New Study on Sea Level Rise Points to Much Higher Risk Than Previously Thought: A new study by acclaimed NASA climate scientist James Hansen and colleagues claims that sea level rise will occur much more rapidly than forecast by the Intergovernmental Panel on Climate Change. Hansen and colleagues project a sea level rise of 5 – 9 meters in 50, 100 or 200 years if fossil fuel emissions continue on a ‘business-as-usual’ course (meaning that emissions as they are now would continue in the future). The rate of sea level rise would be accelerated by parts of the Antarctica and Greenland ice sheets melting, and this melting would bring about a number of climate change ‘feedbacks’, which would in turn increase the rate of melting. However, this study has generated considerable controversy and criticism. Other prominent climate scientists, such as Kevin Trenberth of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, have strongly criticized the study, arguing that Hansen and colleagues made too many assumptions and extrapolations for the study to be taken seriously. However, the IPCC has been criticized in the past for making overly conservative projections, including for sea level rise. Greg Holland, also at NCAR, argues that the actual amount of sea level rise that will occur is probably somewhere between the amount projected by this study and the IPCC.

Ocean acidification may cause dramatic changes to phytoplankton: The uptake of carbon dioxide in the oceans has resulted in a drop of the global average pH from 8.2 to 8.1. By 2100, it is projected to drop further to around 7.8, which is significantly lower than any pH levels seen anywhere in open ocean marine communities around the world. The authors of this study show how ocean acidification by 2100 is projected to affect phytoplankton. Phytoplankton species are projected to exhibit a wide range of responses: some will die out, while others will flourish. Thus the balance of plankton species will be fundamentally altered. Some species will even grow faster than previously, while others will be significantly harmed, perhaps going extinct. Warming temperatures will also significantly affect the locations of phytoplankton. Many species will shift toward the poles as the planet warms. However, the most significant changes will occur from ocean acidification.
 

Using Air Temperature to Model Stream Warming: A new U.S. Forest Service Southern Research Station study demonstrates how long-term historic air temperature data can be used in conjunction with short-term stream temperature data to project future warming in streams. Peter Caldwell, a research hydrologist at the Coweeta Hydrologic Laboratory, led the study. Caldwell and his colleagues showed how only 18 months of stream temperature observations could be used to explain variability in stream temperature for up to 37 years. They used these findings to model historical stream temperatures at 61 sites in the Southeastern United States from 1961 to 2010, and then used these models to project future temperatures from 2011 through 2060. They found that stream temperatures had already increased during the historical period, and those streams located in the Appalachian ecoregion were predicted to be most vulnerable to climate change. These findings were seen as a significant breakthrough, as before it was very difficult to project long-term climate change impacts on stream temperature.

Projecting precipitation throughout the 21^st century over North America: In this new study, high spatial resolution (12 km) simulations were performed using the Weather Research and Forecasting (WRF) model. The purpose of the simulations was to explore mean and extreme precipitation projections for the mid to late 21^st century. Because of the higher spatial resolution of the simulations, the study allowed for resolving precipitation in ways that had not previously been possible (such as over mountain ranges). The authors found that among 10 subregions they studied, the Pacific Northwest showed the greatest increase in the number of days each year when extreme precipitation occurs. This was the case for both emissions scenarios studied, RCP 4.5 and RCP 8.5, but there was a higher increase in the number of days with extreme precipitation for RCP 8.5.  

Groundwater slowly being depleted in the United States: Between 1900 – 2008, the volume of groundwater stored below the United States decreased by almost 1000 cubic kilometers. The areas with the highest amount of storage depletion include the High Plains aquifer the Mississippi Embayment section of the Gulf Coastal Plain aquifer system, and the Central Valley in California. The rate of depletion has accelerated since 2000. Leonard Konikow, the author of the study, introduces a new parameter for studying groundwater depletion, ‘depletion intensity’, to understand how storage changes are occurring geographically. He found that the Central Valley in California had the highest depletion intensity. Groundwater depletion can have a wide range of harmful effects, including reduced well yields, reduced base flow to springs, streams and other surface water bodies, and loss of wetlands. It is also responsible for sea level rise, and Konikow found that groundwater depletion in the United States could explain 1.4% of observed sea level rise that occurred during the study period.

Commentary on Heightened Risk of Drought due to Climate Change: In this commentary piece, Pacific Institute Director Peter Gleick and Pennsylvania State University Meteorologist Michael Mann discuss the state of current literature on drought and climate science. They discuss a new study published in PNAS by Diffenbaugh et al., which shows accumulating evidence that climate change is influencing the frequency, magnitude and duration of drought in California. An increasing number of dry years along with warm years raise the risk of drought, despite the lack of a strong trend in precipitation. These results point to the significance of warming temperatures to changing the availability of water and increasing drought intensity. It is important to note, however, as the authors do, that this is not uncontested. A number of recent studies (some of which focused on a lack of trend in precipitation) concluded that a link between ocean temperatures and drought could not yet be established. Part of the debate, however, has occurred because there are many ways in which drought can be defined. A drought can be meteorological, hydrological, agricultural, and/or socioeconomic. Other parts of the debate stem from attribution. Some studies argue that low levels of precipitation cannot be tied to climate change, while others argue that while this may be true, the low levels of precipitation are caused by an unusually strong ‘atmospheric ridge’ in the Western United States, which was most likely stronger due to climate change.
 
Artificial amplification of warming trends across the mountains of the western United States: A new study suggests that elevation dependent warming may not be occurring as is suggested by observational data. Observations from the mountain climate station network in the Western United States suggest that some higher elevation areas are warming faster than lower elevation areas. This study evaluates temperature observations from the climate network sites and finds that the extreme warming observed at higher elevations is a result of systematic artifacts and not climatic conditions. The authors find that climate data that is widely used for model simulations propagate these temperature trends, which impacts the ability for studies to accurately model climate change impacts in mountainous parts of the Western US.
 

 

Can forests rebound from severe drought: A new study questions whether or not forests can recover from extended drought periods. The study suggests that trees can take years to go back to normal growth after experiencing a drought. Lead author William Anderegg found that trees took an average of two to four years to recover from drought, with two exceptions: trees in California and the Mediterranean actually grow more quickly after a drought. This could be explained by the dominance of oak forests in these regions. Instances of this have already occurred, and the Western US has been particularly hard hit in terms of tree mortality, according to Anderegg. Restoring the natural density of trees could be an important step in the right direction for forests in the Western US.
 

Dry Days Bring Ferocious Start to Fire Season: Record-breaking drought this summer has set off a number of expensive wildfires this summer across the Western United States. Although wildfires used to be predominantly confined to range lands, this summer has brought wildfires even in the rain forests of the Olympic Peninsula, which is one of the wettest regions of the world. The drought has penetrated as far north as Alaska, where 399 fires burned in June, which is twice the number recorded in 2004, the state’s worst recorded fire year. Previously, fires in Alaska had burned tundra, but this year fires destroyed or damaged hundreds of homes. Projections of the nationwide cost of fighting this year’s wildfires are around $2.1 billion. In the Pacific Northwest, recent fires in and near Walla Walla, WA and Wenatchee, WA have already devastated homes and crops. With the current El Nino projections, bleak prospects are ahead – drier temperatures for most of the Pacific Northwest.

Area burned in the western United States unaffected by recent mountain pine beetle outbreaks: Mountain pine beetles have been a serious scourge in the Western US, leading to the death of pine trees across 71,000 cubic kilometers of forestland since the mid-1990s. As a result, it has been widely perceived that an abundance of dead fuels from the death of the pine trees might exacerbate fire behavior and lead to a wider area being burned. The authors of the study examined the effects of beetle outbreaks during the three peak years of wildfire activity since 2002 in the Western US and found that the effect was negligible. Although both fires and beetle outbreaks have increased due to warming temperatures, the occurrence of one does not seem to reinforce occurrence of the other.
 

 

State Has Legal Obligation to Protect Climate: In March of 2015, a group of lawyers, professors and judges from around the world released the Oslo Principles on Global Climate Change Obligations, which stated that an international agreement to cut greenhouse gas emissions was not necessary to compel governments to reduce emissions. Instead, governments are required to do so based on existing human rights and a combination of environmental and tort laws, and a failure to enact such laws will cause serious harm to citizens and the earth. This was the precursor to last month’s order, when King County Superior Court Judge Hollis Hill ordered the Washington Department of Ecology to reconsider a petition that was filed in 2014. The petition called for a reduction in carbon dioxide emissions to ‘protect the climate by considering the best available science when setting emission reduction goals’. In Washington, the state’s Clean Air Act is the primary legal vehicle for enforcing air quality.

New National Research Council fast-track study on extreme weather events: The Board on Atmospheric Sciences and Climate of the National Research Council has announced a new fast-track study on extreme weather events. Specifically, the study examines attributing extreme weather events to anthropogenic induced climate change versus natural variability.

NASA: California “Rain Debt” Equal to Average Full Year of Precipitation: A new NASA study concluded that California has accumulated a debt of around 20 inches of precipitation from 2012 through 2015. This is approximately the amount of precipitation that typically falls in the state in a given year. Between 20-50 percent of California’s precipitation comes from atmospheric rivers, which move over the Pacific Ocean and are responsible for precipitation falling in others of the West Coast as well. The study authors attribute the majority of the precipitation debt to a high-pressure system in the atmosphere over the eastern Pacific Ocean that has prevented the formation of atmospheric rivers since 2011.
 
State of the Climate Report for 2014 Released: The American Meteorological Society has released its State of the Climate Report for 2014. Key findings from the report include: 1) greenhouse gas concentrations continued to rise, reaching historic high values; 2) 2014 was the warmest year on record; 3) the tropical Pacific Ocean is moving toward El Nino Southern Oscillation conditions; 4) sea surface temperatures reached a record high; 5) global average sea level rose to a record high; 6) sea ice extent in the Antarctic reached a record high (that is not a typo!); 7) the number of tropical cyclones was well above the historical yearly average.

For the full report: http://www.ncdc.noaa.gov/bams-state-of-the-climate/2014.php

Weather is becoming more conducive to wildfires: A new study argues that fire risks across the planet are rising as a result of climate change. Wildfire risk may be partially due to a decreasing ability of land and vegetation to extract carbon from the atmosphere and thus partially offset greenhouse gas emissions. As a result, wildfires are acting as a positive feedback – in other words, fires are getting worse because of climate change, while also making climate change worse. Matt Jolly, lead author of the study and a researcher with the U.S. Forest Service’s Fire Sciences Laboratory in Missoula, Montana, found that the duration of weather most conducive to fires has increased by 18.7% between 1979 to 2013. Jolly also found that the area burned increased as well.

Climate Prediction Center Releases New Report on El Nino: The Climate Prediction Center has released a new report on the El Nino Southern Oscillation. The report issues an ‘El Nino Advisory’, stating ‘El Nino conditions are present’, ‘Positive equatorial sea surface temperature (SST) anomalies continue across most of the Pacific Ocean’ and that ‘There is a greater than 90% chance that El Nino will continue through Northern Hemisphere winter 2015-16, and around an 80% chance it will last through early spring 2016.”
 

 

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