Monitoring Planet Earth’s Vital Signs

While the Senate’s effort to take up comprehensive clean energy and climate legislation remains on hold awaiting a resolution of when and if an immigration bill will be considered, EPA just issued a new report that sends a loud and clear reminder about why Congressional action is urgent.  The report, Climate Change Indicators in the United States, presents detailed information documenting 24 different ways in which climate change is altering our nation and the world.

This is not your standard climate report with pages and pages of scenarios and model runs projecting out over time what future climate impacts are possible.  Instead, this report looks back and documents biological and physical changes that have already occurred.  It focuses on actual measurements of real conditions – from increases in greenhouse gas concentrations measured in the atmosphere to changes in sea surface temperatures to shifts in the length of growing seasons.

The 24 indicators cover a wide range of changes that have occurred, some with data documented over 100 years or more.  The report includes detailed information on:  greenhouse gas emissions and concentrations; satellite and land-based temperatures; heat waves, droughts and precipitation; and intensity of tropical cyclones.  A section on indicators related to the oceans deals not just with sea level rise, but also includes information on sea surface temperatures, ocean heat uptake, and ocean acidity.  A section on snow and ice looks at reductions in Arctic sea ice, losses in the volume of water contained in glaciers, and reductions over time in snow pack and snow cover. Each indicator includes a detailed description, documentation and any limitations of the data relied upon.

In many of the indicators, clear trends are apparent.  Increases in emissions of greenhouse gases in the United States (up 14 percent from 1990 to 2008) and in atmospheric concentrations of carbon dioxide (up 38 percent since preindustrial times) have been widely reported.   Also widely known are temperature increases (up 1.3 degrees F over the past century across the lower 48 states) and increases in sea level (0.06 inches per year from 1870 to 2008).  But the report also includes data on the amount of water that has been lost by glaciers worldwide (2,000 cubic miles since 1960) and on increases in sea surface temperatures (0.21 degrees per decade over the last 30 years).  It also reports on declines in snow pack with some areas experiencing relative losses of 75 percent from 1950 to 2000, but with increases in snow pack at some sites in parts of the Sierra Nevada mountains and the Southwest.  It is also worth noting that no long-term trends are apparent in some of the indicators (e.g., heat waves and droughts).  

EPA’s goal is to refine and expand on these 24 indicators and to update the report periodically.  Like other environmental indicators, the goal here is to track progress over time in order to inform future decisions.  Future reports will depend on what we do or do not do:  if we fail to reduce emissions of greenhouse gases, it will help us better understand the extent to which changes continue to occur; if we act, the report will show the improvements in these indicators that result from future policy actions.

Given the current time-out on clean energy and climate legislation in the Senate, this report would be useful reading for all those involved in shaping the future direction of our climate policy.   

Steve Seidel is Vice President for Policy Analysis