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Melting Antarctic ice can trigger effects on the other side of the globe. NASA/Jane Peterson

Melting of Antarctica’s ice can trigger rapid warming on the other side of the planet, according to our new research which details how just such an abrupt climate event happened 30,000 years ago, in which the North Atlantic region warmed dramatically.

This idea of “tipping points” in Earth’s system has had something of a bad rap ever since the 2004 blockbuster The Day After Tomorrow purportedly showed how melting polar ice can trigger all manner of global changes.

But while the movie certainly exaggerated the speed and severity of abrupt climate change, we do know that many natural systems are vulnerable to being pushed into different modes of operation. The melting of Greenland’s ice sheet, the retreat of Arctic summer sea ice, and the collapse of the global ocean circulation are all examples of potential vulnerability in a future, warmer world.

Read more: Chasing ice: how ice cores shape our understanding of ancient climate.

Of course it is notoriously hard to predict when and where elements of Earth’s system will abruptly tip into a different state. A key limitation is that historical climate records are often too short to test the skill of our computer models used to predict future environmental change, hampering our ability to plan for potential abrupt changes.

Fortunately, however, nature preserves a wealth of evidence in the landscape that allows us to understand how longer time-scale shifts can happen.

Core values

One of the most important sources of information on past climate tipping points are the kilometre-long cores of ice drilled from the Greenland and Antarctic ice sheets, which preserve exquisitely detailed information stretching back up to 800,000 years.

The Greenland ice cores record massive, millennial-scale swings in temperature that have occurred across the North Atlantic region over the past 90,000 years. The scale of these swings is staggering: in some cases temperatures rose by 16℃ in just a few decades or even years.

Twenty-five of these major so-called Dansgaard–Oeschger (D-O) warming events have been identified. These abrupt swings in temperature happened too quickly to have been caused by Earth’s slowly changing orbit around the Sun. Fascinatingly, when ice cores from Antarctica are compared with those from Greenland, we see a “seesaw” relationship: when it warms in the north, the south cools, and vice versa.

Attempts to explain the cause of this bipolar seesaw have traditionally focused on the North Atlantic region, and include melting ice sheets, changes in ocean circulation or wind patterns.

But as our new research shows, these might not be the only cause of D-O events.

Our new paper, published today in Nature Communications, suggests that another mechanism, with its origins in Antarctica, has also contributed to these rapid seesaws in global temperature.

Tree of knowledge The 30,000-year-old key to climate secrets. Chris Turney, Author provided

We know that there have been major collapses of the Antarctic ice sheet in the past, raising the possibility that these may have tipped one or more parts of the Earth system into a different state. To investigate this idea, we analysed an ancient New Zealand kauri tree that was extracted from a peat swamp near Dargaville, Northland, and which lived between 29,000 and 31,000 years ago.

Through accurate dating, we know that this tree lived through a short D-O event, during which (as explained above) temperatures in the Northern Hemisphere would have risen. Importantly, the unique pattern of atmospheric radioactive carbon (or carbon-14) found in the tree rings allowed us to identify similar changes preserved in climate records from ocean and ice cores (the latter using beryllium-10, an isotope formed by similar processes to carbon-14). This tree thus allows us to compare directly what the climate was doing during a D-O event beyond the polar regions, providing a global picture.

The extraordinary thing we discovered is that the warm D-O event coincided with a 400-year period of surface cooling in the south and a major retreat of Antarctic ice.

When we searched through other climate records for more information about what was happening at the time, we found no evidence of a change in ocean circulation. Instead we found a collapse in the rain-bearing Pacific trade winds over tropical northeast Australia that was coincident with the 400-year southern cooling.

Read more: Two centuries of continuous volcanic eruption may have triggered the end of the ice age.

To explore how melting Antarctic ice might cause such dramatic change in the global climate, we used a climate model to simulate the release of large volumes of freshwater into the Southern Ocean. The model simulations all showed the same response, in agreement with our climate reconstructions: regardless of the amount of freshwater released into the Southern Ocean, the surface waters of the tropical Pacific nevertheless warmed, causing changes to wind patterns that in turn triggered the North Atlantic to warm too.

Future work is now focusing on what caused the Antarctic ice sheets to retreat so dramatically. Regardless of how it happened, it looks like melting ice in the south can drive abrupt global change, something of which we should be aware in a future warmer world.

Chris Turney receives funding from the Australian Research Council.

Jonathan Palmer receives funding from the Australian Research Council (ARC).

Peter Kershaw has received fundng from the Australian Research Council.

Steven Phipps receives funding from the Australian Antarctic Science Program, the Australian Research Council, the International Union for Quaternary Research, the National Computational Infrastructure Merit Allocation Scheme, the New Zealand Marsden Fund, the University of Tasmania and UNSW Australia.

Zoe Thomas receives funding from the Australian Research Council.

Lawyers for two anti-fracking campaigners argue in high court that injunction obtained by Ineos curtail’s protester rights

The legality of a wide-ranging injunction obtained against anti-fracking protesters by a multinational firm is to be examined in a three-day court hearing.

Two campaigners have launched a legal challenge against the injunction obtained by Ineos, the petrochemicals giant. Joe Corré, the son of the fashion designer Vivienne Westwood, and Joe Boyd, say it is draconian, oppressive and dramatically curtails protesters’ rights.

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Fertile soil is being lost at rate of 24bn tonnes a year through intensive farming as demand for food increases, says UN-backed study

A third of the planet’s land is severely degraded and fertile soil is being lost at the rate of 24bn tonnes a year, according to a new United Nations-backed study that calls for a shift away from destructively intensive agriculture.

The alarming decline, which is forecast to continue as demand for food and productive land increases, will add to the risks of conflicts such as those seen in Sudan and Chad unless remedial actions are implemented, warns the institution behind the report.

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CCTV footage from under Whitechapel in east London shows a fatberg that weighs as much as 11 double decker buses and is the length of two football pitches blocking the sewer. It is mostly made up of fat, wet wipes and nappies, and is expected to take three weeks to clear

• ‘Total monster’: fatberg blocks London sewage system
  

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Thames Water must break up congealed mass of fat, wet wipes and nappies to prevent raw sewage flooding streets

A fatberg weighing the same as 11 double decker buses and stretching the length of two football pitches is blocking a section of London’s ageing sewage network.

The congealed mass of fat, wet wipes and nappies is one of the biggest ever found and would have risked raw sewage flooding on to the streets in Whitechapel, east London, had it not been discovered during a routine inspection earlier this month.

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The RNLI closed Perranporth beach due to the large number of jellyfish-like creatures.

Trump’s NASA nominee Jim Bridenstine is a climate denier who wants to end the agency’s climate research

According to 2016 election exit polls, only 38% of voters considered Donald Trump qualified to be president. 17% of those who thought him unqualified voted for Trump anyway, perhaps because he promised that as a wealthy businessman, he would be able to hire the best people to advise him. That was a claim his daughter Ivanka explicitly made in her speech at the Republican National Convention:

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Eight to 10 members of a remote indigenous group were allegedly killed by men working for illegal prospectors in Javari Valley

Brazilian authorities are investigating reports of a massacre of up to 10 people from an isolated tribe in the Amazon by illegal gold miners.

The killings, alleged to have taken place in Javari Valley, are claimed to have been carried out by men working for gold prospectors who dredge illegally in the region’s rivers.

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Hurricane Irma destroyed up to 90 per cent of buildings on some of the islands it hit.

The pressure from the Prime Minister on AGL has been described as "Venezuela style" politics.

The Government continues to pressure AGL keep open the Liddell power plant, as the energy company races to come up with an alternative.

A hungry arctic fox, mating sea angels and playful brown bears are among the creatures captured by photographers for this year’s competition. The exhibition opens on 20 October at the Natural History Museum

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David Mariuz/AAP

Pressure is mounting on the government to put an end to energy uncertainty as an Australian Energy Market Operator (AEMO) report warns of looming power shortages over the next few years.

Opposition climate change and energy spokesman Mark Butler has written about the toxic divisions on energy policy in his recent book, Climate Wars. He recognises there are challenges in the Coalition partyroom over the Finkel report, but says Labor will negotiate with the government on an energy framework. It wants to avoid an ALP government inheriting the policy chaos.

Responding to the government’s push to extend the life of the Liddell power station, he says Malcolm Turnbull has unfairly concluded there is only one option.

“With a proper investment framework in place, new investment that will last decades, not just a few more years … could take place. At the moment we have an investment strike and if we can’t end the investment strike then yes in five years time in NSW we will be in a position of supply shortage.”

On the future of coal, Butler says it’s still “a massive part of our system”, and while usage will go down over time, it will be a part of the system for “as far as we politically can see”.

“The problem is not old coal power plants closing, it’s that nothing is being put in to replace them.”

On alternative sources like battery power he is optimistic about their potential, while sceptical of expanding hydro power until the results of a feasibility study are produced.

Michelle Grattan 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.

Malcolm Turnbull's extraordinary decision to put his party's hopes on the aged Liddell coal power plant makes no economic, environmental or engineering sense. But there is a grim precedent: the same government's rejection of climate science.

In the magical thinking of Australian policymakers, a pathway of gradual change, constructed over many decades in a growing, prosperous, coal-fired world stretches before us. But that's not the world that currently exists.

Could the new invention spell the end of rooftop fans? Christophe Finot/Wikimedia Commons, CC BY-SA

Specially designed fluid-filled roof panels can help make air conditioning significantly more efficient, according to new research.

These panels work like solar water heaters, except that they extract heat from the flowing fluid, rather than adding it. This has only been made possible through the development of new, highly reflective materials that allow more heat to be taken out of the fluid than finds its way back in, even in the heat of a sunny day.

Read more: How to keep your house cool in a heatwave.

As a result, the researchers, led by Eli Goldstein of Stanford University, calculate that these panels, when integrated into an existing air conditioning system, can use 20-50% less power to deliver the same amount of indoor cooling. This in turn could help smooth out demand peaks on the electricity grid in summer, cut energy bills, and reduce the risk of blackouts.

Cool research

For several years, the Stanford researchers and my own group at UTS in Sydney have been trying to design smart roof materials that will help dissipate heat from air conditioning systems more effectively.

Conventional air-conditioning systems get rid of their heat by simply venting hot air from the system’s outdoor fan unit. But the new design adds an extra step, using a heat exchanger to pass the normal refrigerant heat into the fluid, which can be either water or glycol. This fluid then flows into the rooftop cooling panels so the heat can be dissipated into the sky.

The old system and the new. Goldstein et al. Nature Energy

The previous problem with this approach was that on hot, sunny days – when you need air conditioning the most – the Sun makes the fluid-filled panels heat up, rather than cool down.

This problem has only been solved in the past three years, with the design of super-reflective surfaces that can repel 97% of the incoming solar energy.

Feeling the heat

Nearly all synthetic and natural surfaces absorb at least 5% of incident solar heat. Even the best white roof paints typically absorb more than 10% of the Sun’s heat. The best-performing surface is a shiny, flawless layer of silver, but that doesn’t last very long in outdoor conditions.

But what if we can protect the silver, and maybe even improve its reflective performance by placing it under a layer that also helps to reflect solar energy? Three research groups came up with possible solutions, two involving plastic coverings for the silver, and the third involving a complex layering of different oxide materials.

At UTS, our approach involved using many layers of two different plastics, placed on top of the silver. The resulting material reflects 97% of the incident solar energy, repelling the sun’s heat so effectively that the fluid inside cools down, even on a hot day.

Look to the skies

As the new Stanford research confirms, these super-reflective surfaces can perform a neat trick: getting the rooftop to lose heat during the day in the same way it does on a clear night. On clear nights, upward-facing surfaces can drop to several degrees below the ambient temperature because their heat dissipates high into the sky. The new super-cool roof panels do the same in the daytime as well. For example, they can condense dew well after sunrise even though the outdoor air temperature is above the dew point.

Read more: Air conditioning: we need to talk about indoor climate change.

The panels can easily be retrofitted onto existing air-conditioning systems, ultimately saving money in the long run because of the reduced energy use. By modelling their system’s performance, the Stanford researchers calculate that the panels could reduce air-conditioning costs by 21% for a typical two-storey building in the sunny climate of Las Vegas.

These kind of hybrid systems could become commonplace, combining existing indoor air-conditioning technology with the new panels shedding the heat directly upwards into the sky. If you’ll pardon the pun, things are really looking up for those aiming to bring their energy bills down.

Geoff Smith receives funding from Australian Research Council.

Company behind plans to develop Australia’s largest coal mine begins work on 170MW solar plant in another Queensland coal hub.

AEMO says its advice to the government was "pretty clear" and pragmatic: What the system needs is fast, flexible and reliable capacity to meet peak demand.

Pulborough Brooks, West Sussex One by one, the birds tip dramatically to one side, lowering one wing while raising the other, to lose height

The sharp honking sounds of geese echo across the Brooks. The air is clearing, but the rain still hangs over the low-lying hills in the distance, spreading down the sky like dark ink on wetted paper. As I walk out onto the marshes and towards the river Arun, the sun is rising behind me, spearing through the grey cloud.

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Scottish husband and wife team, aka Plug In Adventures, crossed Mongol Rally finish line on Saturday to become first entrants to complete the trans-continental challenge in an all-electric vehicle – a modified 2016 Nissan LEAF dubbed the AT-EV (All-Terrain Electric Vehicle).