A summary of the state of climate change and extreme weather

Summary: Today we look at climate change politics, as an example of how we are one people. Our Left and Right, each confident it is the reality-based community, remain unaware that they’re mirror images of one another. Each has fears that the other see as exaggerated, neither aware of how easily the 1% manipulate them. We are a gift to our leaders, but it need not be this way. The truth is out there, if only we’d see. Today two  scientists tell us about some vital aspects about climate change — summary of the climate science rebuttal to the doomsters.


The Guardian, 13 June 2011, scaring you with photo of a non-extreme tornado in Baca county CO, May 2010. Willoughby Owen/Getty Images/Flickr

There is no need to rely on paid propagandists to tell interpret the work of climate scientists. They speak for themselves quite clearly through the IPCC, the major climate agencies, and individual scientists relying on their work. Such as the testimony at “A look at the Relationship Between Climate and Weather“, Hearing of the Subcommittee on Environment of the House Committee on Science, Space, and Technology on 11 December 2013


  1. Dr. John R. Christy, Professor & Director, Earth System Science Center, U AL-Huntsville
  2. Dr. Roger Pielke Jr., Professor & Director, Center for Science & Technology Policy Research, U CO
  3. Dr. David Titley, Director, Center for Solutions to Weather & Climate Risk, Pennsylvania State

Titley’s testimony

This was interesting. He gave the straight climate-activists’ line, supported by tiny slivers of carefully arranged data. Amusingly he considers as a reason to act that “the absence of evidence is not the evidence of absence”, which argument Roger Pielke Jr notes was originally devised to prove the existence of God (explained here).

Excerpt from Pieke’s testimony: summary of current state of climate science

There exists exceedingly little scientific support for claims found in the media and political debate that hurricanes, tornadoes, floods and drought have increased in frequency or intensity on climate timescales either in the United States or globally. Similarly, on climate timescales it is incorrect to link the increasing costs of disasters with the emission of greenhouse gases. These conclusion s are supported by a broad scientific consensus, including that recently reported by the Intergovernmental Panel on Climate Change (IPCC) in its Fifth Assessment Report (2013) as well as in its recent special report on extreme events (2012).

Here are some specific conclusions , with further details provided below:


Non-extreme thunderstorm in Montana, from National Geographic
  1. Globally, weather-related losses ($) have not increased since 1990 as a proportion of GDP (they have actually decreased by about 25%) and insured catastrophe losses have not increased as a proportion of GDP since 1960.
  2. Hurricane landfall s have not increased in the US in frequency, intensity or normalized damage since at least 1900. The same holds for tropical cyclones globally since at least 19 70 (when data allows for a global perspective).
  3. Floods have not increased in the US in frequency or intensity since at least 1950. Flood losses as a percentage of US GDP have dropped by about 75% since 1940.
  4. Tornadoes in the US have not increased in frequency, intensity or normalized damage since 1950, and there is some evidence to suggest that they have actually declined.
  5. Drought has “for the most part, become shorter, less frequent, and cover a smaller portion of the U. S. over the last century.” (from US Climate Change Science Program’s 2008 report on extremes in North America.  Globally, “there has been little change in drought over the past 60 years.” (Nature, 15 November 2012)
  6. The absolute costs of disasters will increase significantly in coming years due to greater wealth and populations in locations exposed to extremes. Consequent, disasters will continue to be an important focus of policy, irrespective of the exact future course of climate change.

Because the climate issue is so deeply politicized, it is necessary to include several statements beyond those reported above.

  1. Humans influence the climate system in profound ways, including through the emission of carbon dioxide via the combustion of fossil fuels.
  2. Researchers have detected and (in some cases) attributed a human influence in other measures of climate extremes beyond those discussed in this testimony, including surface temperatures (heat waves) and in some measures of precipitation.
  3. The inability to detect and attribute increasing trends in the incidence of hurricanes, floods, tornadoes and drought does not mean that human-caused climate change is not real or of concern.
  4. It does mean however that some activists, politicians , journalists, corporate and government agency representatives and even scientists who should know better have made claims that are unsupportable based on evidence and research.
  5. Such claims could undermine the credibility of arguments for action on climate change, and to the extent that such false claims confuse those who make decisions related to extreme events, they could lead to poor decision making.
  6. A considerable body of research projects that various extremes may become more frequent and/or intense in the future as a direct consequence of the human emission of carbon dioxide.
  7. Our research, and that of others, suggests that assuming that these projections are accurate, it will be many decades, perhaps longer, before the signal of human-caused climate change can be detected in the statistics of hurricanes (and to the extent that statistical properties are similar, in floods, tornadoes, drought).

The remainder of this written testimony provides data and references to support the claims made in the “take – home points” above. The “take – home points” are broadly supported by peer-reviewed research, US governmental assessments of climate science and the recent report s of the Intergovernmental Panel on Climate Change , specifically its Special Report on Extreme Events (IPCC SREX 2012) and its recently-released Working Group I report of its Fifth Assessment.

Excerpt from Christy’s testimony: about extreme weather

As the global temperature failed to warm over the past 15 years, it became popular to draw attention to the occurrence of extreme weather events as worrisome consequences of postulated climate change due to increasing concentrations of greenhouse gases.

For example, many claims have been made that weather events of the past 50 years are “unprecedented” , therefore must be caused by human influences. However, one can only establish such events as statistically unusual, a lower standard than “unprecedented,” if a minimum of 30 or more such periods with consistent data are available. This means we need 1500 to 2000 years of information with which to compare our recent 50-years of history to determine whether any characteristic is truly unusual.

For a few parameters we have such data. Severe drought leaves a clear mark on the landscape so that we know our nation experienced droughts in the 12th century, the so-called mega-droughts, which were much worse than any we’ve seen in the past century. Thus, droughts of the past 50 years are not unusual and obviously not “unprecedented” …

What does Extreme Weather really tell us?

The point about our lack of understanding of the causes of extreme weather was summed up in an article in Nature magazine with the title “Extreme Weather – Better models are needed before exceptional events can be reliably linked to global warming” (Nature, 20 September 2012) The emphasis in the article agrees with my statement that our level of understanding about the climate system is so low that we cannot predict nor attribute unusual events to human emissions of greenhouse gases using models and/or limited data records. The article discusses the problem that current climate models are not “fit to inform legal and societal decisions” without further “enormous research” because at present they are not ready for such tasks.

The article notes that extreme events “have complex causes, involving anomalies in atmospheric circulation, levels of soil moisture and the like.” The comments of one scientist at a recent workshop on the topic indicated “the coarse and mathematically far-from-perfect climate models used to generate attribution claims … are unjustifiably speculative, basically unverifiable and better not made at all.”

Not all participants felt this way, however Nature reported that, “None of the industry and government experts at the workshop could think of any concrete example in which an attribution might inform business or political decision-making.” In other words, industry and government would prefer an accurate forecast over the notion of attributing that forecast to a particular cause. Unfortunately, the ability to make accurate long-range forecasts is not here yet.

In the examples above, we don’t see increases in extreme events (which is also true for tornadoes, hurricanes, floods, etc. – see my House testimony of 31 March 2011) but we must certainly be ready for more to come as part of nature’s variability.


For More Information

Posts about extreme weather:

  1. Climate Armageddon postponed (again): the melting polar ice, 9 October 2010
  2. Looking into the past for guidance about warnings of future climate apocalypses, 17 October 2010
  3. Run from the rising waves! (The latest climate catastrophe scare), 27 June 2012
  4. Ignorance and propaganda about extreme climate change, 10 July 2012
  5. A look behind the curtain at the news of extreme climate events in the US, 22 August 2012
  6. Hurricane Sandy asks when did weather become exceptional? (plus important info about US hurricanes), 28 October 2012
  7. Has global warming increased the frequency & virulence of extreme weather events?, 10 February 2013
  8. The Oklahoma tornadoes can teach us about our climate, and ourselves, 22 May 2013
  9. The IPCC gives us straight talk about Extreme Weather, 4 October 2013




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