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President's Corner


Mitigate and adapt≠óbut donít forget the science!

by Richard Anthes, UCAR president

There was no escaping climate change in 2007. The topic took center stage throughout the year, from record warmth in midwinter to the stunning loss of Arctic sea ice last summer (see sidebar) to the Nobel Peace Prize in the fall. The past year’s reports from the Intergovernmental Panel on Climate Change (IPCC) make it clear that our planet is warming at an unprecedented rate and that human beings are the major cause. We are heading into an unknown climate, where weather patterns will change significantly over those we have come to know, expect, and coexist with.

We already know enough to begin taking action on two important fronts: mitigation (reducing emissions to reduce future climate change) and adaptation (reacting to current changes and preparing society for predictable and unforeseen changes that are sure to occur no matter what we do). However, that knowledge is no reason to reduce basic and applied research in climate, weather, human interactions, and related areas. In fact, just the opposite is true! The more we can extend and deepen our knowledge about climate change, the more efficient and effective our mitigation and adaptation will be.

Understanding the complex, changing planet on which we live, how it supports life, and how human activities affect its ability to do so in the future is one of the greatest intellectual challenges facing humanity. It is also one of the most important challenges for society as it seeks to achieve ­prosperity, health, and sustainability.

Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond (National Research Council, 2007, www.nap.edu/catalog.php?record_id=11820)

In spite of remarkable progress over the past several decades, our understanding of the complex physical, chemical, and biological Earth system and its interactions with humans remains, on many levels, rudimentary. We’ve identified many research questions where there is more that we don’t know than we do. And there are certainly still more questions we don’t yet even know we should be asking. Even the feedbacks in the Earth system that we recognize as important in a qualitative way are just beginning to be understood in quantitative ways that can be included in weather, climate, and Earth system models. As emphasized in the recent National Research Council (NRC) survey of space-based observations (see box above), understanding of Earth and its inhabitants is indeed one of humankind’s greatest intellectual challenges, and this alone makes additional research an imperative.

Those who doubt the importance of climate change will cite the gaps in our understanding as reasons to slow down or hold off action. Yet stressing the need to learn more is not the same as discounting what we already know from decades of research on greenhouse gases and their effects. For example, a National Academy of Sciences report in 1979 (often called the Charney report after its leader, Jule Charney) estimated that a 3°C (5.4°F) warming could result from a doubling of carbon dioxide. This is actually not far off the mark: Earth’s surface atmosphere has warmed about 0.75°C (1.35°F) in the last century as CO2 concentrations have risen by about 30%.

The fundamentals: observing and computing

crater
Rick Anthes.
(Photos by Carlye Calvin.)

We may know with near-certainty that the climate will continue to warm over the next century, but the odds on whether it might warm a more-or-less-manageable 1°C (1.8°F) or a potentially catastrophic 5°C (9°F) or more are not known with confidence. As for moisture, one of the important conclusions of the 2007 IPCC report was that most subtropical land areas are likely to receive less precipitation, while high latitudes are very likely to receive more. The signal is not so clear across some other regions, though, including much of the United States.

In order to monitor, understand, predict, and adapt to climate change—including the all-important changes in extreme and impactful weather on local and regional scales, where it really counts—we have a long way to go. Now more than ever, we need better Earth observations, increased computer power to process the observations and run the models, improved weather and climate predictions, and enhanced research on how weather and climate affect social order and life on the planet.

Calls for more funding are a familiar aspect of science. What many observers may not realize is that, in recent years, the nation’s investments in the key areas listed above have been decreasing in real dollars.

For example, observations of the entire Earth—its atmosphere, oceans, land, and ice surfaces—are the foundation for improved understanding of climate change and for computer models that accurately predict weather and climate. Yet the number of space-based sensors for monitoring Earth’s atmosphere will drop by 50% by 2015, due to budget reductions and shortfalls at NASA and NOAA. Imagine flying an airplane into uncharted territory during a storm with half of its instrument panel gone dark. To make our way through a changing climate, we cannot afford to fly half-blind.

There is also no substitute for computing power to understand and predict weather and climate. Larger and faster computers allow scientists to effectively combine the suite of diverse global observations into a meaningful whole and to make predictions and warnings with increasing accuracy and detail for local areas. Ever more powerful computers will be needed to build and run Earth system models that contain biological and chemical processes and human interactions. These advanced models will be essential tools in both understanding and predicting climate change and in societal demands for information. Yet computing power at major climate modeling centers such as NCAR is increasing in a business-as-usual way that does not reflect the importance of the science and the need for vastly improved decision support tools related to climate and weather.

The recent downturn in support for basic observing and computing systems puts us at increased risk as we move forward into a very uncertain world, one in which the timing, frequency, and intensity of a whole range of phenomena—from droughts and heat waves to forest fires and hurricanes—are in question.

Seeking new types of answers to burning questions

Beyond the intellectual challenges they pose, climate and weather changes stand to affect almost every part of our society: public health and safety, economic and social stability, agriculture, water supplies and management, energy production and use, transportation, and military readiness. In each of these areas, policy- and decision makers are clamoring for concrete guidance on what to expect as our climate and weather evolve and how to adapt to changes. For example:

• What kinds of crops are best suited to hotter, more drought-prone areas?

•  How might rising sea level, intensified rainfall, and changes in hurricanes affect cities along the Gulf and Atlantic coasts?

• How long will it take for the Arctic Ocean to experience ice-free conditions in summer?

•  How will energy and water demands and supplies change in my city, state, or region?

Surprises at both poles

Daniel Wildcat
As large parts of the Wilkins Ice Shelf disintegrated, they broke into a sky-blue pattern of exposed deep glacial ice. This true-color image of the Wilkins Ice Shelf was taken by NASA’s MODIS (Moderate Resolution Imaging Spectroradiometer) on 6 March. The Wilkins shelf is located on the Antarctic Peninsula, farther from the South Pole than most of Antarctica. (Illustration courtesy National Snow and Ice Data Center.)

The northern and southern polar regions continue to serve as bellwethers of climate change. As reported last fall in the UCAR Quarterly (www.ucar.edu/communications/quarterly/fall07/arcticmelt.jsp), sea-ice coverage in the Arctic Ocean fell to dramatic new lows last summer. The graphic on page 5 illustrates how much this drop exceeded the range of model projections for the past few years. Aside from the obvious message that Arctic ice is melting rapidly, there is another important lesson. Skeptics often discount climate change projections that seem alarming, but we must remember that these model projections, especially on regional scales, also have the potential to be too conservative, as in this prediction of Arctic sea ice.

In the Southern Ocean adjoining Antarctica, the winter of 2007 saw the greatest sea-ice extent on record, although the 2007 IPCC report notes that no significant change has been observed over the time scale of recent decades. A little ­farther away from the pole, along the Antarctic Peninsula—the fastest-warming region on Earth—glaciers are showing increasing signs of instability. In March 2008, scientists from the U.S. National Snow and Ice Data Center, the British Antarctic Survey, and Taiwan’s Earth Dynamic Research Center announced the rapid deterioration of the Wilkins Ice Shelf, which is roughly the size of Connecticut.

During the month of March, a large iceberg fell away from the seaward edge of the Wilkins shelf, which led to disintegration of some 405 square kilometers (160 square miles) of ice (see image). In 1993, British Antarctic Survey scientist David Vaughan had predicted such a collapse but thought it could take up to 30 years to unfold. The rest of the Wilkins Ice Shelf—the ­largest one in West Antarctica threatened to date by a warming climate—is now ­protected from the sea by a strip of ice only 6 kilometers (3.7 miles) wide.

 

 

In addressing these and other key questions, scientists must provide quantitative as well as qualitative information at ­increasingly regional and local scales. We need to work with users to understand what might happen, what will almost certainly happen, and where the science has yet to support firm conclusions. With increased computing and modeling power, we can expand the type of ensemble climate modeling systems that are beginning to tackle questions on the regional level, such as:

• What scenarios are possible? Most likely?

• What are the worst and best cases?

• What are the probabilities of the different scenarios?

• How can we quantify the risks associated with various contemplated courses of action?

crater
In a set of model runs produced for the 2007 IPCC assessment, the NCAR-based Community Climate System Model projected that the Arctic Oceanís summer sea ice would began a sharp decline in coverage during the 2010s. However, the decline from 2000 through 2007 in September ice extent (blue trace) exceeded the projections of any member of this ensemble (ensemble range in yellow, mean in red). (Illustration courtesy CCSM and Marika Holland.)

Meteorologists and social scientists are exploring new types of probabilistic weather prediction (see article, page 10). Society will need similar tools on the much longer time frames of climate prediction.

As for mitigating climate change, there are many ways for individuals and organizations to reduce emissions now, as discussed in my fall 2007 column (www.ucar.edu/communications/quarterly/fall07/president.jsp). There is also growing research and popular interest in bio- and geoengineering techniques for reducing or sequestering emissions on a regional or global scale. These proposals include techniques as varied as afforestation (creating new forests in long-treeless areas), growing biofuels of many types, placing mirrors into orbit, or injecting reflective aerosols (particles) into the atmosphere. The lessons learned from the checkered history of weather modification should be heeded here; unintended consequences may be much more severe when it’s the global climate that is being intentionally modified.

As we consider adaptation and mitigation, we need to be fully aware of important assumptions that may go unacknowledged yet can influence our views of the future profoundly. For example, the IPCC climate scenarios are powerful and sophisticated tools. They take into account various potential changes in population, the economy, technology, and fuel use in depicting how the next century of emissions and associated climate change could unfold. Yet, as pointed out by several researchers in a recent Nature commentary (see article, page 3), the IPCC scenarios implicitly assume that the bulk of the challenge of reducing future emissions will occur in the absence of climate policies, an assumption that may be optimistic. If policymakers fail to take these assumptions into account, they may under­estimate the challenges that lie ahead. It’s not enough for Congress, state and local governments, and corporations to be aware of climate change: they must have as firm a grasp as possible on likelihoods, probabilities, and possibilities.

Caution: science under construction

Our current ideas on how to deal with climate change rest on a scientific foundation that remains only partially built. Especially when it comes to large-scale mitigation efforts, we may know just enough to be dangerous. People will inevitably make choices based on today’s far-from-complete scientific knowledge (society cannot stand still while we do our work), but we must learn more.

Enhanced observations of Earth are needed to validate and improve climate models, support more accurate and precise predictions, confirm or deny these predictions, and detect surprises. Physical as well as social scientists must listen to stakeholders, map out our vulnerabilities to extreme weather, and learn how to increase society’s flexibility and resilience in the face of a climate never before experienced by humans. And we must develop the advanced models that can greatly improve our forecasting and warning systems and sharpen our look into the future.
Will we as a community be able to meet these national needs? As a result of budget battles between the White House and Congress, federal funding for climate, weather, and other Earth science research at NASA, NOAA, and NSF will drop in real terms this year—for the fourth year in a row—while our ability to monitor Earth’s vital signs begins to decline.

Future leaders in the White House and Congress will be forced to juggle many priorities. If climate change ranks among the top threats facing our planet, as I and many others believe, then it seems imperative that we invest in observing, understanding, and predicting our climate at a level commensurate with the risk we face, while at the same time carrying out unprecedented mitigation and adaptation efforts on a local, national, and global basis. ♦

 

Rick Anthes

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