The great carbon boom

On the eve of the UN climate summit in Paris, all delegates would be well advised to reflect on how the story of the man-made global warming debate started.

Svante Arrhenius, winner of the 1905 Nobel Prize, hypothesized over a century ago that increases in atmospheric carbon dioxide (CO2) due to fossil fuel consumption would warm the world. He also hypothesized that higher CO2 levels would stimulate plant growth. These, he reasoned, would reinforce each other and increase the biosphere’s productivity to the benefit of mankind.

Remarkably, proponents of the notion that global warming would be catastrophic unless CO2 emissions are curtailed drastically (or, in short, “warmists,”) embrace the first, but ignore the second hypothesis. “Remarkably,” because both satellite and ground based data confirm that the biosphere’s productivity has increased in managed ecosystems (e.g., agriculture and managed forests) and in unmanaged or natural ecosystems.

The plant-productivity increase has been steady, large and ubiquitous: widespread evidence confirms that the Earth is greener; terrestrial ecosystems’ productivity has increased 14 per cent since 1982. Further, the IPCC estimates that the terrestrial biosphere productivity is five per cent over pre-industrial times, that is, “carbon fertilization” due to rising CO2 levels has helped overcome any productivity loss from deforestation and other habitat loss. (Habitat loss is the greatest threat to terrestrial biodiversity and natural ecosystems.)

This productivity increase is to be expected: the results of thousands of scientific experiments indicate that at current levels of atmospheric CO2, crop yields should increase by nine to 15 per cent relative to pre-industrial levels because higher CO2 increases rates of plant growth (i.e., photosynthesis), improves the efficiency with which plants use water, increases their drought resistance and, possibly, increases resistance of crops to pests and weeds.

These increases in crop yields, in addition to helping feed a larger population, have limited the need to convert existing habitat to farming. The increased crop yields from higher CO2 levels reduced habitat loss by 11-17 per cent compared with what it would otherwise have been. Consequently, more land has been left relatively wild.

Satellite evidence also confirms that increasing CO2 concentrations have resulted in greater productivity of wild terrestrial ecosystems in all vegetation types. Moreover, increasing CO2 concentrations have also increased the productivity of many marine ecosystems, and although this effect may be partially or fully offset by the effect of lower average pH on calcification rates in some marine organisms, the evidence of net harm in wild marine ecosystems remains sparse.

Equally important, contrary to warmists’ claims, since fossil fuels helped start the Industrial Revolution in the mid-18th century and CO2 emissions skyrocketed, so have aggregate indicators of human well-being. Data back to 1750 show the dramatic escalation in measures of well-being and, as the nearby graph shows, the bulk of the increase has occurred since 1900 as global carbon-based industrial development soared.

Since 1750: ❚Carbon dioxide emissions increased from the relatively imperceptible (3-million tons) in 1750 to 9.5-billion tons in 2011; ❚Population increased nine-fold from 800 million to 1.6 billion 1900 and 7.3 billion in 2014; ❚Average GDP per capita, perhaps the best measure of economic and material well-being, increased 13-fold, from $650 to in 1750 to $1,261 in 1900 and $8,500 in 2014 (in 1990 International dollars); ❚Average life expectancy, probably the single best indicator of human wellbeing, has more than doubled from 26 years in 1750 to 31 in 1900 and to 71 years in 2013.

These indicators show no sign of a sustained downturn.

Empirical trends indicate that climate-sensitive indicators of human well-being have also improved markedly over recent decades, notwithstanding the gloomy prognostications of warmists.

The above-noted increases in crop yields reduced chronic hunger in the developing world from 24 per cent of population in 1990—92 to 14 per cent in 2011—13, despite a 37 per cent increase in population. The increase in GDP per capita reduced the absolute poverty level in developing countries by almost three-quarters between 1981 and 2012 (from 54 per cent to 15 per cent). Between 1990 and 2012, more than 2 billion additional people obtained access to better sanitation and safer water. The global mortality rate for malaria, which accounts for about 80 per cent of the burden of vector-borne diseases that may pose an increased risk due to global warming, declined by 95 per cent since 1900. Deaths from extreme weather events have declined by 93 per cent since the 1920s and, once the increase in the amount of wealth-at-risk is accounted for, there has been no increase in economic damages from extreme weather events.

The wide divergence between dystopian warmist claims and empirical reality can be attributed to the fact that those claims derive largely from unvalidated models. Empirical data, however, indicate that these models have overestimated the rate of warming.

A recent study compared projections from 117 simulations using 37 models versus empirical surface temperature data. It found that the vast majority of the simulations/models have overestimated warming, on average by a factor of two for 1993—2012 and a factor of four for 1998—2012. It also estimated that the observed trend for 1998—2012 was marginally positive, but not statistically significant; that is, notwithstanding model results, warming has essentially halted.

Impact models, likewise, have underestimated direct benefits of CO2, overestimated the harms from climate change, and underestimated human capacity to adapt which enables the benefits to be captured even as it also reduces the harms. Consequently, these models overestimate net negative damages. Not surprisingly, dire prognostications of increasing death, disease, and decline of human and environmental well-being from global warming are not reflected in the empirical data.

To summarize, compared with the benefits from CO2 on crop and biosphere productivity, the adverse impacts of CO2-induced warming on the frequencies and intensities of extreme weather, accelerated sea level rise, vector-borne disease prevalence, and human health have been too small to measure, are non-existent or swamped by other factors.

It is very likely that the impact of rising CO2 concentrations is currently net beneficial for both humanity and the biosphere generally. No compelling case has been made that the net impacts of climate change will be negative by the end of this century, particularly given the gradual rate of warming observed recently.

In fact, the more gradual the rate of warming, the greater the likelihood of successful adaptation, and the cheaper that adaptation.

Empirical data confirm that the benefits of CO2 are real whereas the costs of warming are uncertain, dependent as they are on the results of climate models and impact methodologies that tend to overestimate negative impacts.

Halting the increase in CO2 concentrations abruptly, or reducing them, would immediately halt or reverse improvements in plant growth rates, increasing hunger and habitat destruction. On the other hand, any consequential change in warming would happen much more slowly. Thus, any reductions in CO2 emissions would deprive people and the planet of the benefits from CO2 much sooner and more surely than they would reduce any costs of warming.

Carbon dioxide emissions over two centuries have produced massive benefits for humanity — and nature. Halting emissions could increase hunger and habitat destruction

This op-ed is derived from CARBON DIOXIDE: The good news, a paper from the Global Warming Policy Foundation. Indur Goklany, an independent scholar and author, was a member of the U.S. delegation that established the IPCC and helped develop its First Assessment Report. He subsequently served as a U.S. delegate to the IPCC, and an IPCC reviewer.