A recent op-ed in the Houston Chronicle by climate scientists from the state of Texas sums up the state of the science well:
• The global climate is changing.
A 1.5-degree Fahrenheit increase in global temperature over the past century has been documented by NASA and the National Oceanic and Atmospheric Administration (NOAA). Numerous lines of physical evidence around the world, from melting ice sheets and rising sea levels to shifting seasons and earlier onset of spring, provide overwhelming independent confirmation of rising temperatures.
Measurements indicate that the first decade of the 2000s was the warmest on record, followed by the 1990s and the 1980s. And despite the cold and snowy winter we’ve experienced here in Texas, satellite measurements show that, worldwide, January 2010 was one of the hottest months in that record.
• Human activities produce heat-trapping gases.
Any time we burn a carbon-containing fuel such as coal or natural gas or oil, it releases carbon dioxide into the air. Carbon dioxide can be measured coming out of the tailpipe of our cars or the smokestacks of our factories. Other heat-trapping gases, such as methane and nitrous oxide, are also produced by agriculture and waste disposal. The effect of these gases on heat energy in the atmosphere is well understood, including factors such as the amplification of the warming by increases in humidity.
•?Heat-trapping gases are very likely responsible for most of the warming observed over the past half century.
There is no question that natural causes, such as changes in energy from the sun, natural cycles and volcanoes, continue to affect temperature today. Human activity has also increased the amounts of tiny, light-scattering particles within the atmosphere. But despite years of intensive observations of the Earth system, no one has been able to propose a credible alternative mechanism that can explain the present-day warming without heat-trapping gases produced by human activities.
• The higher the levels of heat-trapping gases in the atmosphere, the higher the risk of potentially dangerous consequences for humans and our environment.
A recent federal report, “Global Climate Change Impacts in the United States,” commissioned in 2008 by the George W. Bush administration, presents a clear picture of how climate change is expected to affect our society, our economy and our natural resources. Rising sea levels threaten our coasts; increasing weather variability, including heat waves, droughts, heavy rainfall events and even winter storms, affect our infrastructure, energy and even our health.
While there may be debate around the margins, it is hard to argue comprehensively with the science of climate change. There will always be room for improvement in studies and reports, but small errors should not cause us to ‘throw the baby out with the bathwater.’ The time to act is now, and in spite of what you may have heard from some, the science of climate change is still very clear. For a few more answers to typical climate change skeptic questions, please see this recent article in Scientific American.