Texas Textbook Reviews and Climate Change

Don’t mess with Textbooks!As I mentioned before (and as discussed in the TFN/NCSE press release), evolution was the main focus of denialist comments in the Texas textbook reviews. But given a chance, the creationists were happy to attack climate science, too.

Climate change isn’t part of the biology standards in Texas (unfortunately), so science-denying reviewers had to work a bit to find a way to attack climate change. One reviewer in particular, Ray Bohlin, a fellow with the Discovery Institute and vice-president of the anti-evolution Probe Ministries, focused on a climate change case study in the best-selling Pearson/Prentice-Hall biology textbook. The four-page discussion covers the physical causes of climate change, its impacts on biological systems and the oceans and atmosphere, and discusses what can be done to limit climate change. For the space available, it’s a thorough and thoughtful discussion that gives students the information they’ll will need in order to be scientifically literate citizens of the 21st century.

Bohlin objects to the passage in several places (all typographic errors are from Bohlin’s review):

Question 8 is quite controversial. The connection between carbon dioxide from fossil fuel burning is not as firm as it once was since Carbon dioxide continues to increase but there has been no global warming for 16 years. I would delete the question.

Case Study #3 on Climate Change needs extensive revision. The temperature graph in Figure 6-30 wrongly indicates that temperatures have continued to rise. It is well recognized that global temps have stalled for the last 16 years. This graph does not indicate that. … Additional problems can be found in the CO2 graph on page 178. One axis uses ppm and the other uses ppb. This discrepancy will be asily lost on many HS students and therefore will lead to misinterpretations of the graph. No mention is made of the benefit to plants of higher CO2 concentrations. There is jjst so much wrong with this case study.

The Climate Change case Study fails on manny counts. First we don't really know that the carbon Cycle has been altered. CO2 is being returned to the atmosphere that was sequestered in fossil fuels in earlier times. CO2 levels have been much higher in the past and life survived just fine. Plants always grow better with higher CO2 levels.The earth has not warmed now for 16 years and the sun spot cycle is approaching a long minimum that willreduce temperatures. The authors have failed to evaluate and critique the climate models and data for this phenomenon.

The question focuses on climate change. In reality we don't know what climate change will do to species diversity. Some biomes may show a decrease in biodiversity while others may increase. Question seems to imply that ecosystems will be disrupted which qwe simply don't know yet.

Essentially each sentence in these criticisms is wrong or misleading. Carbon dioxide’s connection to fossil fuel burning is undeniable, both because of the basic chemistry of combustion and because of detailed isotopic comparisons of the carbon in today’s atmosphere with air from earlier eras that was trapped or stored. The greenhouse effect of carbon dioxide in the atmosphere—its ability to trap heat—has been understood since the work of Fourier in the 1820s and Tyndall in the 1850s. As for the claims of a 16-year “stall” in climate change, that’s a timeframe that is cherry-picked to start on a particularly warm year, it’s too short to reliably detect the sort of multi-decade trend attributable to human-caused climate change, and in any event, there’s lots of evidence that climate change is ongoing, as we discussed last week.

The graph described as a “CO2 graph” actually shows atmospheric concentrations of carbon dioxide, nitrate (NO3), and methane. Carbon dioxide is easily measured in hundreds of parts per million, while the other two are more appropriately measured in hundreds of parts per billion. Using the same scale for very different measurements would confuse, not enhance, student understanding.

The sentence claiming that the carbon cycle hasn’t been altered is refuted by the sentence Bohlin wrote next, which rightly notes that humans have added significant carbon dioxide to the atmosphere in the last 200 years. In fact, we’ve added at least 40% more carbon dioxide to the atmosphere, relative to pre-Industrial levels. That has a substantial effect on the atmosphere, and on the oceans (which have absorbed much of the added carbon dioxide as well, and become more acidic in the process). As we observed in the press release, NASA’s Earth Observatory is quite clear on this point: “Today, changes in the carbon cycle are happening because of people. We perturb the carbon cycle by burning fossil fuels and clearing land.”

The evidence that plants grow better with increased carbon dioxide is trickier than it might seem at first glance. Skeptical Science summarizes the research by saying, “The effects of enhanced CO2 on terrestrial plants are variable and complex and dependent on numerous factors.” In a greenhouse, where it is possible to control all other variables (water, temperature and nutrients), plants do indeed grow better with more carbon dioxide. That makes sense, since carbon dioxide is a key ingredient for turning sunlight into biologically usable energy. But carbon dioxide is not the only factor limiting growth of plants in the wild. Researchers have shown that any initial faster growth we might see in a higher CO2 environment, ultimately won't last due to a depletion of other nutrients in the soil.  Unless we are planning on fertilizing and water all of the world's forests, bigger more badass forests are just not very likely.

Furthermore, while carbon dioxide is certainly a crucial ingredient for photosynthesis, photosynthesis also relies on a steady supply of water, and on reasonable temperatures. Climate change has already changed temperatures, rainfall, and humidity, and those trends will only continue, leaving plants to cope with harsher environments. In a greenhouse, growers can adjust the sprinklers and the thermostat, but plant populations in the wild will have to keep up with growth zones as they shift. A recent review of the research on plant responses to recent climate change (Corlett & Westcott, (2013) “Will plant movements keep up with climate change?,” TREE 28(8):482-488) finds “most plant populations have tracked recent warming only partly or not at all. Failure to track climate change is expected to have a large impact on growth and survival, leading to plant extinctions.” While some plants may be able to handle the changing climate, or even benefit from it, “‘losers’ are likely to outnumber ‘winners’ greatly, particularly in the most human-dominated landscapes.”

While life in general has survived past periods of high carbon dioxide (and the concomitant harsher climate), individual species have not fared so well. It is precisely because of our understanding of the extinctions that have accompanied past climate change, and a recognition that modern climate change may be unprecedented in its speed, that scientists are so concerned about the harm climate change is doing and will do to biodiversity. The scientific consensus is that climate change’s effects on biodiversity will be severe. The Intergovernmental Panel on Climate Change summarized that consensus in 2007, writing:

Approximately 20-30% of plant and animal species assessed so far are likely to be at increased risk of extinction if increases in global average temperature exceed 1.5-2.5°C. … For increases in global average temperature exceeding 1.5-2.5°C and in concomitant atmospheric carbon dioxide concentrations, there are projected to be major changes in ecosystem structure and function, species’ ecological interactions, and species’ geographical ranges, with predominantly negative consequences for biodiversity, and ecosystem goods and services e.g., water and food supply.

And the same report found that under all likely scenarios, by the end of this century, global average temperatures are expected to rise by more than 1.5 degrees compared to temperatures at the beginning of the 20th century, putting a third or more of species at risk of extinction, and leading to inevitable severe disruptions to ecosystems and croplands.

If any of the claims advanced in Bohlin’s review were incorporated into the textbook, students would be misinformed about the single greatest challenge that society will face in their lifetimes. Maybe it’s possible to think of a more effective way to undermine science education in Texas, but it’s hard to think what it would be.

Josh Rosenau
Short Bio

Josh Rosenau is a former Programs and Policy Director at NCSE.