Tag: global 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.”

Science Revives “The Hiatus”

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.”

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Just five weeks after Science magazine prominently featured a paper proclaiming that the multidecadal slowdown in the rate of the earth’s average temperature rise—aka, the “pause” or “hiatus”—was but a figment of bad data, comes a new paper in Science magazine explaining the physical mechanisms that have led to the slowdown.

Wait, what?

You read it right. What Science laid to rest but a month ago, Science has now resurrected. Science (with a capital “S”), and those dedicated to it, should not be amused.

But such is the nature of the game. Science the magazine is more interested in generating publicity for itself than in best serving Science the field—a point being increasingly raised by prominent scientific figures.

The new paper, whose title even contains the dreaded H-word (“Recent hiatus caused by decadal shift in Indo-Pacific heating”), is authored by Veronica Nieves and colleagues from the Jet Propulsion Lab (JPL). The paper itself is rather technical look at how the hiatus has manifested itself in various compilations of measurements (and models) of the ocean’s temperatures at depth.

Comments on the USGCRP Climate and Health Assessment

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.”

On June 8th, the public comment period on the draft report on climate and health from the U.S. Global Change Research Program (USGCRP) closed. Never liking to miss an opportunity to add our two cents’ worth to the conversation, we submitted a set of comments that focused on the weakness of the underlying premise of the report, more so than the specific details (although we did include a sample set of those to show just how pervasive the selective and misuse of science is throughout the report).

Our entire Comments are available here. But, for convenience, here’s the highlight reel. In summary, we found:

What is clear from this report, The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment, and all other similar ones that have come before, is that the USGCRP simply chooses not to accept the science on human health and climate and instead prefers to forward alarming narratives, many based on science fiction rather than actual science. To best serve the public, this report should be withdrawn. By going forward without a major overhaul, its primary service [will] be to misinform and mislead the general public and policymakers alike.

Here we lay out the general problem:

The authors of the USGCRP draft of The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment report have an outstanding imagination for coming up with ways that climate change may negatively impact the health and well-being of Americans, but a profound lack of understanding in the manner in which health and well-being is impacted by climate (including climate change).

Is There No “Hiatus” in Global Warming After All?

A new paper posted today on ScienceXpress (from Science magazine), by Thomas Karl, Director of NOAA’s Climate Data Center, and several co-authors[1], that seeks to disprove the “hiatus” in global warming prompts many serious scientific questions.

The main claim[2] by the authors that they have uncovered a significant recent warming trend is dubious. The significance level they report on their findings (.10) is hardly normative, and the use of it should prompt members of the scientific community to question the reasoning behind the use of such a lax standard.

In addition, the authors’ treatment of buoy sea-surface temperature (SST) data was guaranteed to create a warming trend. The data were adjusted upward by 0.12°C to make them “homogeneous” with the longer-running temperature records taken from engine intake channels in marine vessels. 

As has been acknowledged by numerous scientists, the engine intake data are clearly contaminated by heat conduction from the engine itself, and as such, never intended for scientific use. On the other hand, environmental monitoring is the specific purpose of the buoys. Adjusting good data upward to match bad data seems questionable, and the fact that the buoy network becomes increasingly dense in the last two decades means that this adjustment must put a warming trend in the data.

The extension of high-latitude arctic land data over the Arctic Ocean is also questionable. Much of the Arctic Ocean is ice-covered even in high summer, meaning the surface temperature must remain near freezing. Extending land data out into the ocean will obviously induce substantially exaggerated temperatures.

Additionally, there exist multiple measures of bulk lower atmosphere temperature independent from surface measurements which indicate the existence of a “hiatus”[3]. If the Karl et al., result were in fact robust, it could only mean that the disparity between surface and mid-tropospheric temperatures is even larger that previously noted. 

Getting the vertical distribution of temperature wrong invalidates virtually every forecast of sensible weather made by a climate model, as much of that weather (including rainfall) is determined in large part by the vertical structure of the atmosphere.

Instead, it would seem more logical to seriously question the Karl et al. result in light of the fact that, compared to those bulk temperatures, it is an outlier, showing a recent warming trend that is not in line with these other global records.

And finally, even presuming all the adjustments applied by the authors ultimately prove to be accurate, the temperature trend reported during the “hiatus” period (1998-2014), remains significantly below (using Karl et al.’s measure of significance) the mean trend projected by the collection of climate models used in the most recent report from the United Nation’s Intergovernmental Panel on Climate Change (IPCC). 

It is important to recognize that the central issue of human-caused climate change is not a question of whether it is warming or not, but rather a question of how much. And to this relevant question, the answer has been, and remains, that the warming is taking place at a much slower rate than is being projected.

The distribution of trends of the projected global average surface temperature for the period 1998-2014 from 108 climate model runs used in the latest report of the U.N.’s Intergovernmental Panel on Climate Change (IPCC)(blue bars). The models were run with historical climate forcings through 2005 and extended to 2014 with the RCP4.5 emissions scenario. The surface temperature trend over the same period, as reported by Karl et al. (2015, is included in red. It falls at the 2.4th percentile of the model distribution and indicates a value that is (statistically) significantly below the model mean projection.

The distribution of trends of the projected global average surface temperature for the period 1998-2014 from 108 climate model runs used in the latest report of the U.N.’s Intergovernmental Panel on Climate Change (IPCC)(blue bars). The models were run with historical climate forcings through 2005 and extended to 2014 with the RCP4.5 emissions scenario. The surface temperature trend over the same period, as reported by Karl et al. (2015, is included in red. It falls at the 2.4th percentile of the model distribution and indicates a value that is (statistically) significantly below the model mean projection.


[1] Karl, T. R., et al., Possible artifacts of data biases in the recent global surface warming hiatus. Scienceexpress, embargoed until 1400 EDT June 4, 2015.

[2] “It is also noteworthy that the new global trends are statistically significant and positive at the 0.10 significance level for 1998-2012…”

[3] Both the UAH and RSS satellite records are now in their 21st year without a significant trend, for example

You Ought to Have a Look: Climate Change Subtleties, Hurricanes, and Chocolate Bunnies

You Ought to Have a Look is a feature from the Center for the Study of Science posted by Patrick J. Michaels and Paul C. (“Chip”) Knappenberger.  While this section will feature all of the areas of interest that we are emphasizing, the prominence of the climate issue is driving a tremendous amount of web traffic.  Here we post a few of the best in recent days, along with our color commentary.

We highlight a couple of headlines this week that made us chuckle a bit, although what they portend is far from funny.

The first was from the always amusing “Energy and Environment” section of the Washington Post. Climate change beat writer Chris Mooney penned a piece headlined “The subtle — but real — relationship between global warming and extreme weather events” that was a hit-you-over-the-head piece about how human-caused global warming could be linked to various weather disasters of the past week, including the floods in Houston, the heatwave in India and hurricanes in general.

Mooney starts out, lamenting:

Last week, some people got really mad at Bill Nye the Science Guy. How come? Because he had the gall to say this on Twitter:

Billion$$ in damage in Texas & Oklahoma. Still no weather-caster may utter the phrase Climate Change.

Nye’s comments, and the reaction to them, raise a perennial issue: How do we accurately parse the relationship between climate change and extreme weather events, as they occur in real time?

It’s a particularly pressing question of late, following not only catastrophic floods in Texas and Oklahoma, but also a historic heatwave in India that has killed over 2,000 people so far, and President Obama’s recent trip to the National Hurricane Center in Miami, where he explicitly invoked the idea that global warming will make these storms worse (which also drew criticism).

As the Nye case indicates, there is still a lot of pushback whenever anyone dares to link climate change to extreme weather events. But we don’t have to be afraid to talk about this relationship. We merely have to be scrupulously accurate in doing so, and let scientists lead the way.

You Ought to Have a Look: Science Round Up—Less Warming, Little Ice Melt, Lack of Imagination

You Ought to Have a Look is a feature from the Center for the Study of Science posted by Patrick J. Michaels and Paul C. (“Chip”) Knappenberger. While this section will feature all of the areas of interest that we are emphasizing, the prominence of the climate issue is driving a tremendous amount of web traffic. Here we post a few of the best in recent days, along with our color commentary.

As Pope Francis, this week, focused on examining the moral issues of climate change (and largely ignoring the bigger moral issues that accompany fossil fuel restrictions), he pretty much took as a given that climate change is “a scientific reality” that requires “decisive mitigation.” Concurrently, unfolding scientific events during the week were revealing a different story.

First and foremost, Roy Spencer, John Christy and William Braswell of the University of Alabama-Huntsville (UAH)—developers and curators of the original satellite-derived compilation of the temperature history of the earth’s atmosphere—released a new and improved version of their iconic data set. Bottom line: the temperature trend in the lower atmosphere from the start of the data (1979) through the present came in as 0.114°C/decade (compared with 0.14°C in the previous data version). The new warming trend is less than half what climate models run with increasing atmospheric carbon dioxide emissions project to have occurred.

While the discrepancy between real world observations and climate model projections of temperature rise in the lower atmosphere has been recognized for a number of years, the question has remained as to whether the “problem” lies within the climate models or the observations. With this new data release, the trend in the UAH data now matches very closely with the trend through an independent compilation of the satellite-temperature observations maintained by a team of researchers at Remote Sensing Systems (RSS). The convergence of the observed data sets is an indication the climate models are the odd man out.

As with most long-term, real-world observations, the data are covered in warts. The challenge posed to Spencer et al. was how to splice together remotely sensed data collected from a variety of instruments carried aboard a variety of satellites in unstable orbits—and produce a product robust enough for use in climate studies. The details as to how they did it are explained as clearly as possible in this post over at Spencer’s website (although still quite a technical post). The post provides good insight as to why raw data sets need to be “adjusted”—a lesson that should be kept in mind when considering the surface temperature compilations as well. In most cases, using raw data “as is” is an inherently improper thing to do, and the types of adjustments that are applied may vary based upon the objective.

Here is a summary of the new data set and what was involved in producing it:

Version 6 of the UAH MSU/AMSU global satellite temperature data set is by far the most extensive revision of the procedures and computer code we have ever produced in over 25 years of global temperature monitoring. The two most significant changes from an end-user perspective are (1) a decrease in the global-average lower tropospheric (LT) temperature trend from +0.140 C/decade to +0.114 C/decade (Dec. ’78 through Mar. ’15); and (2) the geographic distribution of the LT trends, including higher spatial resolution. We describe the major changes in processing strategy, including a new method for monthly gridpoint averaging; a new multi-channel (rather than multi-angle) method for computing the lower tropospheric (LT) temperature product; and a new empirical method for diurnal drift correction… The 0.026 C/decade reduction in the global LT trend is due to lesser sensitivity of the new LT to land surface skin temperature (est. 0.010 C/decade), with the remainder of the reduction (0.016 C/decade) due to the new diurnal drift adjustment, the more robust method of LT calculation, and other changes in processing procedures.

Figure 1 shows a comparison of the data using the new procedures with that derived from the old procedures. Notice that in the new dataset, the temperature anomalies since about 2003 are less than those from the previous version. This has the overall effect of reducing the trend when computed over the entirety of the record.

Figure 1. Monthly global-average temperature anomalies for the lower troposphere from Jan. 1979 through March, 2015 for both the old and new versions of LT (source: www.drroyspencer.com)

 

Figure 1. Monthly global-average temperature anomalies for the lower troposphere from Jan. 1979 through March 2015 for both the old and new versions of LT. (Source: www.drroyspencer.com)

While this new version, admittedly, is not perfect, Spencer, Christy, and Braswell see it as an improvement over the old version. Note that this is not the official release, but rather a version the authors have released for researchers to examine and see if they can find anything that looks irregular that may raise questions as to the procedures employed. Spencer et al. expect a scientific paper on the new data version to be published sometime in 2016.

But unless something major comes up, the new satellite data are further evidence the earth is not warming as expected.  That means that, before rushing into “moral obligations” to attempt to alter the climate’s future course by restricting energy production, we perhaps ought to spend more time trying to better understand what it is we should be expecting in the first place.

One of the things we are told by the more alarmist crowd that we should expect from our fossil fuel burning is a large and rapid sea level rise, primarily a result of a melting of the ice sheets that rest atop Greenland and Antarctica. All too frequently we see news stories telling tales of how the melting in these locations is “worse than we expected.” Some soothsayers even attack the United Nations’ Intergovernmental Panel on Climate Change (IPCC) for being too conservative (of all things) when it comes to projecting future sea level rise. While the IPCC projects a sea level rise of about 18–20 inches from its mid-range emissions scenario over the course of this century, a vocal minority clamor that the rise will be upwards of 3 feet and quite possibly (or probably) greater. All the while, the sea level rise over the past quarter-century has been about 3 inches.

But as recent observations do little to dissuade the hardcore believers, perhaps model results (which they are seemingly more comfortable with) will be more convincing.

A new study available this week in the journal Geophysical Research Letters is described by author Miren Vizcaino and colleagues as “a first step towards fully-coupled higher resolution simulations with more advanced physics”—basically, a detailed ice sheet model coupled with a global climate model.

They ran this model combination with the standard IPCC emissions scenarios to assess Greenland’s contribution to future sea level rise. Here’s what they found:

The [Greenland ice sheet] volume change at year 2100 with respect to year 2000 is equivalent to 27 mm (RCP 2.6), 34 mm (RCP 4.5) and 58 mm (RCP 8.5) of global mean SLR.

Translating millimeters (mm) into inches give this answer: a projected 21st century sea level rise of 1.1 in. (for the low emissions scenario; RCP 2.6), 1.3 in. (for the low/mid scenario; RCP 4.5), and 2.3 in (for the IPCC’s high-end emission scenario). Some disaster.

As with any study, the authors attach some caveats:

The study presented here must be regarded as a necessary first step towards more advanced coupling of ice sheet and climate models at higher resolution, for instance with improved surface-atmosphere coupling (e.g., explicit representation of snow albedo evolution), less simplified ice sheet flow dynamics, and the inclusion of ocean forcing to Greenland outlet glaciers.

Even if they are off by 3–4 times, Greenland ice loss doesn’t seem to be much of a threat. Seems like it’s time to close the book on this imagined scare scenario.

And while imagination runs wild when it comes to linking carbon dioxide emissions to calamitous climate changes and extreme weather events (or even war and earthquakes),  imagination runs dry when it comes to explaining non-events (except when non-events string together to produce some sort of negative outcome [e.g., drought]).

Case in point, a new study looking into the record-long absence of major hurricane (category 3 or higher) strikes on the U.S. mainland—an absence that exceeds nine years (the last major hurricane to hit the U.S was Hurricane Wilma in late-October 2005). The authors of the study, Timothy Hall of NASA’s Goddard Institute for Space Studies and Kelly Hereid from ACE Tempest Reinsurance, concluded that while a streak this long is rare, their results suggest “there is nothing unusual underlying the current hurricane drought. There’s no extraordinary lack of hurricane activity.” Basically they concluded that it’s “a case of good luck” rather than “any shift in hurricane climate.”

That is all well and good, and almost certainly the case. Of course, the same was true a decade ago when the United States was hit by seven major hurricanes over the course of two hurricane seasons (2004 and 2005)—an occurrence that spawned several prominent papers and endless discussion pointing the finger squarely at anthropogenic climate change. And the same is true for every hurricane that hits the United States, although this doesn’t stop someone, somewhere, from speculating to the media that the storm’s occurrence was “consistent with” expectations from a changing climate.

What struck us as odd about the Hall and Hereid paper is the lack of speculation as to how the ongoing record “drought” of major hurricane landfalls in the United States could be tied in with anthropogenic climate change. You can rest assured—and history will confirm—that if we had been experiencing a record run of hurricane landfalls, researchers would be falling all over themselves to draw a connection to human-caused global warming.

But the lack of anything bad happening? No way anyone wants to suggest that is “consistent with” expectations. According to Hall and Hereid:

A hurricane-climate shift protecting the US during active years, even while ravaging nearby Caribbean nations, would require creativity to formulate. We conclude instead that the admittedly unusual 9-year US Cat3+ landfall drought is a matter of luck. [emphasis added]

Right! A good string of weather is “a matter of luck” while bad weather is “consistent with” climate change.

It’s not like it’s very hard, or (despite the authors’ claim) it requires much “creativity” to come up with ways to construe a lack of major hurricane strikes on U.S. soil to be “consistent with” anthropogenic climate change. In fact, there are loads of material in the scientific literature that could be used to construct an argument that under global warming, the United States should experience fewer hurricane landfalls. For a rundown of them, see p. 30 of our comments on the government’s National Assessment on Climate Change, or check out our piece titled, “Global Savings: Billion-Dollar Weather Events Averted by Global Warming.”

It is not for lack of material, but rather, for lack of desire, that keeps folks from wanting to draw a potential link between human-caused climate change and good things occurring in the world.

References:

Hall, T., and K. Hereid. 2015. “The Frequency and Duration of US Hurricane Droughts.” Geophysical Research Letters, doi:10.1002/2015GL063652

Vizcaino, M. et al. 2015. “Coupled Simulations of Greenland Ice Sheet and Climate Change up to AD 2300.” Geophysical Research Letters, doi: 10.1002/2014GL061142

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