Over the last four years I have been involved in the climate debate on my erstwhile favourite backpackers website. The thread has grown to 3000 comments. Unfortunately the site owner has decided to end commenting rights for non-paying ‘free’ members, because some spam-bots have been creating accounts and hitting the site. I did have a paid up membership a few years ago but decided the benfits weren’t that important to me. I’ve asked one the moderators by email to post the following comment on my behalf as my final contribution:
Short term natural variability in local/regional climate/weather has always far outstripped long term global variability. So a small increase in global temperature won’t make much difference to the decadal variability in precipitation and temperature where you live. Over the centuries, there have been quieter and wilder weather periods, floods and droughts, all perfectly natural. We are at a climate inflexion point with the major oceanic oscillations and some more variable weather will result as the system settles into the new regime for the next 30 years. It was the same in the 70′s as the 30 year cooling gave way to the 30 year warming as the Atlantic and Pacific multi-decadal oscillations changed sign.
I have put together a simple model which replicates sea surface temperature (which drives global lower troposphere temperature and surface temperatures a few months later). The correlation between my model and the SST is R^2=0.874 from 1876 FOR MONTHLY DATA. This is pretty good although I say so myself. You can see the constituent drivers and their relative contributions, and the resulting model/sst match in the two plots here:
Explanatory note on the model:
I have found that a simple model which uses a TSI proxy (sunspot number) fits the OHC data better as a forcing. To build this I first identified the value at which the ocean neither gains nor loses energy from a level period of SST in the C19th, before co2 became an issue. Then I made a cumulative running total of sunspot numbers departing from this ‘ocean equilibrium value’. Then I scaled this to the empirically observed fluctuation over the solar cycle in the 37month smoothed temperature record (around 0.08C). This curve falls from around 1880 to 1935, then rises to 2003 before topping out and falling slightly. It accounts for around 0.3C of the rise in SST over the C20th. I am making the assumption that this includes the terrestrial amplification of the solar signal outlined in Nir Shaviv’s JGR paper ‘using the oceans as a calorimeter’ http://sciencebits.com/calorimeter
I incorporated that curve into a simple model along with the AMO and SOI and CO2. Together they reconstruct HADsst3 quite well. The ‘just for fun’ forward prediction has a few assumptions built in so treat it with as much amusement as you wish. :)
From this I have calculated that co2 has added, at most, around 30% of the warming since 1970. It added almost nothing to the similar warming between 1910 and 1950 so it may be a lot less. Humans are only responsible for at most around 50% of the airborne increase in co2, so we are responsible for, at most, around 15% of 0.4C = 0.06C. So crippling our economies by cutting co2 emissions by 50% would reduce the temperature by 0.03C, which is unmeasurable. In the UK, we are committed by law to do this, and many deaths from the cold will result. 17,000 last year, and the energy bills are rising fast. The battle for good science and equitable society continues. In Greece and Spain, the riots have already started. Time to wake up and smell the cordite.