Climate Science PDFs
Climate Science PDFs Collection
- Enhanced Seasonal Exchange of CO2 by Northern Ecosystems Since 1960
- Seasonal variations of atmospheric carbon dioxide (CO2) in the Northern Hemisphere have increased since the 1950s, but sparse observations have prevented a clear assessment of the patterns of long-term change and the underlying mechanisms. We compare recent aircraft-based observations of CO2 above the North Pacific and Arctic Oceans to earlier data from 1958 to 1961 and find that the seasonal amplitude at altitudes of 3 to 6 km increased by 50% for 45° to 90°N but by less than 25% for 10° to 45°N. An increase of 30 to 60% in the seasonal exchange of CO2 by northern extratropical land ecosystems, focused on boreal forests, is implicated, substantially more than simulated by current land ecosystem models. The observations appear to signal large ecological changes in northern forests and a major shift in the global carbon cycle.
- Pathways for Conservation
- NEXT WEEK, CONSERVATION SCIENTISTS WILL GATHER AT THE INTERNATIONAL CONGRESS FOR Conservation Biology (ICCB) in Baltimore, Maryland, to grapple with the challenges of preserving our natural world in the face of a growing and increasingly consumptive human population. The natural world provides countless services, such as clean water, protection from fl ooding, and carbon sequestration, while offering opportunities for new medicines, foods, and energy production. Yet these valuable services and opportunities are disappearing along with the species and natural areas that supply them. The needs of a growing human population must be met while conserving the planet’s natural systems. Accomplishing both will depend on making clearer connections between scientifi c results regarding issues such as biodiversity loss and the critical decisions that must be made about conditions that underlie change, such as greenhouse gas emissions and freshwater availability. The good news is that today’s conservation scientists are developing innovative tools and strategies. SCIENCE VOL 341
- A Reconstruction of Regional and Global Temperature for the Past 11,300 Years
- Surface temperature reconstructions of the past 1500 years suggest that recent warming is unprecedented in that time. Here we provide a broader perspective by reconstructing regional and global temperature anomalies for the past 11,300 years from 73 globally distributed records. Early Holocene (10,000 to 5000 years ago) warmth is followed by ~0.7°C cooling through the middle to late Holocene (<5000 years ago), culminating in the coolest temperatures of the Holocene during the Little Ice Age, about 200 years ago. This cooling is largely associated with ~2°C change in the North Atlantic. Current global temperatures of the past decade have not yet exceeded peak interglacial values but are warmer than during ~75% of the Holocene temperature history. Intergovernmental Panel on Climate Change model projections for 2100 exceed the full distribution of Holocene temperature under all plausible greenhouse gas emission scenarios.
- Is Embracing Change Our Best Bet?
- Restoration ecology and conservation biology are both under pressure to adapt to accelerated anthropogenic global change. Pristine areas free from human infl uence no longer exist and, arguably, have not for thousands of years ( 1). Major landcover transformations for agriculture affected vast territories more than 3000 years ago ( 2). Large mammal extinctions in the late Pleistocene (circa 12,000 years ago) were related to human expansion ( 3). And relocation of nowwidespread naturalized species was already happening 4230 years ago, when domestic dogs (dingos) were introduced into Australia by way of southeast Asia ( 4). Thus, humansculpted landscapes are what we have been mostly managing for millennia. Because the rate of alteration has dramatically increased over the past 200 years, those ancient localized impacts now affect most of the world. Additionally, other indirect impacts act at a planetary scale—e.g., increased carbon dioxide concentration and nitrogen deposition
- Hell and High Water: PracticeRelevant Adaptation Science
- Adaptation requires science that analyzes decisions, identifies vulnerabilities, improves foresight, and develops options
- Marine Taxa Track Local Climate Velocities
- Organisms are expected to adapt or move in response to climate change, but observed distribution shifts span a wide range of directions and rates. Explanations often emphasize biological distinctions among species, but general mechanisms have been elusive. We tested an alternative hypothesis: that differences in climate velocity—the rate and direction that climate shifts across the landscape—can explain observed species shifts. We compiled a database of coastal surveys around North America from 1968 to 2011, sampling 128 million individuals across 360 marine taxa. Climate velocity explained the magnitude and direction of shifts in latitude and depth much more effectively than did species characteristics. Our results demonstrate that marine species shift at different rates and directions because they closely track the complex mosaic of local climate velocities. SCIENCE VOL 341 13 SEPTEMBER 2013
- Monsoon Melee
- The rhythms of life across South Asia depend on the Indian monsoon. Climate scientists are locking horns over the cause of the summer deluges
- Climate Change Conversations
- THE THOUSANDS OF PRESENTATIONS AT NEXT WEEK’S MEETING OF THE AMERICAN CHEMICAL SOCIETY (ACS) in New Orleans exemplify one of the many ways scientists converse among themselves about the most recent advances in science. Science and technology continue to reshape the world we live in, and appreciating how these changes, both intended and unintended, come about is a necessity for all citizens in a democratic society. Scientists have a responsibility to help their fellow citizens understand what science and technology can and cannot do for them
- The Global Plight of Pollinators
- Wild pollinators are in decline, and managed honeybees cannot compensate for their loss. 29 MARCH 2013 VOL 339 SCIENCE
- Wildlife decline and social conflict
- Policies aimed at reducing wildlife-related conflict must address the underlying causes
- Assemblage Time Series Reveal Biodiversity Change but Not Systematic Loss
- The extent to which biodiversity change in local assemblages contributes to global biodiversity loss is poorly understood. We analyzed 100 time series from biomes across Earth to ask how diversity within assemblages is changing through time. We quantified patterns of temporal a diversity, measured as change in local diversity, and temporal b diversity, measured as change in community composition. Contrary to our expectations, we did not detect systematic loss of a diversity. However, community composition changed systematically through time, in excess of predictions from null models. Heterogeneous rates of environmental change, species range shifts associated with climate change, and biotic homogenization may explain the different patterns of temporal a and b diversity. Monitoring and understanding change in species composition should be a conservation priority.
- From Past to Future Warming
- Analyses of past observations help to predict the human contribution to future climate change. 21 FEBRUARY 2014 VOL 343 SCIENCE
- Carbon Market Lessons and Global Policy Outlook
- Summary: Ongoing work on linking markets and mixing policies builds on successes and failures in pricing and trading carbon. Closing sentence, 1st paragraph: Are carbon markets seriously challenged or succeeding and on the rise?
- Status and Ecological Effects of the World’s Largest Carnivores
- The largest terrestrial species in the order Carnivora are wide-ranging and rare because of their positions at the top of food webs. They are some of the world’s most admired mammals and, ironically, some of the most imperiled. Most have experienced substantial population declines and range contractions throughout the world during the past two centuries. Because of the high metabolic demands that come with endothermy and large body size, these carnivores often require large prey and expansive habitats. These food requirements and wide-ranging behavior often bring them into confl ict with humans and livestock. This, in addition to human intolerance, renders them vulnerable to extinction. Large carnivores face enormous threats that have caused massive declines in their populations and geographic ranges, including habitat loss and degradation, persecution, utilization, and depletion of prey. We highlight how these threats can affect the conservation status and ecological roles of this planet’s 31 largest carnivores.
- Coupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 Million Years
- During the Middle Miocene, when temperatures were ~3° to 6°C warmer and sea level 25 to 40 meters higher than present, pCO2 was similar to modern levels.
- Changes in Wind Pattern Alter Albatross Distribution and Life-History Traits
- Westerly winds in the Southern Ocean have increased in intensity and moved poleward. Using long-term demographic and foraging records, we show that foraging range in wandering albatrosses has shifted poleward in conjunction with these changes in wind pattern, while their rates of travel and flight speeds have increased. Consequently, the duration of foraging trips has decreased, breeding success has improved, and birds have increased in mass by more than 1 kilogram. These positive consequences of climate change may be temporary if patterns of wind in the southern westerlies follow predicted climate change scenarios. This study stresses the importance of foraging performance as the key link between environmental changes and population processes.
- Freshwater Methane Emissions Offset the Continental Carbon Sink
- Acornerstone of our understanding of the contemporary global carbon cycle is that the terrestrial land surface is an important greenhouse gas (GHG) sink (1, 2). The global land sink is estimated to be 2.6 T 1.7 Pg of C year−1 (variability T range, excluding C emissions because of deforestation) (1). Lakes, impoundments, and rivers are parts of the terrestrial landscape, but they have not yet been included in the terrestrial GHG balance (3, 4). Available data suggest, however, that freshwaters can be substantial sources of CO2 (3, 5) and CH4 (6). Over time, soil carbon reaches freshwaters by lateral hydrological transport, where it can meet several fates, including burial in sediments, further transport to the sea, or evasion to the atmosphere as CO2 or CH4 (7). CH4 emissions may be small in terms of carbon, but CH4 is a more potent GHG than CO2 over century time scales. This study indicates that global CH4 emissions expressed as CO2 equivalents correspond to at least 25% of the estimated terrestrial GHG sink.
- Not All About Consumption
- Resource exploitation can lead to increased ecological impacts even when overall consumption levels stay the same 15 March 2013 VOL 339 SCIENCE
- Defaunation in the Anthropocene
- We live amid a global wave of anthropogenically driven biodiversity loss: species and population extirpations and, critically, declines in local species abundance. Particularly, human impacts on animal biodiversity are an under-recognized form of global environmental change. Among terrestrial vertebrates, 322 species have become extinct since 1500, and populations of the remaining species show 25% average decline in abundance. Invertebrate patterns are equally dire: 67% of monitored populations show 45% mean abundance decline. Such animal declines will cascade onto ecosystem functioning and human well-being. Much remains unknown about this “Anthropocene defaunation”; these knowledge gaps hinder our capacity to predict and limit defaunation impacts. Clearly, however, defaunation is both a pervasive component of the planet’s sixth mass extinction and also a major driver of global ecological change 25 JULY 2014 • VOL 345 ISSUE 6195
- How Does Climate Change Affect Biodiversity?
- The most recent and complex bioclimate models excel at describing species’ current distributions. Yet, it is unclear which models will best predict how climate change will affect their future distributions. 8 SEPTEMBER 2006 VOL 313 SCIENCE
