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The Australian Heritage Council has called for comments on the heritage values of Centennial Park and whether it should be included in the National Heritage List. The period for comments closes on 28 April 2017.

The Australian Heritage Council is now assessing the place and has called for comments on its heritage values and whether it should remain in the National Heritage List. The period for comments closes on 28 April 2017

Get ready for heavier rain. Shutterstock

As the planet warms, rainfall and weather patterns will change. As temperatures rise, the amount of water in the atmosphere will increase. Some areas will become wetter, while others, like southern Australia, will likely be drier.

One measure of atmospheric moisture is called “precipitable water”. You may not have heard the term before, but will likely hear about it more often in the future. Both climate scientists and meteorologists are increasingly looking at it when studying weather charts.

There is a lot of uncertainty about future rainfall patterns, but there is one aspect that models have consistently emphasised — a larger proportion of rainfall will be heavy, even in some areas that are becoming drier. Atmospheric moisture is a part of this, and precipitable water is one measure of it.

So why do climate models project that we will get more heavy rainfall as the planet warms? At the heart of it is basic physics, which tells us that a warmer atmosphere can hold more water vapour than a cooler one — about 7% more for every 1℃ rise in temperature.

But meteorology will also play its part, and in the real world we have recently seen the sorts of weather systems that will drive heavier rainfall outside the tropics.

More tropical weather

A stream of very moist air from the tropics can often cause very heavy rain. These streams of moisture are sometimes called atmospheric rivers, but also have names such as the Pineapple Express in the United States or the Northwest Cloudbands here in Australia. An atmospheric river recently drenched California.

These sorts of tropical excursions happen naturally, but relatively infrequently. As the planet warms, however, regions like southern Australia and northern California can expect more tropical rainfall events, even as average rainfall declines.

Following the water

Like rainfall, precipitable water is measured in millimetres. It is derived by calculating how much liquid water you would end up with if you condensed all of the water vapour above your head — from Earth’s surface to the top of the atmosphere.

We calculate this using measurements from weather balloons, from satellite data, or from weather and climate models. The greatest amount of water vapour is generally near Earth’s surface, and it decreases with height.

Higher precipitable water values mean that more water is available for potential rainfall. We generally experience this as hot and humid weather. Just how much rain actually falls is dependent on the accompanying meteorological conditions. Under conditions favourable to thunderstorm activity, for example, high precipitable water translates into heavier rainfall.

Because it shows the location and movement of moisture, precipitable water is a great way for meteorologists to follow the movement of weather systems across the globe. In the animation above, it is easy to see tropical moisture streaming out from the equator toward the poles. Due to climate change, weather forecasters will increasingly be on the lookout for very high or record levels of precipitable water associated with those events.

In Australia, several heavy rainfall events in recent years have been associated with record-high levels of precipitable water. In late December 2016, heavy rainfall across central and southeast Australia was associated with record-high December precipitable water, with weather stations in Giles and Mount Gambier recording their highest values for any month. Heavy rains have continued over the western part of Australia through January 2017.

Earlier in 2016, record-high June precipitable water was also recorded at Sydney and Hobart, with Hobart recording a level on June 6 that was 38% higher than the previous record for that month. Both of these events involved tropical air laden with moisture sourced from record or near-record warm oceans, and drawn over southern Australia.

In both cases, heavy rainfall was widespread, with some record high daily rainfall totals.

Globally, as well as being the warmest year on record, 2016 broke records for global precipitable water in at least one international data set.

It should be noted that these record values are drawn from data covering just the period since 1992, as historical precipitable water values obtained using upper-air measurements of temperature and humidity are not easily comparable with present-day measurements. As such, precipitable water is more useful to weather forecasters than to climate scientists — although it becomes more useful as the length of the dataset increases, and can be used to evaluate model simulations.

The impact

The trend in precipitable water is expected to lead to an increase in the highest possible rainfall intensities and an increase in the frequency of extremely high daily rainfall totals, regardless of how average rainfall may change. A consequence of higher rainfall rates in a warmer world is increased flash flooding and also riverine flooding.

The implications of climate projections for heavier rainfall are many. In future, changes in the upper envelope of extreme rainfall may impact on the way we design things like urban water flows, buildings and flood mitigation. The fact that individual rainfall events can become heavier than the past in regions experiencing overall declines in rainfall and streamflow is an added nuance.

Beyond rainfall, higher moisture levels in the atmosphere also mean slower evaporation of sweat from the skin, making you feel hotter during particular heatwaves, and making evaporative air conditioning systems less effective. Just as changing temperatures influence decisions in areas such as planning, so too will increasing humidity and heavy rainfall events, even when they are episodic.

Karl Braganza is the Head of the Climate Monitoring Section in the Bureau of Meteorology's Environment and Research Division. Karl Braganza 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.

Acacia Pepler is completing a PhD with the ARC Centre of Excellence for Climate System Science, which is funded by the Australian Research Council.

David Jones 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.

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Originally published in the Guardian on 27 February 1967

THE CAIRNGORMS: It didn’t seem at all strange to discover a bedraggled reindeer sheltering from the storm just inside the entrance to the chair-lift the other day, for the wind was like a knife and the ski-runs like tilted ice-rinks. Of course, he might have merely come in for the company – you could see his fellows higher up the snowbound hillside – or he might have been hoping for a chance of something more succulent than the frozen heather roots these creatures seem to live on. But he wasn’t very friendly, responding to a cautious stroking by an angry swing of the head, so I left him standing disconsolate near the ticket office and looking as if he’d lost both Father Christmas and his sledge. I suppose they’re harmless enough although a notice farther down the mountain warns “Beware of Reindeer,” but doesn’t explain why. These were the only wild life we saw in the hills during a wild week, except for the ptarmigan in their white winter plumage hurrying through the snow, and once a handsome pheasant strutting across the track through the Rothiemurchus pines. Indeed, there were days, so fierce the winds, when these popular slopes were even deserted by the humans who normally at this time of year swarm like ants, and one day, especially, when I seemed quite alone in the mountains. Ski-ing that day was out of the question – you needed ice-axe and crampons just to get across the runs – and the wind so strong on the plateau it took you all your time to avoid being blown over the edge. But down by Loch Morlich in the late afternoon the wind suddenly dropped for half an hour, and there was the quiet splendour of purpling hills and a foreground of silvered loch with the birches and pines showing black against a golden sunset like a Chinese painting.

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A crucial decision on a rule change that could have a critical impact on the future of battery storage in Australia has been delayed again by AEMC.

If the third warmest January on record occurred during a La Niña event, scientists are asking what El Niño has in store

Right now south-eastern Australia is having an unbearable summer. Temperatures in Sydney have regularly been in the upper 30s in recent weeks, while inland areas have had several days in the mid-40s.

January was the hottest month on record for Sydney since 1859, and the persistent warmth into February (with many places topping 35C day after day) may topple the New South Wales record of 50 hot days in a row.

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Behavioural science is the latest tool in the battle to save reef.

This array in Indiana is one of a growing number of "community solar gardens" in the US. Robford15/Wikimedia Commons, CC BY-SA

Rising electricity prices have become a fact of life in Australia – and are likely to be so for a few years to come.

However, while the cost of generating electricity will rise as cheap but ageing coal power stations go offline, that doesn’t mean your electricity bills need to follow suit.

Households and businesses can take greater control of their energy future and slash their power bills in a range of cost-effective ways. Solar panels and battery storage are among the most obvious strategies. But not everyone can afford them, which is why we are seeing the rise of community projects that aim to give more people access to clean energy.

Australia now has more than 1.6 million solar roofs. Last year 6,750 battery storage systems were installed, up from just 500 in 2015.

Yet many households and businesses are still effectively “locked out” of this energy revolution. Many renters, apartment-dwellers and lower-income households face a series of market barriers that make these options hard to access.

Renters often find that their landlord does not want to invest in solar. Those living in apartments can have the same problem with their strata or body corporate, with the added problem of not always having access to their own roof.

Poorer households typically can’t afford solar panels or batteries, even if they would save money over the longer term. On top of the expense, buying solar panels and other clean energy products can be complicated and confusing.

Club together

The good news is that there are several initiatives around Australia that aim to get around these barriers. One example is Darebin Solar $avers, a collaboration between local government, community and industry that has installed solar panels on 300 low-income households in Melbourne’s northern suburbs. There was no upfront cost to these households, ensuring they were financially better off from day one.

Another example is the community solar gardens model, which has become popular in the United States. Solar gardens work by installing a central solar array, generally near a population centre. Energy customers are invited to buy (or subscribe to) a share in a handful of the array’s solar panels. The electricity generated is then credited on the customer’s electricity bill. Often, poorer households are offered discounts to be able to participate.

One issue with these kinds of schemes, however, is that they are complicated to set up. They usually involve many partner organisations – at least one of which has to have an interest in ensuring that users are better off. It is hard to see how the market can deliver these schemes on its own.

Where markets fail, it is typically governments’ job to step in and help. So how can governments go about helping people get access to affordable clean energy?

In the United States, the Obama administration set a national target of 1 gigawatt of solar panels to be installed on low- to moderate-income homes by 2020 as part of the Clean Energy Savings for All program. The National Community Solar Partnership brought together 68 organisations to help set up community solar gardens and make them easier to access.

This week, Australia’s second national Community Energy Congress in Melbourne will hear from Barack Obama’s climate and energy adviser, Candace Vahlsing, who will outline how these policies can help ensure wider access to green energy.

In Australia, a proposal to establish a network of 50 Regional Energy Hubs is gaining traction. The federal Labor Party, Greens and Nick Xenophon Team all made commitments in the lead-up to the 2016 federal election.

The Regional Energy Hubs proposal is modelled on the Moreland Energy Foundation, a non-profit organisation in inner-north Melbourne set up in 2000 in the wake of Victoria’s energy privatisation. The foundation has a team of energy and engagement experts working with households, businesses, community groups and governments on innovative approaches to implementing sustainable energy supply – the Darebin Solar $avers program being one example. The idea would be to set up dozens more similar organisations, all linked together across the nation.

The program can be thought of as like Landcare but for clean energy. Landcare is a nationwide network of volunteers who care for our land and water, with the aim of boosting both environmental protection and agricultural productivity. Similarly, energy hubs would aim both to make energy more environmentally friendly, and to make clean energy more affordable and accessible.

This is why we have to move past just talking about “costs” and start thinking about investment. Modelling by Marsden Jacobs and Associates shows that every dollar of government investment in community energy can leverage A$10-17 of community investment. At the same time, this delivers many other benefits to communities: closer connections between neighbours; opportunities to learn new skills or access new income streams; easing social inequity; and improving health.

Given the myriad possible solutions to our energy challenges, we need to nut out what works best, and where. The best way to do this is by putting all of our heads together – local government, state government, federal government, private enterprise, innovators in the clean energy sector, and the communities that stand to benefit. That way we can make the clean energy transition fairer and more accessible to all.

The second national Community Energy Congress is taking place in Melbourne on February 27-28.

Nicky Ison is a Research Associate at the Institute for Sustainable Futures (ISF) at the University of Technology Sydney and a Founding Director of Community Power Agency. ISF undertakes paid sustainability research for a wide range of government, corporate and NGO clients. Community Power Agency is a not-for-profit organisation working to grow a vibrant community energy sector in Australia.

More than 3.5m of the invasive rodents live in Britain, and their presence is harming the welfare of their native red cousins. Luckily, HRH has a cunning plan to reduce their numbers

Name: Grey squirrels.

Age: First introduced to the UK in the 1870s.

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The salad shortage focused attention on the failures of our 24/7 dietary culture. But it also provides a chance to rethink the way we eat fresh fruit, veg and green leaves

I’m afraid the lettuce shortage was just the tip of the iceberg. We may have run low on salad leaves but, more worryingly, we were low on empathy for poor southern Spain where flash floods followed by snow wrecked the crop. Our relentless consumer-rights focus meant that the emphasis was clearly on “weather-related supply challenges”, supermarket speak for “My God, we are running out of salad!” Sustaining a dietary culture of 24/7 access to all fresh fruit and veg in all seasons was never going to be easy.

A packed salad uses at least 10 times more energy than a local lettuce

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