Global Warming and Degree Days, why is there no correlation?

Question

As a part of my job I track heating and cooling degree days. We use this to correlate to energy use, for natural gas and electricity.

You can get teh raw data from the same site that I do. Source NOAA

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/cdus/degree_days/

In the archives section you can get heating and cooling degree days by month and year. They are in pdf format and it will take some time. If you want to double check my numbers I reccommend spot checking...

Detroit Metro Area (region) Year expressed as federal fiscal years (October through September i.e. FY 1998 is Octboer 1997 - September 1998)

Degree Days
Year - HDD - CDD
1998 - 5,475 - 990
1999 - 5,732 - 899
2000 - 5,653 - 674
2001 - 6,322 - 850
2002 - 5,515 - 1,027
2003 - 6,753 - 677
2004 - 5,922 - 630
2005 - 6,099 - 1,056
2006 - 5,634 - 988
2007 - 5,903 - 916
2008 - 6,013 - 827
2009 - 6,456 - 588
2010 - 5,710 - 1,064

Heating and cooling degree days are calculated as follows:
(Days High temp reading + Days low temp reading)/2 - 65

A positive number gives you cooling degree days
A negative number gives you Heating degree days

i.e. High temp 85, Low temp 75 (85+75)/2 - 65 = 15 HDD for that day.

Now if you graph the data I've presented you will find a slight cooling trend for heating degree days and a very slight heating trend for cooling degree days. What you do NOT find is ANY trend supporting any meaningful global warming OR cooling.

So, for a geographical region on planet earth over a 12 year time frame to evidance no statistically significant changes, how can this support global warming?

Please note that the same is true for MULTIPLE regions accross the US and continental europe.

Given a 12 year time frame this is also NOT an arguement of weather vs climate. any weather pattern shown over a multi-year timeframe is definately climate. At least, that is how climate is DEFINED.

so again simply stated,

Global Warming and Degree Days, why is there no correlation?

Answer 1

I agree that if you calculate the heating degree days for the entire world over a time period sufficiently long to actually see a trend, then the degree days should be decreasing. However, what you're giving us is the degree day trend for one metro area over a short time period. You really need to start thinking globally. I've seen also seen trends for other cities that did not really show warming also. What that's saying is that climate and climatic trends vary from place-to-place.



Here is a very interesting article where the authors look at the global temperature record over EVERY possible number of years of length two or greater. I think you might get more out of that than looking at a short, local trend.



g.icess.ucsb.edu/asr/liebmann.2010.bams.global.temp.trends.pdf

Answer 2

The problem with wrapping a two word phrase around a long chain of reasoning it that it confuses people into believing it is a simple all or nothing proposition. Some questions that bear inquiry 1) Are we indeed in a long term warming trend? While there has been a measurable increase in temperatures over the last 150 years, the most recent decade has shown some cooling. 2) Are current climate patterns an aberration or are they well within normal bounds of climate. Given that the Holocene Maximum, an very recent era in geological times was warmer than today, and that we suffered what appear to be unusually cool weather for several centuries is not possible that climate is just regressing to the mean? 3) Is the increase in CO2 actually a cause of warming? Wouldn't warming also contribute to increased CO2 levels? Could they both be effects of some other cause? Or are they just co-incidental. This is not as well known as AGW proponents would have you believe. 4) Could there be other unaccounted factors, such as variability in solar activity. The previous two decades were periods of increased sun spot activity, the current decade has shown little activity, at a time when temperatures are not rising. 5) Is warming necessarily a bad thing. Humans have thrived in warming climates, when agriculture was more productive and the weather not so harsh, while cooling periods have been times of shortened life spans and population declines. We are a tropical animal. 6) Are the doomsday scenarios the only potential outcome? Are they probable? Are they even possible. An average warming of 40 degrees in the interior of Antarctica would leave an environment far below the temperature needed to melt the ice sheet. 7) Do the people who vigorously advance AGW as truth themselves live as if they believe this. Are they walking or taking public transport? Do they own modest dwellings? Ask people what steps they are personally undertaking? The answer I generally receive are vague and inspecific, often something nebulous and unproductive like "well I'm researching a carbon neutral lifestyle", which translates to they are doing nothing. 8) Do the proponents have a vested interest in convincing people of AGW? Are they the head of an organization selling trading credits. Do they have millions invested in a movie whose expense they need to recoup. Are they selling a book? Are they politicians angling for power? Are they scientists looking for research dollars? Even the most scrupulous will come to believe that which justifies their existence. 9) Are the proposed remedies more costly than the problem they would solve? Are they even feasible? Would it not make more sense to strengthen our technology and increase our wealth so that we may be ready for any number of possibilities. We would look like fools spending a fortune for flood gates, sea walls, and movement of cities away from the ocean, only to watch ocean levels drop. 10) Is there an ongoing effort to better understand and explore all avenues of the climate? Or do we hear phrases like "we have the answers", "the debate is over", "the science is in"? Are those the words of scientists seeking knowledge or are they the words of someone looking to squelch inquiry? I'm not looking to convince you yay or nay so much as plant a healthy skepticism of the people who pursue this agenda as well as the ideas and conclusions they have reached. I'm an old dog, I've heard so many disaster in the making stories that never came true.

Answer 3

I wasn't familiar with heating and cooling degree days, but just looking at the data you've presented it's clear that there aren't nearly enough datapoints to justify a trend one way or the other. In fact, after a quick check the standard error in the HDD trend is larger than the trend itself, and the standard error in the CDD is orders of magnitude larger than the trend in that. What does this mean? That you don't have enough data points. Not necessarily that there hasn't been an increase or decrease, just that your timeframe is too short and your data too noisy. Baccheus also notes that 1998 was an anomalously strong El Nino year, which is a poor starting point for long-term trend analysis.



But then there's the question of whether *local* CDD and HDD are a good proxy for *global* temperature trends, and I'm fairly confident they aren't. AGW doesn't say anything in particular about HDD or CDD in Detroit, MI, and despite your claim of "MULTIPLE regions" showing the same thing, my guess is that globally you'd see more decreasing HDD and increasing CDD than the inverse. I say that because global temperature anomalies are trending upwards in a statistically significant manner.

Answer 4

In agriculture, *growing* degree days are calculated much like you state above however 86 degrees is the maximum input and 50 is the minimum. Regardless of what the actual high/low temps are, 86 and 50 are the bounds for the equation.



http://ohioline.osu.edu/agf-fact/0101.html



This might only apply to agricultural settings, but would certainly explain a lack of correlation between global warming and degree days.

Answer 5

I guess that proves it. But on the down side there's progressively more CO2 in our paper thin atmosphere of the isotope that comes from burning fossil fuel. Maybe a rise in CO2 concentration of over 100ppm in less than 200 years has zero to do with anything. That's possible. Maybe CO2 ISN'T a greenhouse gas. That's possible as well. But, if CO2 ISN'T a greenhouse gas then ALL of the known laws of heat and atmosphere are wrong. What a revelation...I see a Nobel Prize here for certain for the guy who publishes first in a peer reviewed publication. Given that a lot of ice is melting, seawater is warming, winds increasing, critters and plants of various kinds are moving north and up there must be something beside beside 'degree days' driving this. Now all we need to know is what this 'something' is. Another Nobel Prize is ripe for the pickin'! Of course ALL of the data concerning melting ice, warming seawater, the type and amount of atmospheric CO2, migrating plants and critters could be wrong or part of a giant ho-ax on the part of insurance companies, several dozen universities, the US Navy, farmers around the world, several thousand scientists and Al Gore, but that's not the way the smart money would bet. As far as no correlation between 'degree days' and 'global warming' is concerned....figure that out and 'bingo'...another Nobel Prize. Meanwhile I'm going to stick with the science, the data and the physics...that seems like the smart thing to do.

Answer 6

It's like everything else, you can make the statistics do what you want them to. I was researching Global Warming and saw that if you look at only the trends in the last 2000 years the graph looks like a huge spike in recent history. However if you back off and look at the graph over the last 100,000 years the earth's temperatures were hotter than they are today but they cooled back down. What ends up happening is people argue back and forth about this subject wanting to know whether man is doing this, or it is natural or maybe a little of both. I contend that if the earth is warming, it is LARGELY part of a natural cycle that repeats every 100,000 years or so. The man made part of that is subject to debate. Maybe part of the equation, but not the sole reason. I mean, if the earth was hotter 100,000 years ago that it is today then cooled back down what made heat up back before fossil fuels or people?



http://www.geocraft.com/WVFossils/last_400k_yrs.html

Answer 7

Recheck you trends. Calculate the slope of linear regression lines. I did graph the data and calculate the regression lines and there is strong warming. Based on your numbers, the total heat on warming days has been increasing by a total of 26 per year. Cooling days have been flat. The total change (warming total degrees - cooling total degrees) is 26.4, meaning on an average day temperatures have been increasing .07 degrees per year. That's .7 degrees per decade; 7 degrees per century. AND consider that you started in 1998 which globally was a very warm year in the atmosphere and ocean surface due to strong El Nino conditions.



Fortunately, this is just one place with small sample size. The atmosphere globally is not warming nearly as fast as your Detroit numbers show. The predicted warming is only 3.6 degrees (F) per century and the satellite record since 1976 is showing only 2.4 degrees (F) per century.



Far from not showing warming, your data shows Detroit warming from a hot year at a rate three times that of actual global warming. Perhaps you are not familiar with statistical analyses.



My point is not to suggest this small data set proves anything, but to correct your statement and show you that your data does show warming. Whopping warming!

Answer 8

I would agree that it doesn't support AGW nor does it refute it very well either. The natural variation is too great to see any minor influence that CO2 might have IMO.