Understanding Climate Risk

Science, policy and decision-making

Posts Tagged ‘global warming

Step change hypothesis and working paper

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Imagine you didn’t know anything about climate change and the greenhouse effect but were interested and you know a bit about general science. Would you accept the following story?

“Earth’s climate is a large, complex system, affected by forces that produce both linear and nonlinear responses. Shortwave radiation – basically UV – from the sun comes in and heats up the planet, producing infrared radiation. Some UV gets reflected straight back out by clouds, snow and ice and stuff. The land can heat up quite a lot, but it cools back down again and doesn’t store much. If a forest is cleared and replaced by buildings, it will warm up a bit but the effect is only local.”

“But the ocean – that’s another story. It absorbs a lot of radiation, so is taking up heat all the time. Huge streams of energy are entering and leaving the ocean store each year. Some is ‘dry’ or sensible heat, which is ordinary warmth. Some is ‘wet heat’ or evaporated moisture. Energy gets taken up when the moisture is evaporated and it will be released again when the moisture cools, condenses and then gets rained out. In this way, the oceans provide a lot of heat to the land every year, largely as rainfall and a bit of snow.”

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Global warming breaks link between SAM and ENSO

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Global warming has caused SAM and ENSO to divorce according to Guojian Wang and Wenju Cai, published in Nature Science Reports on June 20. This is having major impacts on Australia and has contributed to the warm and dry conditions over the southern part of the continent since the late 1960s.

SAM is the Southern Annular Mode surrounding Antarctica, a band of wind and water that distributes hot, high pressure and cold, low pressure lobes around the Southern Ocean. This transfers atmospheric mass (pressure) between the mid and high latitudes. The positive phase is highly correlated with a positive phase of ENSO (the El Niño-Southern Oscillation), La Niña. A positive phase of SAM forces westerlies further south in autumn-winter, but in summer allows the easterly trades greater access, bringing in more moisture from the tropics and enhancing La Niña summer rainfall.

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Sunday Age 10 Questions on Climate Change – the final two

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The Sunday Age – OurSay readers questions on climate change are down to the last two:

  1. ”THE claim ‘the science is settled’ is plainly false due to the many problems with the AGW [anthropogenic global warming] hypothesis (e.g. global temperatures have not risen since 1998 despite rising CO2 levels; alarmism is based on flawed models that do not reflect empirical measurements.)” 
  2. ”Why is the Australian public asked to swallow the ‘carbon dioxide is a dangerous climate-changing pollution’ crap when science shows no observed relationship between global climate and atmospheric carbon dioxide? There is no physical evidence showing a relationship between temperature and CO2, only computer models which give different answers according to whatever assumption data you put in. But there is a very close relationship between temperature and solar activity … Why, when thousands of respected scientists signed a petition saying they don’t agree there is a problem, are we being forced to give up billions in tax dollars to waste on trying to stop carbon dioxide emissions?” 

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