Discuss Climate Change at the Political Discourse; Policy Implications Of Warming Permafrost
Permafrost is perennially frozen ground occurring in about 24% of the exposed land surface ...
Permafrost is perennially frozen ground occurring in about 24% of the exposed land surface in the Northern Hemisphere. The distribution of permafrost is controlled by air temperature and, to a lesser extent, by snow depth, vegetation, orientation to the sun and soil properties. Any location with annual average air temperatures below freezing can potentially form permafrost.
Snow is an effective insulator and modulates the effect of air temperature, resulting in permafrost temperatures up to 6°C higher than the local mean annual air temperature. Most of the current permafrost formed during or since the last ice age and can extend down to depths of more than 700 meters in parts of northern Siberia and Canada. Permafrost includes the contents of the ground before it was frozen, such as bedrock, gravel, silt and organic material. Permafrost often contains large lenses, layers and wedges of pure ice that grow over many years as a result of annual freezing and thawing of the surface soil layer.
Although nearly all domain experts agree that human CO2 emissions are altering the world's climate, segments of the public remain unconvinced by the scientific evidence. Internet blogs have become a vocal platform for climate denial, and bloggers have taken a prominent and influential role in questioning climate science. We report a survey (N > 1100) of climate blog users to identify the variables underlying acceptance and rejection of climate science. Paralleling previous work, we find that endorsement of a laissez-faire conception of free-market economics predicts rejection of climate science (r ~ 0.80 between latent constructs). Endorsement of the free market also predicted the rejection of other established scientific findings, such as the facts that HIV causes AIDS and that smoking causes lung cancer. We additionally show that endorsement of a cluster of conspiracy theories (e.g., that the CIA killed Martin-Luther King or that NASA faked the moon landing) predicts rejection of climate science as well as the rejection of other scientific findings, above and beyond endorsement of laissez-faire free markets. This provides empirical confirmation of previous suggestions that conspiracist ideation contributes to the rejection of science. Acceptance of science, by contrast, was strongly associated with the perception of a consensus among scientists.
Anthropogenic climate change is likely to cause continuing global sea level rise1, but some processes within the Earth system may mitigate the magnitude of the projected effect. Regional and global climate models simulate enhanced snowfall over Antarctica, which would provide a direct offset of the future contribution to global sea level rise from cryospheric mass loss2, 3 and ocean expansion4. Uncertainties exist in modelled snowfall5, but even larger uncertainties exist in the potential changes of dynamic ice discharge from Antarctica1, 6 and thus in the ultimate fate of the precipitation-deposited ice mass. Here we show that snowfall and discharge are not independent, but that future ice discharge will increase by up to three times as a result of additional snowfall under global warming. Our results, based on an ice-sheet model7 forced by climate simulations through to the end of 2500 (ref. 8), show that the enhanced discharge effect exceeds the effect of surface warming as well as that of basal ice-shelf melting, and is due to the difference in surface elevation change caused by snowfall on grounded versus floating ice. Although different underlying forcings drive ice loss from basal melting versus increased snowfall, similar ice dynamical processes are nonetheless at work in both; therefore results are relatively independent of the specific representation of the transition zone. In an ensemble of simulations designed to capture ice-physics uncertainty, the additional dynamic ice loss along the coastline compensates between 30 and 65 per cent of the ice gain due to enhanced snowfall over the entire continent. This results in a dynamic ice loss of up to 1.25 metres in the year 2500 for the strongest warming scenario. The reported effect thus strongly counters a potential negative contribution to global sea level by the Antarctic Ice Sheet.
This study is the first evaluation of dynamical downscaling using the Weather Research and Forecasting (WRF) Model on a 4 km × 4 km high resolution scale in the eastern US driven by the new Community Earth System Model version 1.0 (CESM v1.0). First we examined the global and regional climate model results, and corrected an inconsistency in skin temperature during the downscaling process by modifying the land/sea mask. In comparison with observations, WRF shows statistically significant improvement over CESM in reproducing extreme weather events, with improvement for heat wave frequency estimation as high as 98%. The fossil fuel intensive scenario Representative Concentration Pathway (RCP) 8.5 was used to study a possible future mid-century climate extreme in 2057–9. Both the heat waves and the extreme precipitation in 2057–9 are more severe than the present climate in the Eastern US. The Northeastern US shows large increases in both heat wave intensity (3.05 °C higher) and annual extreme precipitation (107.3 mm more per year).
The basic evidence for the discovery came from the work of the Collaborative Research Centre "Fluids and Volatiles in Subduction Zones (SFB 574). For more than ten years the project has been extensively exploring volcanoes of Central America. "Among others pieces of evidence, we have observations of ash layers in the seabed and have reconstructed the history of volcanic eruptions for the past 460,000 years," says GEOMAR volcanologist Dr Steffen Kutterolf, who has been with SFB 574 since its founding. Particular patterns started to appear. "There were periods when we found significantly more large eruptions than in others" says Kutterolf, the lead author of the Geology article.After comparing these patterns with the climate history, there was an amazing match. The periods of high volcanic activity followed fast, global temperature increases and associated rapid ice melting.
To expand the scope of the discoveries, Dr Kutterolf and his colleagues studied other cores from the entire Pacific region. These cores had been collected as part of the International Integrated Ocean Drilling Program (IODP) and its predecessor programmes. They record more than a million years of Earth's history. "In fact, we found the same pattern from these cores as in Central America" says geophysicist Dr Marion Jegen from GEOMAR, who also participated in the recent study. Together with colleagues at Harvard University, the geologists and geophysicists searched for a possible explanation. They found it with the help of geological computer models. "In times of global warming, the glaciers are melting on the continents relatively quickly. At the same time the sea level rises. The weight on the continents decreases, while the weight on the oceanic tectonic plates increases. Thus, the stress changes within in the Earth to open more routes for ascending magma" says Dr Jegen.
The rate of global cooling at the end of the warm phases is much slower, so there are less dramatic stress changes during these times. "If you follow the natural climate cycles, we are currently at the end of a really warm phase. Therefore, things are volcanically quieter now. The impact from human-made warming is still unclear based on our current understanding" says Dr Kutterolf. The next step is to investigate shorter-term historical variations to better understand implications for the present day.
A rigorous detection of Milankovitch periodicities in volcanic output across the Pleistocene-Holocene ice age has remained elusive. We report on a spectral analysis of a large number of well-preserved ash plume deposits recorded in marine sediments along the Pacific Ring of Fire. Our analysis yields a statistically significant detection of a spectral peak at the obliquity period. We propose that this variability in volcanic activity results from crustal stress changes associated with ice age mass redistribution. In particular, increased volcanism lags behind the highest rate of increasing eustatic sea level (decreasing global ice volume) by 4.0 ± 3.6 k.y. and correlates with numerical predictions of stress changes at volcanically active sites. These results support the presence of a causal link between variations in ice age climate, continental stress field, and volcanism.
Over the past twenty years of United Nations (UN) talks about climate change, little progress has been made in coordinating national efforts to cut the growth of carbon dioxide emissions. In a Commentary on http://www.nature.com/nclimate/journ...imate1783.html Glen Peters and colleagues show that humankind will probably face a rise in temperature of between 4–6 °C by the end of this century if significant mitigation actions do not happen now. They have contributed an estimate of the 2012 global CO2 emissions pathways to the Global Carbon Budget (Carbon Budget) — a report produced by the Global Carbon Project, an international cooperation of scientists working to support policymakers in slowing down the rate at which greenhouse-gas concentrations are increasing in the atmosphere.