Climate Expert: Neither Climate Nor Climate Change Causes, Fuels, or Influences Weather—Part 1

It is now a ubiquitous cultural ritual to blame each and every weather event on climate change.

Those hot days? Climate change. That hurricane? Climate change. The flood somewhere that I saw on social media? Climate change. [emphasis, links added]

With today’s post, the first in a series, I go beyond the cartoonish media caricatures of climate change, which I expect are here to stay, and explore the actual science of extreme events — how they may or may not be changing, and how we think we know what we know, and what we simply cannot know.

Quite apart from the outsized and oversimplified role of climate-fueled extreme weather in culture and politics, climate is fascinating and important — and worth understanding as more than a meme.

This post lays the groundwork for this new THB series, starting with some important definitions and a quantitative thought experiment.

Let’s start with the IPCC (Intergovernmental Panel on Climate Change) definition of climate (bold added):

In a narrow sense, climate is usually defined as the average weather, or more rigorously as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period for averaging these variables is 30 years, as defined by the World Meteorological Organization (WMO). The relevant quantities are most often surface variables such as temperature, precipitation and wind. Climate in a wider sense is the state, including a statistical description, of the climate system.

Climate refers to a “statistical description”¹ of the climate system, defined as:

The global system consisting of five major components: the atmosphere, the hydrosphere, the cryosphere, the lithosphere and the biosphere and the interactions between them. The climate system changes in time under the influence of its own internal dynamics and because of external forcings such as volcanic eruptions, solar variations, orbital forcing, and anthropogenic forcings such as the changing composition of the atmosphere and land-use change.

The climate system is complicated, but at a high level, we can get our brain around it (above). There is a deeper discussion to be had about why the climate research community decided that people are not included as part of the “climate system,” but let’s leave that for another day.²

That brings us to climate change:

A change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forcings such as modulations of the solar cycles, volcanic eruptions and persistent anthropogenic changes in the composition of the atmosphere or in land use.³

Let’s correct one pervasive and pathological misunderstanding endemic across the media and in policy, and sometimes spotted seeping into peer-reviewed scientific research:

Neither climate nor climate change causes, fuels, or influences weather.

Yes, you read that right.

Climate change is a change in the statistics of weather — it is an outcome, not a cause.

I often use hitting in baseball as an analogy. A hitter’s batting average does not cause hits. Instead, a batter’s hits result in their overall batting average. Lots of things can change a batter’s hitting performance, but batting average change is not one of them.

As the Google NGrams figure below indicates, the idea that climate change is a causal agent has become increasingly common in recent decades, departing dramatically from its use in the IPCC and much of the scientific community.

I am sure you can point to examples that you encounter every day.

Using the IPCC definitions, how would we identify “climate change” in the statistics of weather?

The IPCC explains how we detect climate change:

Detection of change is defined as the process of demonstrating that climate or a system affected by climate has changed in some defined statistical sense, without providing a reason for that change. An identified change is detected in observations if its likelihood of occurrence by chance due to internal variability alone is determined to be small, for example, <10%.

Let’s illustrate this through a practical analogy. Hold on to your wallet.

Roger Pielke Jr. has been a professor at the University of Colorado since 2001. Previously, he was a staff scientist in the Environmental and Societal Impacts Group of the National Center for Atmospheric Research. He has degrees in mathematics, public policy, and political science, and is the author of numerous books. (Amazon).

The Honest Broker is written by climate expert Roger Pielke Jr and is reader-supported. If you value what you have read here, please consider subscribing and supporting the work that goes into it.

Read rest at The Honest Broker