On Sunday, April 21, 2013 11:35:26 AM UTC+1, Lawrence13 wrote:
.
I stuck to 11-yr rolling mean to rule out any solar-cycle effect - not
that there seems to be much evidence of one. Of course, when I use a
shorter-length period, I get more of a saw-toothed graph - like the
HadCRUT - with a sharp rise starting in the mid-70s though it could be
argued from the 5-yr rolling mean that the real rise started in '67.
This looks as though it could be due to a difference in the data as '64
is easily the coldest year in that period according to GISS whilst the
HadCRUT graph suggests that '76 is the coldest.
Graham P Davis, Bracknell, Berks.
.
On Sunday, 21 April 2013 11:09:34 UTC+1, Graham P Davis wrote:
On Sun, 21 Apr 2013 10:25:50 +0100
Sutartsorric wrote:
On 2013-04-21 09:07:51 +0000, Graham P Davis said:
On Sat, 20 Apr 2013 21:58:47 +0100
Sutartsorric wrote:
SNIP
As Foster and Rahmstorf showed, the warming trend has not changed:
http://iopscience.iop.org/1748-9326/...6_4_044022.pdf
Well worth a read.
SNIP
However, I am worried that the authors take 1979 as the starting
point for their data because that is precisely when the sudden
upturn in warming began. The advantage to the pro-lobby is that
they dont have to explain the drop in global temperatures over the
previous 20 years. (This gives ammunition to the antis, and also
the GW agnostics such as myself.)
Nor does this 1979 starting point have to explain the sudden
switch from a slow fall to a rapid rise around the late 1970s.
I don't agree that 1979 marked the beginning of the sudden rise in
temperature. Looking at an 11-year rolling mean, the rise started
at the start of the 70s rather than at the end; the rise from 1971
to 1980 was 0.12C.
People mention the sudden surge in car ownership and the
installation of central heating in many first world countries,
installation but there is
supposed to be a ~20 year time lag between cause and effect, so
that would imply a sudden change of energy use around the late
1950s.
Again, going by the 11-year rolling mean, the fall in temperature
occurred during the 40s with a rise in the 50s and flat-lining in
the 60s. (1942-51 fell 0.12C, 1951-62 rose 0.08C, 1962-71 wobbled
between 0.01 and 0.02C below the 51-80 average).
When looking at the behaviour of global temperatures from
1940-1970, I think it might be worth looking at what was happening
to CO2 levels after the Great Depression. There was slowing down in
the increase in CO2 during the 30s and from 1940 there was even a
very slow fall. CO2 levels did not recover above the 1940 level
until 1948. I'm not saying this is largely to blame for the hiatus
in the rise in temperatures during the past century but it may have
had a part to play.
I was using these graphs for my statements:-
http://www.cru.uea.ac.uk/cru/data/te...e/HadCRUT4.png
Just shows what difference the smoothing method makes. ;-)
I'm also using GISS data as the Met Office data ignores the Arctic. Not
sure how they can get away with calling it 'global' when they make no
attempt to include the most important area. The GISS data is also stored
in a more convenient format.
I stuck to 11-yr rolling mean to rule out any solar-cycle effect - not
that there seems to be much evidence of one. Of course, when I use a
shorter-length period, I get more of a saw-toothed graph - like the
HadCRUT - with a sharp rise starting in the mid-70s though it could be
argued from the 5-yr rolling mean that the real rise started in '67.
This looks as though it could be due to a difference in the data as '64
is easily the coldest year in that period according to GISS whilst the
HadCRUT graph suggests that '76 is the coldest.
Graham P Davis, Bracknell, Berks.
Graham
I thought Mauna Loa only started accurately measuring from 1956?
I also have to ask why do you see co2 as the only driver of climate when through our present ice age climate has driven co2. It's such a minute trace gas and the human contribution so small and yet you and others have tagged so much onto the AGW theory that yo cannot accept any other factors.
If the numerous studies of the Greenland and Antarctica ice core samples show that way before and animal on earth released co2 from fossil fuels and wood, peat etc. that the earth seemingly lurched into full scale glacial periods in as little as twenty years and all that with nasty humans
Oh dear. The "It's only a trace gas, so it must only have a trace effect" syndrome. Read and understand (doubtful) this and it will disabuse you of that notion. CO2's contribution to atmospheric warming has been known (though the amount has been refined) for 150 years:
http://www.jcsda.noaa.gov/documents/...fraRadTran.pdf
PS If you don't think a trace amount can have a big effect, try sprinkling a tiny amount of ricin , or strychnine, on your sunday lunch. What a silly thing to say and it just shows ignorance about the science.
PPS No scientist sees CO2 as the only driver of climate. Why would you think they would?