19/03/2021

(USA) Not Just CO2: Rising Temperatures Also Alter Photosynthesis In A Changing Climate

University of Illinois - Diana Yates

From left, Caitlin Moore, Carl Bernacchi, Katherine Meacham-Hensold and their colleagues review how rising temperatures affect photosynthesis in plants and how scientists are addressing the challenges. Photo by Claire Benjamin/RIPE project

CHAMPAIGN, Ill. — Agricultural scientists who study climate change often focus on how increasing atmospheric carbon dioxide levels will affect crop yields. But rising temperatures are likely to complicate the picture, researchers report in a new review of the topic.

Published in the Journal of Experimental Botany, the review explores how higher temperatures influence plant growth and viability despite the greater availability of atmospheric CO2, a key component of photosynthesis.

Excessive heat can reduce the efficiency of enzymes that drive photosynthesis and can hinder plants’ ability to regulate CO2 uptake and water loss, the researchers write.

Structural features can make plants more – or less – susceptible to heat stress.

Ecosystem attributes – such as the size and density of plants, the arrangement of leaves on plants or local atmospheric conditions – also influence how heat will affect crop yields.

The review describes the latest scientific efforts to address these challenges.

Rising temperatures associated with climate change affect plants’ ability to maintain their structural integrity, absorb carbon dioxide, retain water, and grow and reproduce. Graphic by Julie McMahon
“It’s important to have an understanding of these issues across scales – from the biochemistry of individual leaves to ecosystem-level influences – in order to really tackle these problems in an informed way,” said lead author Caitlin Moore, a research fellow at the University of Western Australia and an affiliate research fellow at the Institute for Sustainability, Energy, and Environment at the University of Illinois Urbana-Champaign.

Moore led the review with Amanda Cavanagh, another U. of I. alumna now at the University of Essex in the U.K. “Historically, there’s been a lot of focus on rising CO2 and the impact that it has on plants,” said co-author Carl Bernacchi, a professor of plant biology and of crop sciences and an affiliate of the Carl R. Woese Institute for Genomic Biology at the U. of I.

“And it is an important factor, because we are changing that carbon dioxide concentration enormously. But it’s a small part of the bigger story. Once you throw changing temperatures into the mix, it completely messes up our understanding of how plants are going to respond.”

Co-author Amanda Cavanagh studies the molecular biology and physiology of plants. Photo by Claire Benjamin/RIPE project

“Take Rubisco, the key enzyme that fixes carbon dioxide into sugars, making life on Earth possible,” Cavanagh said. “Rubisco speeds up as the temperature increases, but it’s also prone to making mistakes.”

Instead of fixing carbon dioxide by binding it to sugars, a key step in photosynthesis, Rubisco sometimes fixes oxygen, initiating a different pathway that wastes a plant’s resources.

Higher temperatures make this more likely, Cavanagh said. At even higher temperatures, the enzyme will begin to lose its structural integrity, making it ineffective.

Excessive heat can also undermine a plant’s reproductive output.

Other heat-sensitive enzymes are essential to the light-harvesting machinery of plants or play a role in moving sugars to different plant tissues, allowing the plant to grow and produce grains or fruits.

“If these little molecular machines are pushed out of the temperature range that’s optimal, then they can’t do their job,” Cavanagh said.

When temperatures rise too high, plant leaves open the pores on their surfaces, called stomata, to cool themselves. Stomata also allow plants to absorb carbon dioxide from the atmosphere, but when they’re fully open, the leaf can lose too much moisture.

Caitlin Moore studies how ecosystem-scale factors influence crop responses to climate change. Photo by Claire Benjamin/RIPE project

“Temperature affects the atmosphere above the plant,” Moore said. “As the atmosphere heats up, it can hold additional water, so it’s pulling more water from the plants.”

Scientists at Illinois and elsewhere are looking for ways to enhance crop plants’ resilience in the face of these changes.

Moore, whose work focuses on ecosystem-scale factors, said new tools that can help screen plants on a large scale are essential to that effort.

For example, satellites that can detect changes in chlorophyll fluorescence in plants can indicate whether a crop is under heat stress.

These changes in fluorescence are detectable before the plant shows any outward sign of heat stress – such as their leaves turning brown. Developing these tools may enable farmers to respond more quickly to crop stress before too much damage is done.

Cavanagh, who studies the molecular biology and physiology of plants, said some plants are more heat tolerant than others, and scientists are searching their genomes for clues to their success.

“For example, you can look at wild Australian relatives of rice that are growing in much harsher climates than most paddy rices,” she said. “And you see that their enzymes are primed to work more efficiently at hotter temperatures.”

One goal is to transfer heat-tolerant genes to cultivated rice varieties that are more susceptible to heat stress.

Carl Bernacchi, a research scientist with the U.S. Department of Agriculture’s Agriculture Research Service and a professor of crop sciences and of plant biology at Illinois, studies how climate change affects crop species important to the Midwest. Photo by L. Brian Stauffer
Other strategies include engineering structures that pump more CO2 to the site of carbon fixation to improve Rubisco efficiency; altering the light-gathering properties of leaves at the tops and bottoms of plants to even out distribution of sunlight and maintain moisture levels; and changing the density of stomata to improve their control of CO2 influx and moisture loss.

Collaboration between scientists focused on different scales of ecosystem and plant function – from the atmospheric to the molecular – is essential to the success of efforts to build resilience in crop plants, the researchers said.

“The world is getting hotter at a shocking rate,” Cavanagh said. “And we know from global models that each increase in gross temperature degree Celsius can cause 3% to 7% losses in yield of our four main crops. So, it’s not something we can ignore.

“What makes me optimistic is the realization that so much work is going into globally solving this problem,” she said. 

Links  
at No comments:

(AU) Melbourne’s Real-World Impact On Climate Change

Pursuit: University of Melbourne - Sarah Marinos

A new initiative bringing together multi-disciplinary climate change experts is focused on finding effective global solutions in Australia and beyond

Getty Images
In late 2015, 196 countries signed the Paris Agreement, making a commitment to tackle climate change and global warming. The landmark, legally binding international treaty united countries behind one goal - to combat the impacts of climate change.

Later this year, the parties to the Paris Agreement will meet again at the COP26 UN climate change conference in Glasgow.

Signatories to the Paris Agreement will meet again at the COP26 UN climate change conference in Glasgow. Picture: Getty Images

The University of Melbourne is part of this worldwide effort to confront climate change and is launching a multi-disciplinary initiative - Melbourne Climate Futures (MCF) – bringing together experts from diverse areas, including science, engineering, the humanities and medicine, to develop practical solutions for global climate change.

In the court of climate change

Professor Jacqueline Peel, from Melbourne Law School, is an internationally-recognised expert in environmental and climate change law and the director of MCF. She believes litigation is an effective way to prompt climate action.

“Climate change activists have increasingly used the courts during the past five years and that is pressuring governments and businesses to do more,” says Professor Peel.


Researchers from many different disciplines come together to launch Melbourne Climate Futures.  Read more

“Our expertise is often sought by groups who want advice on the best way to use litigation. They want to know what kinds of court cases have had impact to shape their own litigation strategy.”

Action taken by Mark McVeigh against Retail Employees Superannuation Pty Ltd (REST) showcases the power of court action.

The 22-year-old ecology student from Brisbane took REST to the Federal Court alleging the superannuation fund had breached fiduciary duties owed to him by failing to adequately consider climate change risks.

In November 2020, REST settled and stated its investment managers would now take “active steps to consider, measure and manage financial risks posed by climate change”.

Litigation is an effective way to prompt climate action. Picture: Getty Images

Among other measures, REST committed to achieving a net zero carbon footprint by 2050.

“That kind of action hasn’t been brought anywhere else in the world and it shows how businesses need to change their practices to take account of climate change,” says Professor Peel.

The REST case highlights that indirect impacts can also be meaningful. It provoked widespread discussion in the superannuation industry about the need to take climate change into account.

The investor-led push on climate change.  Read more
“More funds are making climate change a mainstream financial issue that has to be factored into their processes. Without litigation, we may not have seen that level of pace and change,” says Professor Peel.

Increasing climate change ambition

During COP26, Professor Don Henry will be monitoring how countries actually plan to achieve the goals of the Paris Agreement. Professor Henry is Melbourne Enterprise Professor of Environmentalism and an International Board Member of the Climate Reality Project, chaired by the former American Vice President, Al Gore.

Professor Henry’s current focus is how to increase ambition and commitment as nations implement significant policy changes in order to meet their climate change goals.

Nations must implement significant policy changes in order to meet their climate change goals. Picture: Getty Images

“The Paris Agreement was historic because every government, bar a few, agreed that we need to follow science-based targets to reduce greenhouse pollution and to look for new opportunities to build low-carbon economies. But there is a huge amount of work to be done,” says Professor Henry.

“There is a big gap between what countries say they want to do and what they are doing. Building ambition is about building the knowledge and the will to close that gap.”

Pivotal to increasing ambition is generating new knowledge to underpin tangible solutions – universities and initiatives like MCF are a key part of this puzzle.

Our last best chance to stop runaway climate change.  Read more

“Governments need new knowledge about how they can be more successful with climate change solutions. Communities have to be aware of the need and opportunity to support solutions. Business needs to take up the challenge to transition to low-carbon economies, but that requires good knowledge about climate solutions and how to put them in place,” he says.

This kind of collaboration will deepen and quicken knowledge gathering and dissemination.

“It would be good to see universities putting their shoulder to the wheel and committing to do more to generate knowledge for climate solutions – because this is the decade when putting solutions in place is crucial,” says Professor Henry.

The Birrarung/Yarra River became the first river in Australia to be legally recognised as a living entity. Picture: Getty Images

Upholding the rights of rivers

In 2017, the Birrarung/Yarra River became the first river in Australia to be legally recognised as a living entity. Two years later, all rivers in Bangladesh became legal persons, while New Zealand, India, Colombia, the US and Canada have also recognised rivers as living entities with legal rights.

Dr Erin O’Donnell from the Centre for Resources, Energy and Environment Law says recognising rivers as legal people with rights is one effective way of tackling declining water availability, a key impact of climate change in many parts of the world, including on the arid Australian continent.

“What we’re starting to do now is to give rivers rights of their own, so that the river can enforce its own rights and protect itself. Potentially a river with legal rights could actually go to court and sue somebody who polluted it,” says Dr O’Donnell.

The legal rights of rivers.  Read more
One key element of recognising rivers as living entities with legal rights is acknowledging the leadership role of Indigenous peoples as environmental advocates.

Dr O’Donnell points to the New Zealand government’s recognition of the Whanganui River as a legal person which acknowledges the relationship between the river catchment and Maori.

Dr O’Donnell is currently focusing on a Cultural Water for Cultural Economies project – a partnership between the Murray Lower Darling Rivers Indigenous Nations, the University of Melbourne and representatives from 20 Traditional Owner organisations and First Nations people across Victoria.

The project has implications not only for Australia but worldwide.

New Zealand’s recognition of the Whanganui River acknowledges the relationship between the river catchment and Maori. Picture: Getty Images

“First Nations and Traditional Owners have long been sustainably managing rivers and ecosystems in ways that have generated economic return and supported healthy populations of people, but without the damage to ecosystems we see now,” says Dr O’Donnell.

“Recognising rivers as living beings and elevating and amplifying the voices and rights of Traditional Owners, offer new ways to manage our waterways and rivers in an uncertain climate future.”

The global problem of thirsty cities.  Read more

Innovating for Cities

Equipping cities with the knowledge, tools and funding they need to meet climate action ambitions is yet another key piece of the cleaner, greener future puzzle.

Dr Cathy Oke, Enterprise Senior Fellow in Informed Cities in the Connected Cities Lab, is identifying gaps in city climate change science as a critical path to meeting national and global climate targets.

As a special advisor to the Innovate4Cities initiative of the Global Covenant of Mayors for Climate and Energy (GCoM), Dr Oke is working with city networks and city researchers to enable cities to take even more effective climate action in areas such as planning, buildings, transport, energy supply and finance.

Identifying gaps in city climate change science is a critical path to meeting climate targets. Picture: Getty Images
“Urban centres have a huge impact on emissions, so it goes without saying that making better decisions locally can have huge positive potential on a global scale ,” says Dr Oke.

She pinpoints innovation, working across the nexus of research policy and practice, and translating city climate change science so it speaks the language of city decision-makers, as important steps.

“Cities need the greatest science and evidence to make bold policy decisions, universities need to do better in providing that material in way that is useful. We have to get better at understanding what cities want in the first place.”

NOTE: Melbourne Climate Futures will be launched on Tuesday, 23 March, with an all-day program of online panel discussions. Register for the event and see the full program and list of speakers.

Links
at No comments:

(AU) Wake Up, Mr Morrison: Australia’s Slack Climate Effort Leaves Our Children 10 Times More Work To Do

The Conversation -  |  |  | 

Dan Himbrechts/AAP
Authors
  •  is Professor, Department of Biological Sciences, Macquarie University
  •  is Professor and Chair, Tax and Transfer Policy Institute, Crawford School of Public Policy, Australian National University
  •  is A/Prof., School of Earth Sciences, The University of Melbourne
  •  is Emeritus Professor, Fenner School of Environment & Society, Australian National University
There is much at stake at the highly anticipated United Nations climate summit in Glasgow this November. 

There, almost 200 nations signed up to the Paris Agreement will make emissions reduction pledges as part of the international effort to avoid catastrophic climate change.

Many countries recognise the urgent task at hand. Ahead of the meeting, more than 110 governments have already pledged to achieve net-zero emissions by 2050. So where is Australia in terms of global ambition?

We, some of Australia’s most senior climate change scientists and policymakers, have come together to address these and other pressing questions, informed by sound science and policy.

Our report, released today, pinpoints the emissions reduction burden Australians will bear in future decades if our Paris targets are not increased.

 Alarmingly, people living in the 2030s and 2040s could be forced to reduce emissions by ten times as much as people this decade, if Australia is to keep within its 2℃ “carbon budget”.

Without policy change, people living in coming decades will have to reduce emissions by far more than the current rate. Dean Lewins/AAP
‘Manifestly inadequate’

A “carbon budget” identifies how much carbon dioxide (CO₂) the world can emit if it’s to limit global temperature rise to internationally agreed goals. Those goals include keeping warming to well below 2℃ – and preferably below 1.5℃ – this century.

National emissions reduction targets are key to staying within a carbon budget. Australia’s target, under the Paris Agreement, is a 26-28% reduction between 2005 and 2030.

In a report released in January, we showed how that target is manifestly inadequate. To remain within its 2°C carbon budget, Australia must cut emissions by 50% between 2005 and 2030, and reach net-zero emissions by 2045.

To remain inside the 1.5°C budget, we must reduce emissions by 74% between 2005 and 2030, and reach net zero emissions by 2035.

Since that report was released, the Australian government has doubled down on its 2030 target. But Prime Minister Scott Morrison appears to be inching closer to a net-zero commitment. Last month he declared his government’s goal was “to reach net-zero emissions as soon as possible, and preferably by 2050”.

Our latest report set out to determine how the burden of emissions reduction would be spread after 2030 if Australia’s 2030 target is not increased.

The Morrison government is sticking with its inadequate Paris pledge. Shutterstock
What we found

Our analysis used the methodology adopted by the Climate Change Authority. This statutory body was established by the Gillard Labor government in 2012, and was charged with providing independent expert policy advice.

In 2014, the authority identified the level of climate ambition required for Australia to do its fair share in the global effort. It recommended a 30% emissions reduction between 2000 and 2025, reaching 40-60% by 2030.

But the Abbott Coalition government ignored this advice. Instead, it pledged the far weaker target of 26-28% emissions reduction.

We wanted to determine what happens if Australia sticks to that inadequate target – and so delays substantive climate action until later decades.

To meet the weak Paris target, Australia need only reduce emissions by 1.2% each year from 2020 to 2030. If Australia persists with this target but still decides to stay inside the 2℃ carbon budget, that leaves just 1,329 million tonnes of greenhouse gases we can emit after 2030.

Keeping to this limit would be extremely challenging. If done in a straight-line trajectory, it would mean a 12.9% cut in emissions each year from 2030, until net-zero emissions were reached in 2037.

This represents an annual challenge ten times greater than what’s needed in each year this decade to meet the current 2030 goals. It would require an annual emissions reduction of 66.8 million tonnes of greenhouse gases – more than every car and light commercial vehicle on Australia’s roads emits in a year.

Author provided/The Conversation, CC BY-ND
Second, we looked at the emissions trajectory if Australia was to achieve net-zero emissions by 2050, while still keeping the inadequate 2030 Paris targets. We found people living in the 2030s and 2040s would have to reduce emissions by three times more than what’s required this decade.

Emissions include land-use, landuse change and forestry emissions. A drop in widespread land clearing creates the impression of overall reduced emissions. But underlying fossil fuel and industrial emissions have steadily increased since the 1990s - with the exception of brief moments when Australia had an effective price on carbon. Author provided/The Conversation, CC BY-ND
Clearly, the inadequate 2030 target is the source of the problem. By requiring very little emissions reduction this decade, the Morrison government is kicking the climate can down the road for our children to pick up. It means Australia is also failing on its moral obligation to do its fair share in the global climate effort.

Australia trails the world

This sad state of affairs is not news to the rest of the world. Australia is widely viewed as an international climate laggard. In the 2020 Climate Change Performance Index, it received the lowest rating of 57 countries and the European Union. It also ranked second-worst on climate action, out of 177 countries, in the 2020 UN Sustainable Development Report.

The Glasgow climate summit, known as the 26th Conference of the Parties or COP26, seeks to hold governments to account for their climate pledges. Nations are expected to front up with ambitious short-term plans for emissions reduction.

Many nations have risen to the challenge. Countries to adopt a target of net-zero by 2050 include the United States, Japan, South Korea and the European Union. China will aim to achieve this target by 2060.

Even more importantly, some governments have ramped up their 2030 targets. For example the European Union will now reduce emissions by 55% and the United Kingdom by 68% – both on 1990 levels.

Under President Joe Biden, the US will work towards net-zero emissions by 2050. Carolyn Kaster/AP/AAP
A critical decade

The importance of COP26 cannot be overstated. Under current global pledges, an average temperature rise of 3℃ or more is distinctly possible this century. This increases the risk of abrupt and irreversible changes in the Earth’s climate system - known as tipping points - bringing disastrous consequences for both human and natural systems.

The Morrison government is failing to protect Australia from this devastating future. It’s also ignoring a major economic opportunity that should - in a rational country - bring all sides of politics together.

Over the past decade, renewable energy costs have plummeted and significant advances have been made in electric vehicles and regenerative agriculture. This opens up vast new opportunities for Australia.

These days, few in the federal Coalition would deny climate science outright. But the government’s softer form of denial – failing to grasp the need for urgent action – will have the same tragic outcome.

Links
at No comments: