Human greenhouse gas emissions have continued to warm the planet over the past 16 years. However a persistent myth has emerged in the mainstream media challenging this. As a simple illustration of why the myth is wrong this video clarifies how the interplay of natural and human factors have affected the short-term temperature trends, and demonstrates that underneath the short-term noise, the long-term human-caused global warming trend remains as strong as ever.

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We have attempted to keep the language in this video at the same non-technical level as the media stories it refutes. As a result, it has been necessary to simplify much of the terminology. The following notes are for technically literate readers.
“is the same as before”: i.e. If a change in gradient is allowed at 1997 then the change in gradient is not statistically significant.
“in line with projections”: i.e. Within the envelope of AR4 trend projections.
“we will see faster warming”: On the basis of both AR4 projections and that global GHG emissions are increasing.

Mankind has continued to warm the planet through greenhouse gas emissions over the past 16 years. However, a persistent myth has emerged in the mainstream media challenging this fact. Let us examine what has been happening.
Here are observed global temperatures for the past 130 years from NASA. The last 35 years show a significant increase in global temperature. However the rate of warming is not uniform – there is a lot of variation from year to year.
Some of the variation comes from natural causes. Major volcanic eruptions inject small particles into the upper atmosphere, which trigger a strong cooling effect over a few years. Ocean cycles such as El Nino also affect temperature: El Nino years tend to be warmer and La Nina years cooler.
The longer term warming trend arises from greenhouse gas warming driven by human emissions.
Is there any evidence for a slow-down in greenhouse warming over the last 16 years?
In order to detect a change in the human contribution to climate change, we have to first separate out the natural contributions.
First, we remove the cooling effect of the volcanoes, along with the smaller effect of changes in solar activity.
Next we remove the pattern of warm and cool years caused by El Nino and La Nina.
What is left is the human contribution to climate change, plus some wiggles due to weather.
So is there any evidence of a change in the rate of human-caused warming over the last 16 years?
No. The human contribution over the last 16 years is the same as before. Human-caused greenhouse warming, while partially hidden by natural variations, has continued in line with projections. Unless greenhouse gas emissions are brought under control we will see faster warming in future.

Category: Science, Video

Please use the comments to demonstrate your own ignorance, unfamiliarity with empirical data and lack of respect for scientific knowledge. Be sure to create straw men and argue against things I have neither said nor implied. If you could repeat previously discredited memes or steer the conversation into irrelevant, off topic discussions, it would be appreciated. Lastly, kindly forgo all civility in your discourse . . . you are, after all, anonymous.

3 Responses to “Global warming over the last 16 years”

  1. Centurion 9.41 says:


    This video does not show fact. It shows the results of models in which not only is the true relationships of the variables not known but also ignores the fact that science does not know for certain all the variables involved.

    The fact is the world in the 1700 went through a “little ice age” and before that, after the dark ages, which were another period of colder than normal temperatures, the world experienced a period of above average temperatures – that’s probably just two reasons why the chart in the beginning of the video only went back to the late 1800s.

    There has always been global climate change. But to argue, based on ALL the scientific data that man is responsible is, on scientific principles, simply an losing argument.

    The problem with the public climate change debate is the same as the financial crisis debate, it’s being waged using incomplete theories and models being paraded out as fact to a public which is extremely ignorant of valid scientific methods, data integrity and reasoning.

  2. romerjt says:

    I’m sure its comforting to think this has all happened before and that one is being tough-minded to be skeptical but let’s be clear, ice ages in 1200ad are irrelevant to the issue. Everyone on agrees there are natural climatic changes but that in no proves that there can’t also be changes caused by human activity. I have yet to see a skeptic disprove the science of green house gasses, I have yet to see science that proves unlimited amounts of CO2 can be added to the atmosphere and nothing will happen. That is the losing argument.

    Facts you say. . . . The fact that 2012 was the warmest year on record is interesting but that itself is not much of a concern. The fact that up until 2012 the difference between the coolest year 1917 (50.1) and the warmest, 1998 (54.3) was 4.2 degrees but 2012 was a full degree 55.3 warmer than the previous record is just not normal. While this itself doesn’t prove anything you can’t do “data integrity” and not be taken back a bit by this data.

  3. victor says:

    At the risk of sounding as a layman, limiting/reducing CO2 emissions into the atmosphere has got to be a good thing all around. The US has now been a leader in this worthwhile effort with the massive switch from coal to natural gas, an effort that so far has gotten little media attention. The US is back to the 1992 CO2 emissions levels and the trend is only accelerating.