Antinuclear

Australian news, and some related international items

New climate models suggest that Australia could reach 7C temperature rise by 2100

Just how hot will it get this century? Latest climate models suggest it could be worse than we thought, The Conversation, May 18, 2020 , Michael Grose, Climate Projections Scientist, CSIRO, Julie Arblaster, Associate Professor, Monash University   Climate scientists use mathematical models to project the Earth’s future under a warming world, but a group of the latest models have included unexpectedly high values for a measure called “climate sensitivity”.

Climate sensitivity refers to the relationship between changes in carbon dioxide in the atmosphere and warming.

The high values are an unwelcome surprise. If they’re right, it means a hotter future than previously expected – warming of up to 7℃ for Australia by 2100 if emissions continue to rise unabated.

  1. Our recent study analyses these climate models (named CMIP6), which were released at the end of last year, and what insights they give for Australia.

    These models contain the latest improvements and innovations from some of the world’s leading climate modelling institutes, and will feed into the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report in 2021.

    But the new climate sensitivity values raise the question of whether previous climate modelling has underestimated potential climate change and its effects, or whether the new models are overdoing things.

    If the high estimate is right, this would require the world to make greater and more urgent emission cuts to meet any given warming target.

  2. What is climate sensitivity?

    Climate sensitivity is one of the most important factors for climate change, strongly influencing our planning for adaptation and mitigation of greenhouse gas emissions.

  3. It’s a standardised measure of how much the climate responds when carbon dioxide concentrations in the atmosphere double. There are a few indices of climate sensitivity that the scientific community uses, and perhaps the most commonly used is “equilibrium climate sensitivity”. ……
  4. What this means for our future

    Higher equilibrium climate sensitivity values mean a hotter future climate than previously expected, for any given scenario of future emissions.

  5. According to these new models, Australian warming could crack more than 7℃ by 2100 under a scenario where greenhouse gas emissions continue to increase through the century.

    These higher temperature changes are not currently presented in the national climate projections, as they didn’t occur under the previous generation of models and emission scenarios.

    So what does this mean in practice?

    Higher climate sensitivity means increases to heat extremes. It would mean we’ll see greater flow-on changes to other climate features, such as extreme rainfall, sea level rise, extreme heatwaves and more, reducing our ability to adapt……..

  6. Essentially, the jury is still out on the exact value of equilibrium climate sensitivity, high values can’t be ruled out, and the results from the new models need to be taken seriously.

    In any case, the new values are a worrying possibility that no one wants, but one we must still grapple with. As researchers in one study conclude: “what scares us is not that the models’ [equilibrium climate sensitivity] is wrong […] but that it might be right”.  https://theconversation.com/just-how-hot-will-it-get-this-century-latest-climate-models-suggest-it-could-be-worse-than-we-thought-137281

May 17, 2020 - Posted by | AUSTRALIA - NATIONAL, climate change - global warming

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