The 2013 National Climate Assessment


The National Climate Assessment (NCA) is a report released every four years (last assessment was in 2009) to inform Congress and the President on recent advances in climate change impacts in the United States.  However, almost all of the components that go into the production of this report are made available to the public. Some of the components (e.g. technical inputs) are intended for use by scientists and managers as documents that provide an overview of the science and uncertainties within the sector, while other components (summary chapters) need to be in plain language so that the content is clear to law-makers and the general populace.

My role in the NCA was to serve on the Steering Committee and act as a coordinating lead author for the Impacts of Climate Change on Biodiversity, Ecosystems, and Ecosystem Services workgroup.  Here I outline some of the goals and challenges our team faced as we prepared this extensive assessment report.

The Biodiversity, Ecosystems, and Ecosystem Services team consisted of over 60 experts from State and Federal agencies, academia, and non-governmental organizations.  Through a series of webinars, weekly conference calls, and one in person meeting at the Gordon and Betty Moore Foundation in Palo Alto California, our team assessed 1) how climate change has affected biodiversity, ecosystems, and ecosystem services to date, 2) the projected impacts during the coming century, and 3) potential response options for managers and policy makers. Like many climate-related issues, this was an incredibly broad topic to tackle.  The Steering Committee spent the first two months trying to decide how to approach the subject matter so that we could adequately capture all the major issues and summarize the key messages in a way that was impactful and informative to all our potential audiences.

Our workgroup ended up splitting into multiple sub-groups of 10-15 people each so that we could assess each field of study (e.g. biodiversity, ecosystems, and ecosystem services) in depth. My group (the biodiversity sub-group) was populated with a diverse group of scientists, feds, folks from non-profit organizations, and natural resource managers – many of which expressed that they didn’t really consider themselves ‘experts’ in climate change. I certainly didn’t consider myself an expert either, up until a few months prior to beginning the project I had been working on issues related to fisheries. I was trying to come up to speed on the recent literature at the same time I led our group forward. This in itself was incredibly challenging, because the rate that new publications were and continue to be released on climate change issues is really quite astounding. It is difficult for experts to keep up on the literature in this field, so it is not surprising that many early career climate scientists or really anyone who is trying to learn the field may feel overwhelmed at times.

When our group had organized the content we wanted to include in the report and began the writing process, we were challenged in determining how best to communicate our key messages without using too much jargon, how to account for uncertainty, and keeping the audience interested. When I read the first draft of the biodiversity workgroup’s report, it was obvious that we were still struggling with how best to present the idiosyncratic responses of biodiversity to climate change. Almost every section of our draft report had a rhythm to the writing that went something like – “we know this, and we’ve observed this, BUT there was this exception, so we can’t say this is the rule of thumb, or we don’t fully understand why this organism responded this way”. This pattern repeated over and over again throughout the document. Eventually we transformed this pattern into our first key finding: “Climate change is causing many species to shift their geographical ranges, distributions, and phenologies at faster rates than were previously thought; however, these rates are not uniform across species”.

Another challenge was finding positive story lines so that the take away for readers wasn’t all doom and gloom. There are a growing number of success stories out there of species benefiting from climate change; hopefully nature will continue to find ways to surprise us. After the report was done, I actually found myself apologizing during a presentation at a conference that I knew how negative most of our findings were. I still don’t know how to completely resolve this except by referring to some of the key principals of adaptation, which have embraced what I like to think of as an ‘acceptance’ approach of what climate change is bringing, and shifting goals from managing resources to achieve past conditions towards a mindset of managing for change.

The final report that our workgroup produced is being called the most comprehensive assessment of climate impacts on ecological systems conducted to date in the United States. It is available to the public on the US Global Change Research Program’s website ( and we are currently preparing a special issue for the journal, Frontiers in Ecology and the Environment.  In addition, we are working with the communications organization, Climate Nexus ( to generate media coverage and hopefully a national conversation about the main findings of the report. Stay tuned for more on that in the next few months – I am excited to see how Climate Nexus thinks we should (re?)package our messages to the public!

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