Q&A On Two Climate Science Questions – A Contribution By Tom Stohlgren

As part of my weblog posts, I am inviting internationally well-respected climate science colleagues to answer two questions that I have posted to them.  Today’s scientist is Tom Stohlgren who is Invasive Species Science Branch Chief, U.S. Geological Survey of the Fort Collins Science Center, and Senior Scientist and Affiliate Faculty at the Natural Resource Ecology Laboratory (NREL), Colorado State University (CSU).

The CSU NREL website provides the following short summary of Tom’s biography in which his professional focus is

Assessing landscape-scale and regional effects of land use change on natural ecosystems, and monitoring the effects of multiple stresses on native and exotic plant diversity. (2) linking information at landscape-, regional-, national-scales. (3) Developing GIS-based, predictive spatial and temporal ecological models to guide management of public lands. (4) Teaching courses in ecology and training graduate students.

Tom’s climate science contributions include his book  from Oxford University Press entitled “Measuring Plant Diversity  Lessons from the Field”. 

The Q&A with Tom follows:

1. Is global warming (and cooling) a subset of climate change or does it dominate climate change?

Tom’s Answer

I don’t understand this question. These are all loosely defined terms, often misused terms, and definitions are confusing and scale dependent (in space and time). If climate change is taken in it’s broadest way possible, then the other terms would be subsets. I have no idea what you mean by second question. Does “It” dominate climate change? This answer would depend on the metrics used to define dominance, and they also would be definition-dependent and scale dependent (in space and time). We can say with certainty that the earth has had periods of warming and cooling over time. We can say with some certainty that we are in a general warming trend globally over the past 150 years or so, with a lot of annual and regional variation. We, as a group, have wonderful powers of hindsight.

2. What evidence exists that the multi-decadal global climate models can skillfully predict i) the real-world observed behavior of large-scale atmospheric-ocean circulation features such as ENSO, the NAO, the PDO, ect. and ii) CHANGES in the statistics (patterning and in time) of these circulation features?

Tom’s Answer

I have seen no peer-reviewed publications that have accurately predicted regional climate (and precipitation and temperature seasonality) for several regions across temporal scales from 10 to 50 years. I am not overly familiar with very recent literature on the topic, so please send me a paper proving predictive power (with independent validation) if it exists. We, as a group, have very poor predictive capabilities on scales that matter.

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