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Toby Bolsen and Matthew A. Shapiro
The importance of framing as a concept is reflected by the massive amount of attention it has received from scholars across disciplines. As a communicative process, framing involves making certain considerations salient as a way to simplify or shape the way in which an audience understands a particular problem and its potential solutions. As recently as the early 2000s, social scientists began to examine how strategic frames in a communication affect both individuals’ beliefs about climate change and the actions they are willing to support to mitigate the likely effects. Research on the effects of how strategic frames influence the attitudes, beliefs, and preferences of individuals in this domain primarily builds on insights from framing theory, which explains that an individual’s attitude or preference in any given context depends on the available, accessible, and most applicable (i.e., perceived strongest) considerations. But it is much more than theory: frames related to the effects and potential solutions for climate change have been employed strategically by various actors in an effort to shape public opinion and public policy.
Perceptions of scientific consensus on climate change are thought to play an important role in determining support for policy actions. Consequently, strategic actors promote a particular agenda by accentuating the inherent uncertainty of climate science, thus casting doubt on the scientific consensus. This has contributed to partisan polarization on climate change and the rise of protective forms of information processing and reasoning in this domain. Strategic messages and frames that resonate with particular subgroups have no effect, or may even backfire, on other segments of the population. Additionally, as individuals who possess different partisan identities become more knowledgeable and numerate, they become increasingly likely to accept information and messages that bolster their existing group loyalties and to reject communications that challenge those identities. Science communicators are thus presented with a considerable barrier to building consensus among the public for action on climate change. In response, scholars have begun to identify strategies and approaches for addressing audiences with the kinds of messages that are most likely to resonate with individuals possessing a diverse range of values and political identities. Further research must identify ways to overcome partisan motivated reasoning on climate change and the persistent and deleterious effects that have resulted from the politicization of climate science.
R. Kelly Garrett
Misperceptions about climate change are widespread, and efforts to correct them must be grounded in an understanding of the factors, both individual and social, that contribute to them. These factors can be organized into four broad categories: motivated reasoning, non-motivated information processing biases, social dynamics, and the information environment. Each type of factor is associated with a host of related strategies for countering false information and beliefs. Motivated biases can be reduced with affirmations, by attempting to depoliticize the issue, and via an evidentiary “tipping point.” Other cognitive biases highlight the importance of clarity, simplicity, and repetition. When correcting errors that contain an inaccurate causal explanation, it is also important to provide an alternative account of the event in question. Message presentation techniques can also facilitate updating beliefs. Beliefs have an important social dimension. Attending to these factors shows the importance of strategies that include: ensuring that lay people consistently have the tools that help them evaluate experts; promoting confidence among those who hold accurate beliefs; facilitating diverse, unsegregated social networks; and providing corrections from unexpected sources. Finally, the prevalence of misinformation in the information environment is highly problematic. Strategies that news organizations can employ include avoiding false balance, adjudicating among contradictory claims, and encouraging accuracy on the part of political elites via fact checking. New technologies may also prove an important tool: search engines that give preferential treatment to accurate information and automated recommendations of accurate information following exposure to inaccuracies both have the potential to change how individuals learn about climate change.
Judith L. Lean
Emergent in recent decades are robust specifications and understanding of connections between the Sun’s changing radiative energy and Earth’s changing climate and atmosphere. This follows more than a century of contentious debate about the reality of such connections, fueled by ambiguous observations, dubious correlations, and lack of plausible mechanisms. It derives from a new generation of observations of the Sun and the Earth made from space, and a new generation of physical climate models that integrate the Earth’s surface and ocean with the extended overlying atmosphere. Space-based observations now cover more than three decades and enable statistical attribution of climate change related to the Sun’s 11-year activity cycle on global scales, simultaneously with other natural and anthropogenic influences. Physical models that fully resolve the stratosphere and its embedded ozone layer better replicate the complex and subtle processes that couple the Sun and Earth.
An increase of ~0.1% in the Sun’s total irradiance, as observed near peak activity during recent 11-year solar cycles, is associated with an increase of ~0.1oC in Earth’s global surface temperature, with additional complex, time-dependent regional responses. The overlying atmosphere warms more, by 0.3oC near 20 km. Because solar radiation impinges primarily at low latitudes, the increased radiant energy alters equator-to-pole thermal gradients, initiating dynamical responses that produce regions of both warming and cooling at mid to high latitudes. Because solar energy deposition depends on altitude as a result of height-dependent atmospheric absorption, changing solar radiation establishes vertical thermal gradients that further alter dynamical motions within the Earth system.
It remains uncertain whether there are long-term changes in solar irradiance on multidecadal time scales other than due to the varying amplitude of the 11-year cycle. If so the magnitude of the additional change is expected to be comparable to that observed during the solar activity cycle. Were the Sun’s activity to become anomalously low, declining during the next century to levels of the Maunder Minimum (from 1645 to 1715), the expected global surface temperature cooling is less than a few tenths oC. In contrast, a scenario of moderate greenhouse gas increase with climate forcing of 2.6 W m−2 over the next century is expected to warm the globe 1.5 to 1.9oC, an order of magnitude more than the hypothesized solar-induced cooling over the same period.
Future challenges include the following: securing sufficiently robust observations of the Sun and Earth to elucidate changes on climatological time scales; advancing physical climate models to simulate realistic responses to changing solar radiation on decadal time scales, synergistically at the Earth’s surface and in the ocean and atmosphere; disentangling the Sun’s influence from that of other natural and anthropogenic influences as the climate and atmosphere evolve; projecting past and future changes in the Sun and Earth’s climate and atmosphere; and communicating new understanding across scientific disciplines, and to political and societal stakeholders.
Bridie McGreavy and David Hart
Direct experience, scientific reports, and international media coverage make clear that the breadth, severity, and multiple consequences from climate change are far-reaching and increasing. Like many places globally, the northeastern United States is already experiencing climate change, including one of the world’s highest rates of ocean warming, reduced durations of winter ice cover on lakes, a marked increase in the frequency of extreme precipitation events, and climate-mediated ecological disruptions of invasive species. Given current and projected changes in ecosystems, communities, and economies, it is essential to find ways to anticipate and reduce vulnerabilities to change and, at the same time, promote sustainable economic development and human well-being.
The emerging field of sustainability science offers a promising conceptual and analytic framework for accelerating progress towards sustainable development. Sustainability science aims to be use-inspired and to connect basic and applied knowledge with solutions for societal benefit. This approach draws from diverse disciplines, theories, and methods organized around the broad goal of maintaining and improving life support systems, ecosystem health, and human well-being. Partners in New England have been using sustainability science as a framework for stakeholder-engaged, interdisciplinary research that has generated use-inspired knowledge and multiple solutions for more than a decade. Sustainability science has helped produce a landscape-scale approach to wetland conservation; emergency response plans for invasive species that threaten livelihoods and cultures; decision support tools for improved water quality management and public health for beach use and shellfish consumption; and the development of robust partnership networks across disciplines and institutions. Understanding and reducing vulnerability to climate change is a central motivating factor in this portfolio of projects because linking knowledge about social-ecological systems with effective policy action requires a holistic view that addresses complex intersecting stressors.
One common theme in these varied efforts is the way that communication fundamentally shapes collaborative research and social, technical, and policy outcomes from sustainability science. Communication as a discipline has, for more than two thousand years, sought to understand how environments and symbols shape human life, forms of social organization, and collective decision making. The result is a body of scholarship and practical techniques that are diverse and well adapted to meet the complexity of contemporary sustainability challenges. The complexity of the issues that sustainability science aspires to solve requires diversity and flexibility to be able to adapt approaches to the specific needs of a situation. Long-term, cross-scale, and multi-institutional sustainability science collaborations show that communication research and practice can help build communities and networks, and advance technical and policy solutions to confront the challenges of climate change and promote sustainability now and in future.
This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Climate Science. Please check back later for the full article.
Dramatic climate changes have occurred in the Baltic Sea region caused by changes in orbital movement in the earth–sun system and the melting of the Fennoscandian Ice Sheet. Added to these longer-term changes, changes have occurred at all timescales, caused mainly by variations in large-scale atmospheric pressure systems due to competition between the meandering midlatitude low-pressure systems and high-pressure systems. Here we follow the development of climate science of the Baltic Sea since observations started in the 18th century to the present. The question of why the water level is sinking around the Baltic Sea coasts could not be answered until the idea of postglacial uplift and the thermal history of the earth were better understood in the 19th century and periodic behavior in time series attracted scientific interest. Herring and sardine fishing successes and failures have led to investigations of fishery and climate change and to the realization that fisheries themselves have strongly negative effects on the marine environment, calling for international assessment efforts. Scientists later introduced the concept of regime shifts when interpreting their data, attributing these to various causes. The increasing amount of anoxic deep water in the Baltic Sea and anthropogenic eutrophication have prompted debate about what is natural and what is anthropogenic, and the scientific outcome of these debates now forms the basis of international management efforts to reduce nutrient leakage from land. The observed increase in atmospheric CO2 and its effects on global warming have focused the climate debate on trends and generated a series of international and regional assessments and research programs that have greatly improved our understanding of climate and environmental changes, bolstering the efforts of earth system science, in which both climate and environmental factors are analyzed together.
In regions such as the Baltic Sea, attributing the causes of climate variability and change has been hampered by the spatial and temporal limitations of observations and by an incomplete understanding of driving mechanisms, leaving room for speculation as to both the reasons for changes and the role of the climate in them. Major achievements of past centuries were developing and organizing regular observation and monitoring programs. The free availability of data sets has supported the development of more accurate forcing functions for Baltic Sea models and made it possible to better model the Baltic Sea–North Sea system, including the development of coupled land–sea–atmosphere models. Most indirect and direct observations of the climate find great variability and stochastic behavior, so conclusions based on short time series are problematic, leading to qualifications about periodicity, trends, and regime shifts. Starting in the 1980s, systematic research into climate change has considerably improved our understanding of regional warming and multiple threats to the Baltic Sea. Several aspects of regional climate and environmental changes and how they interact are, however, unknown and merit future research.
Martin Claussen, Anne Dallmeyer, and Jürgen Bader
There is ample evidence from palaeobotanic and palaeoclimatic reconstructions that during early and mid-Holocene between some 11,700 years (in some regions, a few thousand years earlier) and some 4200 years ago, subtropical North Africa was much more humid and greener than today. This African Humid Period (AHP) was triggered by changes in the orbital forcing, with the climatic precession as the dominant pacemaker. Climate system modeling in the 1990s revealed that orbital forcing alone cannot explain the large changes in the North African summer monsoon and subsequent ecosystem changes in the Sahara. Feedbacks between atmosphere, land surface, and ocean were shown to strongly amplify monsoon and vegetation changes. Forcing and feedbacks have caused changes far larger in amplitude and extent than experienced today in the Sahara and Sahel. Most, if not all, climate system models, however, tend to underestimate the amplitude of past African monsoon changes and the extent of the land-surface changes in the Sahara. Hence, it seems plausible that some feedback processes are not properly described, or are even missing, in the climate system models.
Perhaps even more challenging than explaining the existence of the AHP and the Green Sahara is the interpretation of data that reveal an abrupt termination of the last AHP. Based on climate system modeling and theoretical considerations in the late 1990s, it was proposed that the AHP could have ended, and the Sahara could have expanded, within just a few centuries—that is, much faster than orbital forcing. In 2000, paleo records of terrestrial dust deposition off Mauritania seemingly corroborated the prediction of an abrupt termination. However, with the uncovering of more paleo data, considerable controversy has arisen over the geological evidence of abrupt climate and ecosystem changes. Some records clearly show abrupt changes in some climate and terrestrial parameters, while others do not. Also, climate system modeling provides an ambiguous picture.
The prediction of abrupt climate and ecosystem changes at the end of the AHP is hampered by limitations implicit in the climate system. Because of the ubiquitous climate variability, it is extremely unlikely that individual paleo records and model simulations completely match. They could do so in a statistical sense, that is, if the statistics of a large ensemble of paleo data and of model simulations converge. Likewise, the interpretation regarding the strength of terrestrial feedback from individual records is elusive. Plant diversity, rarely captured in climate system models, can obliterate any abrupt shift between green and desert state. Hence, the strength of climate—vegetation feedback is probably not a universal property of a certain region but depends on the vegetation composition, which can change with time. Because of spatial heterogeneity of the African landscape and the African monsoon circulation, abrupt changes can occur in several, but not all, regions at different times during the transition from the humid mid-Holocene climate to the present-day more arid climate. Abrupt changes in one region can be induced by abrupt changes in other regions, a process sometimes referred to as “induced tipping.” The African monsoon system seems to be prone to fast and potentially abrupt changes, which to understand and to predict remains one of the grand challenges in African climate science.
Neil T. Gavin
Television and cable are two routes by which broadcasters reach the public. Citizens are known to rely on a variety of media sources; however, television is seen by people in a very wide range of geographical locales, as a main or major source of reliable and trusted information. The coverage of climate change by broadcasters is, however, modest relative to press coverage of the topic and reports on topics other than global warming. Journalists in the televisual media can struggle to justify the inclusion of climate change in programming because it can lack the “newsworthiness” that draws editors and reporters to other issues. A range of incentives and pressures have tended to ensure that commentary and claims that stand outside the scientific consensus are represented in “balanced” reporting. The literature on broadcast programming output on climate change is highly diverse and often country specific. Nevertheless, certain features do stand out across locales, notably a focus on alarming (and possibly alarmist) commentary, limited reporting on the causes and consequences of climate change, and widespread reproduction of climate sceptic claims. These common forms of coverage seem unlikely to prompt full understanding of, serious engagement with, or concern about the issue.
Edward Maibach, Bernadette Woods Placky, Joe Witte, Keith Seitter, Ned Gardiner, Teresa Myers, Sean Sublette, and Heidi Cullen
Global climate change is influencing the weather in every region of the United States, often in harmful ways. Yet, like people in many countries, most Americans view climate change as a threat that is distant in space (i.e., not here), time (i.e., not now), and species (i.e., not us). To manage risk and avoid harm, it is imperative that the public, professionals, and policy-makers make decisions with an informed understanding of our changing climate. In the United States, broadcast meteorologists are ideally positioned to educate Americans about the current and projected impacts of climate change in their community. They have tremendous reach, are trusted sources of climate information, and are highly skilled science communicators. When our project began in 2009, we learned that many U.S.-based TV weathercasters were potentially interested in reporting on climate change, but few actually were, citing significant barriers including a lack of time to prepare and air stories, and lack of access to high-quality content that can be rapidly used in their broadcasts, social media, and community presentations. To test the premise that TV weathercasters can be effective climate educators—if supported with high-quality localized climate communication content—in 2010 George Mason University, Climate Central, and WLTX-TV (Columbia, SC) developed and pilot-tested Climate Matters, a series of short on-air (and online) segments about the local impacts of climate change, delivered by the station’s chief meteorologist. During the first year, more than a dozen stories aired. To formally evaluate Climate Matters, we conducted pre- and post-test surveys of local TV news viewers in Columbia. After one year, WLTX viewers had developed a more science-based understanding of climate change than viewers of other local news stations, confirming our premise that when TV weathercasters report on the local implications of climate change, their viewers learn. Through a series of expansions, including the addition of important new partners—the American Meteorological Society, National Aeronautical and Space Administration (NASA), National Oceanic and Atmospheric Administration (NOAA), and Yale University—Climate Matters has become a comprehensive nationwide climate communication resource program for American broadcast meteorologists. As of March 2016, 313 local weathercasters nationwide (at 202 stations in 111 media markets) are participating in the program, receiving new content on a weekly basis. Some leaders in the World Meteorological Organization are now promoting the concept of “TV weather presenters as climate change communicators,” and collaborative discussions are underway with Climate Central. In this article, we review the theoretical basis of the program, detail its development and national scale-up, and conclude with insights for how to develop climate communication initiatives for other professional communities of practice in the U.S. and other countries.
International climate negotiations seek to limit warming to an average of two degrees Celsius (2°C). This objective is justified by the claim that scientists have identified two degrees of warming as the point at which climate change becomes dangerous. Climate scientists themselves maintain that while science can provide projections of possible impacts at different levels of warming, determining what constitutes an acceptable level of risk is not a matter to be decided by science alone, but is a value choice to be deliberated upon by societies as a whole. Hence, while climate science can inform debates about how much warming is too much, it cannot provide a definitive answer to that question. In order to fully understand how climate change came to be defined as a phenomenon with a single global dangerous limit of 2°C, it is necessary to incorporate insights from the social sciences.
Political economy, culture, economics, sociology, geography, and social psychology have all played a role in defining what constitutes an acceptable level of climate risk. These perspectives can be applied through the framework of institutional analysis to examine reports from the Intergovernmental Panel on Climate Change and other international organizations. This interdisciplinary approach offers the potential to provide a comprehensive history of how climate science has been interpreted in policy making. An interdisciplinary analysis is also essential in order to move beyond historical description to provide a narrative of considerable explanatory power. Such insights offer a valuable framework for considering current debates about whether or not it will be possible to limit warming to 2°C.
An orbitally induced increase in summer insolation during the last glacial-interglacial transition enhanced the thermal contrast between land and sea, with land masses heating up compared to the adjacent ocean surface. In North Africa, warmer land surfaces created a low-pressure zone, driving the northward penetration of monsoonal rains originating from the Atlantic Ocean. As a consequence, regions today among the driest of the world were covered by permanent and deep freshwater lakes, some of them being exceptionally large, such as the “Mega” Lake Chad, which covered some 400 000 square kilometers. A dense network of rivers developed.
What were the consequences of this climate change on plant distribution and biodiversity? Pollen grains that accumulated over time in lake sediments are useful tools to reconstruct past vegetation assemblages since they are extremely resistant to decay and are produced in great quantities. In addition, their morphological character allows the determination of most plant families and genera.
In response to the postglacial humidity increase, tropical taxa that survived as strongly reduced populations during the last glacial period spread widely, shifting latitudes or elevations, expanding population size, or both. In the Saharan desert, pollen of tropical trees (e.g., Celtis) were found in sites located at up to 25°N in southern Libya. In the Equatorial mountains, trees (e.g., Olea and Podocarpus) migrated to higher elevations to form the present-day Afro-montane forests. Patterns of migration were individualistic, with the entire range of some taxa displaced to higher latitudes or shifted from one elevation belt to another. New combinations of climate/environmental conditions allowed the cooccurrences of taxa growing today in separate regions. Such migrational processes and species-overlapping ranges led to a tremendous increase in biodiversity, particularly in the Saharan desert, where more humid-adapted taxa expanded along water courses, lakes, and wetlands, whereas xerophytic populations persisted in drier areas.
At the end of the Holocene era, some 2,500 to 4,500 years ago, the majority of sites in tropical Africa recorded a shift to drier conditions, with many lakes and wetlands drying out. The vegetation response to this shift was the overall disruption of the forests and the wide expansion of open landscapes (wooded grasslands, grasslands, and steppes). This environmental crisis created favorable conditions for further plant exploitation and cereal cultivation in the Congo Basin.