Is the Climate Still Changing?

Last Modified 5/27/2009
  Some have said that the climate simply follows solar irradiance, claiming that no human influence on the climate is perceptible. Some have recently claimed that the climate is no longer getting warmer, that cooling has already started. We will use data collected over the last 30 years to examine these claims. We will find that the data shows problems with both of these claims.  
 

Solar Irradiance vs. Global Surface Temperatures

Over the last 400 years, graphs show strong evidence that global surface temperatures have roughly tracked solar irradiance So, it would seem reasonable to assume the same still occurs. So let's look at both solar irradiance and global temperatures over the last 30 years.
The sun has gone through its 11 year oscillations, but temperatures have risen with mild oscillations. This naturally leads us to ask, how have both solar irradiance and surface temperatures changed from one cycle to the next? We can test that by taking the differences over 11 years.
When we do so, we see even clearer that the trends do not match. Solar irradiance has declined over the previous cycle for 12 of the last 20 years. But global surface temperatures have risen for 17 of the last 20 years. Temperatures are rising even as solar irradiance is falling.
Conclusion 1: Solar irradiance has not been the primary factor in Earth's climate changes in the last 30 years. This is evident in the climate getting warmer even while irradiance declines. Solar irradiance has contributed to the oscillations. This is evident in the narrow variance in the 11-year climate differential.
Data Sources
solar & climate
 

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Analysis of Climate Trends

Since we know that the sun drives our climate, and that the sun has an 11 year cycle, we can borrow an analysis technique from signal processing called frequency rejection. This method will let us see clearer how the climate is changing without looking at the solar oscillation. The idea behind frequency rejection is simple: average the global temperatures over the 11 year solar cycle. This will cancel out the 11 year oscillation in the climate measure.

When we do this, we see a very distinct rising pattern. Every 11-year average since 1992 has either been a new record, or tied a previous record. No dropping has occurred. In fact, we can even see evidence that the rate of heating is accelerating. The blue shows a linear extrapolation of the pattern, the pink shows a curved extrapolation.

It is interesting to notice a 7-year oscillation in the 11-year average. This suggests we can also, use 7-year frequency rejection to analyze the climate trends.

The 7-year climate averages, also rise without a single drop from 1984 through 2007. Thus every 7-year climate average since 1984 meets or breaks the previous record! The 7-year averages also show strong evidence of the heating accelerating. Again, to make it visual, we use blue to show a linear extrapolation, and pink to show a curved extrapolation.
Conclusion 2: Global warming is still happening. Warming not only has not stopped, it appears to be accelerating. The claim that the climate has stopped heating up is blatantly false.

For 1986 - 2007 data:

  • 11yr ave slope: 0.01635 'C/yr
  • 7 yr ave slope: 0.0174 'C/yr
  • best fit curve: parabolic
 

Annual Temperature Projections

To make predictions that people can test from common sources, we need to turn these multi-year averages back into single year predictions. Using our linear and curved projections and a little algebra, as well as previous year's data, we can provide the analysis for future climate reports below. (Temperatures in the chart all refer to the global climate anomaly.) (Red indicates above the previous record.)
Year slowing linear accelerating
2008 below 0.40 'C 0.50 to 0.60 'C above 0.69 'C
2009 below 0.55 'C 0.73 to 0.74 'C above 0.80 'C
2010 below 0.30 'C 0.48 to 0.67 'C above 0.55 'C
2011 below 0.30 'C 0.48 to 0.74 'C above 0.71 'C
2012 below 0.45 'C 0.64 to 0.74 'C above 0.82 'C

Future conclusions can be based on how the climate compares to the current trends. If the annual global temperature anomaly drops below the numbers in the "slowing" column, only then do we have evidence that warming might have stalled. If the annual climate anomaly is in the range of the numbers in the middle then we have evidence that the climate is warming at a linear rate. If the annual climate anomaly goes above the numbers in the last column, we have strong evidence that the warming is accelerating. These projections can be used to test people making claims on either extreme.

Methods:

  • slowing: lower than 11 years ago
  • linear: extrapolate both 7 & 11 year averages with (11 yr average rounded up.)
  • accelerating: higher value of both 11 and 7 year curves extrapolated

* These projections do not take into account known factors such as volcanoes and airplane traffic. They are simply mathematical projections derived from the 11-year and 7 year averages. These projections do not account for the interaction of the 11-year and 7-year oscillations.

** 2008 appears to be the year that the 11-year and 7-year oscillations both go low together. In 2012 the two oscillation may peak together.

 
 
 

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