by Matt Owens January 23, 2013
Weather is not climate. This cold snap over the eastern half of the US is a bitter reminder of that. At the same time, it's supposed to be 64ºF (17.8ºC) in Denver tomorrow - and indeed it was in the 60's today. This is weather. Climate is weather ...when there's a whole lot of it in a data series. Years in fact. So here's Denver's five year weather record with daily values used to create a moving average (click to enlarge):
A five-year period certainly doesn't define climate for any region, but it's a whole lot better than a five-day period.
Interestingly, the precipitation trend has been on the rise while max humidity has been falling. This hints at some of the complexities that govern how moist or dry the soil is (i.e. drought). The dynamic interaction of those complexities and a poor data collection network are conspiring to assault the US with a potentially much worse drought than is being openly talked about. Of course, nature really doesn't conspire - it bites, hurts, punches you in the face, or crushes deception. And let's not forget, the truth will set you free, as the saying goes.
Since a 5 year trend of one location is not really good enough for a decent view of global-scale climate change, looking at several other areas and their five year trends over the same time will increase the robustness of the view. The following data is all from land, none from over open ocean or over the poles, so there's still a missing piece from the puzzle. But that data exists too.
The five year trend for Dallas (whose future was recently discussed in another post on this site):
Omaha Nebraska, still suffering from some of the most prolonged drought conditions it has ever seen:
Moving north, into the vast Canadian expanses brings us closer to the Arctic tundra and permafrost. There, and on the other side of the shallow Arctic Ocean, warming temperatures will unlock potentially massive volumes of greenhouse gasses from the soil. Those permafrost gasses are now realized to include not just the two familiar warmers, methane and carbon dioxide, but also nitrous oxide, better known for its role in farming emissions. Precipitation data was not available for data sets outside US:
Both Canadian sites show a rise in max humidity. As the globe warms, the northern zones warm fastest for a number of reasons through a process called polar amplification. Actually, both the Arctic and the Antarctic warm faster, although the process has more reinforcing positive feedbacks in the Arctic. One expected outcome of this amplification is more rainfall in the polar zones.
Another consequence of warming is an increasing capacity for the air to hold water vapor. Warm air can hold much more water volume per air volume than cold air. This means that everywhere on the planet will see an increase in maximum potential intensity of rainfall and also maximum potential intensity of storm types that are driven by water vapor content of the air. Those storm types include hurricanes, tornadoes, and thunderstorms. So, as the recent all-time high temperature in Australia demonstrates, new all-time high temperatures will soon become quite normal, and thereby enable storm systems to reach levels of intensity never-before-seen in recorded human history.
Drought in mid-latitudes (like the US plains) is yet another side-effect of this increased capacity to hold water. Interestingly - and unfortunately, this changing vapor capacity of the air will cause mostly damage and destruction, not bountiful harvests and wealth as has been falsely stated by some.
On the other side of the Arctic Ocean, in the Russian subarctic is Hatanga (also spelled Khatanga). It's one of the most northern inhabited areas of Russia, or should I say Siberia?
Sydney, the first downward trend in temperature. But, those recent record breaking all time highs, that required meteorologists to add colors to the map - that really puts a damper on any enthusiasm.
In fact, by shifting the five year period forward (i.e starting on January 23, 2008 and ending on January 23, 2013) results in the downward trend nearly vanishing:
And now, to Brazil: Pernambuco, a site not too far from the Atlantic coast (the state of the same name stretches fully to the Atlantic). The data site has seen some bad drought lately, and the temperature trend shows increasing highs and decreasing lows, which is what would be expected if the area were turning to desert:
Further south, Buenos Aires sits directly on the Atlantic - although the coastline there is set back by a large open-mouthed bay. It's climate is known for showing high variability. In the last five years, it has cooled, with a negative trend of about 2.5ºC.
Now, on to the most erratic 5-year record of all: Lusaka, the capital of Zambia. This area is in a zone that is already feeling the pinch of climate change, and models indicate it could see extreme change in the coming century. The region to the north of Zambia is expected to get much wetter, while Zambia itself gets much drier. But, that's on average, which likely means that there will be wide fluctuations year-to-year. Zambia experiences a wet and dry season, and such variability is often associated with what could be described as an inherent instability in regional climate:
And finally, two coasts, two cities named Portland, and one overall trend:
On the Maine side, the daily low temperature showed a stronger move upwards than the daily high temp. But even the high temp moved up nearly 5ºC over the period. On the Oregon side of things the rise was about half as intense, at about 2.5ºC, and close to equal for both the high and low temperatures.