An increasing carbon sink?

September 2015 - via Science Journal Since 1870, Earth's oceans have absorbed more than one-quarter of the carbon dioxide emitted to the atmosphere from fossil fuel burning and other human activities, thereby dramatically slowing climate change (1). The Southern Ocean is responsible for ~40% of this global ocean carbon sink (2). Recent studies have suggested that the rate of carbon uptake by the Southern Ocean may be slowing (3, 4). Such a positive climate feedback effect would reduce the Southern Ocean's capacity to slow climate change. On page 1221 of this issue, Landschützer et al. show that although the rate of carbon uptake by the Southern Ocean slowed between the 1980s and early 2000s, it began to strengthen again in 2002 and continued to do so until at least 2012 (5). Read more: An increasing carbon sink?

Meteorology: Big coastal storms to come

September 2015 - via Nature Journal Three major coastal cities on different continents could get walloped by tropical cyclones during the next century because of climate change. Ning Lin of Princeton University in New Jersey and Kerry Emanuel of the Massachusetts Institute of Technology in Cambridge ran statistical models of how storms form near the cities of… Read more: Big coastal storms to come

Carbon dioxide levels peak up high

August 2015 - via Nature Journal The carbon dioxide concentration in Earth's upper atmosphere is increasing at more than twice the average rate observed at the surface. Jia Yue of Hampton University in Virginia and his colleagues analysed CO2 measurements at different atmospheric heights and latitudes between 2002 and 2014 using a satellite-borne infrared radiometer. They found… Read more: Carbon dioxide levels peak up high

Soil carbon trends

August 2015 - via Nature Climate Change Soils contain the largest carbon stock in the terrestrial biosphere, so their response to climate change is important. However, soil carbon responses to warming from both modelling and experimental studies are mixed, and the net effect remains unclear. Read more: Soil carbon trends

Temperate forest health in an era of emerging megadisturbance

August 2015 - via Science Journal Although disturbances such as fire and native insects can contribute to natural dynamics of forest health, exceptional droughts, directly and in combination with other disturbance factors, are pushing some temperate forests beyond thresholds of sustainability. Interactions from increasing temperatures, drought, native insects and pathogens, and uncharacteristically severe wildfire are resulting in forest mortality beyond the levels of 20th-century experience. Additional anthropogenic stressors, such as atmospheric pollution and invasive species, further weaken trees in some regions. Although continuing climate change will likely drive many areas of temperate forest toward large-scale transformations, management actions can help ease transitions and minimize losses of socially valued ecosystem services. Read more here: Temperate forest health in an era of emerging megadisturbance

Beef farming brings on warming

August 2015 - via Science Journal The most climate-friendly methods of beef production may not be enough to reduce the environmental effects of raising cattle. Mark Newman/FLPA/imagebroker/REX Raymond Pierrehumbert at the University of Oxford, UK, and Gidon Eshel at Bard College in Annandale-on-Hudson in New York modelled the warming effects of five different ways of producing beef, including intensive feedlot systems (pictured) and pasture-based methods. Their analysis was based on the known amounts of greenhouse gases produced by each method. Read more: Beef farming brings on warming

Drought effects on carbon cycling

July 2015 - via Science Journal The impacts of climate extremes on terrestrial ecosystems are poorly understood but important for predicting carbon cycle feedbacks to climate change. Coupled climate–carbon cycle models typically assume that vegetation recovery from extreme drought is immediate and complete, which conflicts with the understanding of basic plant physiology. We examined the recovery of stem growth in trees after severe drought at 1338 forest sites across the globe, comprising 49,339 site-years, and compared the results with simulated recovery in climate-vegetation models. We found pervasive and substantial “legacy effects” of reduced growth and incomplete recovery for 1 to 4 years after severe drought. Legacy effects were most prevalent in dry ecosystems, among Pinaceae, and among species with low hydraulic safety margins. In contrast, limited or no legacy effects after drought were simulated by current climate-vegetation models. Our results highlight hysteresis in ecosystem-level carbon cycling and delayed recovery from climate extremes. Read more: Pervasive drought legacies in forest ecosystems and their implications for carbon cycle models

Recent hiatus caused by decadal shift in Indo-Pacific heating

July 2015 - by Veronica Nieves, Josh K. Willis, William C. Patzert - via Science Journal Recent modeling studies have proposed different scenarios to explain the slowdown in surface temperature warming in the most recent decade. Some of these studies seem to support the idea of internal variability and/or rearrangement of heat between the surface and the ocean interior. Others suggest that radiative forcing might also play a role. Our examination of observational data over the past two decades shows some significant differences when compared to model results from reanalyses and provides the most definitive explanation of how the heat was redistributed. We find that cooling in the top 100-meter layer of the Pacific Ocean was mainly compensated for by warming in the 100- to 300-meter layer of the Indian and Pacific Oceans in the past decade since 2003. Read more: Recent hiatus caused by decadal shift in Indo-Pacific heating

Sea warming caused extreme rain (Russia 2012)

July 2015 - via Nature Journal Intense rainfall that caused a devastating flash flood in a Russian town in 2012 (pictured) has been linked to the increasing surface temperature of the Black Sea. Mikhail Mordasov/AFP/Getty The flood in the town of Krymsk killed more than 170 people after an unprecedented amount of rain — twice the previous record — fell in a single night. Edmund Meredith at the GEOMAR Helmholtz Centre for Ocean Research in Kiel, Germany, and his co-workers used an atmospheric model to study the sensitivity of this event to Black Sea warming. They found that simulations using current Black Sea surface tem… Read more: Black Sea warming caused extreme rain

Sea-level rise due to polar ice sheet loss during past warm periods

July 2015 - via Science Journal BACKGROUND Although thermal expansion of seawater and melting of mountain glaciers have dominated global mean sea level (GMSL) rise over the last century, mass loss from the Greenland and Antarctic ice sheets is expected to exceed other contributions to GMSL rise under future warming. To better constrain polar ice-sheet response to warmer temperatures, we draw on evidence from interglacial periods in the geologic record that experienced warmer polar temperatures and higher GMSLs than present. Coastal records of sea level from these previous warm periods demonstrate geographic variability because of the influence of several geophysical processes that operate across a range of magnitudes and time scales. Inferring GMSL and ice-volume changes from these reconstructions is nontrivial and generally requires the use of geophysical models. ADVANCES Interdisciplinary studies of geologic archives have ushered in a new era of deciphering magnitudes, rates, and sources of sea-level rise. Advances in our understanding of polar ice-sheet response to warmer climates have been made through an increase in the number and geographic distribution of sea-level reconstructions, better ice-sheet constraints, and

Air pollution triggers floods (China 2013)

July 2015 - via Nature In July 2013, heavy rainfall resulted in a devastating flood in the mountains northwest of the Sichuan Basin in China (pictured). The basin has seen increasing industrial activity in the past few decades. Jiwen Fan at the Pacific Northwest National Laboratory in Richland, Washington, and her team modelled the region's atmospheric processes during the storm using different levels of aerosol emissions. By setting the modelled emissions at a level similar to that before China'… Read more: Air pollution triggers floods

15 Strangest Weather Events So Far in 2015

June 2015 - by Jon Erdman - via The Weather Channel The first half of 2015 has featured some truly strange weather. Floods have hammered places in exceptional drought -- some that are typically the driest in the world. We've seen feet of snow in a matter of weeks, as well as a stunning lack of snow with potentially dire consequences. Read more here: 15 Strangest Weather Events So Far in 2015