An act of God, or just bad management? Why trees fall and how to prevent it

AP

Gregory Moore, The University of MelbourneThe savage storms that swept Victoria last week sent trees crashing down, destroying homes and blocking roads. Under climate change, stronger winds and extreme storms will be more frequent. This will cause more trees to fall and, sadly, people may die.

These incidents are sometimes described as an act of God or Mother Nature’s fury. Such descriptions obscure the role of good management in minimising the chance a tree will fall. The fact is, much can be done to prevent these events.

Trees must be better managed for several reasons. The first, of course, is to prevent damage to life and property. The second is to avoid unnecessary tree removals. Following storms, councils typically see a spike in requests for tree removals – sometimes for perfectly healthy trees.

A better understanding of the science behind falling trees – followed by informed action – will help keep us safe and ensure trees continue to provide their many benefits.

We must try to stop trees falling over to prevent damage to life and property.
James Ross/AAP

Why trees fall over

First, it’s important to note that fallen trees are the exception at any time, including storms. Most trees won’t topple over or shed major limbs. I estimate fewer than three trees in 100,000 fall during a storm.

Often, fallen trees near homes, suburbs and towns were mistreated or poorly managed in preceding years. In the rare event a tree does fall over, it’s usually due to one or more of these factors:

1. Soggy soil

In strong winds, tree roots are more likely to break free from wet soil than drier soil. In arboriculture, such events are called windthrow.

A root system may become waterlogged when landscaping alters drainage around trees, or when house foundations disrupt underground water movement. This can be overcome by improving soil drainage with pipes or surface contouring that redirects water away from trees.

You can also encourage a tree’s root growth by mulching around the tree under the “dripline” – the outer edge of the canopy from which water drips to the ground. Applying a mixed-particle-size organic mulch to a depth of 75-100 millimetres will help keep the soil friable, aerated and moist. But bear in mind, mulch can be a fire risk in some conditions.

Root systems can also become waterlogged after heavy rain. So when both heavy rain and strong winds are predicted, be alert to the possibility of falling trees.

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A combination of heavy rain and strong winds can cause trees to fall.
Shutterstock

2. Direct root damage

Human-caused damage to root systems is a common cause of tree failure. Such damage can include roots being:

• cut when utility services are installed
• restricted by a new road, footpath or driveway
• compacted over time, such as when they extend under driveways.

Trees can take a long time to respond to disturbances. When a tree falls in a storm, it may be the result of damage inflicted 10-15 years ago.

This elm, growing very close to a footpath, fell in Melbourne during a 2005 storm.
Author provided

3. Wind direction

Trees anchor themselves against prevailing winds by growing roots in a particular pattern. Most of the supporting root structure of large trees grows on the windward side of the trunk.

If winds come from an uncommon direction, and with a greater-than-usual speed, trees may be vulnerable to falling. Even if the winds come from the usual direction, if the roots on the windward side are damaged, the tree may topple over.

The risk of this happening is likely to worsen under climate change, when winds are more likely to come from new directions.

4. Dead limbs

Dead or dying tree limbs with little foliage are most at risk of falling during storms. The risk can be reduced by removing dead wood in the canopy.

Trees can also fall during strong winds when they have so-called “co-dominant” stems. These V-shaped stems are about the same diameter and emerge from the same place on the trunk.

If you think you might have such trees on your property, it’s well worth having them inspected. Arborists are trained to recognise these trees and assess their danger.

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Storms can trigger falling trees which block roads.
Shutterstock

Trees are worth the trouble

Even with the best tree management regime, there is no guarantee every tree will stay upright during a storm. Even a healthy, well managed tree can fall over in extremely high winds.

While falling trees are rare, there are steps we can take to minimise the damage they cause. For example, in densely populated areas, we should consider moving power and communications infrastructure underground.

By now, you may be thinking large trees are just too unsafe to grow in urban areas, and should be removed. But we need trees to help us cope with storms and other extreme weather.

Removing all trees around a building can cause wind speeds to double, which puts roofs, buildings and lives at greater risk. Removing trees from steep slopes can cause the land to become unstable and more prone to landslides. And of course, trees keep us cooler during summer heatwaves.

Victoria’s spate of fallen trees is a concern, but removing them is not the answer. Instead, we must learn how to better manage and live with them.

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Read more:
Here are 5 practical ways trees can help us survive climate change

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Gregory Moore, Doctor of Botany, The University of Melbourne

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

Some good news for a change: Australia’s greenhouse gas emissions are set to fall

Renewable energy being installed at a community in the Northern Territory. Researchers have predicted Australia’s emissions are set to fall, but warn the renewables deployment rate must continue.
Lucy Hughes-Jones/AAP

Andrew Blakers, Australian National University and Matthew Stocks, Australian National University

For the past few years, Australia’s greenhouse gas emissions have headed in the wrong direction. The upward trajectory has come amid overwhelming evidence that the world must bring carbon dioxide emissions down. But the trend is set to change.

In a policy brief released today, we predict that Australia’s greenhouse gas emissions will peak during 2019-20 at the equivalent of about 540 million tonnes of carbon dioxide.

After a brief plateau, we expect they will decline by 3-4% over 2020-22, and perhaps much more in the following years – if backed by government policy.

The peak will occur because Australia’s world-leading deployment of solar and wind energy is displacing fossil fuel combustion. Emissions from the electricity sector are about to fall much faster than increases in emissions from all other sectors combined.

This is a message of hope for rapid reduction of emissions at low cost. But we cannot rest on our laurels. If renewable energy deployment stops or slows, emissions may rise again.

Figure 1: Historical and projected total Australian emissions in megatonnes of CO2 (equivalent) per year. Black line: Government emissions projections which assume solar and wind deplpoyment almost stops. Green line: Deployment continues at the current rate.
ANU

Australia: a renewables superstar

Deployment of solar and wind energy is the cheapest and quickest way to make deep emissions cuts because of its low and falling cost. Higher deployment rates would yield deeper emissions cuts, but this requires supportive government policy.

Wind and solar constitute about two-thirds of global net new electricity capacity. Gas, hydro and coal comprise most of the balance. Solar and wind comprise virtually all new generation capacity in Australia because they are cheaper than alternatives.

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Australia is the runaway global leader in building new renewable energy

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Australia is a global renewable energy superstar because it is installing new solar and wind capacity four to fives times faster per capita than China, the European Union, Japan or the United States. This allows Australia to stabilise and then reduce its greenhouse emissions and sends a globally important message.

Figure 2 shows the rapid increase in the proportion of solar and wind energy from 2018 in the National Electricity Market, which covers the eastern states and comprises about 85% of national electricity generation. The proportion of renewable energy generation has reached 25%, including hydro.

Figure 2: Monthly solar and wind fraction of electricity generation in the NEM over 2014-19 showing sharp increase in 2018.
ANU

We are confident Australia’s emissions will fall in 2020, 2021 and probably 2022 because 16-17 gigawatts of wind and solar is locked in for deployment in 2018-20. This reduces emissions in the electricity sector by about 10 million tonnes a year.

The federal government projects that emissions outside the electricity system will increase by about 3 million tonnes per year on average over the 2020s. The difference leaves an overall decline of 7 million tonnes of emissions per year.

100% clean electricity is within our grasp

Beyond our projections for the next few years, continued falls in emissions are not assured. The emissions trajectory for 2022 and beyond depends largely on the level of renewables deployed.

Federal government projections assume solar and wind deployment almost stops in the 2020s. This would mean annual emissions increase from current levels to 563 million tonnes in 2030.

Wind turbines adjacent to the Tesla batteries at Jamestown, north of Adelaide, in 2017.
DAVID MARIUZ/AAP

But it doesn’t need to be this way. If the current renewables deployment rate continued, Australia would reach 50% renewable electricity in 2024, and potentially 80% renewables in 2030. This transformation would be technically straightforward and affordable. It requires governments, mostly the federal government, to encourage more transmission power lines to deliver renewable electricity to where it’s needed. Other off-the-shelf methods to support renewables include energy storage such as pumped hydro and batteries, and managing electricity demand.

The benefits of a consistent renewables rollout would be large. Australia’s electricity emissions in 2030 would be 100 million tonnes lower than government projections and the nation would meet its Paris target of a 26-28% emissions reduction between 2005 and 2030. This could be achieved without the controversial proposal to carry over carbon credits earned in the Kyoto Protocol period.

It should be noted that changes in land clearing rates or coal and gas mining or economic activity would also affect future national emissions.

Electricity infrastructure at the Snowy Hydro scheme. Such hydro projects are key to firming up intermittent renewable energy.
Lukas Coch/AAP

The emissions road ahead

Continued rapid deployment of solar and wind requires that governments enable construction of adequate electricity transmission and storage.

State governments should also continue efforts to establish renewable energy zones, with or without cooperation from the federal government. These zones would be located where there is good wind, sun and pumped hydro energy storage, bringing sustainable investment and jobs to regional areas.

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In the longer term, solar and wind can cut national emissions by two-thirds. Beyond the electricity sector, this involves electrifying motor vehicles, residential heating and cooling and industrial heating. National emissions could be cut by another 10% by stopping exports of fossil fuels, which creates fugitive emissions.

It is clear that solar and wind are the most practical route, globally and in Australia, to cheap, rapid and deep emissions cuts – and government policy will be key.

Andrew Blakers, Professor of Engineering, Australian National University and Matthew Stocks, Research Fellow, ANU College of Engineering and Computer Science, Australian National University

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

Australia: Queensland – Bushwalker Ordeal

Australia falls further in rankings on progress towards UN Sustainable Development Goals

John Thwaites, Monash University and Tahl Kestin, Monash University

Australia is performing worse than most other advanced countries in achieving the Sustainable Development Goals (SDGs), according to the global SDG Index, which compares different nations’ performance on the goals.

According to the SDG Index, released yesterday in New York, Australia is ranked 37th in the world – down from 26th last year, and behind most other wealthy countries including New Zealand, Canada, the United States and the United Kingdom.

The best-performing countries are the northern European nations of Sweden, Denmark, Finland and Germany, all of which have a history of balancing economic, social and environmental issues.

The SDG Index measures progress against the 17 SDGs agreed by all countries at the United Nations in 2015. The goals encompass a set of 169 targets to be met by 2030 to achieve economic prosperity, social inclusion and environmental sustainability.

Yet despite the progress made by some countries, all nations still have a way to go to achieve all of the goals.

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Australia: the world’s worst on climate action

The latest SDG Index shows that Australia is performing relatively well in areas such health and wellbeing, and providing good-quality education. But its results for the environmental goals and climate change are among the worst in the OECD group of advanced nations.

The new index ranks Australia as the worst-performing country in the world on climate action (SDG 13). The measure takes into account greenhouse gas emissions within Australia; emissions embodied in the goods we consume; climate change vulnerability; and exported emissions from fossil fuel shipments to other countries.

One of the reasons why Australia has slumped so far in the rankings is that the SDG Index is now taking into account the so-called “spillover” effects that countries have on other nations’ ability to meet the SDGs. These effects may be positive, such as providing development aid; or negative, such as importing or exporting products that create pollution.

The report shows that G20 nations account for the largest negative economic, environmental, and security spillover effects. Despite being among the richest nations in the world, the US, the UK and Australia are rated worst in the G20 for negative spillovers.

The UK, for instance, rates particularly badly on the tax haven score, which makes it harder for other countries to raise the tax revenue needed to provide health, education and other services to their citizens.

This year’s SDG Index also includes a key environmental spillover indicator: carbon dioxide emissions embodied in fossil fuel exports, calculated using a three-year average of coal, gas and oil exports.

Australia’s annual exported CO₂ emissions are a colossal 44 tonnes per person. This outstrips even Saudi Arabia (35.5 tonnes per person), and is orders of magnitude larger than the figure for the US (710kg per person).

G20 leading the way?

With all countries still falling short of achieving the SDGs, the SDG Index also assesses what actions G20 governments are taking to help close this gap. Most G20 countries have begun to implement the goals but there are large variations among G20 countries in how the SDGs are being embraced by political leaders and translated into action.

Composite score of national coordination and implementation mechanisms for the SDGs in G20 countries.
SDSN and Bertelsmann Stiftung, 2018 SDG Index and Dashboards Report

Brazil, Mexico and Italy have taken the most significant steps among G20 countries to achieve the goals, illustrated for instance by the existence of SDG strategies, coordination units in governments, or online platforms. India and Germany have at least partially already undertaken an assessment of investment needs.

According to this assessment, Australia has taken some initial steps to support SDG implementation. Supportive actions taken by the government include setting up a cross-departmental committee, co-chaired by the Department of Foreign Affairs and Trade and the Department of Prime Minister and Cabinet, to coordinate Government SDG activities. The Senate has established an inquiry to examine the opportunities to implement the goals.

Significantly, the federal government has also prepared a Voluntary National Review report on progress in implementing the goals, which it will present to the UN’s High Level Political Forum next week. The report addresses how Australia is performing against each of the goals and includes many case studies of implementation from business, civil society, academia, youth and all levels of government. It is accompanied by a new Australian SDG case study hub. Many of these activities occurred after the cut-off period for the SDG Index, so Australia’s overall performance on SDG implementation is actually higher than the SDG Index gives it credit.

However, Australia is not taking more deliberative action to address the SDGs, such as developing a national implementation plan or setting aside funding for SDG implementation. Nor are individual departments identifying the gaps in Australia’s SDG performance and identifying what they plan to do differently to address them.

Given Australia’s poor performance on some of the SDGs there is clearly a need for targeted action if we are to achieve the goals by the 2030 deadline.

John Thwaites, Chair, Monash Sustainable Development Institute & ClimateWorks Australia, Monash University and Tahl Kestin, Sustainable Development Solutions Network Manager, Monash Sustainable Development Institute, Monash University

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

Climate and the rise and fall of civilizations: a lesson from the past

Andrew Glikson, Australian National University

2015 will likely be the hottest year on record, beating the previous record set only in 2014. It is also likely to be the first year the global average temperature reaches 1℃ above pre-industrial temperatures (measured from 1880-1899). Global warming is raising temperatures, and this year’s El Niño has pushed temperatures higher still.

Although 2015 is unusually hot, 1℃ symbolically marks the halfway point to 2℃, widely considered to be the threshold of “dangerous” climate change. In fact an additional 0.5-1℃ is actually masked by sulphur aerosols which we have added to the atmosphere alongside greenhouse gases.

A temperature level of 1℃ (above pre-industrial levels) is similar to or warmer than the peak temperatures of the early Holocene epoch approximately 8,000-7,200 years ago. Studies of the early Holocene provide clues to what was such a world like.

The climate roller-coaster

The last ice age (or Last Glacial Maximum) peaked around 26,000 years ago. The earth warmed over the coming millennia, driven by an increase in radiation from the sun due to changes in the earth’s orbit (the Milankovic cycles) amplified by CO₂ released from warming water, which further warmed the atmosphere.

But even as the earth warmed it was interrupted by cooler periods known as “stadials”. These were caused by melt water from melting ice sheets which cool large regions of the ocean.

Marked climate variability and extreme weather events during the early Holocene retarded development of sustainable agriculture.

Sparse human settlements existed about 12,000 – 11,000 years ago. The flourishing of human civilisation from about 10,000 years ago, and in particular from 7,000 years ago, critically depended on stabilisation of climate conditions which allowed planting and harvesting of seed and growing of crops, facilitating growth of villages and towns and thereby of civilisation.

Peak warming periods early in the Holocene were associated with prevalence of heavy monsoons and heavy floods, likely reflected by Noah’s ark story.

We can’t measure historical temperatures directly, so scientists use oxygen measurements instead. Human civilisation arose in a period of mostly settled climate.
Bruce Railback’s Geoscience Resources

Early civilisations

The climate stabilised about 7,000 – 5,000 years ago. This allowed the flourishing of civilisations along the Nile, Tigris, Euphrates, Indus and the Yellow River.

The ancient river valley civilisations cultivation depended on flow and ebb cycles, in turn dependent on seasonal rains and melting snows in the mountain sources of the rivers. These formed the conditions for production of excess food.

When such conditions declined due to droughts or floods, civilisations collapsed. Examples include the decline of the Egyptian, Mesopotamian and Indus civilisations about 4,200 years ago due to severe drought.

Throughout the Holocene relatively warm periods, such as the Medieval Warm Period (900-1200 AD), and cold periods, such as the Little Ice Age (around 1600 – 1700 AD), led to agricultural crises with consequent hunger, epidemics and wars. A classic account of the consequences of these events is presented in the book Collapse by Jared Diamond.

It’s not just Middle Eastern civilisations. Across the globe and throughout history the rise and fall of civilisations such as the Maya in Central America, the Tiwanaku in Peru, and the Khmer Empire in Cambodia, have been determined by the ebb and flow of droughts and floods.

Changing the game

Greenhouse gas levels were stable or declined between 8,000-6,000 years ago, but then began to rise slowly after 6,000 years ago. According to William Ruddiman at the University of Virginia, this rise in greenhouse gases was due to deforestation, burning and land clearing by people. This stopped the decline in greenhouse gases and ultimately prevented the next ice age. If so, human-caused climate change began much earlier than we usually think.

Rise and fall in solar radiation continued to shift the climate. The Medieval Warm Period was driven by an increase in solar radiation, while the Little Ice Age was caused at least in part by a decrease.

Now we’ve changed the game again by releasing over 600 billion tonnes of carbon into the atmosphere since the Industrial Revolution, raising CO₂ concentrations from around 270 parts per million to about 400 parts per million.

One of the consequences of this rise is an extraordinary decline in the North Atlantic Ocean Circulation as cold water from melting of Greenland ice enters the sea. This could potentially lead to a collapse of the Atlantic Meridional Ocean Circulation and a short, regional human-caused cold period, or “stadial”, mostly affecting Europe and North America, similar to those that occurred in the early Holocene.

CO2 concentrations in November 2015. The blue circle shows an area of reduced CO2 corresponding to cooler sea temperatures in the North Atlantic Ocean.
NASA, Author provided

While this may sound like “global cooling”, a cold period could have deleterious effects on agriculture and is bound to be succeeded by further warming due to the high atmospheric CO₂ concentrations.

The current shift in state of the atmosphere-ocean-ice system signifies a return to conditions such as existed at the early Holocene, which were less favourable for farming. But it doesn’t stop there.

A further rise in CO₂ and temperature would lead to conditions which existed in the Pliocene before 2.6 million years ago, including many metres of sea level rise (around 10-40 metres), posing an existential threat to the future of civilisation.

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Andrew will be on hand for an Author Q&A between 2 and 3pm AEST on Friday, December 11, 2015. Post your questions in the comments section below.

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

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

Why Buildings Fall in Earthquakes

Camping: 9 Ways to Transition from Summer to Fall

Girly Camping®

9 Ways to Transition from Summer to Fall

As summer is coming to an end, its time to put our bathing suits away and bust out the warmer sleeping bags to prepare for camping in the Fall. With cooler weather, shorter daylight, and more sight seeing, here are 9 ways to transition from Summer to Fall:

Experience warmer climates- Camping in the desert may be too extreme the summer but with the temperature dropping, Spring and Fall are the ultimate seasons to go camping in warmer climates.

Sip hot cocoa-Cooler weather means colder nights and what better way to warm up than with hot cocoa around the campfire!

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Canada: Japan’s Tsunami Debris Making Land Fall

Amazon: Deforestation Continuing to Fall

The link below is to an article that examines deforestation in the Amazon, with a trend now developing showing that deforestation is slowing, but more more needs to be done.

For more visit:
http://www.guardian.co.uk/environment/2012/aug/03/amazon-deforestation-falls-again

Holiday Update

My latest holiday plan has gone flop – the back packing holiday is a no-goer. Reason? It would seem from all reports that the Tops to Myalls Heritage Trail has been abandoned, with parts of the route now so overgrown as to be unrecognizable. I have been told of walkers in recent times having to back track a fair distance when the way ahead was no longer able to be walked. So as disappointing as it is I have abandoned the trail myself and will now do something else.

With time running out for a settled option, I have decided to fall back on an earlier idea and that is to visit the Cathedral Rocks National Park and possibly do some further walks at the Dorrigo National Park. I have booked a vehicle (car rental) for the trip so things are fairly settled now as far as the destination is concerned. I am now going to put some meat on the bones of my idea and draw up an itinerary, Google Map, etc. So some real detail of what I plan to do will be coming over the next few weeks.

This isn’t going to be an expensive holiday or a long one, but is mean’t to be a simple time-out break and one that will allow me to plan some much bigger holidays for later in the year and into the coming year also.