Climate in the Golden State: A Look at “Cal-Adapt”

By David Kroodsma

As a resident of the Golden State, I was thrilled to see the new Cal-Adapt website. The site uses interactive graphics and maps to show how climate change is expected to affect the state, and it allowed me to see what is predicted for where I live.

The background: In 2009, the California Natural Resources Agency, working in conjunction with numerous other state agencies, published a 200-page document entitled California Climate Adaptation Strategy. In great detail, drawing on numerous scientific studies, the document outlined how the state is at risk to rising temperatures, reduced snowpack, increased wildfires, and higher sea levels. Well-aware that 200-page reports don’t often gain wide readership, the authors recommended building a website to better share their findings.

Nearly two years later, in an effort led by UC Berkeley’s Geospatial Innovation Facility and supported by public and private agencies, the result is the Cal-Adapt website. While originally designed for “decision makers” and technical users, the site’s interface makes it easy for any Californian to understand how climate change may affect their community.

The main feature is a series of interactive maps where the user can enter in their location (or click on it on the map), and get detailed statistics about what climate models project for that location. Users can look at projections of forest fires, sea level rise, temperature change, precipitation, or even snowpack thickness. They can select among four different climate models and two “emissions scenarios.” It is even possible to download the raw data, which has been provided by a number of research institutions.

Below are a few screenshots from the site, as well as some of the major take-aways from climate projections in California. The first map below shows how wildfires are expected to change in the state. The scale, ranging from 0 to 10, shows how much more common wildfires will be later this century compared to today. For much of the northern Pacific coast and Sierra Nevada, by 2085 wildfires are expected to be two to 10 times more common. (The results are an average of four climate models using an emissions scenario in which society uses fossil fuels unabated.)



The next two maps show how snowpack may change. Snowpack thickness is measured in inches of water-equivalent — that is, how much water would be on the ground if the snow were melted. On the maps below I’ve zoomed in on the Sierra Nevada Mountains to show the results for snowpack thickness in April of 2000 and April of 2090 (assuming the “A2” high-emissions scenario). In 2000, much of the Sierras had 20 inches or more of water-equivalent snow in April. By 2090, nearly everywhere in this projection has less than 10 inches. You can also hit “play” and watch the snowpack “melt” over the course of the century.



And of course, you can see how temperatures will change, too. Below is the expected change in high temperatures in August for the state between today and 2090, assuming the same emissions scenario. Note that the warming will be much greater the farther you are from the coast: San Francisco may warm by only 5°F, but parts of the Sierra Nevada could see August high temperatures nearly 10 degrees hotter, on average, than they are today. 


The site also allows you to see precipitation trends, how sea level rise might affect a given county, and how daily high and low temperatures may change for any given month. This range of options is almost overwhelming — if it weren’t for the attractive interface, a user could quickly get lost.

Of course, there is room for improvement. The interactive maps use only four climate models. More than 20 different global climate models exist, and most scientists argue that considering all of these models gives more useful results, especially with regard to understanding and reducing uncertainties.  

But perhaps the biggest piece that is missing is how extreme events will change. A good deal of city and regional planning is centered around such events. For instance, city sewage systems are not built to withstand the average storm, but the strongest. Electrical grids must also be prepared for extreme heat waves, when air conditioning drives energy demand to its highest levels. And levees need to be built not only for rising sea levels, but also for the possibility of major storms that dump huge amounts of precipitation. In order to fully understand and prepare for the impacts of climate change, such extremes must be considered. Of course, the reason that the site lacks these projections is not because of laziness — it is because the science of projecting changes in extremes is still being refined.

The authors of the website note that it will be updated as better data becomes available. And overall, this site is a huge step forward in communicating the impacts of climate change. If you live in California, I strongly recommend taking a good look at these maps and seeing what climate models predict for your community.