Genome and satellite technology reveal recovery rates and impacts of climate change on southern right whales

University of Auckland tohorā research team, Department of Conservation permit DJI

Emma Carroll

After close to a decade of globe-spanning effort, the genome of the southern right whale has been released this week, giving us deeper insights into the histories and recovery of whale populations across the southern hemisphere.

Up to 150,000 southern right whales were killed between 1790 and 1980. This whaling drove the global population from perhaps 100,000 to as few as 500 whales in 1920. A century on, we estimate there are 12,000 southern right whales globally. It’s a remarkable conservation success story, but one facing new challenges.

A southern right whale calf breaches in the subantarctic Auckland Islands.
University of Auckland tohorā research team, Author provided

The genome represents a record of the different impacts a species has faced. With statistical models we can use genomic information to reconstruct historical population trajectories and patterns of how species interacted and diverged.

We can then link that information with historical habitat and climate patterns. This look back into the past provides insights into how species might respond to future changes. Work on penguins and polar bears has already shown this.

But we also have a new and surprising short-term perspective on the population of whales breeding in the subantarctic Auckland Islands group — Maungahuka, 450km south of New Zealand.

Spying on whales via satellite

Known as tohorā in New Zealand, southern right whales once wintered in the bays and inlets of the North and South Islands of Aotearoa, where they gave birth and socialised. Today, the main nursery ground for this population is Port Ross, in the subantarctic Auckland Islands.

Adult whales socialise at both the Auckland and Campbell Islands during the austral winter. Together these subantarctic islands are internationally recognised as an important marine mammal area.

In August 2020, I led a University of Auckland and Cawthron Institute expedition to the Auckland Islands. We collected small skin samples for genetic and chemical analysis and placed satellite tags on six tohorā. These tags allowed us to follow their migrations to offshore feeding grounds.

It matters where tohorā feed and how their populations recover from whaling because the species is recognised as a sentinel for climate change throughout the Southern Hemisphere. They are what we describe as “capital” breeders — they fast during the breeding season in wintering grounds like the Auckland Islands, living off fat reserves gained in offshore feeding grounds.

Females need a lot in the “bank” because their calves need a lot of energy. At 4-5m at birth, these calves can grow up to a metre a month. This investment costs the mother 25% of her size over the first few months of her calf’s life. It’s no surprise that calf growth depends on the mother being in good condition.

---

Read more:
I measure whales with drones to find out if they’re fat enough to breed

---

Females can only breed again once they’ve regained their fat capital. Studies in the South Atlantic show wintering grounds in Brazil and Argentina produce more calves when prey is more abundant, or environmental conditions suggest it should be.

The first step in understanding the relationship between recovery and prey in New Zealand is to identify where and on what tohorā feed. The potential feeding areas for our New Zealand population could cover roughly a third of the Southern Ocean. That’s why we turn to technologies like satellite tags to help us understand where the whales are going and how they get there.

Where tohorā go

So far, all tracked whales have migrated west; away from the historical whaling grounds to the east near the Chatham Islands. As they left the Auckland Islands, two whales visited other oceanic islands — skirting around Macquarie Island and visiting Campbell Island.

It also seems one whale (Bill or Wiremu, identified as male using genetic analysis of his skin sample) may have reached his feeding grounds, likely at the subtropical convergence. The clue is in the pattern of his tracks: rather than the continuous straight line of a whale migrating, it shows the doughnuts of a whale that has found a prey patch.

Migratory track of southern right whale Bill/Wiremu, where the convoluted track could indicate foraging behaviour.

The subtropical convergence is an area of the ocean where temperature and salinity can change rapidly, and this can aggregate whale prey. Two whales we tracked offshore from the Auckland Islands in 2009 visited the subtropical convergence, but hundreds of kilometres to the east of Bill’s current location.

As Bill and his compatriots migrate, we’ve begun analysing data that will tell us about the recovery of tohorā in the past decade. The most recent population size estimate we have is from 2009, when there were about 2,000 whales.

---

Read more:
Humans threaten the Antarctic Peninsula’s fragile ecosystem. A marine protected area is long overdue

---

I am using genomic markers to learn about the kin relationships and, in doing so, the population’s size and growth rate. Think of it like this. Everybody has two parents and if you have a small population, say a small town, you are more likely to find those parents than if you have a big population, say a city.

This nifty statistical trick is known as the “close kin” approach to estimating population size. It relies on detailed understanding of the kin relationships of the whales — something we have only really been able to do recently using new genomic sequencing technology.

Global effort to understand climate change impacts

Globally, southern right whales in South Africa and Argentina have bred less often over the past decade, leading to a lower population growth rate in Argentina.

Concern over this slowdown in recovery has prompted researchers from around the world to work together to understand the relationship between climate change, foraging ecology and recovery of southern right whales as part of the International Whaling Commission Southern Ocean Research Partnership.

The genome helps by giving us that long view of how the whales responded to climate fluctuations in the past, while satellite tracking gives us the short view of how they are responding on a day-to-day basis. Both will help us understand the future of these amazing creatures.

Emma Carroll, Rutherford Discovery Fellow

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

Advertisement

Climate explained: why we need to cut emissions as well as prepare for impacts

Research shows the cost of damage through climate change will be much greater than the costs of reducing emissions.
from http://www.shutterstock.com, CC BY-ND

Ralph Brougham Chapman, Victoria University of Wellington

CC BY-ND

Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.

If you have a question you’d like an expert to answer, please send it to climate.change@stuff.co.nz

First, let’s accept climate change is happening and will have major negative impacts on New Zealand. Second, let’s also accept that even if New Zealand did absolutely everything possible to reduce emissions to zero, it would still happen, i.e. our impact on climate change is negligible. Third, reducing our emissions will come with a high financial cost. Fourth, the cost of dealing with the negative impacts of climate change (rising seas etc), will also come at a high financial cost. Based on the above, would it not be smarter to focus our money and energy on preparing New Zealand for a world where climate change is a reality, rather than quixotically trying to avert the unavoidable? – a question from Milton

To argue that we should not act to reduce emissions because it is not in our interests to make a contribution to global mitigation is ultimately self-defeating. It would be to put short-term self-interest first, rather than considering both our long-term interests and those of the wider global community.

Our options on climate are looking increasingly dire, since we as a global community have postponed combating climate change so long. But in New Zealand – and indeed in any country – we should still do as much as we can to reduce the extent of climate change, and not, at this stage, divert significant resources away from mitigation into “preparing for” it.

Starting with the physics, it is clear that climate change is not a given and fixed phenomenon. It is unhelpful to say simply that “it is happening”. How much heating will occur will be determined by human actions: it is within humanity’s grasp to limit it.

Any significant action taken over the next decade in particular will have high payoffs in terms of reducing future warming. The Intergovernmental Panel on Climate Change (IPCC) in effect says emission cuts of 45% or more over the next decade might just avert catastrophic change. Inaction, on the other hand, could condemn humankind to experiencing perhaps 3℃ or more of heating. Each further degree represents a huge increase in human misery – death, suffering and associated conflict – and increases the threat of passing dangerous tipping points.

Climate outcomes are so sensitive to what we do over the next decade because eventual heating depends on the accumulated stock of greenhouse gases in the atmosphere. We are still adding to that stock every year, and we are still raising the costs of cutting emissions to an “acceptable” level (such as that consistent with 1.5℃ or 2℃ of heating).

---

Read more:
Climate explained: will we be less healthy because of climate change?

---

Limiting future warming

Under President Obama, a report was published which pointed out that every decade of delay in making cuts in emissions raises the cost of stabilising within a given target temperature (e.g. 2℃) by about 40%.

Each year’s emissions add to the stock of greenhouse gases in the atmosphere, even though some of the gases are absorbed into oceans, trees and soils. Until we can get global emissions down close to zero, atmospheric concentrations will rise. When the Paris agreement was adopted in 2015, it was expected that government pledges at the time might limit heating to under 2℃, conceivably 1.5℃ degrees, if pledges were soon strengthened. It is now even more vital to cut emissions, as it reduces the risk of even higher, and nastier, temperatures.

What of New Zealand’s role in this? New Zealand is indeed a small country. Like most groups of five million or so emitters, we generate a small fraction of global emissions (less than 0.2%). But because we are a well respected, independent nation, with a positive international profile, what we do has disproportionate influence. If we manage to find creative and effective ways to cut emissions, we can be sure the world will be interested and some countries may be motivated to follow suit.

Just as we notice Norway’s effective promotion of electric vehicles, and Denmark’s success with wind power, so too can New Zealand have an outsized impact if we can achieve breakthroughs in mitigation. Reaching 100% renewable electricity generation would be a significant and persuasive milestone, as would any breakthroughs in agricultural emissions.

---

Read more:
Climate explained: why plants don’t simply grow faster with more carbon dioxide in air

---

Reducing emissions makes economic sense

In economic terms, mitigation is an excellent investment. The Stern Review crystallised the argument in 2007: unmitigated climate change will cause damage that would reduce worldwide incomes by substantially more than the costs of active mitigation. Since then, further research has underlined that the cost of damage through climate change will be much greater than the costs of mitigation. Put in investment terms, the benefits from mitigation vastly exceed the costs.

Mitigation is one of the best investments humanity will ever make. Recent findings are that increasing mitigation efforts to ensure that warming is limited to 1.5℃, rather than 2℃ or more, will yield high returns on investment, as damage is averted. We also now know many energy and transport sector mitigation investments, such as in electric vehicles, generate good returns.

So why haven’t we invested enough in mitigation already? The answer is the free rider problem – the “I will if you will” conundrum. The Paris agreement in 2015 is the best solution so far to this: essentially all countries globally have agreed to cut emissions, so relatively concerted action is likely. Given this, it is worthwhile for New Zealand to act, as our efforts are likely to be matched by the actions of others. In addition, of course, we have an ethical duty to future generations to cut emissions.

The fact that New Zealand is a small country with limited emissions is irrelevant to these arguments. We must play our part in the global push to cut emissions. The reality is that it is worthwhile to mitigate, and we are committed to doing so. In this situation, it makes no sense to move mitigation resources away to preparation for climate change. We do of course need to plan and prepare for the impacts of climate change, in myriad ways, but not at the expense of mitigation.

Ralph Brougham Chapman, Associate Professor , Director Environmental Studies, Victoria University of Wellington

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

Australia has two decades to avoid the most damaging impacts of climate change

Iain Stewart, ClimateWorks Australia

The long-awaited special report on the science underpinning the Paris Agreement goal of limiting global warming to 1.5℃ has been released today by the Intergovernmental Panel on Climate Change.

It tells us that hitting this goal will be challenging, but not impossible. And it highlights the benefits of hitting the target, by pointing out that global warming will be vastly more damaging if allowed to reach 2℃.

---

Read more:
The UN’s 1.5°C special climate report at a glance

---

The report says that for a 66% chance at limiting global warming to 1.5℃, an additional 550 billion tonnes of carbon dioxide (or its equivalent) can be emitted globally from the beginning of 2018. Increasing the risk to a 50% chance at limiting global warming to 1.5℃, that figure becomes 750Gt CO₂e.

Based on previous calculations, Australia’s fair share of the global carbon budget is roughly equivalent to 1%. That would put Australia’s remaining carbon budget at 5.5Gt and 7.5Gt for a 66% and 50% chance, respectively.

The simplified trajectory below shows that Australia would therefore need to reach net zero greenhouse emissions by 2038 for a 66% chance of limiting global warming to 1.5℃, and by 2045 for a 50% chance.

ClimateWorks Australia, Author provided

In practical terms, this gives Australia two decades to deliver on our part, for a good chance of avoiding the most devastating impacts of a warming climate. Globally, we must reach net zero greenhouse emissions by 2047 for a 66% chance of limiting global warming to 1.5℃, and by 2058 for a 50% chance. Australia will have to hit net zero before it is achieved globally because we currently have among the highest per person emissions, so our decarbonisation trajectory needs to be steeper.

But Australia’s emissions are rising

From 2006 to 2013, Australian emissions decreased, but they have since begun to rise again. As shown in ClimateWorks Australia’s recently released report, Tracking Progress, we are not yet on track meet our current Paris commitment of cutting emissions by 26-28% relative to 2005 levels by 2030. Nor are we on track to reach net zero.

Yet our research also showed we have the potential to get back on track. There have been recent periods when sectors of our economy have cut carbon at or near the pace required to achieve net zero emissions by 2050.

---

Read more:
Australia is not on track to reach 2030 Paris target (but the potential is there)

---

Reaching net zero from here will require rapid, economy-wide action, including:

• increasing the share of renewable electricity
• improving energy efficiency
• electrifying transport and industry where possible
• switching to lower-emission fuels such as gas
• land use changes (reforestation, reduced land clearance, and best practice farming).

There are already many examples of these kinds of approaches. For example, since 2010, solar photovoltaic prices have fallen by around 70% and battery prices by around 80%, while uptake rates have surpassed expectations. This has been the result of research, investment, government incentives, shifting consumer preferences, and economies of scale.

Consumers are beginning to embrace trends such as electric vehicles and 3D printing, and we can expect more technological disruptions throughout the economy such as building optimisation, smart grids, and solar-hydrogen, which all have the potential to reduce emissions significantly.

The goal is still in reach (just)

The new IPCC report is adamant that the goal of limiting global warming to 1.5℃ is still achievable – despite previous fears that it is already out of reach. Yes, it is tight, but the challenge is in going faster, not the lack of solutions.

Crucially, the report also points out that 2℃ of global warming would be vastly more damaging than 1.5℃, and that 2℃ cannot be treated as a “safe” limit.

At 2℃, the report predicts it is “very likely that there will be at least one sea-ice-free Arctic summer per decade”. In contrast, holding warming to 1.5℃ rather than 2℃ would protect an extra 10.4 million people from rising sea levels.

Some of these people are our neighbours in Pacific Island nations, many of which are implementing some of the most ambitious climate policies in the world. For low-lying countries and island states, the reality is “1.5 to stay alive”.

Australia’s climate at stake

Closer to home, the impacts of climate change on Australia will continue to manifest themselves in extreme weather events such as droughts, floods and bushfires. Increasing impacts are expected to extend to water, food and even border security, creating the potential for millions of climate refugees in our region before the end of the century.

As a wealthy, emissions-intensive country with abundant natural resources, in a region highly vulnerable to climate impacts, Australia should take its Paris climate targets very seriously. Australia has the means to become a regional leader in climate action, positioning ourselves as a “clean energy superpower” and helping our neighbours work towards becoming carbon-neutral.

---

Read more:
Lack of climate policy threatens to trip up Australian diplomacy this summit season

---

There are many examples within Australia of commitments already made to reach net zero emissions. States and territories representing 80% of Australia’s emissions – along with the federal opposition – have committed to reaching net zero emissions by 2050. Tasmania has already reached net zero. The ACT has legislated to do so by 2045.

Other organisations have also pledged to go carbon-neutral or use 100% renewable energy, including multinational companies, major cities such as Melbourne, Sydney and Adelaide, and universities.

These initiatives prove that setting targets for emissions reduction actually ignites action. The IPCC’s new report sets us perhaps the most important target of all: the world must hit net zero emissions by mid-century if we are to stand a good chance of avoiding the worst impacts of global warming.

Iain Stewart, Analyst, ClimateWorks Australia

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

Target Earth: how asteroids made an impact on Australia

Gosses Bluff impact crater in the Northern Territory.
NASA’s Earth Observatory

Andrew Glikson, Australian National University

Our planet has had a few close encounters with asteroids of late.

Asteroid 2018 CC came within about 184,000km of Earth on February 6 this year. A few days later asteroid 2018 CB came within 64,000km, which is less than one-fifth the distance of Earth to the Moon.

Animation showing how asteroid 2018 CB passed closely by Earth on February 9. (NASA/JPL-Caltech)

Thankfully, both asteroids were relatively small (estimated between 15m and 40m). Neither posed a risk to Earth (this time), but Earth has not been so lucky in the past.

---

Read more:
Ancient asteroid impacts yield evidence for the nature of the early Earth

---

Research in Australia and other countries indicates that, in the distant geological past, asteroids as large as Eros (about 34.4km long and 11.2km wide) have impacted Earth. These have triggered major changes in the structure and evolution of the crust and mantle, as I’ve written about before.

Asteroid Eros.
NASA

The impact of asteroids on the Australian continent and marine shelves is examined more closely in my new book, Asteroid impacts, crustal evolution and mineral systems, with special reference to Australia, co-authored by Franco Pirajno.

In the firing line

The terrestrial planets of the inner solar system – Mars, Earth, Venus and Mercury – are all affected by asteroids deflected from the asteroid belt, located between Mars and Jupiter, and by comets falling off the Kuiper belt beyond Neptune.

The cratered surface of Mercury.
NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Many of these impact craters are clearly seen on Mars and Mercury as well as on our Moon. Venus too has its craters, but its thick atmosphere obscures these.

When Earth is viewed from space, it displays little or no cratering despite also being located in the trajectory of these asteroids and comets.

Earth doesn’t look very cratered from space.
NASA

But this impression is apparent rather than real. Many of the impact scars are covered or masked due to the dynamic nature of Earth and the oceans that extend over some two-thirds of the planet’s surface. The masking processes include the accretion and subduction of tectonic plates as well as intensive erosion processes.

It was not until about 1981 that the scientific community began to recognise the significance of extraterrestrial impacts for the mass extinction of species about 66 million years ago, which wiped out the dinosaurs and many other groups.

The American scientists Louis and Walter Alvarez and their colleagues had unearthed a telltale iridium-rich sedimentary layer around the 66 million-year-old Cretaceous-Tertiary boundary at Gubbio, Italy. The element iridium, typically enriched in asteroids, is a signature within sediments for material from a meteorite impact.

The discovery re-established the idea that catastrophes shaped much of Earth’s history, a theory originally promoted by the French zoologist Georges Cuvier.

Impacts on the Earth

Beyond forming craters, the impact of large asteroids on Earth resulted in the formation of structural domes due to elastic rebound of the crust. Examples include the Vredefort dome in South Africa and the buried Woodleigh dome under and east of Shark Bay in Western Australia.

The impacts also caused major seismic activity and faulting, large tsunami events, ejection of masses of particles and dust, and – as mentioned earlier – in some instances the mass extinction of species due to rapid environmental changes.

The asteroid impact record on Earth is thus to a large extent concealed and the subject of an extensive search using structural, geophysical, geochemical and other methods.

Since many impact records are covered by the oceans or were eroded, old stable parts of the Earth crust, named “cratons”, are the best places to look. This is where the scars of ancient asteroid impacts are preserved and can be found, including craters and their deep-seated roots and rebound dome structures.

Australian impacts

The criteria applied for recognition of asteroid impact structures and meteorite craters allowed the identification of at least 38 confirmed impact structures on the Australian continent and surrounding continental shelf.

There are an additional 43 examples of exposed and buried circular ring and dome features, many of which are of possible or probable impact origin.

The red circles show confirmed impact structures, green circles are impact craters, the yellow circles are possible-to-probable ring structures, red outer rings are impact structures larger than 100km in diameter, and outer white rings are impact structures less than 50km.
Google Earth/Andrew Glikson, Author provided

Examples of exposed confirmed impact structures include Gosses Bluff in the southern Northern Territory, Shoemaker in central Western Australia, and Acraman and Lawn Hill in northwestern Queensland.

A Google Earth image of the central ring of the Gosses Bluff impact structure, central Australia, Northern Territory. It is 14km in diameter and was formed around 142 million years ago.

A Google Earth image of the Shoemaker impact structure, Nabberu Basin, in Western Australia. It is 30km in diameter and was likely formed around 1,630 million years ago.

A Google Earth image of the centre of the Acraman impact structure in southern South Australia. It is 90km in diameter and was formed around 590 million years ago.

A Google Earth image of the centre of the Lawn Hill impact structure in northwestern Queensland. It is is 18km in diameter and was formed more than 515 million years ago.

The impact record of Australia thus includes exposed impact structures, buried impact structures, meteorite craters and geophysical ring anomalies of unproven origin.

Examples of large geophysical multi-ring features – total magnetic intensity anomalies, circular gravity anomalies and seismic domes – include probable buried twin impact structures in the Warburton Basin in northeast South Australia, a confirmed buried impact structure at Woodleigh in WA, and confirmed buried impact structures at Tookoonooka and Talundilly in the Eromanga Basin in southwest Queensland.

Seismic tomographic (identified 3D images) anomalies of the Warburton twin structures, South Australia, representing probable impact structures, and the Woodleigh impact structure, Western Australia.
Saygin and Kennett 2010/Andrew Glikson, Author provided

Fallout of asteroid impacts

Structures and craters caused by asteroid impacts are not the only thing we find. In the Australian landscape there are also the rock fragments and melt drops derived from clouds ejected from the impact craters.

The melt drops, condensed from impact-ejected vapour, are termed “microkrystites”. These are recognised by their radiating quench (cooling) textures and abundance of platinum group element anomalies.

Impact condensate spherules (called microkrystites) from the 2.63 billion-years-old Jeerinah Impact layer, central Pilbara Craton, Western Australia.
Bruce Simonson, Author provided

In at least one instance the evidence suggests that an impact by a cluster of large asteroids resulted in an abrupt transformation of crustal structure on the Pilbara, northwestern Australia, as well as the Barberton greenstone belt in South Africa, from a granite/greenstone system to semi-continental crustal environment.

---

Read more:
World’s largest asteroid impact site could be right here in Australia

---

Between 3.26 and 3.24 billion years ago these impacts caused a sharp tectonic uplift and magmatic activity, leading to to an onset of semi-continental crustal conditions.

Thus, far from being free from impacts, the Australian landscape has been shaped many times over millions and billions of years by asteroids falling to Earth.

As studies of Australian impact structure and impact ejecta progress, the critical role of asteroid impacts in the early evolution of the Earth and in the development of the Australian continent are becoming clearer.

Andrew Glikson, Earth and paleo-climate scientist, Australian National University

This article was originally published on The Conversation. Read the original article.

Noise Pollution: Squids and Octopuses

The following link is to an article that looks into how noise pollution impacts squids and octopuses. An enlightening article on an issue that is becoming clearer all of the time.

For more visit:
http://www.treehugger.com/files/2011/04/oceans-noise-pollution-causing-massive-trauma-squids-octopuses.php