-
A globally coherent fingerprint of climate change impacts across natural systems
-
Causal attribution of recent biological trends to climate change is complicated because non-climatic influences dominate local, short-term biological changes. Any underlying signal from climate change is likely to be revealed by analyses that seek systematic trends across diverse species and geographic regions; however, debates within the Intergovernmental Panel on Climate Change (IPCC) reveal several definitions of a ‘systematic trend’. Here, we explore these differences, apply diverse analyses to more than 1,700 species, and show that recent biological trends match climate change predictions. Global meta-analyses documented significant range shifts averaging 6.1 km per decade towards the poles (or metres per decade upward), and significant mean advancement of spring events by 2.3 days per decade. We define a diagnostic fingerprint of temporal and spatial ‘sign-switching’ responses uniquely predicted by twentieth century climate trends. Among appropriate long-term/large-scale/multi-species data sets, this diagnostic fingerprint was found for 279 species. This suite of analyses generates ‘very high confidence’ (as laid down by the IPCC) that climate change is already affecting living systems.
Located in
Resources
/
Climate Science Documents
-
Autopsy of two mega-heatwaves
-
Record-breaking heatwaves in 2003 and 2010 surprised both the public and experts. Observations provide new insights into how temperatures escalated to unprecedented values through the interaction of boundary-layer dynamics and land surface drying.
Located in
Resources
/
Climate Science Documents
-
Committed terrestrial ecosystem changes due to climate change
-
Targets for stabilizing climate change are often based on considerations of the impacts of different levels of global warming, usually assessing the time of reaching a particular level of warming. However, some aspects of the Earth system, such as global mean temperatures1 and sea level rise due to thermal expansion2 or the melting of large ice sheets3 , continue to respond long after the stabilization of radiative forcing. Here we use a coupled climate–vegetation model to show that in turn the terrestrial biosphere shows significant inertia in its response to climate change. We demonstrate that the global terrestrial biosphere can continue to change for decades after climate stabilization. We suggest that ecosystems can be committed to long-term change long before any response is observable: for example, we find that the risk of significant loss of forest cover in Amazonia rises rapidly for a global mean temperature rise above 2 ◦ C. We conclude that such committed ecosystem changes must be considered in the definition of dangerous climate change, and subsequent policy development to avoid it.
Located in
Resources
/
Climate Science Documents
-
An extreme climatic event alters marine ecosystem structure in a global biodiversity hotspot
-
Extreme climatic events, such as heat waves, are predicted to increase in frequency and magnitude as a consequence of global warming but their ecological effects are poorly understood, particularly in marine ecosystems1–3. In early 2011, the marine ecosystems along the west coast of Australia -- a global hotspot of biodiversity and endemism 4,5 -- experienced the highest-magnitude warming event on record. Sea temperatures soared to unprecedented levels and warming anomalies of 2–4 ◦ C persisted for more than ten weeks along >2,000 km of coastline. We show that biodiversity patterns of temperate seaweeds, sessile invertebrates and demersal fish were significantly different after the warming event, which led to a reduction in the abundance of habitat-forming seaweeds and a subsequent shift in community structure towards a depauperate state and a tropicalization of fish communities. We conclude that extreme climatic events are key drivers of biodiversity patterns and that the frequency and intensity of such episodes have major implications for predictive models of species distribution and ecosystem structure, which are largely based on gradual warming trends.
Located in
Resources
/
Climate Science Documents
-
Consequences of widespread tree mortality triggered by drought and temperature stress
-
Forests provide innumerable ecological, societal and climatological benefits, yet they are vulnerable to drought and temperature extremes. Climate-driven forest die-off from drought and heat stress has occurred around the world, is expected to increase with climate change and probably has distinct consequences from those of other forest disturbances. We examine the consequences of drought- and climate-driven widespread forest loss on ecological communities, ecosystem functions, ecosystem services and land–climate interactions. Furthermore, we highlight research gaps that warrant study. As the global climate continues to warm, understanding the implications of forest loss triggered by these events will be of increasing importance.
Located in
Resources
/
Climate Science Documents
-
Energy consumption and the unexplained winter warming over northern Asia and North America
-
The worldwide energy consumption in 2006 was close to 498 exajoules. This is equivalent to an energy convergence of 15.8 TW into the populated regions, where energy is consumed and dissipated into the atmosphere as heat. Although energy consumption is sparsely distributed over the vast Earth surface and is only about 0.3% of the total energy transport to the extratropics by atmospheric and oceanic circulations, this anthropogenic heating could disrupt the normal atmospheric circulation pattern and produce a far-reaching effect on surface air temperature. We identify the plausible climate impacts of energy consumption using a global climate model. The results show that the inclusion of energy use at 86 model grid points where it exceeds 0.4 W m−2 can lead to remote surface temperature changes by as much as 1K in mid- and high latitudes in winter and autumn over North America and Eurasia. These regions correspond well to areas with large differences in surface temperature trends between observations and global warming simulations forced by all natural and anthropogenic forcings 1. We conclude that energy consumption is probably a missing forcing for the additional winter warming trends in observations.
Located in
Resources
/
Climate Science Documents
-
Analysing fossil-fuel displacement
-
It is commonly assumed that fossil fuels can be replaced by alternative forms of energy. Now research challenges this assumption, and highlights the role of non-technological solutions to reduce fossil-fuel consumption.
Located in
Resources
/
Climate Science Documents
-
Comment: Don’t judge species on their origins
-
SUMMARY: Conservationists should assess organisms on environmental impact rather than on whether they are natives, argue Mark Davis and 18 other ecologists. FROM THE TEXT: Nativeness is not a sign of evolutionary fitness or of a species having positive effects.The insect currently suspected to be killing
more trees than any other in North Americais the native mountain pine beetle Dendroctonus ponderosae. Classifying biota according to their adherence to cultural standards of belonging, citizenship, fair play and
morality does not advance our understanding of ecology. Over the past few decades, this perspective has led many conservation and restoration efforts down paths that make little ecological or economic sense
Located in
Resources
/
Climate Science Documents
-
Activation of old carbon by erosion of coastal and subsea permafrost in Arctic Siberia
-
The future trajectory of greenhouse gas concentrations depends on interactions between climate and the biogeosphere1,2. Thawing of Arctic permafrost could release significant amounts of carbon into the atmosphere in this century3. Ancient Ice Complex deposits outcropping along the 7,000-kilometre-long coastline of the East Siberian Arctic Shelf (ESAS)4,5, and associated shallow subsea permafrost6,7, are two large pools of permafrost carbon8, yet their vulnerabilities towards thawing and decomposition are largely unknown9–11. Recent Arctic warming is stronger than has been predicted by several degrees, and is particularly pronounced over the coastal ESAS region12,13. There is thus a pressing need to improve our understanding of the links between permafrost carbon and climate in this relatively inaccessible region. Here we show that extensive release of carbon from these Ice Complex deposits dominates (57 6 2 per cent) the sedimentary carbon budget of the ESAS, the world’s largest continental shelf, over- whelming the marine and topsoil terrestrial components. Inverse modelling of the dual-carbon isotope composition of organic carbon accumulating in ESAS surface sediments, using Monte Carlo simulations to account for uncertainties, suggests that 44 6 10 teragrams of old carbon is activated annually from Ice Complex permafrost, an order of magnitude more than has been suggested by previous studies14. We estimate that about two-thirds (66 6 16 per cent) of this old carbon escapes to the atmosphere as carbon dioxide, with the remainder being re-buried in shelf sediments. Thermal collapse and erosion of these carbon-rich Pleistocene coastline and seafloor deposits may accelerate with Arctic amplification of climate warming 2,13.
Located in
Resources
/
Climate Science Documents
-
Carbon loss from an unprecedented Arctic tundra wildfire
-
Arctic tundra soils store large amounts of carbon (C) in organic soil layers hundreds to thousands of years old that insulate, and in some cases maintain, permafrost soils1,2. Fire has been largely absent from most of this biome since the early Holocene epoch3, but its frequency and extent are increasing, probably in response to climate warming4. The effect of fires on the C balance of tundra landscapes, however, remains largely unknown. The Anaktuvuk River fire in 2007 burned 1,039 square kilometres of Alaska’s Arctic slope, making it the largest fire on record for the tundra biome and doubling the cumulative area burned since 1950 (ref. 5). Here we report that tundra ecosystems lost 2,016 6 435 g C m22 in the fire, an amount two orders of magnitude larger than annual net C exchange in undisturbed tundra6. Sixty per cent of this C loss was from soil organic matter, and radiocarbon dating of residual soil layers revealed that the maximum age of soil C lost was 50 years. Scaled to the entire burned area, the fire released approximately 2.1 teragrams of C to the atmosphere, an amount similar in magnitude to the annual net C sink for the entire Arctic tundra biome averaged over the last quarter of the twentieth century7. The mag- nitude of ecosystem C lost by fire, relative to both ecosystem and biome-scale fluxes, demonstrates that a climate-driven increase in tundra fire disturbance may represent a positive feedback, potentially offsetting Arctic greening 8 and influencing the net C balance of the tundra biome.
Located in
Resources
/
Climate Science Documents
