaepfer concluded.

Climate justice

Load More