Lava Lake in the Madison Range just south of Bozeman is a favorite destination for participants in our summer programs for federal judges and law professors. Most years the lake trail is clogged with snow until early July. But that’s changing.

Shorter, warmer winters and drier summers are here. Warmer spring temperatures cause our rivers to peak about two weeks earlier than in the past. Good news, perhaps, for kayakers, but troubling for agriculture, fish habitat, and summer wildfires.

These changes are consistent with global climate models predicting the greatest warming over the higher latitudes during winter. This warming is likely due to human activity.

But the uncertainty is deep, and we cannot rule out that some significant part of these changes is also a reflection of natural variability. Evidence from ice cores in Antarctica and Greenland indicate that the range of natural climate change can be large and varied at local and regional scales over very short periods, e.g., a decade.

Dr. Jerry Mahlman is a Senior Research Fellow at the National Center for Atmospheric Research. He’s lectured in our programs. He’s explained that atmospheric concentrations of carbon dioxide have ranged from 190 to 280 parts per million from the beginning to the end of the last ice age. Since the start of the industrial revolution, atmospheric carbon dioxide has increased to 367 parts per million. Mahlman expects this number to go much higher.

Mahlman notes that regardless of what America and other developed nations do, in the next decade there is no reasonable scenario in which atmospheric CO2 will not double. It will probably quadruple. This is due to the physical chemistry of carbon dioxide that makes it a long-lived resident in the atmosphere. The consequences, however, will not become evident for several decades due to the buffering capacity of the oceans. Climate change, whether anthropogenic or natural, is inevitable. Our challenge is to deal with it responsibly.

Here’s an important policy generalization that will help -- there are no solutions, only trade-offs. In a world of limited resources, we must make choices. For example, the resources spent eradicating smallpox and polio are not available to research breast cancer and juvenile diabetes. Such trade-offs are inescapable. Those clamoring for dramatic, immediate action on climate change are irresponsible if they ignore this logic.

Climate-change policy is complex. First, reducing greenhouse gases will be extremely expensive. Estimates range from the hundreds of billions to trillions of dollars if the world fully implements the Kyoto Protocol. This is money not available to combat river blindness and vitamin deficiency, both endemic, devastating problems across Africa. Second, there’s the problem of political economy. When benefits accrue to future generations while the costs are born today, politicians avoid responsible actions.

Consider the recent reaction of German Chancellor Gerhard Schroeder. He recommends that Europe should not rush to reach its greenhouse emissions targets. Why? He estimates the costs to his constituents include increased gasoline and diesel prices, a shrinking GDP, and a reduction in employment of 1 million jobs annually between 2008 and 2012.

In addition, it’s clear that climate change is not the most pressing problem we face. For example, it’s not even on the UN’s priority list for its Millennium Development Goals project.

There are many problems in the developing world requiring immediate action. For example, 2 million people die each year from malaria, 90 percent are children under 5. I believe that eradicating malaria, providing access to clean drinking water, reducing infant mortality, increasing female literacy, and increasing access to primary education, are higher priorities than climate change.

Because the world will be much wealthier and more technologically adept in several decades, the best climate-change policy is to emphasize present economic growth, especially in the developing world. Wealth dramatically increases resiliency to all sorts of stress, including climate change.

Some elements of Montana’s ecosystems will suffer from significant warming. White bark pine and mountain caribou are especially vulnerable. I mourn their displacement. However, feel-good but foolish climate-change policies are likely to divert scarce resources from efforts to help the world’s poorest. This great truth is often ignored in the debate over climate change.