Is the Climate Still Changing?

Last Modified 7/10/2011

  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.
We can take the ratio of surface temperatures to solar radiation to see how closely they relate. When we do this the rise becomes very apparent. Earth's temperature is not simply tracking solar irradiance.

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
monthly

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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

 

 

 

 

 

 

 

 

* A previous version had temperature projections. This section will be replaced on another page. New averages for determining anomalies are determined periodically. The data above is not calibrate to the new averages.

 

Monthly Data

Above, we looked at an annual data set. Here we can evaluate some claims, and make predictions using a monthly data set.

Claim: the climate is cooling. A graph starting in 1998 and ending in 2008 has appeared on many websites. It appears to show the climate cooling. Below we contrast that graph to a longer term graph.
 

A few problems are apparent in the way the graph was made. First, the graph starts at a record high, an outlier. The graph ends at the solar minimum - the lowest solar irradiance in over 30 years. Second, the graph focuses on short-term data and hides long-term trends. When we extend the graph in both directions, and plot a longer term moving average, we see rising not falling.

More Data: Above we looked at an annual data set for the globe. Let's look at a 7.2 year integral of monthly data sets for the globe, land, and ocean.

We can notice a few things here. We see stable spells and rising spells. Yes, there was a slight decline after a long rise around 2005. Land temperatures are rising the fastest (as predicted.) Even with la nina in 2010, ocean temperatures are at near record highs.

We can use our 10.7 year integral (solar oscillation) and our 7.2 year integral (unknown oscillation) to analyze coming trends. If new temperatures are higher than typical highs (we pick 75 percentile) 10.7 and 7.2 years ago, then warming is occurring. If new temperatures are lower than typical lows (we pick 25 percentile) than 10.7 and 7.2 years ago, then cooling is occurring. Between those values temperatures are in a stable phase. Let's look at how this would play out.

Year half
falling (below)
stable (between)
rising (above)
actual
 
2008 1st
-0.10
0.04
-.16
During the solar minimum we had 12 months slightly below stable, and 12 months stable. We see that in the slight drop in the graph above.
  2nd
0.04
0.41
0.08
2009 1st
0.17
0.56
0.08
  2nd
007
0.31
0.29
2010 1st
-0.10
0.23
0.48
In 2010, the climate returned to the distinctly rising region. We can see the rising slope in the graph above.
  2nd
-0.09
0.19
0.35
2011 1st
-0.08
0.28
0.08
In the coming years, if the averages are below the falling column, then we have evidence of falling temperatures, above the rising column, then we have evidence of rising temperatures, between we have evidence of stable temperatures.
  2nd
-0.05
0.15
2012 1st
0.05
0.23
  2nd
0.17
0.29

Conclusions: In spite of some small declines this last decade, we still see more rising than falling. It is necessary to use long term trends and frequency rejection to analyze the data. We can use two identifiable oscillations to predict what ranges of future temperatures will indicate rise, and what range will indicate declines.

We should note in projections below that falling temperatures does not mean that the earth is cooling below the average. Falling means the earth is headed back towards average. We can see in the graph that even with the slight drops, temperatures remain high.
 
 
 

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