This Year's Drought is Making Climate Change Real

By Lisa Micheli, PhD

Often when people learn I work on climate change they ask me how I can avoid becoming depressed. I don't get depressed because humanity has demonstrated over and over again its capacity for change. But honestly sometimes I do get frightened looking at what the next century and beyond may hold for our children and theirs, especially if we do not take actions to stem the pace of climate change now. This year in particular, when each new catastrophic headline points to the impact of a weather extreme, it feels eerily like the climate models I've been staring at since about 2007 are starting to unfold in our material world. And now concern about how we will actually handle our local climate extremes is not limited just to me and my in-the-know colleagues, but is one of the chief topics being debated at cafés, gas stations and grocery stores throughout my neighborhood in light of the California drought now fully upon us. (While last weekend’s storm has brought some immediate relief, we are still in a drought!)

In science we know that all models are wrong, but some models are useful. I estimate that back in the early 90s I was approximately the last person let into an Earth Sciences doctorate program without any computer programming experience. I lived through a transition in my chosen field of hydrology from an emphasis on measuring the planet to a fixation on modeling the planet. When I was at UC Berkeley I had the honor of belonging to the Energy and Resources Group, probably one of our most prestigious energy and climate think tanks. But at the time my interest was zeroed in on urgent challenges in water resources. I spent my time in with the geomorphology research group both in the field and on the computer researching how to restore California's rivers, a problem we faced in the moment, not something projected for the future by a computer model. I simply left the question of climate change to my colleagues.

It took the extreme heat waves of 2007 (over 115 degrees Fahrenheit in Sonoma) to steer my attention towards the inevitability of climate trends, and in turn, the necessity for conservation practitioners like myself to start to take climate change seriously. I perceived this as an obligation particularly because we were engaged in building habitat restoration projects that would take centuries to mature and fulfill their promised potential. Soon after I helped to found the North Bay Climate Adaptation Imitative which will be working with the County of Sonoma on a Climate Ready regional climate vulnerability analysis under the auspices of the State Coastal Conservancy and Pepperwood this year.

Scientists know that our climate system is complex enough that we cannot point to a single event and say this was caused by greenhouse gas emissions, and by copping to that we create fodder for a lot of debate in the media. But now there is increasing certainty around climate trends that recent advances in computer modeling can customize to local regions like our own, and now our weather station measurements are increasingly confirming those modeled trends.

One of my roles at Pepperwood is to facilitate scientific teams like the Terrestrial Biodiversity Climate Change Collaborative (TBC3) which I co-chair with Prof. David Ackerly of UC Berkeley. We just completed a two-year study thanks to the Gordon and Betty Moore Foundation. The cornerstone of TBC3's 2013 products is a set of climate projections for the Bay Area crafted by the USGS' Lorraine and Alan Flint in concert with geospatial analyst extraordinaire Dr. Stuart Weiss of the Creekside Center for Earth Observation. Under the expert guidance of IPCC scientists, this team selected 18 climate futures that represent the full statistical extent of the IPCC's global analyses. Then we “downscaled” these projections to 18-acre "pixels" for the San Francisco Bay Area. As a result, land and water managers in the Bay Area finally have climate projections at a scale they can incorporate into their long-term planning processes.  (You can now access a subset of the TBC3 climate futures data at bayarealands.org via the Explorer Tool's new Climate Portfolio Report for your own region of interest.)

The trend for the Bay Area we identified in our original 2012 publication was that despite the potential range in total quantities of winter rainfall projected for the future, our watersheds are going to be prone to becoming more arid. In other words, there is a risk of increasingly short winter wet periods and increasingly extended dry periods, also known as droughts, as in exactly what we are experiencing this year in Northern California. One of the tools developed by Dr. Weiss to visualize the Flints' Basin Characterization Model data set are water cycle diagrams that depict seasonal fluctuations in rainfall and its products. Below is a graph of the average annual water cycle for the Upper Sonoma Creek watershed, using historical data (1980-2009).

Upper Sonoma Creek - Average Annual Water Cycle (1980-2009)

The total height of the "wave" moving through each month of the season is equivalent to the total rainfall received over that month. The area in light green evaporates directly to the atmosphere or through plant respiration. The area in dark green is the water that stored in the soils for plants to use. The area in dark blue refills our underground groundwater basins. The area in light blue is the water available to feed our streams and reservoirs. The area in red that grows at the end of the summer season is the climatic “water deficit,” a measure of drought stress.

Now below is the same diagram representing the drought of 1975 to 1976 on Upper Sonoma Creek. As you can see it is almost all light green and red – meaning that all the incoming rainfall, which was very limited that year, was used up by plants with almost no water left to recharge the groundwater or feed streams. And that is similar to what is happening to our watersheds this year.

 

Upper Sonoma Creek (1975-1976) Drought Event

It's interesting to me that those of us who wear water goggles all the time – i.e. we look out at the world through the lens of water – probably considered us to be in trouble at the end of last year's wet season, when despite experiencing flood conditions in November, the absence of any further rain left us in a drought by May. Now in May we didn't know what this winter would hold, but there's always a chance of another dry year following a drought year, and when this happens three years in a row the water managers consider this an emergency. Dr. Weiss's preliminary analyses of the climate futures for the Bay Area suggests that three-year droughts could be a more frequent event.

I was reassured to have recently learned from a sociologist presenting at the Nature Conservancy's annual science symposium that what I felt in my gut about people was true. That is that while there can be relatively predictable divisions along political lines regarding the theory of climate change, there is in fact almost unanimous bi-partisan support for ensuring that communities in the US are prepared to deal with natural resource crises such as this year's drought. We see this as our community comes together to face this challenge, to support the ranchers who cannot feed their cattle because there's no water to make the grass grow, to support the water districts in their need to stretch a stressed supply. However that is one of the mysteries to me about our social response – why are we just starting to talk about water conservation measures now, when it was clear last May we were already facing risks to our water security?

Thanks to Dr. David Ackerly's TBC3 long-term forest monitoring project at Pepperwood, we will have data to evaluate hypotheses about how this drought is impacting our forests. Informed observers say things like "the forest looks stressed to me," or "I think I am seeing more brown tipped leaves," or "I think species X is having a really hard time." I now have some rigorous measurements in place to test these emerging hypotheses. Thanks to Dr. Ackerly and his laboratory at Berkeley's Department of Integrative Biology, there are 50 sites at Pepperwood where every single plant has been identified and measured. Now when we conduct our repeat measurements we will have actual data capable of showing the impact of the drought on plant composition and survival. This kind of scientific research will be absolutely critical to better understanding how our natural resources will respond to increasing climate and water stresses.

What the TBC3 project at Pepperwood does is provide a high resolution portal on local changes in the context of global climate science. Fran Ulmer, chair of the US Arctic Research Commission recently shared upon release of the Arctic Report Card 2013  the following perspective: The Arctic is not like Las Vegas: whathappens in the Arctic does not stay in the Arctic. 

So while my personal mission is one of equipping our communities to be resilient in the face of climate change based on real-time local data, the magnitude of the challenge we face will be directly proportional to our ability to steer our energy consumption patterns away from carbon-based fuels. Another catchphrase which has been in the forefront of my mind is the following. There are known alternatives to fossil fuels. There are no known alternatives to water.