Tag: carbon dioxide

You Ought to Have a Look: Lukewarming, Carbon Taxes, and the HFC Agreement

You Ought to Have a Look is a regular feature from the Center for the Study of Science.  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.

One of our favorite lukewarmers, Matt Ridley, was invited by the Global Warming Policy Foundation to give its 2016 Annual Lecture. He certainly did not disappoint. While Matt titled his speech “Global Warming Versus Global Greening” that title only suggested part of what he had to say. We offer “The Hows and Whys of Lukewarming” to be a more apt descriptor:

These days there is a legion of well paid climate spin doctors. Their job is to keep the debate binary: either you believe climate change is real and dangerous or you’re a denier who thinks it’s a hoax.

But there’s a third possibility they refuse to acknowledge: that it’s real but not dangerous. That’s what I mean by lukewarming, and I think it is by far the most likely prognosis.

I am not claiming that carbon dioxide is not a greenhouse gas; it is.

I am not saying that its concentration in the atmosphere is not increasing; it is.

I am not saying the main cause of that increase is not the burning of fossil fuels; it is.

I am not saying the climate does not change; it does.

I am not saying that the atmosphere is not warmer today than it was 50 or 100 years ago; it is.

And I am not saying that carbon dioxide emissions are not likely to have caused some (probably more than half) of the warming since 1950.

I agree with the consensus on all these points.

I am not in any sense a “denier”, that unpleasant, modern term of abuse for blasphemers against the climate dogma…. I am a lukewarmer.

And from there, Ridley goes on to do a laudable job of laying out the case that future climate change from human activities will prove to be towards the low end of climate model projections—but squarely within the bounds of consensus expectations. As Matt puts it:

…I am not disagreeing with the consensus on climate change.

There is no consensus that climate change is going to be dangerous. Even the IPCC says there is a range of possible outcomes, from harmless to catastrophic. I’m in that range: I think the top of that range is very unlikely. But the IPCC also thinks the top of its range is very unlikely.

Be sure to check out the whole thing for a great review of why carbon dioxide emissions are not the civilization-ending monster that many climate activists would have you believe (plus there are a few surprises in there that you won’t want to miss).

A CO2-Induced Increase in Subtropical North Atlantic Coccolithophore Abundance

Coccolithophores are calcifying phytoplankton that comprise the base of marine food webs all across the world ocean. They play an important role in the cycling of carbon into the deep ocean and act as a feedback to climate change. Anything that alters their function or abundance, therefore, could have significant impacts on marine ecosystems and global climate. Thus, it is no surprise that scientists are interested in how coccolithophores will respond to future changes in atmospheric CO2 and climate. And in this regard, Krumhardt et al. (2016) say there has been “much speculation [that has] inspired numerous laboratory and mesocosm experiments, but how they are currently responding in situ is less well documented.” Working to provide just such an in situ analysis, the team of four researchers thus set out to analyze coccolithophore abundance in the subtropical North Atlantic over the period 1990 to 2014.

To accomplish their objective, Krumhardt et al. used coccolithophore pigment data collected at the Bermuda Atlantic Time-series Study (BATS) site (located at 31.7°N, 64.2°W in the Sargasso Sea) in conjunction with satellite estimates of surface chlorophyll and particulate inorganic carbon as a proxy measure of coccolithophore abundance. Results of their analysis revealed that “coccolithophore populations in the North Atlantic subtropical gyre have been increasing significantly over the past two decades. More specifically, they note there was a 37 percent increase in euphotic zone-integrated (integrated from 140 m depth) in coccolithophore pigment abundance at BATS and a larger 68 percent increase in the upper 30 m of the water column (see figure below). Such findings, in the words of the authors, add to those of a growing number of studies showing that coccolithophores in the North Atlantic “are increasing in abundance and are likely stimulated by additional carbon from anthropogenic sources.”

A Century of Precipitation Trends in Victoria, Australia

In the debate over CO2-induced global warming, projected impacts on various weather and climate-related phenomena can only be adjudicated with observed data. Even before the specter of dreaded global warming arose, scientists studied historical databases looking for secular changes or stability. With the advent of general circulation climate models, using historical data, scientists can determine whether any observed changes are consistent with the predictions of these models as atmospheric carbon dioxide increases. An example of the pitfalls in such work was recently presented by Rahmat et al. (2015), who set out to analyze precipitation trends over the past century at five locations in Victoria, Australia. More specifically, the authors subjected each data set to a series of statistical tests to “analyze the temporal changes in historic rainfall variability at a given location and to gain insight into the importance of the length of data record” on the outcome of those tests. And what did their analyses reveal?

When examining the rainfall data over the period 1949-2011 it was found that all series had a decreasing trend (toward less rainfall), though the trends were significant for only two of the five stations. Such negative trends, however, were reversed to positive in three of the five stations when the trend analyses were expanded over a longer time domain that encompassed the whole of the 20th century (1900-2011 for four stations and 1909-2011 for the fifth one). In addition, the two stations with statistically significant negative trends during the shorter time period were also affected by the longer analysis. Though their trends remained negative, they were no longer statistically significant when calculated over the expanded 112 years of analysis. In summation, in the expanded analysis the “annual rainfall time series showed no significant trends for any of the five stations.”

In light of the above findings, Rahmat et al. write that “conclusions drawn from this paper point to the importance of selecting the time series data length in identifying trends and abrupt changes,” adding that due to climate variability, “trend testing results might be biased and strongly dependent on the data period selected.” Indeed they can be; and this analysis shows the absolute importance of evaluating climate model projections using data sets that have been in existence for sufficiently long periods of time (century-long or more) that are capable of capturing the variability of climate that occurs naturally. And when such data sets are used, as in the case of the study examined here, it appears that the modern rise in CO2 has had no measurable impact on rainfall trends in Victoria, Australia.

 

Reference

Rahmat, S.N., Jayasuriya, N. and Bhuiyan, M.A. 2015. Precipitation trends in Victoria, Australia. Journal of Water and Climate Change 6: 278-287.

You Ought to Have a Look: Smoke, Clouds and Snowfall

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.

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In this week’s YOTHAL edition, we’ll focus on some recent climate science findings that deserve further mention and are worthy of a deeper dive. If and when you have the time and/or inclination, you ought to have a look.

First up is a collection of papers that describe the results of a several experiments looking into cloud formation—or rather, into the availability and development of the aerosol particles that aid in cloud formation. The tiny aerosols are called cloud condensation nuclei (CCN) and without them, it is very difficult for clouds to form. 

It’s well known that sulfate particles, formed as a by-product of fossil fuel burning (primarily coal and oil), make for a good source of CCN. In fact, the change in cloud characteristics resulting from this form of air pollution are thought to have asserted a cooling pressure on the earth’s surface temperature—a cooling that has acted to offset a certain portion of the warming caused by the co-incidental emissions of carbon dioxide and other greenhouse gases.

The Shallow Back Reef Environment of Ofu, American Samoa

Writing as background for their work, the six-member research team of Koweek et al. (2015) cite several concerns about the future of Earth’s corals that have been projected to result from the so-called twin evils of global warming and ocean acidification, including “coral bleaching (Glynn, 1993; Hughes et al., 2003; van Hooidonk et al., 2013), increased dissolution and bioerosion (Andersson and Gledhill, 2013; Dove et al., 2013; Reyes-Nivia et al., 2013), decreased biodiversity (Fabricius et al., 2011), and shifts toward algal-dominated reefs (Hoegh-Guldberg et al., 2007; Kroeker et al., 2010; 2013).” However, despite these concerns, which have captured the attention of scientists and policy makers for more than two decades now, such worries may well be overestimated and overplayed.

The reason for such growing optimism has to do with the corals themselves, which along with other marine organisms appear to have an inherent ability “of controlling their own biogeochemical environments.” Such biologically-mediated controls, if they are of sufficient magnitude, could potentially offset future changes in the marine environment brought about by rising atmospheric CO2 (projected ocean warming and pH decline). It is therefore of considerable importance for scientists to continue investigating these biological feedbacks in order to better ascertain the future of these precious marine species, for as noted by Koweek et al., “the paradigm of coral reefs as passive responders to their biogeochemical environments is rapidly changing.”

In further expanding the scientific knowledge on this important topic, the six American researchers set out to conduct a “short, high-resolution physical and biogeochemical pilot field study” on the back reefs of Ofu, American Samoa, where they measured a number of hydrodynamic and biogeochemical parameters there over a seven-day period in November, 2011. The specific study location was Pool 100 (14.185°S, 169.666°W), a shallow lagoon containing 85 coral species and various kinds of crustose coralline algae and non-calcifying algae. Koweek et al. selected Pool 100 because, as they state, shallow back reefs “commonly experience greater thermal and biogeochemical variability owing to a combination of coral community metabolism, environmental forcing, flow regime, and water depth.”

Results of their data collection and analysis revealed that temperatures within the shallow back reef environment were consistently 2-3°C warmer during the day than that observed in the offshore environment. In addition, and as expected, the ranges of the physical and biogeochemical parameters studied in Pool 100 greatly exceeded the variability observed in the open ocean. Inside Pool 100, the pH values fluctuated between a low of 7.80 and a high of 8.39 across the seven days of study, with daily ranges spanning between 0.5 and 0.6 of a unit (Figure 1). What is more, Koweek et al. report that the reef community in Pool 100 spent far more time outside of the offshore pH range than within it (pH values were between 8.0 and 8.2 during only 30 percent of the observational period, less than 8.0 for 34 percent of the time and greater than 8.2 for the remaining 36 percent of the observations). Additional measurements and calculations indicated that these fluctuations in pH were largely the product of community primary production and respiration, as well as tidal modulation and wave-driven flow.

Figure 1. Time series of pHT (top panel) and pCO2 (bottom panel) in Pool 100, Ofu, American Samoa from November 16-20, 2011. Vertical blue and orange lines show the occurrence of high and low tides, respectively. Gray vertical shading shows the period from sundown to sunrise. The different colored circles represent data that were collected from different locations in Pool 100 and the dashed horizontal black lines represent the mean value of each parameter in the offshore ocean. Adapted from Koweek et al. (2015).

Figure 1. Time series of pHT (top panel) and pCO2 (bottom panel) in Pool 100, Ofu, American Samoa from November 16-20, 2011. Vertical blue and orange lines show the occurrence of high and low tides, respectively. Gray vertical shading shows the period from sundown to sunrise. The different colored circles represent data that were collected from different locations in Pool 100 and the dashed horizontal black lines represent the mean value of each parameter in the offshore ocean. Adapted from Koweek et al. (2015).

Commenting on these and other of their findings, Koweek et al. write that “our measurements have provided insight into the physical–biogeochemical coupling on Ofu.” And that insight, they add, “suggests a significantly more nuanced view of the fate of coral reefs” than the demise of global reef systems that is traditionally forecast under the combined stresses of climate change and ocean acidification.

Indeed, if these ecosystems presently thrive under such variable (and more severe) environmental conditions than those predicted for the future—which conditions are largely derived and modulated by themselves—why wouldn’t they persist?

 

References

Andersson, A.J. and Gledhill, D. 2013. Ocean acidification and coral reefs: effects on breakdown, dissolution, and net ecosystem calcification. Annual Review of Marine Science 5: 321-348.

Dove, S.G., Kline, D.I., Pantos, O., Angly, F.E., Tyson, G.W. and Hoegh-Guldberg, O. 2013. Future reef decalcification under a business-as-usual CO2 emission scenario. Proceedings of the National Academy of Sciences, USA 110: 15342-15347.

Fabricius, K.E., Langdon, C., Uthicke, S., Humphrey, C., Noonan, S.H.C., De’ath, G., Okazaki, R., Muehllehner, N., Glas, M.S. and Lough, J.M. 2011. Losers and winners in coral reefs acclimatized to elevated carbon dioxide concentrations. Nature Climate Change 1: 165-169.

Glynn, P.W. 1993. Coral reef bleaching: ecological perspectives. Coral Reefs 12: 1-17.

Hoegh-Guldberg, O., Mumby, P.J., Hooten, A.J., Steneck, R.S., Greenfield, P., Gomez, E., Harvell, C.D., Sale, P.F., Edwards, A.J., Caldeira, K., Knowlton, N., Eakin, C.M., Iglesias-Prieto, R., Muthiga, N., Bradbury, R.H., Dubi, A. and Hatziolos, M.E. 2007. Coral reefs under rapid climate change and ocean acidification. Science 318: 1737-1742.

Hughes, T.P., Baird, A.H., Bellwood, D.R., Card, M., Connolly, S.R., Folke, C., Grosberg, R., Hoegh-Guldberg, O., Jackson, J.B.C., Kleypas, J.A., Lough, J.M., Marshall, P., Nystrom, M., Palumbi, S.R., Pandolfi, J.M., Rosen, B. and Roughgarden, J. 2003. Climate change, human impacts, and the resilience of coral reefs. Science 301: 929-933.

Koweek, D.A., Dunbar, R.B., Monismith, S.G., Mucciarone, D.A., Woodson, C.B. and Samuel, L. 2015. High-resolution physical and biogeochemical variability from a shallow back reef on Ofu, American Samoa: an end-member perspective. Coral Reefs 34: 979-991.

Kroeker, K.J., Kordas, R.L., Crim, R.N. and Singh, G.G. 2010. Meta-analysis reveals negative yet variable effects of ocean acidification on marine organisms. Ecology Letters 13: 1419-1434.

Kroeker, K.J., Kordas, R.L., Crim, R.N., Hendriks, I.E., Ramajo, L., Singh, G.S., Duarte, C.M. and Gattuso, J.-P. 2013. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology 19: 1884-1896.

Reyes-Nivia, C., Diaz-Pulido, G., Kline, D.I., Hoegh-Guldberg, O. and Dove, S.G. 2013. Ocean acidification and warming scenarios increase microbioerosion of coral skeletons. Global Change Biology 19: 1919-1929.

van Hooidonk, R., Maynard, J.A. and Planes, S. 2013. Temporary refugia for coral reefs in a warming world. Nature Climate Change 3: 508-511.

Projecting the Impacts of Rising CO2 on Future Crop Yields in Germany

Noting that the influence of atmospheric CO2 on crop growth is “still a matter of debate,” and that “to date, no comprehensive approach exists that would represent all related aspects and interactions [of elevated CO2 and climate change on crop yields] within a single modeling environment,” Degener (2015) set out to accomplish just that by estimating the influence of elevated CO2 on the biomass yields of ten different crops in the area of Niedersachsen, Germany over the course of the 21st century.

To accomplish this lofty objective the German researcher combined soil and projected future climate data (temperature and precipitation) into the BIOSTAR crop model and examined the annual difference in yield outputs for each of the ten crops (winter wheat, barley, rye, triticale, three maize varieties, sunflower, sorghum and spring wheat) under a constant CO2 regime of 390 ppm and a second scenario in which atmospheric CO2 increased annually through the year 2100 according to the IPCC’s SRES A1B scenario. Degener then calculated the difference between the two model runs so as to estimate the quantitative influence of elevated CO2 on projected future crop yields. And what did that difference reveal?

As shown in the figure below, Degener reports that “rising [CO2] concentrations will play a central role in keeping future yields of all crops above or around today’s level.” Such a central, overall finding is significant considering Degener notes that future temperatures and precipitation within the model both changed in a way that was “detrimental to the growth of crops” (higher temperatures and less precipitation). Yet despite an increasingly hostile growing environment, according to the German researcher, not only was the “negative climatic effect balanced out, it [was] reversed by a rise in CO2” (emphasis added), leading to yield increases on the order of 25 to 60 percent.

Figure 1. Biomass yield difference (percent change) between model runs of constant and changing atmospheric CO2 concentration. A value of +20% indicates biomass yields are 20% higher when modeled using increasing CO2 values with time (according to the SRES A1B scenario of the IPCC) instead of a fixed 390 ppm for the entire run.

Figure 1. Biomass yield difference (percent change) between model runs of constant and changing atmospheric CO2 concentration. A value of +20% indicates biomass yields are 20% higher when modeled using increasing CO2 values with time (according to the SRES A1B scenario of the IPCC) instead of a fixed 390 ppm for the entire run.

The results of this model-based study fall in line with the previous work of Idso (2013), who calculated similar CO2-induced benefits on global crop production by mid-century based on real-world experimental data, both of which studies reveal that policy prescriptions designed to limit the upward trajectory of atmospheric CO2 concentrations can have very real, and potentially serious, repercussions for global food security.

 

References

Degener, J.F. 2015. Atmospheric CO2 fertilization effects on biomass yields of 10 crops in northern Germany. Frontiers in Environmental Science 3: 48, doi: 10.3389/fenvs.2015.00048.

Idso, C.D. 2013. The Positive Externalities of Carbon Dioxide: Estimating the Monetary Benefits of Rising Atmospheric CO2 Concentrations on Global Food Production. Center for the Study of Carbon Dioxide and Global Change, Tempe, AZ.

A Historic Perspective on the Greenland Ice Sheet and its Contribution to Global Sea Level

One of the most feared of all model-based projections of CO2-induced global warming is that temperatures will rise enough to cause a disastrous melting/destabilization of the Greenland Ice Sheet (GrIS), which would raise global sea level by several meters. But how likely is this scenario to occur? And is there any way to prove such melting is caused by human activities?

The answer to this two-part question involves some extremely complex and precise data collection and understanding of the processes involved with glacial growth and decay. Most assuredly, however, it also involves a scientifically accurate assessment of the past history of the GrIS, which is needed to provide a benchmark for evaluating its current and future state. To this end, a recent review paper by Vasskog et al. (2015) provides a fairly good summary of what is (and is not) presently known about the history of the GrIS over the previous glacial-interglacial cycle. And it yields some intriguing findings.

Probably the most relevant information is Vasskog et al.’s investigation of the GrIS during the last interglacial period (130-116 ka BP). During this period, global temperatures were 1.5-2.0°C warmer than the peak warmth of the present interglacial, or Holocene, in which we are now living. As a result of that warmth, significant portions of the GrIS melted away. Quantitatively, Vasskog et al. estimate that during this time (the prior interglacial) the GrIS was “probably between ~7 and 60% smaller than at present,” and that that melting contributed to a rise in global sea level of “between 0.5 and 4.2 m.” Thus, in comparing the present interglacial to the past interglacial, atmospheric CO2 concentrations are currently 30% higher, global temperatures are 1.5-2°C cooler, GrIS volume is from 7-67% larger, and global sea level is at least 0.5-4.2 m lower, none of which signal catastrophe for the present.

Clearly, therefore, there is nothing unusual, unnatural or unprecedented about the current interglacial, including the present state of the GrIS. Its estimated ice volume and contribution to mean global sea level reside well within their ranges of natural variability, and from the current looks of things, they are not likely to depart from those ranges any time soon.

 

References

Reyes, A.V., Carlson, A.E., Beard, B.L., Hatfield, R.G., Stoner, J.S., Winsor, K., Welke, B. and Ullman, D.J. 2014. South Greenland ice-sheet collapse during Marine Isotope Stage 11. Nature 510: 525–528.

Vasskog, K., Langebroek, P.M., Andrews, J.T., Nilsen, J.E.Ø. and Nesje, A. 2015. The Greenland Ice Sheet during the last glacial cycle: Current ice loss and contribution to sea-level rise from a palaeoclimatic perspective. Earth-Science Reviews 150: 45-67.