Tag: climate change

The Resilience of an American Pika Metapopulation to Global Warming

The American pika (Ochotona princeps) is an insanely cute critter often found in above-timberline rock fields in the western U.S.  

A Pika

Because they often live near mountain peaks, there’s been concern that global warming could push them over the top, to extinction. Writing in the Journal of Mammalogy, Smith and Nagy (2015) state that American pikas (Ochotona princeps) “have been characterized as an indicator species for the effects of global warming on animal populations,” citing the works of Smith et al. (2004), Beever and Wilkening (2011) and Ray et al. (2012). Indeed, as they continue, “a consideration of the effects of climate, primarily recent warming trends due to climate change, has dominated much of the recent literature on American pikas and their persistence.” Hoping to provide some additional insight on the subject, the two Arizona State University researchers set out to investigate the resilience of a pika metapopulation residing near Bodie, California, USA, that was exposed to several decades of natural warming.

Tree-ring Temperature Reconstructions May have Masked Prior Warmth

Global Science Report is a feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

Proxy temperature records serve a significant purpose in the global warming debate – they provide a reality check against the claim that current temperatures are unprecedentedly warm in the context of the past one to two thousand years. If it can be shown that past temperatures were just as warm as, or warmer than, they are presently, the hypothesis of a large CO2-induced global warming is weakened. It would thus raise the possibility that current temperatures are influenced to a much greater degree by natural climate oscillations than they are by rising atmospheric CO2.

Tree ring data account for one of the most commonly utilized sources of proxy temperatures. Yet, as with any substitute, proxy temperatures derived from tree ring data do not perfectly match with standard thermometer-based measurements; and, therefore, the calculations and methods are not without challenge or controversy. For example, many historic proxies are based upon a dwindling number of trees the further the proxy extends back in time. Additionally, some proxies mix data from different trees and pool their data prior to mass spectrometer measurement, which limits the ability to discern long-term climate signals among individual trees. Though it has the potential to significantly influence a proxy record, this latter phenomenon has received little attention in the literature – until now.

In an intriguing new study, Esper et al. (2015) recognize this deficiency by noting “climate reconstructions derived from detrended tree-ring δ13C data, in which δ13C level differences and age-trends have been analyzed and, if detected, removed, are largely missing from the literature.” Thus, they set out to remedy this situation by developing “a millennial-scale reconstruction based on decadally resolved, detrended, δ13C measurements, with the climate signal attributed to the comparison of annually resolved δ13C measurements with instrumental data.” Then, they compared their new proxy with proxies derived from a more common, but presumably inferior, method based on maximum latewood density (MXD) data. The location of study was at a sampling site near lake Gerber (42.63°N, 1.1°E), Spanish Pyrenees, at the upper treeline (2400 m).

Warming-Assisted Rapid Evolution of a Parasitic Host

In 1980, heated water from a nuclear power plant in Forsmark, Sweden (60.42°N, 18.17°E) began to be discharged into Biotest Lake, an artificial semi-enclosed lake in the Baltic Sea created in 1977 that is adjacent to the power plant and covers an area of 0.9 km2 with a mean depth of 2.5 m. The heated water has raised the temperature of the lake by 6-10°C compared to the surrounding Baltic Sea, but aside from this temperature difference, the physical conditions between the lake and the sea are very similar.

A few years after the power plant began operation, scientists conducted a study to determine the effect of the lake’s increased temperatures on the host-parasite dynamics between a fish parasite, the eyefluke (Diplostomum baeri), and its intermediate host, European perch (Perca fluviatilis). That analysis, performed in 1986 and 1987, revealed that perch in Biotest Lake experienced a higher degree of parasite infection compared to perch living in the cooler confines of the surrounding Baltic Sea (Höglund and Thulin, 1990), which finding is consistent with climate alarmist concerns that rising temperatures may lead to an increase in infectious diseases.

Fast forward to the present, however, and a much different ending to the story is observed.

Nearly three decades later, Mateos-Gonzales et al. (2015) returned to Biotest Lake and reexamined the very same host-parasite dynamic to learn what, if anything, had changed in the intervening time period. According to the team of researchers, Biotest Lake “provides an excellent opportunity to study the effect of a drastically changed environmental factor, water temperature, on the evolution of host-parasite interactions, in a single population recently split into two.” Specifically, it was their aim “to examine if the altered conditions have produced a change in prevalence and/or intensity of infection, and if these potential variations in infection have led to (or might have been caused by) a difference in parasite resistance.”

CO2-induced Greening of the Earth: Benefiting the Biosphere While Lifting the Poor out of Poverty

In the “Agriculture” chapter of Cato’s 2012 Addendum to the federal government’s “Second National Assessment” of the effects of climate change on the United States, I wrote the following:

At a fundamental level, carbon dioxide is the basis of nearly all life on Earth, as it is the primary raw material or “food” that is utilized by plants to produce the organic matter out of which they construct their tissues…

Typically, a doubling of the air’s CO2 content above present-day concentrations raises the productivity of most herbaceous plants by about one-third; this positive response occurs in plants that utilize all three of the major biochemical pathways of photosynthesis.

There is no doubt elevated concentrations of atmospheric CO2 lead to enhanced plant photosynthesis and growth. This well-known fact has been confirmed over and over again in literally thousands of laboratory and field studies conducted by scientists over the past several decades. In recent years, however, the growth-enhancing benefits of atmospheric CO2 have been increasingly studied and observed in the real world of nature using Earth-orbiting satellites. Such instruments have the capability to remotely sense plant growth and vigor at altitudes miles above the Earth’s surface; and they have generated a spatial and temporal record of vegetative change that now spans more than three decades. And what has that record revealed?

The Progressive Increase of the Urban Heat Island’s Influence on Temperature Records

Global Science Report is a feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

Perhaps no other climatic variable receives more attention in the debate over CO2-induced global warming than temperature. Its forecast change over time in response to rising atmospheric CO2 concentrations is the typical measure by which climate models are compared. It is also the standard by which the climate model projections tend to be judged; right or wrong, the correctness of global warming theory is most often adjudicated by comparing model projections of temperature against real-world measurements. And in such comparisons, it is critical to have a proper baseline of good data; but that is easier acknowledged than accomplished, as multiple problems and potential inaccuracies have been identified in even the best of temperature datasets.

One particular issue in this regard is the urban heat island effect, a phenomenon by which urban structures artificially warm background air temperatures above what they normally would be in a non-urbanized environment. The urban influence on a given station’s temperature record can be quite profound. In large cities, for example, urban-induced heating can be as great as Tokyo’s 10°C, making it all the more difficult to detect and discern a CO2-induced global warming signal in the temperature record, especially since the putative warming of non-urbanized areas of the planet over the past century is believed to be less than 1°C.  Yet, because nearly all long-term temperature records have been obtained from sensors initially located in towns and cities that have experienced significant growth over the past century, it is extremely important that urbanization-induced warming – which can be a full order of magnitude greater than the background trend being sought – be removed from the original temperature records when attempting to accurately assess the true warming (or cooling!) of the natural non-urban environment. A new study by Founda et al. (2015) suggests this may not be so simple or straightforward a task.

On the Bright Side: Three Full Decades of CO2-Induced Vegetative Greening in China

Here we introduce a new feature from the Center for the Study of Science, “On the Bright Side.” OBS will highlight the beneficial impacts of human activities on the state of our world, including improvements to human health and welfare, as well as the natural environment. Our emphasis will typically focus on the oft-neglected positive externalities of carbon dioxide emissions and associated climate change. Far too often, the media, environmental organizations, governmental panels and policymakers concentrate their efforts on the putative negative impacts of potential CO2-induced global warming. We hope to counter that pessimism with a heavy dose of positive reporting on the considerable good humans are doing for themselves and for the planet.

According to Piao et al. (2015), the reliable detection and attribution of changes in vegetation growth are essential prerequisites for “the development of successful strategies for the sustainable management of ecosystems.” And indeed they are, especially in today’s world in which so many scientists and policy makers are concerned with what to do (or not do) about the potential impacts of CO2-induced climate change. However, detecting vegetative change, let alone determining its cause, can be an extraordinarily difficult task to accomplish. Nevertheless, that is exactly what Piao et al. set out to do in their recent study.

More specifically, the team of sixteen Chinese, Australian and American researchers set out to investigate trends in vegetational change across China over the past three decades (1982-2009), quantifying the contributions from different factors including (1) climate change, (2) rising atmospheric CO2 concentrations, (3) nitrogen deposition and (4) afforestation. To do so, they used three different satellite-derived Leaf Area Index (LAI) datasets (GLOBMAP, GLASS, and GIMMIS) to detect spatial and temporal changes in vegetation during the growing season (GS, defined as April to October), and five process-based ecosystem models (CABLE, CLM4, ORCHIDEE, LPJ and VEGAS) to determine the attribution.

Spin Cycle: Is Climate Change Already Taking Lives in New England?

The Spin Cycle is a reoccurring feature based upon just how much the latest weather or climate story, policy pronouncement, or simply poo-bah blather spins the truth. Statements are given a rating between 1-5 spin cycles, with fewer cycles meaning less spin. For a more in-depth description, visit the inaugural edition.

The headline from a CBS News story read “Study: Climate change may be costing lives in the U.S.” The tone is in perfect keeping with the White House wanting the media to focus on the (negative) health impacts from climate change to help drive home the “moral imperative” of administration’s greenhouse gas emissions regulations.

There is one key problem: the findings from the “study” do nothing to shed light on whether “climate change” is taking lives in New England (the region that the study focused on) or anywhere else in the United States. In fact, taking the literature as a whole (including the results of the new study), the more appropriate headline would have been “Studies: Climate change may be saving lives in the U.S.”

The new study in question appears in the journal Nature Climate Change written by a research team headed by Liuhua Shi from the Harvard School of Public Health. Shi and colleagues examined how temperature and temperature variability during the summer and winter seasons impacts the annual mortality of Medicare recipients (i.e., a population aged 65+) residing in New England.

In general, Shi and colleagues found that warmer summers slightly increased mortality while warmer winters slightly lowered it. They also found that more variable temperature (in either winter or summer) led to increases in overall mortality.

Aside from the very real possibility that the statistical significance of these findings was inflated by the mythological design (over inflation of the number of independent data points), the most obvious flaw is that the study didn’t look for any trends in their results. This means, of course, that they aren’t very applicable when it comes to trying to ascertain future behavior (under climate change or not).