Climate Change Blog Posts

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Can Marine Reserves Help Mitigate the Effects of Climate Change?


Map of different kinds of protected marine areas up and down the California coast
Marine reserves such as those along the California coast may be able to help buffer and mitigate the effects of climate change. CA Department of Fish and Game Image.

Protected marine areas, such as those that dot the length of the California coast, protect a wide range of marine life and habitats. The recent article, “Marine reserves can mitigate and promote adaptation to climate change” looks at how well-managed reserves may help marine ecosystems and human populations adapt to the effects of climate change, including ocean acidification, sea-level rise, more intense storms, species distribution changes, and decreased marine productivity. Read the abstract and find the link to the full PNAS article (for purchase for non-members), or learn more about California’s marine reserves and other marine protected areas on the Department of Fish and Wildlife website.

How Will Climate Change Effect Key Marine Ecosystem Drivers?


A recent paper, “Rapid emergence of climate change in environmental drivers of marine ecosystems” describes how quickly multiple drivers of marine ecosystem change may develop under two future climate change scenarios: “business-as-usual” and a mitigation scenario representative of the conditions of the Paris Agreement. By looking at a number of different models, the authors found that climate change-driven trends in multiple ecosystem drivers emerge in 55% of the ocean and encompass 86% by 2050 under the ‘business-as-usual’ scenario. However, with mitigation that number drops to 34%. Mitigation also slows the pace at which multiple drivers emerge, allowing an additional 20 years for adaptation. Read more in the full Nature Communications article available here.

Climate Change Impacts on California Coastal Upwelling


As winds that blow from the north along the U.S. West Coast push surface waters away from the shore, cold, nutrient-rich waters from below rise up to take their place. This upwelling phenomenon supports a diverse and rich array of marine life, as well as helps drive onshore fog and temperature patterns. It is hypothesized that global warming will accelerate these winds, which meditate upwelling in the California Current System (CCS) running from southern British Columbia to the southern Baja California Peninsula.

A recent Geophysical Research Letters article estimates changes in CCS upwelling from 1920 to 2100. The authors suggest that CCS upwelling will become more intense in the spring and less intense in the summer, and that these changes will arise mostly in the second half of the century. “Emergent anthropogenic trends in California Current upwelling” is available for rent or purchase here.

Rising Seas in California: An Update on Sea-Level Rise Science


A King Tide along San Francisco's waterfront in January 2017 portends what future sea level rise might look like. 
Photo by Dave R.
A King Tide along San Francisco's waterfront in January 2017 portends what future sea level rise might look like. Photo by Dave R.

This report, initially adopted in 2010 and updated in 2013, provides guidance to state agencies for how to incorporate sea-level rise projections into planning, design, permitting, construction, investment, and other decisions.

The latest version, just released this month, reflects recent advances in ice loss science and projections of sea-level rise. It also includes new information on the expected sea level changes that will occur based on different greenhouse gas emission scenarios.

Key findings include:

  • Projections of future sea-level rise under high emissions scenarios have increased substantially over the last few years, primarily due to improved understanding of mass loss from continental ice sheets.
  • The rate of ice loss from the Greenland and Antarctic Ice Sheets is increasing. These ice sheets will soon become the primary contributor to global sea-level rise, overtaking contributions from ocean thermal expansion and melting mountain glaciers and ice caps.
  • Ice loss from Antarctica, and especially from West Antarctica, causes higher sea-level rise in California than the global average. For every foot of global sea-level rise caused by loss of ice from West Antarctic, sea-level will rise approximately 1.25 feet along the California coast.
  • After 2050, sea-level rise projections increasingly depend on the trajectory of greenhouse gas emissions.
  • With very successful mitigation efforts there is a 67 percent probability that the Bay Area will experience sea level rise between 1.0 foot and 2.4 feet by 2100. However, if no significant mitigation efforts are taken, that rise increases to between 1.6 and 3.4 feet.
  • While model results have revealed the potential for high rates of ice loss and extreme sea-level rise during this century if greenhouse gas emissions continue unabated, the precise magnitude and timing of substantial Antarctic Ice Sheet contributions to rising sea levels is uncertain.

See the full report for additional information about these projections and recommended actions.

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.