Regional temperature and precipitation changes under high-end (≥4°C) global warming

Climate models vary widely in their projections of both global mean temperature rise and regional climate changes, but are there any systematic differences in regional changes associated with different levels of global climate sensitivity? This paper examines model projections of climate change over the twenty-first century from the Intergovernmental Panel on Climate Change Fourth Assessment Report which used the A2 scenario from the IPCC Special Report on Emissions Scenarios, assessing whether different regional responses can be seen in models categorized as 'high-end' (those projecting 4°C or more by the end of the twenty-first century relative to the preindustrial). It also identifies regions where the largest climate changes are projected under high-end warming. The mean spatial patterns of change, normalized against the global rate of warming, are generally similar in high-end and 'non-high-end' simulations. The exception is the higher latitudes, where land areas warm relatively faster in boreal summer in high-end models, but sea ice areas show varying differences in boreal winter. Many continental interiors warm approximately twice as fast as the global average, with this being particularly accentuated in boreal summer, and the winter-time Arctic Ocean temperatures rise more than three times faster than the global average. Large temperature increases and precipitation decreases are projected in some of the regions that currently experience water resource pressures, including Mediterranean fringe regions, indicating enhanced pressure on water resources in these areas.     

Water availability in +2°C and +4°C worlds

While the parties to the UNFCCC agreed in the December 2009 Copenhagen Accord that a 2°C global warming over pre-industrial levels should be avoided, current commitments on greenhouse gas emissions reductions from these same parties will lead to a 50?:?50 chance of warming greater than 3.5°C. Here, we evaluate the differences in impacts and adaptation issues for water resources in worlds corresponding to the policy objective (+2°C) and possible reality (+4°C). We simulate the differences in impacts on surface run-off and water resource availability using a global hydrological model driven by ensembles of climate models with global temperature increases of 2°C and 4°C. We combine these with UN-based population growth scenarios to explore the relative importance of population change and climate change for water availability. We find that the projected changes in global surface run-off from the ensemble show an increase in spatial coherence and magnitude for a +4°C world compared with a +2°C one. In a +2°C world, population growth in most large river basins tends to override climate change as a driver of water stress, while in a +4°C world, climate change becomes more dominant, even compensating for population effects where climate change increases run-off. However, in some basins where climate change has positive effects, the seasonality of surface run-off becomes increasingly amplified in a +4°C climate.     

Rethinking adaptation for a 4°C world

With weakening prospects of prompt mitigation, it is increasingly likely that the world will experience 4°C and more of global warming. In such a world, adaptation decisions that have long lead times or that have implications playing out over many decades become more uncertain and complex. Adapting to global warming of 4°C cannot be seen as a mere extrapolation of adaptation to 2°C; it will be a more substantial, continuous and transformative process. However, a variety of psychological, social and institutional barriers to adaptation are exacerbated by uncertainty and long timeframes, with the danger of immobilizing decision-makers. In this paper, we show how complexity and uncertainty can be reduced by a systematic approach to categorizing the interactions between decision lifetime, the type of uncertainty in the relevant drivers of change and the nature of adaptation response options. We synthesize a number of issues previously raised in the literature to link the categories of interactions to a variety of risk-management strategies and tactics. Such application could help to break down some barriers to adaptation and both simplify and better target adaptation decision-making. The approach needs to be tested and adopted rapidly.     

Heat conductivity of water near 4°C

The results of short-term nonsteady-state measurements do not confirm the view that the heat conductivity of water behaves abnormally in the vicinity of 4°C.Notation L thickness of the liquid layer, m - T temperature, K - q heat flux, W/m² - thermal conductivity, W/m·deg K. Indices 0 and L denote the beginning and end of the layer, respectively Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 39, No. 2, pp. 339–342, August, 1980.     

Climate-induced population displacements in a 4°C+ world

Massive population displacements are now regularly presented as one of the most dramatic possible consequences of climate change. Current forecasts and projections show that regions that would be affected by such population movements are low-lying islands, coastal and deltaic regions, as well as sub-Saharan Africa. Such estimates, however, are usually based on a 2°C temperature rise. In the event of a 4°C+ warming, not only is it likely that climate-induced population movements will be more considerable, but also their patterns could be significantly different, as people might react differently to temperature changes that would represent a threat to their very survival. This paper puts forward the hypothesis that a greater temperature change would affect not only the magnitude of the associated population movements, but also--and above all--the characteristics of these movements, and therefore the policy responses that can address them. The paper outlines the policy evolutions that climate-induced displacements in a 4°C+ world would require.     

A global carbon market?

This paper explores the prospects for a global carbon market as the centerpiece of any serious attempt to reach the ambitious goal for greenhouse gas (GHG) reductions set by climate scientists. My aim is to clarify the extent to which we know what policy might best support global decarbonisation. We begin by discussing what we might mean by a global carbon market and its theoretical properties. We then go on to discuss the EU Emissions Trading System experience and the recent experience with the Australian carbon tax. Next, we assess recent carbon market initiatives in the US and in China. My argument is that while establishing the amount of emissions required and dividing it up acceptably between countries requires an enormous scientific and international negotiations effort, the economic instruments to deliver the agreed targets are readily at hand.     

1700°C热校准风洞

1700°C热校准风洞是一台高温、高速的稳态与动态温度校准装置.本文介绍了1700°C热校准风洞的主要性能和特点,以及为此而采取的保温与冷却相结合的结构设计、高温内壳设计和其它一些技术方法.     

Bicycle helmet legislation: can we reach a consensus?

Debate continues over bicycle helmet laws. Proponents argue that case-control studies of voluntary wearing show helmets reduce head injuries. Opponents argue, even when legislation substantially increased percent helmet wearing, there was no obvious response in percentages of cyclist hospital admissions with head injury-trends for cyclists were virtually identical to those of other road users. Moreover, enforced laws discourage cycling, increasing the costs to society of obesity and lack of exercise and reducing overall safety of cycling through reduced safety in numbers. Countries with low helmet wearing have more cyclists and lower fatality rates per kilometre. Cost-benefit analyses are a useful tool to determine if interventions are worthwhile. The two published cost-benefit analyses of helmet law data found that the cost of buying helmets to satisfy legislation probably exceeded any savings in reduced head injuries. Analyses of other road safety measures, e.g. reducing speeding and drink-driving or treating accident blackspots, often show that benefits are significantly greater than costs. Assuming all parties agree that helmet laws should not be implemented unless benefits exceed costs, agreement is needed on how to derive monetary values for the consequences of helmet laws, including changes in injury rates, cycle-use and enjoyment of cycling. Suggestions are made concerning the data and methodology needed to help clarify the issue, e.g. relating pre- and post-law surveys of cycle use to numbers with head and other injuries and ensuring that trends are not confused with effects of increased helmet wearing.     

When are Superconductors Really Superconducting?

While the most striking aspect of superconductivity is dissipation-free current flow, it is not straightforward to experimentally demonstrate whether the resistance is truly zero or merely immeasurably small. The distinction between zero or very small resistance is important, because the true superconducting state can be destroyed by thermodynamic fluctuations. This paper discusses a variety of different superconducting systems: two-dimensional superconductors, Josephson-junction arrays, and three-dimensional superconductors in zero and nonzero magnetic field, and the experiments conducted to determine which, and under what conditions, systems are really superconducting.     

Agriculture and food systems in sub-Saharan Africa in a 4°C+ world

Agricultural development in sub-Saharan Africa faces daunting challenges, which climate change and increasing climate variability will compound in vulnerable areas. The impacts of a changing climate on agricultural production in a world that warms by 4°C or more are likely to be severe in places. The livelihoods of many croppers and livestock keepers in Africa are associated with diversity of options. The changes in crop and livestock production that are likely to result in a 4°C+ world will diminish the options available to most smallholders. In such a world, current crop and livestock varieties and agricultural practices will often be inadequate, and food security will be more difficult to achieve because of commodity price increases and local production shortfalls. While adaptation strategies exist, considerable institutional and policy support will be needed to implement them successfully on the scale required. Even in the 2°C+ world that appears inevitable, planning for and implementing successful adaptation strategies are critical if agricultural growth in the region is to occur, food security be achieved and household livelihoods be enhanced. As part of this effort, better understanding of the critical thresholds in global and African food systems requires urgent research.     

Multizone Furnace for Analysis of Fixed-Point Realizations in the Range from 1,000°C to 1,700°C

In this article, the development of a laboratory furnace specially designed for analysis of fixed-point plateau realizations in the range from 1,000 °C to 1,700 °C that enables control of various temperature distribution settings along the heating zone length is presented. A total of 13 thermocouples are built into the furnace tube wall to control the temperature as well as to measure the temperature distribution. The furnace is divided into seven independently controlled heating zones. Each heating zone comprises a MoSi₂ heating element and its dedicated DC power supply module. The furnace temperature is controlled by manipulating the output voltage of each power supply to control the temperature of each heating element, as estimated from its electrical resistance. The heating power and temperature measurement are fully controlled by a computer using an application written in Lab VIEW, allowing very flexible furnace control. The furnace can be used in air as well as in an inert atmosphere. Measurements of the temperature distribution of the furnace during a melting-point realization are presented.     

Pendent drop measurements of the polypropylene/polystyrene interfacial tension between 220°C and 270°C

The interfacial tensions of molten polypropylene/polystyrene have been measured using the pendent drop method between 220°C and 270°C. The obtained tension values are comparable with those of most of the molten polymer pairs, though their linear decrease as a function of temperature is steeper. The interaction parameter of Good and Girifalco lies within the range of values for all other polymer pairs.