This is a bit of a ‘mixed bag’ in that it is largely a bunch of islands, but then includes Australia as well. It’s a bit of a PITA to do a v1 vs v2 of “Oceana minus Australia” as there’s a long list of Country Codes to list in the selection step. Yeah, I can do it (and I likely will), just not soon.
The thing that I find interesting here is that the Oceana data become more volatile in v3. The down spikes are a bit further than the up spikes, so there’s a small tendency to pull down the trend in the baseline middle of the curve. Still, all that water makes for modest swings. The scale here is from 2 C to -2 C range. The typical change of value from v1 to v3 is eyeballing about 1/4 C for most of the duration.
We again have the volatility impact. For most of the record, data range is about 1/2 C to 1 C, then in the 1980s it drops to about 1/4 C with a single 1/2 C drop in 1984. Overall, the suppression of downward volatility looks to be as important to creating a ‘warming trend’ as any actual trend in the data.
Also of note is that the temperature range is substantially constant at about -1/2 C to 0 C over the entire record from 1852 to the 1990 start of the graph; with only occasional 3/4 to 1 C cold “spikes”. There is no real trend in this data. It starts at ‘near zero’ at the far right and ends at zero at the far left. The only thing I see in the data is just a suppression of volatility in the data at the recent end of the graph. “Why” is an interesting question (could be tarmac keeping fields warm at night, could be the “QA Process”, perhaps just removing those thermometers in “high cold places” from the record. Mountains are subject to more cold spikes than down in the valley at the airport…) but the more important point is that temperatures are just bouncing into that zero line from right to left. It’s a lid. We aren’t “warming”, we’re just dropping some cold spikes. I’m good with that…