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The State of Earth's Terrestrial Biosphere: How is it Responding to Rising Atmospheric CO2 and Warmer Temperatures?


For well over a century, scientists have been concerned about potential consequences of Earth's rising atmospheric carbon dioxide (CO2) concentration on the biosphere. Driven by gaseous emissions from the burning of fossil fuels such as coal, gas and oil, the air's CO2 content has risen steadily from a mean concentration of about 280 parts per million (ppm) in 1800 to a value of approximately 392 ppm today. And if current fuel consumption trends continue, it is projected that the planet's atmospheric CO2 concentration may double sometime before the end of this century (IPCC, 2007). In light of such projections, it is only natural that scientists have long sought to understand how this important trace constituent of the atmosphere might affect the climate and biology of our planet; and tens of billions of research dollars have been spent investigating this issue over the past few decades. So what has been learned from this effort?

In short, two conflicting viewpoints have emerged. One is that which is proffered by the UN's Intergovernmental Panel on Climate Change (IPCC), which has subsequently been mirrored by the U.S. Environmental Protection Agency and many other organizations throughout the world, where it is claimed that the increasing carbon dioxide content of the atmosphere will lead to catastrophic global warming, which will further produce all sorts of undesirable consequences, including catastrophic sea level rise, dramatic increases in extreme weather phenomena such as droughts, floods and hurricanes, reduced agricultural output, and the destruction of many natural ecosystems. Those holding this viewpoint are often referred to as climate alarmists, because they are alarmed by these potentially negative consequences.

Opposite this constituency are those, including the Nongovernmental International Panel on Climate Change (NIPCC), who - although conceding that humans are indeed causing the air's CO2 concentration to rise - contend that many of the IPCC's conclusions far outstrip or even contradict the implications of a vast array of real-world data that should have informed the theoretical models upon which the alarmists' concerns are based. These climate skeptics, as they have come to be known, maintain that many more of the IPCC's claims have also been reached without considering the findings of important scientific studies that refute their alarmist assertions.

One such topic of disagreement concerns the future productivity of Earth's biosphere. Based on computer model projections, climate alarmists have long suggested that CO2-induced global warming will wreak havoc on Earth's natural and agro-ecosystems by reducing plant growth and development, potentially leading to the extinction of many species. Climate skeptics, on the other hand, foresee a much different future. Citing empirical observations of enhanced vegetative growth in numerous CO2-enrichment experiments conducted on a host of different plants, coupled with productivity measurements made over the past several decades out in the real-world of nature, they assert it is far more likely that just the opposite will occur. To them, higher atmospheric CO2 concentrations and warmer temperatures will significantly stimulate the planet's vegetation, creating a bright and more prosperous future for Earth's biosphere.

Which of these two worldviews is the closest to reality? Perhaps the best way to answer this question is to compare the model-based projections of the climate alarmists with the real-world observations of the climate skeptics. Theoretical projections may or may not be correct, but real-world observations are always right; and as such, the only truly objective method of evaluating climate model projections and their biological implications is by comparing them with real-world data. In what follows, therefore, we conduct just such an appraisal, examining real-world observations of Earth's vegetative productivity over the most recent era of global warming and rising atmospheric CO2 concentrations to see how they compare with model-based predictions of vegetative decline.

Both global temperature and atmospheric CO2 concentration have experienced significant increases over the past century, rising to levels that climate alarmists claim are unprecedented over thousands of years (temperature) to millions of years (CO2 concentration). Over just the past three decades, in fact, the Earth has experienced the warmest temperatures of the instrumental temperature record and a handful of intense and persistent El Niño events, while the air's CO2 content has increased by 16% over the past three decades and by 30% over the past century.

Clearly, if there ever was a period of time over which to test the model-based projections of biospheric decline in response to rising atmospheric temperature and CO2 concentration, this is it! And in the following pages we do just that, conducting an expansive investigation into the pertinent peer-reviewed scientific literature and reporting what many hundreds of scientists have found to be the case.

Our examination begins with a discussion of what has been learned with respect to the terrestrial biosphere as a whole, after which we proceed with a regional analysis, exploring terrestrial productivity trends on continental and sub-continental scales. Finally, we conclude with a brief summarization of the vast array of findings and offer our best estimate of the state of Earth's terrestrial biosphere in response to temperatures and CO2 concentrations projected by climate-alarmist models for the end of the current century.

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