There is a general problem when looking for climate trends: you have to look at weather data. That’s a problem because weather data goes back thousands of years, and it’s always changing. As a result it’s never clear what start year to use for the trend. If you start too early or too late the trend disappears. If you start your trend line in a hot year, like in the late roman period, the trend will show global cooling. If you start in a cold year, like the early 1970s, or the small ice age (1500 -1800) you’ll find global warming: perhaps too much. Begin 10-15 years ago, and you’ll find no change in global temperatures.
Ice coverage data shows the same problem: take the Canadian Arctic Ice maximums, shown below. If you start your regression in 1980-83, the record ice year (green) you’ll see ice loss. If you start in 1971, the year of minimum ice (red), you’ll see ice gain. It might also be nice to incorporate physics thought a computer model of the weather, but this method doesn’t seem to help. Perhaps that’s because the physics models generally have to be fed coefficients calculated from the trend line. Using the best computers and a trend line showing ice loss, the US Navy predicted, in January 2006, that the Arctic would be ice-free by 2013. It didn’t happen; a new prediction is 2016 — something I suspect is equally unlikely. Five years ago the National Academy of Sciences predicted global warming would resume in the next year or two — it didn’t either. Garbage in -garbage out, as they say.
Arctic Ice in Northern Canada waters, 1971-2014 from the Canadian ice service 2014 is not totally in yet , but is likely to exceed 2013. If you are looking for trends, in what year do you start?
The same trend problem appears with predicting sea temperatures and el Niño, a Christmastime warming current in the Pacific ocean. This year, 2013-14, was predicted to be a super El Niño, an exceptionally hot, stormy year with exceptionally strong sea currents. Instead, there was no el Niño, and many cities saw record cold — Detroit by 9 degrees. The Antarctic ice hit record levels, stranding a ship of anti warming activists. There were record few hurricanes. As I look at the Pacific sea temperature from 1950 to the present, below, I see change, but no pattern or direction: El Nada (the nothing). If one did a regression analysis, the slope might be slightly positive or negative, but r squared, the significance, would be near zero. There is no real directionality, just noise if 1950 is the start date.
El Niño and La Niña since 1950. There is no sign that they are coming more often, or stronger. Nor is clear evidence that the ocean is warming.
This appears to be as much a fundamental problem in applied math as in climate science: when looking for a trend, where do you start, how do you handle data confidence, and how do you prevent bias? A thought I’ve had is to try to weight a regression in terms of the confidence in the data. The Canadian ice data shows that the Canadian Ice Service is less confident about their older data than the new; this is shown by the grey lines. It would be nice if some form of this confidence could be incorporated into the regression trend analysis, but I’m not sure how to do this right.
It’s not so much that I doubt global warming, but I’d like a better explanation of the calculation. Weather changes: how do you know when you’re looking at climate, not weather? The president of the US claimed that the science is established, and Prince Charles of England claimed climate skeptics were headless chickens, but it’s certainly not predictive, and that’s the normal standard of knowledge. Neither country has any statement of how one would back up their statements. If this is global warming, I’d expect it to be warm.
Robert Buxbaum, Feb 5, 2014. Here’s a post I’ve written on the scientific method, and on dealing with abnormal statistics. I’ve also written about an important recent statistical fraud against genetically modified corn. As far as energy policy, I’m inclined to prefer hydrogen over batteries, and nuclear over wind and solar. The president has promoted the opposite policy — for unexplained, “scientific” reasons.
Check out http://gizmodo.com/62-years-of-global-warming-in-one-terrifying-gif-1505871978. The first bottom number looks like 1951.
The main problem with that movie of global temperatures is that the first 30 years of it – from 1950 to 1980 — are estimated values. They are values estimated by working backward from today using the same computer program that predicted the Arctic would be ice free by 2012. We didn’t have earth temperature satellites to any significant extent till the early 80s as you can see from the Canadian ice data. Before 1980 we had some local temperature measures, like the sea temperature off Chile that I show, but for the whole globe, it’s pretty much estimates. What’s more, though they don’t show it, the 1940s were a very warm decade that led people to believe a new ice age was coming. Further, and 2013-2014 are pretty cold years, as you may have noticed, some of the coldest of the century. Where you start taking data has a big effect on whether you see global warming, global cooling, or nothing.
Yes – new projection for the arctic ice per http://news.discovery.com/earth/global-warming/arctic-sea-ice-reaches-new-record-low-120920.htm:
“The final collapse … is now happening and will probably be complete by 2015/16,” We’ll see.
Thank goodness that there is a sensible logical person such as you, analysing climate data. I analysed climate data extensively from many sources many years ago, after the IPCC first said that CO2 from fossil fuels was causing warming and I concluded that they were wrong. After every Ice Age which happens every 100,000 years, the temperature was always up to 3C warmer than now, with CO2 at only 285ppm. The CO2 is now 400ppm a 115ppm increase which indicates that CO2 is not the cause of climate change. DEFRA advised me that CO2 from fossil fuels is deficient in ‘Carbon 13’ and that the current atmospheric CO2 contains only 20ppm deficient in ‘Carbon 13’, so an additional 95ppm has come from other non specified sources, but nobody in the media tells us this and they continue to blame fossil fuels. The main source of CO2 that has changed since the CO2 was at 285ppm, is the population of the world, which has increased from 2 billion to 5 billion and will be 10 billion by 2050. One person breathes out as much CO2 in a day as the average car use. All these people breathing out CO2 and emitting Methane from their backsides, could be the main source of the increase, along with the additional animals bred to feed these people, all emitting CO2 and methane. Unfortunately, only China, Russia and Finland are trying to control population growth. I believe that the 100,000 year changing elliptical path of our planet around the sun and the 26,000 year 30 degree wobble on the axis, is the cause of long term climate change. When the temperature reaches more than 2C more than now, the ocean currents change and cause the Northern Hemisphere to get colder, thus starting the downward trend into another ice age. If the same pattern continues as has happened in previous glacial maxima, then in 900 years time we will be trying to stop another ice age rather than trying to stop global warming.