Dear EarthTalk: I keep meeting people who say that human-induced global warming is only theory, that just as many scientists doubt it as believe it. Can you settle the score? — J. Proctor, London, UK

So-called “global warming skeptics” are indeed getting more vocal than ever, and banding together to show their solidarity against the scientific consensus that has concluded that global warming is caused by emissions from human activities.

Upwards of 800 skeptics (most of whom are not scientists) took part in the second annual International Conference on Climate Change-sponsored by the Heartland Institute, a conservative think tank-in March 2009. Keynote speaker and Massachusetts Institute of Technology meteorologist Richard Lindzen told the gathering that “there is no substantive basis for predictions of sizeable global warming due to observed increases in minor greenhouse gases such as carbon dioxide, methane and chlorofluorocarbons.”

Most skeptics attribute global warming-few if any doubt any longer that the warming itself is occurring, given the worldwide rise in surface temperature-to natural cycles, not emissions from power plants, automobiles and other human activity. “The observational evidence…suggests that any warming from the growth of greenhouse gases is likely to be minor, difficult to detect above the natural fluctuations of the climate, and therefore inconsequential,” says atmospheric physicist Fred Singer, an outspoken global warming skeptic and founder of the advocacy-oriented Science and Environmental Policy Project.

But green leaders maintain that even if some warming is consistent with millennial cycles, something is triggering the current change. According to the nonprofit Environmental Defense, some possible (natural) explanations include increased output from the sun, increased absorption of the sun’s heat due to a change in the Earth’s reflectivity, or a change in the internal climate system that transfers heat to the atmosphere.

But scientists have not been able to validate any such reasons for the current warming trend, despite exhaustive efforts. And a raft of recent peer reviewed studies-many which take advantage of new satellite data-back up the claim that it is emissions from tailpipes, smokestacks (and now factory farmed food animals, which release methane) that are causing potentially irreparable damage to the environment.

To wit, the U.S. National Academy of Sciences declared in 2005 that “greenhouse gases are accumulating in Earth’s atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise,” adding that “the scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action.” Other leading U.S. scientific bodies, including the American Meteorological Society, the American Association for the Advancement of Science and the American Geophysical Union have issued concurring statements-placing the blame squarely on humans’ shoulders.

Also, the Intergovernmental Panel on Climate Change (IPCC), a group of 600 leading climate scientists from 40 nations, says it is “very likely” (more than a 90 percent chance) that humans are causing a global temperature change that will reach between 3.2 and 7.2 degrees Fahrenheit by the end of this century.

CONTACTS: Heartland Institute, www.heartland.org; Science and Environmental Policy Project, www.sepp.org; U.S. National Academy of Sciences, www.nas.edu; IPCC, www.ipcc.ch.

Dear EarthTalk: Are elephant populations stable these days? – Reuben Perrin, Hartford, CT

Far from it. The double whammy of poaching (illegal hunting) and habitat loss has led to a dramatic decline in populations of both African and Asian elephants in recent decades. In 1930, there were between five and 10 million wild African elephants, plying the entire African continent in large bands. Just 60 years later, when they were added to the international list of critically endangered species, only about 600,000 were scattered across a few African countries. Today that number is likely less than 500,000.

While Asian elephants were never as numerous as their African counterparts, their population numbers have also dropped precipitously, from an estimated 200,000 a century ago to less than 40,000 today. Conservationists fear that unless demand dries up for ivory, and people stop moving into prime elephant habitat, the world’s largest land mammal could become just a memory within another hundred years.

Putting an end to habitat loss may be next to impossible as more and more people vie for fewer and fewer resources and move out further into the countryside, so conservationists working to save elephants tend to concentrate on reducing or eliminating poaching. While trophy hunting of elephants may have been big decades ago, today most elephant hunters are after the ivory in the tusks, which have been a hot commodity across Asia for years as raw material for highly prized and often ornate carvings. Despite elephants’ inclusion in Appendix I of the Convention on International Trade in Endangered Species (CITES) in 1990-meaning the sale of tusks and other elephant parts is a violation of international law-poaching is bigger business than ever, with prices for ivory rising more than 16-fold in recent years.

Some countries, such as Tanzania and Kenya, are working hard to hold up their end of the CITES agreement, hiring patrols of young men-some of them former poachers themselves-to monitor local elephant populations and enforce national and international laws against killing these and other endangered species. Conservation groups like the African Wildlife Foundation (AWF) and the Wildlife Conservation Society (WCS) are working hand-in-hand with local officials to improve elephant habitat and keep poachers at bay. These organizations hope that the people in these regions can learn how to bring in revenues from tourism instead of hunting.

But elsewhere governments are not as committed to the ivory ban, let alone to following laws imposed by outsiders. Government officials in Zimbabwe, South Africa and Botswana, for example, argue that trade in ivory should be regulated, not prohibited. They maintain that countries that are managing their elephants well should be allowed to sell ivory in order to pay for conservation measures.

In part to test such waters, the first legal sale of ivory in a decade took place in October 2008, despite protests from conservationists. Buyers, mostly from China and Japan, eagerly snatched up some 100 tons of stockpiled elephant tusks-no elephants were killed recently or illegally for the sale-with the proceeds going to groups working to save the elephant and its habitat. But with the legal ivory sale has come an uptick in elephant poaching, leaving conservationists with that “one step forward, two steps back” feeling.

CONTACTS: CITES, www.cites.org; AWF, www.awf.org; WCS, www.wcs.org.

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