The Forum > General Discussion > A drying climate in Australia? Don't run off, there's more to the story....
A drying climate in Australia? Don't run off, there's more to the story....
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Posted by GrahamY, Friday, 7 August 2015 2:52:30 PM
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Graham
Global temperatures declined or flat lined from 1940 to about 1970. The increase in CO2 was only about 15ppm for the period 1900 to 1970, and temperatures could possibly be within natural limits. On the other hand from 1970 to the present CO2 levels have risen by about 75ppm, also we have had a marked increase in other GHGs such as methane, fluorocarbons and nitrous oxide. http://ete.cet.edu/gcc/?/resourcecenter/slideshow/3/1 http://www.climateemergencyinstitute.com/uploads/AR5_Emissions_all_GHGs.png http://www1.ncdc.noaa.gov/pub/data/cmb/images/indicators/global-temp-and-co2-1880-2009.gif I accept that the term extreme is not scientific, but nevertheless there has been an obvious change in precipitation rates over Australia especial since 1970. I would also point out the grain growing areas have been particularly affected Posted by warmair, Friday, 7 August 2015 4:23:59 PM
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Hi, what your graph demonstrates is that CO2 emissions took off in 1940, which is the appropriate point to start looking at manmade increases.
However, your graph has a number of problems, which most scientists in this area don't seem to understand, so not surprising you're perpetuating them. One is that the effect of CO2 on temperature is logarithmic. So it is not appropriate to attribute the same effect to the last say 50 ppm as the first 50 ppm, which is what you are tending to do. Your justification for using 1970 is therefore spurious. Posted by GrahamY, Friday, 7 August 2015 5:08:53 PM
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My justification for using 1970 is that this is when global temperatures noticeably started to rise, but I am willing to concede that The IPPC says that the appropriate point is the 1950s. I would also add that accurate atmospheric readings did not start until 1958 when Keeling started taking readings at Hawaii and the Antarctic although data from ice cores is considered to be quite good.
Quote IPCC's Fifth Assessment Report (AR5) "Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased" While I am in a charitable mode I will also admit I made a mistake in my previous post where I should have said the increase in CO2 from 1940 (not 1900) to 1970 was 15 ppm. I am well aware of the logarithmic effect of CO2 concentrations, as is anybody who has taken more than a passing interest in climate science, but this is no means the whole story as feed backs amplify the CO2 warming effect by an estimated 3 times or more. The most important feedback is an increase atmospheric water vapour, which in turn is a powerful greenhouse gas, an increase of 1 deg C has the potential to increase evaporation by up to 17%. Below is a very crude calculation based on (log CO2 level year2 minus log CO2 year1) Times 3 Year___CO2ppm __increase____ theoretical increase warming effect on globe Dec C 1850___285.2_______N/A__________N/A 1900__ 295.7________10.5________0.047 1940__ 311.3 _______15.6 ________0.067 1970__ 325.54_______14.24_______0.058 2015__ 400.01_______74.46_______0.268 But the effect of other GHGs such as methane and NO2 means that we have add in another 82 ppm CO2 equivalent to the 2015 figure. this gives us a theoretical temperature increase pretty close to that actually measured of around 0.7 Deg C. Data source:- http://data.giss.nasa.gov/modelforce/ghgases/Fig1A.ext.txt Posted by warmair, Saturday, 8 August 2015 2:49:45 PM
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Chosing an area does not prove or disprove anything. You need to look planetary. Weather patterns, water has rising acidity as well as rising temperature and it is us that is causing rapid change.
Posted by lamp, Monday, 10 August 2015 2:30:05 PM
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Those of us who follow alternative media have known this one is BS for a long time.
Climate Change is a tool being used to support UN Agenda 21. https://sustainabledevelopment.un.org/index.php?page=view&nr=23&type=400 A tool to support global carbon taxes and to help a push for global government. They've even got the Pope trying to push these policies now. (The Catholic Church was infiltrated in part because of the sex scandals.) - And our pollies are like tapeworms with the UN. They don't just want to climb right up in there, they want to make themselves a home. How can they support a global agenda and by loyal to our nation at the same time? Never could understand this 'War on Carbon'. Don't they know increased carbon is making the planet greener?? Posted by Armchair Critic, Thursday, 13 August 2015 8:33:07 AM
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But even if you were correct that it did start then, you would need to start your graph before that to demonstrate drying, not at that point.
And you don't really get climate. The 30 year figure is a figure for a minimum period. Climate changes over much longer cycles than that, it's just that you can't say much sensible for periods of less than 30 years.
We probably need more than 100 years to make any sensible comments. We've had two little ice ages in the last 400 or so, which is getting more to the levels where you might have a little more certainty. In fact 10,000 years ago it was warmer than now, so to strengthen the probability that man is causing the warming you'd need to really wait until that temperature was eclipsed. Even then it would be statistically iffy.
You also don't get "extreme". When they talk about extreme they mean much greater variation, and your maps don't demonstrate variation at all, just trends.