2016 is likely to be the world’s hottest year: here’s why

Andrew King, University of Melbourne and Ed Hawkins, University of Reading

We’re not even halfway through the year but already you may have heard talk of 2016 being the hottest on record. But how can scientists be so sure we’re going to beat the previous record, set just last year?

Even before the end of 2015, the UK Met Office was forecasting with 95% confidence that 2016 would beat the record. Since then, that confidence has grown still further, as record after record has tumbled. April 2016 broke the record for the hottest April after we had experienced the hottest February and March on record already this year.

NASA climatologist Gavin Schmidt recently estimated at least a 99% likelihood of 2016 being hotter than 2015.

The role of El Niño

The main reason why scientists are so sure that 2016 will be the hottest year is El Niño, which is associated with warmer sea surface temperatures in the eastern Pacific Ocean. The 2015-16 El Niño was among the strongest on record and has increased global average temperatures.

Even though the El Niño is now decaying, the second year of a major El Niño event is often associated with much warmer than normal conditions and is typically warmer than the first.

For instance, the 1997-98 El Niño was by some measures the strongest on record, and contributed to 1998 becoming the hottest year on record globally at the time.

Since the start of this year, we have seen global temperature records smashed time and time again. This means that much colder temperatures for the second half of the year would be needed for 2016 not to surpass the 2015 record.

Even a strong La Niña event (the cooler opposite of El Niño), which some analysts are forecasting, is unlikely to produce cold enough temperatures.

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One thing that could prevent 2016 becoming a record-breaking hot year is a major volcanic eruption in the tropics. Volcanic eruptions at low latitudes can eject aerosols high into the atmosphere reducing the amount of energy from the sun reaching the Earth’s surface.

Previous eruptions such as Pinatubo in 1991 and Tambora in 1815 (which caused 1816 to be “the year without a summer”) reduced temperatures across much of the globe.

However, it is the year after the eruption that often experiences the most severe cooling, so an eruption would have to be pretty soon and very strong to scupper 2016’s chances of being the hottest year on record.

What about climate change?

The role of climate change is smaller because we’re comparing 2016 with last year (the previous record). Over such short periods of time, the contribution from global warming doesn’t change much.

However, scientists estimated that 2015 was about 1℃ hotter than it would have been without human-caused climate change. As the human influence on the climate has not increased greatly since last year this 1℃ estimate will also apply to 2016.

The highly likely record temperature of 2016 will join the previous 17 record-breaking hot years back to 1937 which were all made more likely due to human-caused climate change (the rising global temperatures were even noticed as far back as 1938).

So even if El Niño is driving the 2016 record, we can say that the temperatures of this year (and indeed the temperatures associated with all the records over the last few years) would be virtually impossible without climate change.

Climate change has been increasing the likelihood of global temperature records for many decades. The vertical red bars show the record-breaking hot years we can attribute to human-induced climate change. The shorter yellow bars show ranges of estimates for how much more likely a record hot year becomes each year.
Andrew King, Author provided

An omen for the future?

We expect 2016 to beat the 2015 record for global average temperature as the decaying El Niño event pushes up surface temperatures.

This year, we’ve already seen devastating events associated with unusually warm temperatures, like the mass coral bleaching in the Great Barrier Reef, which has been largely attributed to human-induced climate change.

In future, we can expect to see more extreme heat events, like we’ve already seen in 2016, impacting society and ecosystems across the world.

And even though 2016 is likely to be the hottest year by some margin, we wouldn’t bet on this record lasting too long. While 2017 is very likely to be cooler due to a possible La Niña, with the strong warming trend the world’s experiencing it’s only a matter of time before we have another record-breaking hot year.

Only if we substantially reduce our greenhouse gas emissions now will we see the benefit of fewer record heat events in the future.

Andrew King, Climate Extremes Research Fellow, University of Melbourne and Ed Hawkins, Associate professor of climate science , University of Reading

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

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Are toxic algal blooms the new normal for Australia’s major rivers?

Darren Baldwin, La Trobe University

For much of this year, up to 1,700 kilometres of the Murray River has been hit by a serious outbreak of potentially toxic blue-green algae, which has flourished in the hotter-than-average conditions. After three months, the river is now recovering with the arrival of wet weather. But we are unlikely to have seen the last of these poisonous microbes.

Large blue-green algal blooms are a relatively new phenomenon in inland waterways. In 1991 an algal bloom affected more than 1,000 km of the Darling River, the first time such an event had been reported in an Australian river, and one of the few times internationally. It was an environmental disaster, killing livestock and striking a telling blow against Australia’s reputation as a clean, green farming nation.

The response was decisive: a state of emergency was declared, and the bloom ultimately gave rise to significant investment by state and federal governments into freshwater research, particularly in the Murray-Darling Basin.

Why no emergency now?

Fast forward two and a half decades to the latest bloom afflicting the Murray River, one of Australia’s most socially, economically and culturally significant waterways. The past decade has seen four similar blooms on the Murray River: in 2007, 2009, 2010 and now. Yes, they have garnered press attention, but there has not been the same call to arms that we saw when the Darling River was struck in 1991.

It is almost as if such significant environmental events are now simply seen as the new normal. Why the apparent complacency?

The 2007, 2009 and 2010 algal blooms on the Murray River all happened during the Millennium Drought, and hence were probably ascribed to an aberration in the weather. In reality, the situation may have more to do with how we manage water in Australia – particularly during periods of scarcity, such as the one we may well be entering now.

Those three earlier events all started in Lake Hume, a large reservoir in the Murray River’s upper reaches, originally created in the 1930s to help “drought-proof” Australia. All of the blooms began after the water level was drawn down to below 10% of the lake’s capacity. At these low levels, disturbances (such as when transferring water between the Snowy River and Murray River systems) can easily lead to the mixing of warm surface waters (ideal for bloom formation) with nutrient-rich water at the bottom of the reservoir (ideal for feeding the bloom).

The resulting blooms were then released downstream into the Murray River by managed water releases from Lake Hume. The blooms most likely reformed in other constructed water bodies downstream – most notably Lake Mulwala, a shallow reservoir about 250 km along the river from Lake Hume.

Lake Mulwala’s principal purpose is to create hydraulic pressure to allow irrigation water to be diverted into farmland in southern New South Wales and northern Victoria. As a result, its shallow depth and mostly still waters make it an ideal incubator for blue-green algae.

The climate factor

This year’s algal bloom on the Murray River is different. The main blue-green alga in the current outbreak, Chrysosporium ovalisporum, has previously been reported in the river, but generally in very low numbers. It has never before formed a bloom in the Murray River since monitoring began in 1978. But crucially, this species flourishes in very warm temperatures; overseas blooms of this species have occurred when water temperatures reach 26℃.

The other difference between the current and earlier blooms is that, when this year’s event started, Lake Hume was much fuller, at about 30% capacity. So reservoir operation probably had less to do with the bloom’s formation than other factors, such as the climate. Both the maximum and minimum temperatures were consistently above the long-term average during the past few months, as was the amount of sunlight reaching the surface of Lake Hume.

The algae-stricken river at Barmah in northern Victoria.
Darren Baldwin, Author provided

We still do not know exactly what triggered this year’s bloom, but if it was indeed a result of unusually warm temperatures, it is very likely that we will see more blooms of this type in the future.

Are we really ready for recurrent blue-green algal blooms on the Murray River? These blooms come at a significant economic cost: drinking water has had to be specially treated to remove potential toxins, and the bloom has impacted on regional tourism, coinciding with the Labour Day and Easter long weekends. It also hit farmers, who had to get drinking water for their livestock from elsewhere.

More importantly, what do these frequent blooms say about how we manage water in this country – especially as we start to see the impacts of climate change on our environment? Dwindling water could mean more than just drought – it could also fill much of the water that remains with poisonous microbes.

Darren Baldwin, Environmental Scientist, La Trobe University

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

EcoCheck: Victoria’s flower-strewn western plains could be swamped by development

Georgia Garrard, RMIT University and Sarah Bekessy, RMIT University

Our EcoCheck series takes the pulse of some of Australia’s most important ecosystems to find out if they’re in good health or on the wane.

When Europeans first saw Victoria’s native grasslands in the 1830s, they were struck by the vast beauty of the landscape, as well as its productive potential.

The explorer Sir Thomas Mitchell described the western Victorian plains as “an open grassy country, extending as far as we could see … resembling a nobleman’s park on a gigantic scale”. His fellow pioneer John Batman, in 1835, described the grassy plains to the north and west of what is now Melbourne as “the most beautiful sheep pasturage I ever saw in my life”.

Victoria’s volcanic plain, home to a rich variety of wildflowers.
Hesperian/IBRA/Wikimedia Commons

The native temperate grasslands of southeastern Australia are a group of ecosystems defined mainly by the presence of dominant native grasses. Trees are either completely absent, or occur in very low numbers.

In Victoria, native grasslands can be found on the volcanic plains that stretch from Melbourne as far west as Hamilton. Despite their rather plain name, native grasslands are extraordinarily diverse, containing many species of wildflowers that grow between the tussocks of grasses.

It is possible to find more than 25 different plant species in a single square metre of native grassland, and the wildflowers produce dazzling displays of colour during spring.

Anything but plain.
Ryan Chisholm, Author provided

The animals that inhabit these grasslands are equally diverse and fascinating. The striped legless lizard, grassland earless dragon and golden sun moth are three that live there today, although many others are now locally extinct. One can only imagine how impressive it would have been to see brolgas, rufous bettongs and eastern barred bandicoots roaming, nesting and digging on these plains.

Grassland earless dragon.
John Wombey/CSIRO/Wikimedia Commons, CC BY

Native grasslands were a significant food source for Aboriginal people. They provided both meat (kangaroos and other grazing animals were attracted to the open grassy landscapes) and vegetables.

Many of the native forb plants produce energy-rich tubers or bulbs that can be eaten much like a potato. These made up a large part of the diet of Aboriginal people living in these areas.

Fire is critical to maintaining the diversity and health of native grasslands, and fire regimes used by Indigenous people are an important aspect of grassland management.

Plains to pasture

The story of Victoria’s native grasslands since European settlement is not a happy one. Grasslands offer extremely fertile land (by Australian standards, at least), which made them attractive for agriculture and grazing. Overgrazing by sheep and cattle, the addition of fertilisers to “improve” pastures, and changes to the frequency and extent of fires in the landscape led to a noticeable degradation of Victoria’s native grasslands by the early 20th century.

Since then, habitat loss and degradation from intensive grazing, cropping and – more recently – urbanisation have reduced the native grasslands of the Victorian volcanic plain to less than 1% of their original extent (as documented in the paper titled “Vegetation of the Victorian Volcanic Plain” available here).

Land clearing for urban development continues to pose a major threat to Victoria’s native grasslands. Many remnants exist in and around Melbourne’s key urban growth corridors.

A 15,000-hectare grassland reserve is planned to the west of the city to offset the losses that will occur as Melbourne grows. This is an exciting prospect – such a large reserve would provide an opportunity to showcase this threatened ecosystem on a landscape-wide scale.

But successful implementation of this reserve requires significant investment in restoration and management, and only time will tell whether it truly compensates for the inevitable losses elsewhere.

Saving what remains

A major challenge for the conservation of Victoria’s native grasslands is to maintain the patches that remain. These remnants, nestled in agricultural and urban landscapes, are often small and fragmented, and are subject to threats such as weed invasion and broad-scale use of herbicides and fertilisers.

Without regular fires or some other form of biomass removal, the native grasses grow too big and smother the wildflowers. Over time, grasslands can lose their species diversity, and with it the intricate beauty of their varied wildflowers.

Redreaming the Plain.
Digital composite created for Imagine The Future (ITF) Inc. by Csaba Szamosy, 1996, from photographs by James Ross (Victorian National Parks Association), Mike Martin (Victoria University), Tom Wheller (VNPA), Vanessa Craigee (Department of Natural Resources and Environment), John Seebeck (NRE) and Ian McCann (courtesy NRE/McCann Collection), and based on a concept by Merrill Findlay for ITF.

On the face of it, the prognosis for these grasslands does not look great. They are certainly one of Australia’s most endangered ecosystems, and their conservation must necessarily occur alongside human-dominated land uses. This brings social challenges as well as ecological ones.

Native grasslands suffer from a public relations problem. The need for regular fires is not always well aligned with objectives for human land uses. What’s more, all those wildflowers only appear in season, and even then their beauty is only really evident at close quarters.

But grasslands have a few tricks up their sleeves. First, high-quality grasslands can be maintained in relatively small patches. There are some great examples around Melbourne, including the Evans Street Native Grassland, which covers just 4 hectares. But as tiny as they are, these reserves can be just as diverse as larger grassland remnants.

Second, native grasslands can be surprisingly resilient, in both urban and agricultural landscapes. A case in point is the tiny grassland at the Watergardens shopping centre northwest of Melbourne, which has been maintained despite being completely surrounded by a car park. Several high-quality grasslands in pastoral areas have been maintained for decades under grazing at low stocking rates.

Third, native grasslands represent a great opportunity to engage urban residents with nature in cities. Many beautiful remnants exist in some of Melbourne’s newest suburbs. Some already benefit from the efforts of dedicated community groups, while others are still waiting to be discovered.

Grasslands in other parts of the world, such as North America’s prairies or the African savannah, are viewed with romanticism and awe. In the Australian consciousness, grasslands take a back seat to the mythical outback. But the future of the grasslands of southeastern Victoria may well depend on our capacity to generate the same public profile for this truly remarkable but critically endangered ecosystem.

Are you a researcher who studies an iconic Australian ecosystem and would like to give it an EcoCheck? Get in touch.

Georgia Garrard, Research fellow, Interdisciplinary Conservation Science Research Group, RMIT University and Sarah Bekessy, Associate professor, RMIT University

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