Climate Change Blog Posts

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Complexities in Modeling the Link Between Drought and Fire


Does a hotter and drier future climate necessarily equal more fires? The authors of a recent Ecological Applications paper “Climate change and the eco-hydrology of fire: Will area burned increase in a warming western USA?” say maybe not.

The authors looked at ecosystems across the western US along a moisture gradient from desert to temperate rain forest. They found that while models show the correlation between drought and fire seems particularly strong in ecosystems in the middle of the gradient, it does not hold as well outside of that range, or it is dependent on fuels and/or the previous year’s rainfall and climate. They argue that influence humans have, through fire ignition and suppression, will also impact the scale of future fires. Read more in the full article available here.

Drivers of Low Snow Levels Examined in New Paper


A recent paper published in Geophysical Research Letters looks at the impacts of the ongoing drought on snowpack levels in California, Oregon, and Washington. “Perspectives on the causes of exceptionally low 2015 snowpack in the western United States” describes how a number of crowd-sourced regional climate model simulations were used to show that both human influence and sea surface temperature anomalies (the warm water “blob”) were primary contributors to the low levels of snow seen in Oregon and Washington. Furthermore, they found that sea surface temperature anomalies contributed about twice as much as human influences did. In California however, these factors played a much smaller role.

Warm Water Blob Caused Massive 2015 Pacific Ocean Algae Bloom


A new study has found that a large area of warm water called the “warm anomaly,” or just the “blob,” caused the massive algae bloom that closed razor clam, rock crab, and Dungeness crab fisheries all along the U.S. West Coast in 2015.

The bloom included the diatom Pseudo-nitzschia, which produces the neurotoxin domoic acid that can cause seizures, gastrointestinal distress, and sometimes death in animals (including humans) that consume it.

Although seasonal algae blooms in this region are not uncommon, warmer water in 2015 allowed the diatoms to thrive and expand well north of their usual range. The onset of normal seasonal upwelling patterns then brought the nutrients needed to trigger the bloom, and spring storms moved the bloom towards coastal areas. The connection between warmer water and large-scale blooms is an important, yet concerning discovery as global ocean temperatures continue to rise.

The original article published inGeophysical Research Letters is available at

How Elephant Seals are Handling the Heat


Northern elephant seals come on shore at Point Reyes National Seashore beaches every winter to give birth and mate. In recent years, ambient temperature during these winter months has been increasing and there has been concern about how these large animals with their thick blubber will be able to handle the heat load.

Point Reyes National Seashore marine ecologist Sarah Codde and her colleagues conducted a study using infrared thermography to investigate how environmental variables affected adult female and pup thermoregulation at the Drakes Beach elephant seal colony. Both solar radiation and ambient temperature were found to be the main environmental factors that affected the surface temperature of females and pups. The research suggested that circulatory adjustments to bypass the blubber layer were sufficient to allow seals to dissipate heat under most current environmental conditions. This study is the first to document a novel behavior of females and pups entering the water on days with high solar radiation. This is unusual behavior at most other elephant seal colonies because pups are unable to swim during the first month of life. However, at Drakes Beach, the calm water allows for pups to be in the shallow area with less risk of drowning. These results may predict important breeding habitat features for elephant seals in response to a changing climate.

Two thermograms of elephant seals with inset digital pictures to aid in identifying the seals.
Two thermograms of elephant seals with inset digital pictures to aid in identifying the seals. The red and white hotspots are "thermal windows", or areas where the seals' circulation has adjusted to bypass the blubber layer and dissipate heat. From Codde, 2016.

To learn more about this study, you can read the full article published in the Journal of Thermal Biology, or contact

Record High Temperatures Continue


Graph of seasonal global average temperature changes from 1880 to 2016. The 2016 line sits almost wholly above lines for previous years.
Graph of seasonal changes in global average temperature from 1880 to 2016. NASA.

According to NASA’s monthly analysis of global temperatures, July was the warmest month the Earth has experienced since modern record keeping began in 1880. August went on to tie that record, even though July is typically the hottest month in any given year. August was also the 11th month in a row to set a new monthly high temperature record. It is now basically certain that 2016 will surpass last year as the warmest year on record in terms of global average temperature.




Meet the National Park Service’s Principal Climate Change Scientist


Yosemite valley in the winter.
Yosemite valley. Though he serves all national parks, Yosemite National Park is a personal favorite of National Park Service principal climate change scientist Dr. Patrick Gonzalez.

Dr. Patrick Gonzalez, the principal climate change scientist of the National Park Service, and a San Francisco Bay Area resident, was featured in a recent article in High Country News. The piece takes readers from Gonzalez's early climate change research in Senegal, to the work he is doing now to help national parks across the country understand and manage the myriad challenges of climate change.

Dr. Gonzalez also recently wrote an article for The Conversation explaining his research on how climate change is leaving its mark on national park ecosystems, and on what changes the future may have in store. Protected from most non-climate threats, national parks are unique laboratories for studying climate change. Gonzalez’s piece highlights the scale and scope of what is happening from the Golden Gate National Recreation Area to Everglades National Park, and how national park management is beginning to adapt. He also reminds us that reducing carbon emissions remains an effective and achievable way to avoid the most damaging effects of climate change in our parks.

The comprehensive report released earlier this summer on climate change in San Francisco Bay Area national parks was also the work of Dr. Gonzalez.

Wildfire in a Time of Climate Change


Severe die-off of ponderosa pines in a mixed conifer forest

With multiple wildfires raging throughout California, it is easy to wonder to what extent climate change may be to blame. Scientists are attempting to tackle this question, and to model what future fire regimes might look like as the climate changes, but there are few simple answers. As ecologists Jon Keeley and Alexandra Syphard put it in their recent article published in Geosciences, “Predicting future fire regimes is not rocket science; it is far more complicated than that.”

On a global scale, models generally predict increased fire activity as a result of a climate change. This is supported by historical links between fire and climate. In particular, higher temperatures and reduced precipitation lead to greater burned area by impacting fuel (vegetation) moisture and amount. Climate change models are not yet precise enough, however, to be useful for drawing local conclusions about future wildfire patterns. Local precipitation and temperature predictions still vary, and could end up forming new patterns that have few historical analogs. In addition, it is higher seasonal temperatures rather than higher average annual temperatures that are historically associated with higher burned area in certain regions, but current climate change models focus primarily on the latter.

Climate change will also indirectly affect fire activity by influencing vegetation patterns and plant productivity, further complicating future projections. A new analysis by researchers at South Dakota State University concludes that climate-induced vegetation change may increase fire frequency and size more than direct changes in temperature and precipitation.  Another new study led by USDA Forest Service researchers concludes that fire severity could decrease across the western US by mid-century if vegetation changes track with the changing climate (e.g., denser vegetation is replaced with sparser, lower fuel volume plant communities in areas that become drier). They note that fire severity could temporarily increase, though, as others have predicted under static plant community scenarios, if fire suppression or other factors serve to delay plant community transitions.

In the end, Keeley and Syphard point out that there are other human forces at play as well that could prove even more important than climate change in determining future fire regimes. For instance, human population growth (and thus more fire ignitions) and land management decisions could be very influential in some landscapes.

Photo: Die-off of ponderosa pines in the southern Sierra Nevada Range in July 2016, following years of severe drought and high pathogen activity, both exacerbated by climate change. High tree density from more than a century of fire suppression also influences the area's susceptibility to wildfire and complicates calculating the size of global warming's influence. Photo by Jon E. Keeley from Keeley and Syphard, 2016.

New Report on Climate Change in Bay Area Parks


Climate report cover page

A new National Park Service report by Dr. Patrick Gonzalez presents original analyses and a comprehensive literature review related to past and projected climate change in Bay Area national parks. Specifically, it covers parks in counties bordering the San Francisco Bay including Golden Gate National Recreation Area, Muir Woods National Monument, Point Reyes National Seashore, John Muir National Historic Site, and the five smaller historical and cultural parks.

As might be expected, human-caused climate changes have already taken place in these parks. The analyses show temperature increases throughout the parks since 1895, and especially since 1950. The highest increases occurred north of Muir Woods and around the City of San Jose. Precipitation hasn’t changed much for the parks over time, but given increased evaporation associated with higher temperatures, conditions have become more arid. Climate change impacts have also already been measured in Bay Area parks, including sea level rise and bird range shifts.

Analyses of what future climate change scenarios might look like inside Bay Area park boundaries is broken out in the report by park, emissions scenario, and time of year. Overall, if emissions are not reduced by 40-70%, substantial warming and slight precipitation increases are projected. Drought probabilities rise since the chances of hot and dry conditions occurring at the same time is increased. The report goes on to summarize research on how physical, terrestrial, and aquatic park resources may be vulnerable to future climate change.

Finally, the report examines the role of Bay Area park ecosystems in storing carbon and lessening climate change. It notes that the nine parks contained as much carbon in their terrestrial plants in 2010 as 370,000 ± 140,000 Americans emit in a year. They have the capacity to store even more in places like the growing coast redwood trees of Muir Woods and Phleger Estate, or in any wetlands that may be restored. An increase in carbon storage took place in Point Reyes due to vegetation growth between 2001 and 2010.

Carbon Dioxide Concentrations Reach New Milestone


The low sun and flags over the South Pole Observatory. NSF photo.

For the most recent 800,000 years of atmospheric history (a period scientists have investigated through ice cores), carbon dioxide (CO2) levels in the atmosphere never exceeded 300 parts per million (ppm). Concentrations have been climbing since the start of the Industrial Revolution, and in recent years, NOAA and international partners have recorded in excess of 400 ppm of CO2 in the atmosphere. The number was first reached at monitoring sites in the Arctic in the spring of 2012. The following year, measurements at NOAA’s Mauna Loa Observatory began crossing the threshold as well. Last spring, monthly averages from remote monitoring locations across the globe also began surpassing 400 ppm.

Now a new 400 ppm milestone has been reached. On May 23, the South Pole became the last place on Earth to record daily average CO2 concentrations above that level. Such concentrations have not occurred in the South Pole for some four million years. The annual global concentration of CO2, which was 399 ppm in 2015, is also likely to break the 400 ppm barrier this year. NOAA scientists note that because CO2 remains in the atmosphere for hundreds or thousands of years, such concentrations are here to stay for our lifetimes.

Four hundred ppm is not a fixed climate tipping point, but it does represent increasingly uncharted territory for humanity. For many, it is a powerful, symbolic reminder that unless more action is taken to reduce fossil fuel consumption, CO2 concentrations and the impacts of climate change will continue to intensify. Many scientists consider 450 ppm to be high risk, finding instead that CO2 concentrations would need to be reduced to 350 ppm to limit global warming and maintain a planet resembling the one we know today. Meanwhile, NOAA’s data seems to indicate that annual CO2 concentrations are rising at an increasing and unprecedented pace. Visit the recent NOAA article on this latest milestone for more information, or for more hopeful news, check out another NOAA article on how the US electricity sector could dramatically and affrordably cut emissions over the next 15 years.

Many California Plant Communities Vulnerable to Climate Change


Report cover page

A recent report prepared by researchers at UC Davis for the California Department of Fish and Wildlife finds that 18 out of 29 plant communities in California are highly or nearly highly vulnerable to climate change. The remaining 11 communities are found to be moderately vulnerable, while none were found to have a low vulnerability. Fresh and saltwater marshes ranked among the six most vulnerable communities; coast redwood forest, coastal sage scrub, and grasslands ranked among 12 near highly vulnerable communities; and chaparral is an example of a community ranked as moderately vulnerable.

The report uses a detailed 2015 map of existing plant community distribution across the state, and looks at how climate conditions are expected to change in different areas under different climate and emissions scenarios. It also takes into account factors like the potential adaptability of key plant species in the various communities and how far the communities would need to shift geographically to maintain suitable climate conditions. The findings are likely conservative given that many indirect effects of climate change, some of which are already having an impact, are not part of the analysis. These include wildfires, extreme events (i.e. prolonged droughts), insect outbreaks, and the spread of invasive species.

The results are not intended to be taken as definitive predictions for what will happen where, but a wealth of additional information is available in the report for interpreting the results for individual plant communities and locations under different scenarios. Download the full document via the Climate Commons website.