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Slims River: Climate change causes "river piracy" in Canada's Yukon
Trump aides abruptly postpone meeting on whether to stay in Paris climate deal
Unlikely coalition of fossil fuel firms, environmental groups and Republicans are calling on president to stay despite his pledge to ‘cancel’ agreement
Donald Trump’s aides have abruptly postponed a meeting to determine whether the US should remain in the Paris climate agreement, with an unlikely coalition of fossil fuel firms, environmental groups and some Republicans calling on the president to stick with the deal.
Trump’s top advisers were set to meet on Tuesday to provide the president with a recommendation ahead of a G7 meeting in May. However, a White House official said the meeting had been postponed due to conflicting schedules. It is unclear when it will now take place.
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Google Earth adds Attenborough world tours
'The truth needs an advocate': why scientists will be marching on Saturday
The hands of the Doomsday Clock currently stand at two-and-a-half-minutes to midnight. Professor Ray Pierrehumbert of Oxford University and the Bulletin of Atomic Scientists explains why support for science and the global March for Science on 22 April is crucial
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Scientists to take to the streets in global march for truth
March for Science on 22 April will see scientists and supporters at more than 500 locations stand up for evidence-based thinking
Scientists and science supporters will take to the streets in a global March for Science on 22 April . What began as a small Facebook group in the US capital, Washington DC has spiralled into a global phenomenon that will now see marches and other events in more than 500 locations around the world, from Seattle to Seoul.
It is great news that so many people are prepared to stand up and defend the need for evidence-based thinking and the scientific method. But it is also a sad comment on our times that a March for Science is needed at all. Post-truth populism has infected democracies around the world, scientific objectivity is under threat from multiple sources and there seems a real danger of falling into a modern dystopian dark age.
Continue reading...Science strikes back: anti-Trump march draws thousands to Washington
Scientists are ditching their labs for the streets in a mass protest against the Trump administration’s war on facts, but will the effort resonate with skeptics?
On Saturday, thousands of scientists are set to abandon the cloistered neutrality of their laboratories to plunge into the the political fray against Donald Trump in what will likely be the largest ever protest by science advocates.
The March for Science, a demonstration modeled in part on January’s huge Women’s March, will inundate Washington DC’s national mall with a jumble of marine biologists, birdwatchers, climate researchers and others enraged by what they see as an assault by Trump’s administration upon evidence-based thinking and scientists themselves.
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Macquarie reported to have acquired 330MW of solar PV in India
Nuvation begins shipping utility-grade low-voltage battery management systems
NSW could be dark horse of Australia’s renewable energy boom
Something is amiss with the Yare valley rooks
Claxton, Norfolk At Thorpe Hall near Haddiscoe, 340 pairs of rooks once nested, but this spring there is not one
Assessing the rook population in the Yare valley has long been a favourite ritual of my springs. Since the nests are coarse bundles of sticks in the bare treetops it is easy to combine the serious census work with the season’s wider pleasures: the sounds of first chiffchaffs or blackcaps, the lemon wings of male brimstone butterflies, and the year’s first glamorous colour from primroses, marsh marigolds and walls of blackthorn blossom.
However, by the time I reached the third of my 30 rookeries, I sensed that this year would be different. A site that had once held 100 nests was completely empty. Thereafter, each old place revealed the new story of absence.
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Innovation: Nano-Nouvelle battery boosting technology one step closer to market
March was a record month for renewable power in Germany
February 2017 Australian Petroleum Statistics now available
Where the old things are: Australia's most ancient trees
![](https://cdn.theconversation.com/files/165009/width496/image-20170412-25888-1jhrjzu.jpg)
They say that trees live for thousands of years. Like many things that “they” say, there is a germ of truth in the saying (even though it is mostly false).
The vast majority of trees that burst forth from seeds dropped on the Australian continent die before reaching maturity, and in fact most die within a few years of germination.
But depending on how you define a tree, a very select few trees can live for an astoundingly long time.
What are the oldest trees?If we define a “tree” as a single stemmed woody plant at least 2 metres tall, which is what most people would identify as a tree, then the oldest in Australia could be a Huon Pine (Lagarostrobos franklinii) in Tasmania, the oldest stem of which is up to 2,000 years old.
However, the Huon Pine is also a clonal life form – the above-ground stems share a common root stock. If that common root stock is considered to be the base of multi-trunked tree, then that tree could be as old as 11,000 years.
But if you accept a clonal life form as a tree, even that ancient Huon age pales into insignificance against the 43,000-year-old king’s holly (Lomatia tasmanica), also found in Tasmania.
![](https://cdn.theconversation.com/files/163068/width754/image-20170329-1642-9n0qxh.jpg)
Once you accept that a common, genetically identical stock can define a tree, then the absolute “winner” for oldest tree (or the oldest clonal material belonging to a tree) must go to the Wollemi Pine (Wollemia nobilis). It may be more than 60 million years old.
The Wollemi pine clones itself, forming exact genetic copies. It was thought to be extinct until a tiny remnant population was discovered in Wollemi National Park in 1994. The trunk of the oldest above-ground component, known as the Bill Tree, is about 400-450 years old. But the pine sprouts multiple trunks, so the Bill Tree’s roots may be more than 1,000 years old.
There is also substantial evidence that the tree has been cloning itself and its unique genes ever since it disappeared from the fossil record more than 60 million years ago.
How do you date a tree?If no humans were around to record the planting or germination of a tree, how can its age be determined? The trees themselves can help tell us their age, but not just by looking at their size. Big trees are not necessarily old trees - they might just be very healthy or fast-growing individuals.
A much more reliable way to determine age of a tree is through their wood and the science of dendrochronology (tree-ring dating).
![](https://cdn.theconversation.com/files/164987/width754/image-20170412-26741-1ahi7f5.jpg)
Many trees lay down different types of cell wall material in response to seasonal patterns of light, temperature or moisture. Where the cell walls laid down at the beginning of the growth season look different to those laid down at the end of the season, rings of annual growth can be seen in cross-sections of the tree.
This map of growth patterns can also be cross-dated or correlated with major events like multi-year droughts or volcanic eruptions that spewed material into the atmosphere to be incorporated into the wood of the tree. But the cell walls are more than just calendars.
Why so old?Individual tree stems can live for so long because of the structure of the wood and the tree’s defence mechanisms. The woody cell walls are very strong and resist breakage.
In fact, scientists have recently discovered that these walls contain a structure – nanocrystaline cellulose – that is currently the strongest known substance for its weight.
Wood can, however, be broken down by insects and fungi. Even though there is little nutrition or energy in wood, there is some – and there are plenty of organisms that will try and use it.
But trees are not defenceless, and can fight back with physical barriers or even chemical warfare. When one tree is attacked by these destructive forces, individuals may even signal to other trees to be aware and prepare their own defences to fight off death and decay.
The death of treesSo why don’t all trees live for centuries or millennia, and why do so many die before even reaching maturity?
![](https://cdn.theconversation.com/files/165014/width237/image-20170412-25859-1crgl1c.jpg)
Seedlings and young trees may die because they have germinated in an area where there’s not enough water, nutrients or light to keep them alive as adults. Young trees also haven’t had much time to develop barriers or defences against other organisms and may be browsed or eaten to death.
Some trees simply fall prey to accidents: wind storms, fires or droughts. This is just as well, because there is a vast number of plants and animals – including humans – which rely on the wood and other components of these dead trees for their food and shelter.
But increasingly we may see trees dying because the environment is changing around them and they may not be able to cope. This is not just due to climate change; urban development and agricultural expansion, pollution and even too much fertiliser acting as a poison – even our most remote environments are subject to these changes.
But that doesn’t necessarily mean we will have no more very old trees. The Wollemi Pine’s genes have already survived over millions of years, multiple ice ages and warming periods and even the fall of the dinosaurs and rise of humans. And now, people have deliberately spread Wollemi Pine trees all around the world so they are living in a wide range of countries and climates, meaning that the risk of them all dying out is substantially reduced.
Maybe we can do the same for other trees, ensuring that trees will outlive us all.
![The Conversation](https://counter.theconversation.edu.au/content/65893/count.gif)
Cris Brack is a member of the Institute of Foresters of Australia and Director National Arboretum, Canberra Foundation.
Matthew Brookhouse does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.