Climate Science PDFs
Climate Science PDFs Collection
- The Hot Summer of 2010: Redrawing the Temperature Record Map of Europe
- The summer of 2010 was exceptionally warm in eastern Europe and large parts of Russia. We provide evidence that the anomalous 2010 warmth that caused adverse impacts exceeded the amplitude and spatial extent of the previous hottest summer of 2003. 'Mega-heatwaves' such as the 2003 and 2010 events broke the 500-yr long seasonal temperature records over approximately 50% of Europe. According to regional multi-model experiments, the probability of a summer experiencing 'megaheatwaves' will increase by a factor of 5 to 10 within the next 40 years. However, the magnitude of the 2010 event was so extreme that despite this increase, the occurrence of an analogue over the same region remains fairly unlikely until the second half of the 21st century.
- Global Resilience of Tropical Forest and Savanna to Critical Transitions
- It has been suggested that tropical forest and savanna could represent alternative stable states, implying critical transitions at tipping points in response to altered climate or other drivers. So far, evidence for this idea has remained elusive, and integrated climate models assume smooth vegetation responses. We analyzed data on the distribution of tree cover in Africa, Australia, and South America to reveal strong evidence for the existence of three distinct attractors: forest, savanna, and a treeless state. Empirical reconstruction of the basins of attraction indicates that the resilience of the states varies in a universal way with precipitation. These results allow the identification of regions where forest or savanna may most easily tip into an alternative state, and they pave the way to a new generation of coupled climate models.
- Time to Adapt to a Warming World, But Where’s the Science?
- With dangerous global warming seemingly inevitable, users of climate information— from water utilities to international aid workers—are turning to climate scientists for guidance. But usable knowledge is in short supply VOL 334 SCIENCE
- The 2010 Amazon Drought
- Several global circulation models (GCMs) project an increase in the frequency and severity of drought events affecting the Amazon region as a consequence of anthropogenic greenhouse gas emissions (1). The proximate cause is twofold, increasing Pacific sea surface temperatures (SSTs), which may intensify El Niño Southern Oscillation events and associated periodic Amazon droughts, and an increase in the frequency of historically rarer droughts associated with high Atlantic SSTs and northwest displacement of the intertropical convergence zone (1, 2). Such droughts may lead to a loss of some Amazon forests, which would accelerate climate change (3). In 2005, a major Atlantic SST–associated drought occurred, identified as a 1-in-100-year event (2). Here, we report on a second drought in 2010, when Atlantic SSTs were again high.
- Climate Outlook Looking Much The Same, or Even Worse
- Climate scientists have been feverishly preparing analyses for inclusion in the fifth climate assessment report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) due out in 2013. At the meeting, they gave colleagues a peek at where climate science stands 5 years after their last push to inform the authoritative international evaluation . The climate models are bigger and more sophisticated than ever, speakers reported, but they are yielding the same wide range of possible warming and precipitation changes as they did 5 years ago. But when polled on other areas of concern, researchers say they see more trouble ahead than the previous IPCC assessment had, though less than some scientists had feared
- The Global Extent and Determinants of Savanna and Forest as Alternative Biome States
- Theoretically, fire–tree cover feedbacks can maintain savanna and forest as alternative stable states. However, the global extent of fire-driven discontinuities in tree cover is unknown, especially accounting for seasonality and soils. We use tree cover, climate, fire, and soils data sets to show that tree cover is globally discontinuous. Climate influences tree cover globally but, at intermediate rainfall (1000 to 2500 millimeters) with mild seasonality (less than 7 months), tree cover is bimodal, and only fire differentiates between savanna and forest. These may be alternative states over large areas, including parts of Amazonia and the Congo. Changes in biome distributions, whether at the cost of savanna (due to fragmentation) or forest (due to climate), will be neither smooth nor easily reversible.
- Navigating the Anthropocene: Improving Earth System Governance
- The United Nations conference in Rio de Janeiro in June is an important opportunity to improve the institutional framework for sustainable development. VOL 335 SCIENCE
- Impacts of Biodiversity Loss
- How much diversity is needed to maintain the productivity of ecosystems? VOL 336 SCIENCE
- Generic Indicators for Loss of Resilience Before a Tipping Point Leading to Population Collapse
- Theory predicts that the approach of catastrophic thresholds in natural systems (e.g., ecosystems, the climate) may result in an increasingly slow recovery from small perturbations, a phenomenon called critical slowing down. We used replicate laboratory populations of the budding yeast Saccharomyces cerevisiae for direct observation of critical slowing down before population collapse. We mapped the bifurcation diagram experimentally and found that the populations became more vulnerable to disturbance closer to the tipping point. Fluctuations of population density increased in size and duration near the tipping point, in agreement with the theory. Our results suggest that indicators of critical slowing down can provide advance warning of catastrophic thresholds and loss of resilience in a variety of dynamical systems. SCIENCE VOL 336 1
- Ocean Salinities Reveal Strong Global Water Cycle Intensification During 1950 to 2000
- Fundamental thermodynamics and climate models suggest that dry regions will become drier and wet regions will become wetter in response to warming. Efforts to detect this long-term response in sparse surface observations of rainfall and evaporation remain ambiguous. We show that ocean salinity patterns express an identifiable fingerprint of an intensifying water cycle. Our 50-year observed global surface salinity changes, combined with changes from global climate models, present robust evidence of an intensified global water cycle at a rate of 8 T 5% per degree of surface warming. This rate is double the response projected by current-generation climate models and suggests that a substantial (16 to 24%) intensification of the global water cycle will occur in a future 2° to 3° warmer world. SCIENCE VOL 336
- The Greenhouse Is Making the Water-Poor Even Poorer
- How bad will global warming get? The question has long been cast in terms of how hot the world will get. But perhaps more important to the planet’s inhabitants will be how much rising greenhouse gases crank up the water cycle. Theory and models predict that a strengthening greenhouse will increase precipitation where it is already relatively high—tropical rain forests, for example— and decrease it where it is already low, as in the subtropics. SCIENCE VOL 336 27 APRIL 2012
- Plant Species Richness and Ecosystem Multifunctionality in Global Drylands
- Experiments suggest that biodiversity enhances the ability of ecosystems to maintain multiple functions, such as carbon storage, productivity, and the buildup of nutrient pools (multifunctionality). However, the relationship between biodiversity and multifunctionality has never been assessed globally in natural ecosystems. We report here on a global empirical study relating plant species richness and abiotic factors to multifunctionality in drylands, which collectively cover 41% of Earth’s land surface and support over 38% of the human population. Multifunctionality was positively and significantly related to species richness. The best-fitting models accounted for over 55% of the variation in multifunctionality and always included species richness as a predictor variable. Our results suggest that the preservation of plant biodiversity is crucial to buffer negative effects of climate change and desertification in drylands.
- Financial Costs of Meeting Global Biodiversity Conservation Targets: Current Spending and Unmet Needs
- World governments have committed to halting human-induced extinctions and safeguarding important sites for biodiversity by 2020, but the financial costs of meeting these targets are largely unknown. We estimate the cost of reducing the extinction risk of all globally threatened bird species (by ≥1 International Union for Conservation of Nature Red List category) to be U.S. $0.875 to $1.23 billion annually over the next decade, of which 12% is currently funded. Incorporating threatened nonavian species increases this total to U.S. $3.41 to $4.76 billion annually. We estimate that protecting and effectively managing all terrestrial sites of global avian conservation significance (11,731 Important Bird Areas) would cost U.S. $65.1 billion annually. Adding sites for other taxa increases this to U.S. $76.1 billion annually. Meeting these targets will require conservation funding to increase by at least an order of magnitude.
- Simultaneously Mitigating Near-Term Climate Change and Improving Human Health and Food Security
- Tropospheric ozone and black carbon (BC) contribute to both degraded air quality and global warming. We considered ~400 emission control measures to reduce these pollutants by using current technology and experience. We identified 14 measures targeting methane and BC emissions that reduce projected global mean warming ~0.5°C by 2050. This strategy avoids 0.7 to 4.7 million annual premature deaths from outdoor air pollution and increases annual crop yields by 30 to 135 million metric tons due to ozone reductions in 2030 and beyond. Benefits of methane emissions reductions are valued at $700 to $5000 per metric ton, which is well above typical marginal abatement costs (less than $250). The selected controls target different sources and influence climate on shorter time scales than those of carbon dioxide–reduction measures. Implementing both substantially reduces the risks of crossing the 2°C threshold.
- Carbon Storage with Benefits
- Biochar—a material related to charcoal—has the potential to benefit farming as well as mitigate climate change.
- Biotic Multipliers of Climate Change
- A focus on species interactions may improve predictions of the effects of climate change on ecosystems.
- Old Trees: Extraction, Conservation Can Coexist
- BECAUSE LARGE OLD TREES ARE ESSENTIAL FOR FOREST ECOSYSTEM INTEGRITY AND BIODIVERsity, timber extraction in managed forests should preferentially be concentrated where large old trees are least likely to develop (“Global decline in large old trees,” D. B. Lindenmayer et al., Perspectives, 7 December 2012, p. 1305). However, timber extraction and the conservation of large old trees are not necessarily mutually exclusive. Current forest policy and management practices in Flanders, Belgium, aim to convert even-aged stands (areas in which trees are all the same age) to stands with trees of varying ages in an effort to increase forest ecosystem stability and resilience and to allow trees to grow old. As part of their ecologically sustainable forest management, public forest managers have adopted a large-tree retention approach [see also (1, 2)]. Tree islands within stands managed for production of high-quality timber are reserved for conservation, and trees within these islands will never be extracted. Large old trees of commercially valuable species that have grown beyond the commercially optimal dimensions will not be logged either. And no tree beyond a threshold diameter [currently set at dbh (diameter at breast height) of more than 102 cm] will ever be logged. The strip-shelterwood system (in which trees are cut in linear strips and surrounding trees are given time to grow old) and the coppice-with-standards system (in which some trees are left to grow while others around them are cut) are two examples of forest management that allows the combination of sustainable forest exploitation and conservation of large old trees
- What Does Zero Deforestation Mean?
- Ambiguous defi nitions and metrics create risks for forest conservation and accountability. SCIENCE VOL 342
- Physical Laws Shape Biology
- IN THE PERSPECTIVE “A DYNAMICAL-SYSTEMS VIEW OF STEM CELL biology” (12 October 2012, p. 215), C. Furusawa and K. Kaneko discuss the relevance of dynamic systems biology approaches and the concept of “attractors” to understand cell differentiation and proliferation. We share their excitement in using computational models that apply physical laws to cell fate decision.
- Water in the Balance
- Satellite data may enable improved management of regional groundwater reserves. VOL 340 SCIENCE
