Keeping warming to 1.5 degrees to shield Australia from big extremes.

Australia will endure more heatwavesA period of abnormally hot weather. Heat waves and warm spells have various and in some cases overlapping definitions (IPCC-SREX, 2014), droughtsA period of abnormally dry weather long enough to cause a serious hydrological imbalance. Drought is a relative term, therefore any discussion in terms of precipitation deficit must refer to the particular precipitation-related activity that is under discussion. For example, shortage of ... and coral bleachingThe paling in colour which results if a coral loses its symbiotic, energyproviding, organisms. (IPCC) at 1.5 degrees of warming but the extremes will be considerably less than if global temperatures increase by 2 degrees, new research shows.

In some of the first research on the impacts for Australia of the 1.5 degree to 2 degree range agreed at the Paris climate summit in 2015, Melbourne University scientists have found the chances of a repeat of events such as the “angry summer” of 2012-13 are significantly reduced at the lower end of the warming scale.

Up Next

How Aussies cope with a downpour

null

Video duration
01:21

More Environment News Videos

Dire environment warning

Australia lacks a national environment policy amid the increasing impact of climate changeClimate change is a lasting change in weather patterns over long periods of time. It can be a natural phenomena and and has occurred on Earth even before people inhabited it. Quite different is a current situation that is also referred to as climate change, anthropogenic climate change, or ... according to a scathing independent environment report. Courtesy ABC News 24.

That summer, which remains the country’s hottest, was already about 10 times more likely than without the 1 degree of warming already experienced since pre-industrial times, said Dr Andrew King, a Melbourne University climate scientist and lead author of the paper published in Nature Climate Change.

At warming of 1.5 degrees, the odds of such a summer with its heat extremes and bush fire-conducive weatherWeather refers to the state of the atmosphere with regard to temperature, cloudiness, rainfall, wind, and other meteorological conditions. (UKCIP) increases from about 44 per cent now to 57 per cent. The chance rises to 77 per cent in a 2-degree warmer world, the researchers found.

coral-bleaching

Australian droughts, too, are likely to be made worse with warming to 1.5 degrees – but less so than compared with heating beyond that level. For instance, the extremely dry year of 2006 would be about a 50-50 proposition in any year at 1.5 degrees, but almost a three-in-four years chance at 2 degrees.

Advertisement

Almost all of the increase in droughtA period of abnormally dry weather long enough to cause a serious hydrological imbalance. Drought is a relative term, therefore any discussion in terms of precipitation deficit must refer to the particular precipitation-related activity that is under discussion. For example, shortage of ... risks comes from warming temperatures adding to evaporation, rather than changes in rainfall deficits, the models show.

(See chart below of the likelihood of extremes in any year as temperatures rise.)

Drying out

However Will Steffen, an emeritus professor at the Australian National University and a member of the Climate Council, said rainfallRain is liquid water in the form of droplets that have condensed from atmospheric water vapor and then precipitated—that is, become heavy enough to fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It ... changes are harder to predict than temperature rises and models may be underestimating the shift.

“The drop in rainfall that we’ve seen in south-eastern Australia in the last 20 to 30 years – across Victoria, southern NSW and southern South Australia – is about where the models were predicting for 2030 or 2035,” Professor Steffen said.

“We may actually experience bigger swings in rainfall than the models are capable of simulating.”

The research, though, is valuable in demonstrating risks are unlikely to increase steadily but jump sharply in ways that affect wildlife, humans and agricultureCultivation of the ground and harvesting of crops and handling of livestock, the primary function is the provision of food and feed. alike, he said.

“A lot of ecosystemsA system of living organisms interacting with each other and their physical environment. The boundaries of what could be called an ecosystem are somewhat arbitrary, depending on the focus of interest or study. Thus, the extent of an ecosystem may range from very small spatial scales to, ... do not respond linearly to rainfall or waterClimate change is expected to exacerbate current stresses on water resources from population growth and economic and land-use change, including urbanisation. On a regional scale, mountain snow pack, glaciers and small ice caps play a crucial role in freshwater availability. Widespread mass ... availability changes,” Professor Steffen said. “There are thresholds and tipping points.”

(See Bureau of Meteorology chart showing how more than half of Australia had summer heat in the top 10 per cent of years in 2012-13.)

Coral Sea dangers

Among the most extreme impacts of a warming world are already being witnessed on the Great Barrier ReefRock-like limestone structures built by corals along ocean coasts (fringing reefs) or on top of shallow, submerged banks or shelves (barrier reefs, atolls), most conspicuous in tropical and subtropical oceans. (IPCC), where two hot summers have resulted in unprecedented coral bleaching with as much as two-thirds of reefs affected.

The research found a repeat of the marine heatwaveA period of abnormally hot weather. Heat waves and warm spells have various and in some cases overlapping definitions (IPCC-SREX, 2014) in the Coral Sea in 2016 – which alone killed off more than one-fifth of the Great Barrier Reef corals – would rise from about a one-in-three chance at current conditions to a 64 per cent chance at 1.5 degrees of warming.

“If we follow high-emission scenariosA plausible representation of the future development of emissions of substances that are potentially radiatively active (e.g., greenhouse gases, aerosols), based on a coherent and internally consistent set of assumptions about driving forces (such as demographic and socioeconomic development, ..., events like last year would be really cold events by the mid to late-21st century,” Dr King, who is also a researcher at the ARC Centre of Excellence for Climate System Science, said. “It’s really quite alarming.”

Both Dr King and Professor Steffen said the threat facing the reef should prompt policymakers to act to ensure temperature rises are kept to 1.5 degrees. Drastic and urgent cuts to greenhouse gas emissionsGreenhouse gas emissions cause dangerous anthropogenic climate change. Emissions include CO2, fluoridated gases, methane which are emitted by human activity such as deforestation and burning fossil fuels, and water vapour. – beyond what was pledged at Paris – would be needed to reach that goal.

“When you look at Australia versus other OECD nations, our pledges are more like a 3.5 degree to 4-degree world, so we are woefully, woefully inadequate in terms of our action given these sorts of projections,” Professor Steffen said.

Powered by WPeMatico

Translate »
Support