Becky Fried, Policy Analyst,
Office of Science and Technology Policy, Executive Office of the President
Last week, the Interior Departmentâ€™s US Geological Survey (USGS) released details about a landmark airborne survey of permafrost in the Yukon Flats of Alaska that yielded some of the most detailed, data-rich maps of permafrost ever generated. Permafrostâ€”frozen ground that remains at or below waterâ€™s freezing point for at least two yearsâ€”accounts for only 0.022% of all water on Earth, but it covers more than 20% of exposed land of Earthâ€™s northern high latitudes (in addition to areas of Antarctica and the Patagonia region), where it plays a potentially important role in climate dynamics.
There are many reasons scientists seek to understand where permafrost is and how it is changing. One reason is that changes in permafrost can impact ground stability, affecting infrastructure such as roads, home foundations, water treatment facilities, and industrial sites. Another is that it changes in response to changes in temperature and water systems, and so is a key indicator of climate change.
But the permafrost-climate connection is a two-way street, in which changes in permafrost can also spur changes in climate. In part thatâ€™s because massive stores of carbon are locked up in permafrost. As temperatures rise, permafrost thaws, making these stores of carbon increasingly available for release into the atmosphereâ€”which contributes to warming.
Permafrost surveys are typically conducted on the ground through surface monitoring and borehole measurementsâ€”a painstaking process. But the survey published last week was conducted by helicopter by towing an instrument that sends electromagnetic pulses downward and measures how the earth below responds to the pulses.
This information was used to create three-dimensional images of permafrost over larger areas than can be captured by ground-based methods, down to depths of more than 300 feet below the surface. The Yukon Flats of Alaska fall at a critical boundary between areas of continuous permafrost (to the north) and discontinuous permafrost (to the south)â€”making the region especially important to understanding how permafrost behaves under different conditions.
The study released last week demonstrated that this new airborne technique can complement USGSâ€™s ongoing ground-based efforts and provide critical new information to hydrologists, ecologists, climate scientists, and land managers in the Yukon Flats and elsewhere.
Philip B Duffy, Senior Policy Analyst,
Office of Science and Technology Policy, Executive Office of the President
This week, the National Oceanic and Atmospheric Administration (NOAA) and the National Aeronautics and Space Administration (NASA) released temperature data showing that 2011 was one of the warmest years since record-keeping began in 1880. Â The global temperature continued to be extremely warm even though at least two factors acted to push it downwards in the short term.
Despite a slight drop of about 0.2Â°F from 2010â€”which had tied with 2005 for the warmest year ever recordedâ€”the data show that Earth continues to experience warmer temperatures than a few decades ago. NOAAâ€™s analysis ranked 2011 as the 11th warmest year, while NASAâ€™s showed 2011 to be the 9th warmest (rankings are expected to differ slightly because temperature differences between the warmest years are extremely small). Both rankings are consistent with a clear trend of increasing global temperaturesâ€”with the 12 hottest years on record all occurring since 1997, and the decade that started in 2000 the hottest in recorded history.
Still, the data also show that temperatures have not changed much since 2005, the year that tied 2010 as the warmest ever recorded. If temperatures have not risen recently, does that mean climate change has stopped? Â Actually, no. Â Just as stock prices do not go up every day in a bull market, global temperatures do not rise every year in an era of warming. Â In both cases, to understand if an upward trend will continue, one must look at the underlying forces that drive it.
In the case of climate change, the most important underlying force is increasing amounts of greenhouse gases in the atmosphere. Â This results primarily from human burning of fossil fuels (coal, oil, and natural gas). Â Fossil fuel use not only continues, but is growing. Â And because carbon dioxide, the most important greenhouse gas, remains in the atmosphere for many decades, the amount in the atmosphere increases even in those unusual years when emissions are flat or decrease slightly. Â For example when global carbon dioxide emissions dipped by about 1% as a result of the recent global recession, the amount of carbon dioxide in the atmosphereâ€”which is the force that drives temperatureâ€”continued to increase. Â And in most years emissions increase, so the amount of carbon dioxide in the atmosphere increases at an even greater rate.
So why donâ€™t temperatures go up every year? Because although increasing greenhouse gases are the most important force driving the global temperature, they are not the only force. Â Weather variations, for example, push the global temperature up or down slightly every year. Â Powerful volcanic eruptions can cause noticeable cooling for a couple of years. Â And the energy output of the sun varies slightly (although since satellite measurements started in 1980 there has been no steady up or down trend in the sun). Â These and other forces cause global temperatures to vary slightly from year to year. Â To get a reliable indication of trends, one needs to consider at least a decade or two.
Itâ€™s noteworthy that 2011 was very warm despite two temporary cooling influences. The figure below shows that global temperatures were high in 2011 even though a weather variation known as La NiÃ±a caused colder than average temperatures over much of the Pacific Ocean. Â (La NiÃ±a is a temporary cooling of temperatures in the Eastern tropical Pacific region, which has widespread impacts, including a slight global cooling.) Â And between about 2005 and 2010 the sunâ€™s energy output was lower than ever recorded, which also pushed temperatures down a little. Â Both these forces are likely to reverseâ€”in fact the sunâ€™s energy output already hasâ€”which can be expected to drive future temperatures upwards in coming years.
Although the temperatures discussed above, which are measured just above the ground or ocean, are the most common way to gauge the global temperature, other data can be useful as well. Â In particular, the â€œocean heat content,â€ which involves ocean temperatures from the surface down to about 6,000 feet, is less susceptible to year-to-year variations. Â This shows a steady march upwards, with each of the last 10 years setting a new record.
The continued high temperaturesâ€”despite downward pressure from La NiÃ±a and the sun, together with ongoing increases in atmospheric greenhouse gases and ocean heat contentâ€”show that global warming continues.
Figure: Map showing 2011 temperatures as differences from the long-term average of 1971 through 2000. Â Red indicates warmer than average temperatures, blue colder than average. Â Colder than average temperatures in the Pacific Ocean region show the influence of La NiÃ±a, a common weather variation. Â Despite this strong temporary cooling influence, global temperatures remained very high in 2011.
The carbon cycle science community in the United States has just finished its planning process for carbon cycle research for the upcoming decade. This reassessment of the U.S. carbon cycle science priorities was initiated by the U.S. Carbon Cycle Interagency Working Group (CCIWG) and Carbon Cycle Science Steering Group (CCSSG) in 2008. This planning process has culminated in the publication of the new U.S. Carbon Cycle Science Plan. The new Plan is intended to provide guidance for U.S. research efforts on the global carbon cycle for the next decade.
The Plan outlines priorities for research in carbon cycle science, including a substantial expansion in the scope of the field. In addition to reaffirming the need for basic research and for continuing the current areas of research in carbon cycle science, the Plan outlines specific recommendations for new priorities:
With greenhouse-gas concentrations rising rapidly, active management of the global carbon cycle is increasingly urgent. The plan outlines the need for carbon-cycle research on the efficacy and environmental consequences of carbon management policies, strategies, and technologies.
Because humans are an integral part of the carbon cycle, both through influences on â€œnaturalâ€ systems and through direct emissions of greenhouse gases, study of the human elements of the carbon cycle must be more thoroughly integrated into the future research agenda.
The Plan recommends increased exploration of the direct impact of rising greenhouse gas concentrations and carbon-management decisions on ecosystems, species, and natural resources.
Finally, because decisions about the carbon cycle will inevitably be made with imperfect knowledge, the Plan emphasizes the need for a better understanding of uncertainly in all aspects of the global carbon cycle, and improved ways of conveying those uncertainties to policy and decision makers, as well as society at large.
The Belmont Forum, recognizing the valuable contribution of the social sciences to the understanding of and response to global environmental change, invited theISSC to represent the international social science community as a member of the forum in January of 2010.
Shortly after joining the Forum, the need to bring together a global group of representatives of the disciplines embodied in the social sciences in order to critically reflect on the Belmont Forum White Paper, and identify ways to mobilize the broader social science communities to increase the production of social science research relevant to the Belmont Challenge and global environmental change more broadly. Click here to read the report.