Briefing Report: More on the Brown Administration's Climate Change Indicators

Wednesday, September 11, 2013

This report further examines some of the issues presented in, "Indicators of Climate Change in California" by the California Environmental Protection Agency (CalEPA), which the agency describes as "reveal[ing] evidence of the already discernible impacts of climate change, highlighting the urgency for the state, local government [sic] and others to undertake mitigation strategies." Last week's Senate Republican Caucus briefing report, "What Does the Brown Administration's Report on Climate Change Indicators Really Indicate", lays out the numerous caveats and contradictions contained within the report itself. This report builds upon those and provides additional examples of potential weaknesses from a selection of the 36 "indicators of climate change" identified.


As Californians begin to feel the burn of first-of-its-kind greenhouse gas (GHG) reduction policies, in the form of higher energy prices, transportation costs, land prices, and such, policymakers have a new challenge: a lack of climactic burn to justify this regulatory regime. Indeed, global temperatures have stagnated for nearly 20 years now while global GHG emissions continued their rise, and the incongruence between "settled science" and reality is becoming clearer. A recent article in Nature Climate Change is only the latest acknowledgement of this fact, finding that none of the 37 climate models issued by the International Panel on Climate Change (IPCC) has predicted the climate accurately and in fact most have overestimated warming by more than double.

Rather than acknowledge the inadequacy of the science and the premature nature of the forecasts for catastrophic global warming, a rhetorical shift has taken place. Now we hear global warming is "having an impact already," in areas besides temperatures. The CalEPA report outlines such an approach, with supposed indicators warning of rising seas, warming lakes, and burning forests.

While it is well-established that the Earth's climate has warmed moderately over the last century, and it can be stated with fair certainty that this warming has had an impact on our natural resources, it is not at all clear from this report that a declaration of climate emergency is necessary. Not only does the report undermine many of its own findings, it relies heavily on thin evidence or cherry-picked data, or ignores competing factors.

Tahoe Lake Clarity

Perhaps the most glaringly obvious oversight relates to the clarity of Lake Tahoe. The CalEPA review cites a UC Davis report from 2011 showing that as of 2010, the lake waters were the cloudiest they had been since 1997.

Anyone paying attention to the issue knows that Tahoe clarity readings have actually improved, and dramatically so, in recent years. In 2011, the UC Davis survey reported that overall lake clarity had increased from 64.4 feet (the maximum depth at which a survey disk is visible from the top of the lake) to 68.9 feet. The following year, it rose again to over 75 feet for the first time since 2002, and remarkably within three feet of the conservation target.

It should be said that the rapid increase in lake clarity may or may not be a sign of improving water quality; lower runoff during the last two years is likely responsible for a great deal of the clearing, just as higher-than-normal runoff in 2010 was probably responsible for most of the new cloudiness. Nevertheless, it is curious why information widely available six months earlier - from the same source cited by CalEPA - was not included in this report.

Sea Level Rise

Concurrent with the pause in global temperature warming is the cessation of sea level rise here in California. The threat of sea-level rise is certainly alarming in a state where two-thirds of the residents live in the coastal region, and the state has spent many millions acquiring wetlands on the thought that it will one day protect coastal residents. The state's Climate Action Team predicted as much as 55 inches of sea level rise on the coast by century's end, and in the range of five to nine inches between 2000 and 2030. Yet, almost halfway to 2030, and since the mid-1990s actually, there still has been no measurable increase in sea levels.

This is somewhat surprising even to the skeptic, because the Pacific Coastline saw a fairly consistent rise in sea levels throughout the 20th Century, culminating in seven inches of overall rise measured at the Golden Gate Bridge. But even that marginal trend has disappeared in the last two decades. The CalEPA report admits as much: "The measurements at San Francisco Bay and La Jolla show a leveling off of sea level rise in the past two decades." Yet the agency is undeterred in pursuing their suspect: "One possibility is that a change in wind patterns ... may have mitigated the rising trend in regional sea level rise on the west coast... Another possibility is that the ocean may not respond like one big bathtub; subtle shifts in the location of mass as polar ice melts and its water is redistributed might cause different responses in different regions...." (p. 90). So the validity of this alleged indicator of climate change is staked on mere "possibilities."

Tahoe Air Temperatures

CalEPA reports that daily minimum temperatures (overnight lows) in the Tahoe Basin have warmed dramatically over the last century, by an average of four degrees Fahrenheit, while maximum temperatures have increased only about a degree. The figure provided shows an impressive spike in temperatures beginning in the early 1980s. Governor Brown cited these statistics at this month's Tahoe Summit.

The report is based on a single set of readings from a single weather station in Tahoe City. No reason is given as to why only Tahoe City is used. But it is important to note that significant overnight warming at these weather stations often can be an indication of "urban heat island effect," wherein increased development and urbanization near a weather station can affect results. "Heat sinks" such as buildings and roads can hold heat accumulated during the daytime and emit heat throughout the night.

Interestingly, the Tahoe City cooperative weather station was identified as a prime example of a poorly-sited station in a recent independent evaluation. It's not the only one: a 2011 General Accounting Office report found nearly 35% of these weather stations providing data to the National Oceanic and Atmospheric Agency (NOAA) were sited too close to heat sinks or other obstructions, and a total of 42% were out of compliance. The independent study found that data from these noncompliant weather stations tends to produce results that exaggerate warming trends by about twice the margin of properly-sited stations. NOAA is now performing its own study on the matter, and has reportedly closed 600 such stations in just the last two years. The Tahoe City station was found near condominium tennis courts, installed around 1980, or about the same time the station data shows a sharp overnight warming trend.

Sierra Lake Warming

The report presents several indicators based on limited data. One such indicator is the warming of Sierra Nevada lakes, as 20 years of lake temperatures at six of the hundreds of lakes as an indication of global warming. As the report itself notes, "the sensitivity, accuracy and calibrations of these instruments have varied over time," and could cause discrepancies when analyzing the thermal data. Even that aside, we know the level of snowmelt is a key determinant of the seasonal temperatures of mountain lakes, and the very short timeframe presented represents just one cycle of extended drought and wet years. Thus, the several wet years at the outset (1995, 1996, 1998) and dry years at the conclusion (2007, 2008, 2009) appear to enhance the warming trend at these lakes. The measurements exclude years prior to 1992, which happened to be the final year of an extended six-year drought in the Sierra Nevada region. How would this data look different if it included those drought years, the flood years of 1983 and 1986, and prior cycles, and how do those cycles compare? Sierra lakes may well be on a warming trend, but much more information is needed to establish whether that trend is long-term or just cyclical.

Wine Grape Bloom

Thinner evidence yet is presented to support variations in the timing of wine grape blooms. According to CalEPA's report, "Bloom is relatively easy to observe, and is highly temperature sensitive, making it a good indicator of...changes in climate. However, long-term data on the timing of wine grape bloom in California's Napa and Sonoma Valleys... have been difficult to obtain." So difficult, the report produces just one set of data for bloom of pinot noir grapes at one site in Napa Valley, for which "no trend is evident" over the course of just 16 years. The study upon which it is based does find a strong correlation between weather and bloom, and so a finding of "no trend" is perhaps more confirmation of the lack of warming over the same time period.


As with Sierra lake temperatures, the identification of a trend depends on the period of time being examined. Another such case is a study presented on Central Valley butterflies. The study indicates a trend toward an earlier emergence of butterflies in the spring, over the course of the period being studied. Researchers used 39 years of life-cycle data on 23 species of butterfly and ranked each year in order based on the date of first flight, with Year 1 being the earliest-recorded first flight and Year 39 the latest.  

While some of the findings related to individual species varied widely (from 20 days earlier in the year to 30 or more days later for others) they found an overall trend of earlier emergence, quantified as a progression from approximately Year 22 to Year 20 measurements over those four decades. Left out of this mild trend is a sharp change in life-cycle patterns that occurred after about 1983 (which happened to be one of the strongest El Niño events on record, and which marked the onset of a major climactic shift, a subject for another report). Since that time, the trend appears to lean toward no trend at all, and perhaps a later butterfly emergence. If the study data were as limited as it is for other factors in this report - say, to just 20 or even 30 years - it could present an entirely different argument.


At the Tahoe Summit last month, Governor Brown challenged skeptics to "look at the facts." As presented, these "facts" appear to be as oversold as the rest of the product that promises an anthropogenic global warming catastrophe. While some warming may be in our long-term future, there is nothing in this report or any other that has established a need for continuing the comprehensive state control of carbon emissions.

For more information on this report or other Natural Resources & Water issues, contact Steve McCarthy, Senate Republican Office of Policy at 916/651-1501.