Climate Change Blog Posts

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Implications of Sea Level Rise on Mediterranean-Climate Marsh Species


Marco image of Salicornia pacifica, a dominant salt marsh plant. Photo by Steve Matson ©2006.
The presence of S. pacifica, also known as Pacific pickleweed, affected species diversity in a set of recent field experiments testing the effects of sea level rise on marsh plants. Photo by Steve Matson ©2006.

Sea level rise is predicted to change both salinity and inundation levels—conditions that are already the two biggest stressors on plants living in Mediterranean-climate salt marshes. A recent study moved plants from higher elevations to lower ones in a southern California marsh to simulate the effects of sea level rise and test how it might affect competitive interactions and plant species diversity. This move was paired with manipulations of the dominant plant species, Salicornia pacifica, otherwise known as Pacific pickleweed, to see if plant species interactions became more competitive or facilitative.

The study found that both S. pacifica and the subordinate species were affected by inundation, but that levels of the subordinate plant species decreased with the presence of S. pacifica. Based on these results, the authors predict that increased competition and species interactions as a result of sea level rise may reduce plant diversity and exacerbate the effects of climate change on these plant communities. They conclude that restoration projects attempting to maintain a full suite of ecosystem functions should try to account for these changes by planting a high diversity of species in areas expected to see increased inundation.

Read more in the full PLoS ONE article “Early Stages of Sea-Level Rise Lead to Decreased Salt Marsh Plant Diversity through Stronger Competition in Mediterranean-Climate Marshes.”

Planning for Vegetation Change Under Different Climate Change Scenarios


Golden Gate Supervisory Vegetation Ecologist Alison Forrestel presenting suggested management tools from breakout group discussions after the scenario planning exercise.
Golden Gate Supervisory Vegetation Ecologist Alison Forrestel shares suggested management tools from breakout group discussions after the scenario planning exercise.

Representatives from Pepperwood’s Terrestrial Biodiversity and Climate Change Collaborative (TBC3) convened a workshop for open space managers and researchers to focus on management responses to vegetation change triggered by a changing climate. Through a scenario planning exercise, participants identified current and new conservation strategies that can be implemented under different future scenarios (e.g., drought-induced oak diebacks, catastrophic fires, or increased precipitation) in response to new plant species arriving or expanding, and existing species declining. In addition, the group evaluated the utility of existing vegetation models as decision support tools for climate-smart open space management in the North Bay. The input provided by participants will now be used to improve TBC3’s Climate Ready Vegetation Reports and Climate Ready Management Implications document.

New Measures of Coastal Erosion Reveal the Effects of 2015–2016 El Niño


Locations of the six regions where co-located wave, water-level and beach survey data were analysed. 
Figure 2 from: Extreme oceanographic forcing and coastal response due to the 2015–2016 El Niño
Locations of the six regions where co-located wave, water-level and beach survey data were analyzed. From Figure 2 in "Extreme oceanographic forcing and coastal response due to the 2015–2016 El Niño."

The winter of 2015–2016 saw the strongest El Niño-Southern Oscillation in 145 years along the US West Coast. The phenomena—which even in a normal cycle is powerful enough to affect ocean conditions and climate across the entire Pacific Ocean—increases wave energy and water levels, which in turn increase coastal erosion and flooding.

A new study, led by USGS scientist Patrick Barnard, looked at two decades of data from LIDAR and topographic beach surveys, as well as sand level measurements for 29 beaches along about 2,000 km of coastline. The research team found that the average shoreline retreat in 2015–2106 was 76% above normal and 27% higher than that recorded for any previous El Niño. Ocean Beach along the Great Highway alone lost up to180 feet of sand.

Sediment that would normally be brought to the shore by coastal rivers to replenish the beaches was also in short supply due to lower than average rainfall levels. Understanding the effects of events like these is essential, as climate change projections predict higher temperatures, lower rainfall, increased sea levels, and the potential for more extreme and more frequent El Niño events.

Read more about this study in the original Nature Communications article and in this recent San Francisco Chronicle piece.

Can Stream Restoration Mitigate the Effects of Climate Change on Salmon Populations?


Fish like this steelhead trout may benefit from certain stream restoration practices that help maintain cooler water temperatures in the face of climate change.  Photo by Michael REichmuth/NPS
Fish like this steelhead trout may benefit from certain stream restoration practices that help maintain cooler water temperatures in the face of climate change. Photo by Michael Reichmuth/NPS

Cold water fish such as chinook salmon (Oncorhynchus tshawytscha) and steelhead trout (O. mykiss) need the water temperature of the streams where they live to stay below a certain threshold in order to survive. However, the temperature of many salmon-bearing streams in the Western US has been affected by changes in air temperature and precipitation due to climate change, as well as decreased stream flow from water withdrawals, stream widening/channelization, and reduced shade caused by deforestation or other stream bank vegetation loss.

A recent study using a water temperature simulation model found that intensive, large-scale riparian reforestation and channel narrowing could reduce current peak summer water temperatures to levels that are beneficial to chinook salmon in northeast Oregon. Temperatures in some portions of the study’s watersheds, especially the lower reaches, still remained too high, suggesting that additional restoration actions might be required in some areas.

The authors acknowledge the challenges of implementing watershed-wide restoration; however, they stress that certain aspects of riparian restoration are key to reducing stream temperature for salmonids, and offer their modeling and prioritization framework as a tool for other land managers and restoration practitioners.

The full article is available in the latest issue of the Journal of Environmental Management.


Looking to the Past to Plan for the Future


Although conservation efforts have often focused on preserving individual species, the authors of a recent Science article make the case for also thinking about how to understand and maintain ecological roles and functions regardless of which specific species may fill those roles.

The article, “Merging paleobiology with conservation biology to guide the future of terrestrial ecosystems” uses examples from Joshua Tree, Yellowstone, and other national parks around the world to show how plant and animal fossils can reveal important things about the biology and ecology of the species that lived in a particular area, including critical information about their sensitivity to changes in climate and habitat. The authors argue that understanding how species and systems adapted to change in the past can help managers shift from preserving “idealized” ecosystems to understanding how to preserve ecosystem functions and adaptive capacity in the future.

The abstract is available for free, and the full text may be downloaded by AAAS members.

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.