全球变暖的物理基础和科学简史

全球变暖不仅是当今大气科学乃至整个地球科学的热门研究领域,也是国际社会争论较多的热门话题.文章的目的并不是为了澄清这些争论,而是集中于简要阐述全球变暖的物理学基础,回顾其近200年的科学发展历史.藉此希望对非大气科学背景的学者理解有关全球变暖的科学问题有所帮助.     

气候系统和全球变暖 ——解读2021年诺贝尔物理奖

2021年诺贝尔物理学奖授予了两位气候学家和一位理论物理学家,以表彰他们在“理解复杂物理系统领域所做出的开创性贡献”.相信很多人会感到惊讶,为什么诺贝尔物理学奖授予了两位气候学家.本文将从以下几方面给予解读:为什么气候系统被称为复杂的物理系统,全球变暖的现状和未来,全球变暖的物理基础和科学简史,两位气候学家是如何基于基础物理理论建立了预测全球变暖的模型,以及检测和归因人类活动导致全球变暖的方法.     

温室效应的物理基础

2009年12月18日在哥本哈根举行的全球气候会议中心议题是二氧化碳减排,提倡低碳经济,以缓解全球气候变暖.全球气候为什么会变暖呢?人所共知这是温室效应所闯的祸.下面从物理的角度对温室效应加以分析.     

大气科学的热点问题

随着社会的发展和科学的进步,人类对于地球大气的认识在不断深入,关注在不断增加,但未知领域和迷惑依旧存在。这里,我们将针对当前大气科学领域的几个热点问题展开讨论,希望了解大气科学的现状和未来,促进大气科学的健康发展。     

复杂气候系统和全球变暖

两位气候学家和一位理论物理学家共同荣获2021年诺贝尔物理学奖。诺贝尔物理学奖委员会在背景介绍材料中指出,他们在“理解复杂物理系统领域做出了开创性贡献”。相信很多人会对两位气候学家获奖而感到惊讶,物理学奖委员会进一步具体指出,人类活动导致全球变暖这一论断建立在坚实的科学基础之上,两位气候学家获奖是因为他们基于物理原理模拟地球气候、量化气候变率、可靠地预测全球变暖所做出的杰出贡献。物理学奖委员会将诺贝尔奖授予两位气候学家,表明对基于物理理论解决现实世界复杂物理问题的高度重视,尤其是对人类身处其中的气候环境问题的重视。文章将解读两位气候学家的学术贡献,尤其是如何基于基础物理理论建立预测全球变暖的模型以及检测和归因人类活动导致全球变暖的方法。     

大气研究的热点问题

大气科学正越来越受到关注,热点问题层出不穷。全球温度变化的主流观点认为,人类活动影响导致了全球增暖,并且增暖还将持续。然而也有研究发发现21世纪前十年的温度并未上升,     

近50年中国降水及温度变化在干旱形成中的影响

根据中国气象局1958—2007年194站的温度、降水和Palmer旱涝指数（Palmer Drought Severity Index, PDSI）均一化数据库,构建统计模型量化了温度和降水变化在干旱形成中所占的比重,尤其讨论了中国8个气候区域温度和降水变化在干旱成因中的特征.受全球增温趋势的影响,未来中国北方地区的干旱化趋势仍将继续.未来五年内干旱发生概率较大的地区主要分布在中国华北,且有持续向南扩张的趋势,一直延伸到江淮地区.在全球变暖的背景下,降水减少仍然是中国东部干旱形成的主要因素.相对于南方地 关键词： 降水 全球变暖 干旱     

气候变化中高温破纪录事件的蒙特卡罗模拟研究

采用蒙特卡罗方法,分析了南京市1961年—2000年40?a日观测温度资料中的高温破纪录事件的统计规律,并比较了20世纪全球变暖和南京市近40年来区域变暖背景对其统计规律的影响. 理论分析和蒙特卡罗模拟结果均表明：近40年来南京市第ｋ个高温破纪录事件的最概然发生强度与k（k=1,2,3,\:）呈线性增长,而年发生高温破纪录事件的频率随时间t呈1/（t+1）的衰减趋势,且平均温度高的年份,发生高温破纪录事件的概率较大,反之,概率较小. 结果还表明：20世纪的全球变暖速率（ｖ=0.006?℃/a）和南京市区域的变暖速率（ｖ=0.017?℃/a）在短期内还不至于引起高温破纪录事件的发生强度和发生频率有明显变化,但持续变暖最终将会使年发生高温破纪录事件的频率渐渐地收敛于一个常数,近似等于变暖速率的值. 此外,还研究了日温度之间的自相关和方差变化对高温破纪录事件的影响,研究发现异方差和弱的自相关对高温破纪录事件的发生强度和概率的影响基本可以忽略. 关键词： 高温破纪录事件 蒙特卡罗模拟 全球变暖     

历史上地球平均温度的上升滞后于大气中CO2浓度的上升

在距今19000年以前的一段时间，地球处于所谓最后一个冰期．之后，在距今19000年至10000年期间，整个地球逐渐变暖，冰原从北半球的大陆消退，同时大气组分也发生明显变化．专业人士称上述转变为“冰川终止（glacial termination）”，有许多专家试图解释触发和维持上述变化的机制，不幸至今仍然缺乏有说服力的理论．在最近出版的Nature周刊上，Shakun等重构了全球温度分布随时间的变化规律，证明：“冰川终止”变暖过程的发生，实际上是南北两个半球温度反相（antiphased）变化叠加的结果．因此说，在距今19000年至10000年期间，地球所经历的是某种全球变暖．海洋环流的变化分别控制了南北半球反相温度变化的幅度，它似乎是影响这一变暖过程的最重要因素．     

中国近50年气候破纪录温度事件发生概率分析

随着全球变暖趋势的不断增强,破纪录温度事件（record breaking temperature events, RBTE）发生的频次呈现不断增加的特点.基于已知当前年份的温度记录,未来五年内这个记录被打破的概率是多少？即未来五年内发生新的RBTE的概率是多少？这是目前国内外学术界关注的前沿科学问题之一.文中基于概率统计模型研究在不同情景下RBTE发生概率,并与实际观测资料检测结果作对比分析,研究近50年中国RBTE发生概率的变化与全球增暖的关系.结果显示,RBTE发生概率的大小依赖于温度的增长趋势和相 关键词： 破纪录温度事件 全球增暖 极端事件     

全球变暖背景下温室效应的光谱能量分布分析

利用一维辐射传递方程及LBLRTM逐线积分模式建立计算模型,对工业革命前与目前大气构成情况下温室效应的能量分布及其光谱吸收机理进行分析,在保持温室气体浓度为当前水平的基础上,研究温室效应能量分布与地表温度之间的相互耦合机理.结果表明:工业革命前地球的温暖环境主要来自于大气温室气体的(100~370)cm^-1、(640~710)cm^-1以及(1370~2000)cm^-1三个强吸收带对于地球长波辐射的吸收,而地球当前的变暖则源自于大气的(370~640)cm^-1和(710~1370)cm^-1两个弱吸收带的作用,其对工业革命以来所额外增加的温室效应贡献分别达到了25%和55%;地表温度升高,温室效应在全波段范围内也会随之增强,但不同谱带处的温室效应贡献以地球平均温度所对应的辐射峰值波数为界线,峰值波数右侧的温室效应贡献将会增加,在其左侧的贡献比例则会减小.     

Nonhydrostatic icosahedral atmospheric model (NICAM) for global cloud resolving simulations

A new type of ultra-high resolution atmospheric global circulation model is developed. The new model is designed to perform “cloud resolving simulations” by directly calculating deep convection and meso-scale circulations, which play key roles not only in the tropical circulations but in the global circulations of the atmosphere. Since cores of deep convection have a few km in horizontal size, they have not directly been resolved by existing atmospheric general circulation models (AGCMs). In order to drastically enhance horizontal resolution, a new framework of a global atmospheric model is required; we adopted nonhydrostatic governing equations and icosahedral grids to the new model, and call it Nonhydrostatic ICosahedral Atmospheric Model (NICAM). In this article, we review governing equations and numerical techniques employed, and present the results from the unique 3.5-km mesh global experiments—with O(10⁹) computational nodes—using realistic topography and land/ocean surface thermal forcing. The results show realistic behaviors of multi-scale convective systems in the tropics, which have not been captured by AGCMs. We also argue future perspective of the roles of the new model in the next generation atmospheric sciences.     

温室效应和TEWI值

1前言当前一个重要的环境变化就是全球变暖，其直接原因是大气中CO_2和其它温室气体浓度的增加。毫无疑问，增加的CO_2来自大量燃烧化石燃料、砍伐森林和绿地的减少，其它温室气体大多亦是人造气体，。总之是人为破坏环境的结果。本文以当今人们最为关心的全球变暖问题为背景，对制冷工质和系统的温室效应问题进行深入的研究和分析。2地球CO_2浓度变化的历史随着年代的变迁，CO_2的浓度在地球历史上一直在变化。分析南极冰层中气泡成份可得到16万年以来CO_2浓度变化数据，在冰川期为180PPmv，在温暖期为280PPmv。CO_2的浓度变化直接…     

Predictions of climate changes caused by man-made emissions of greenhouse gases: A critical assessment

Predictions of the most advanced computer models of the changes in the global climate that may result from man-made emissions of greenhouse gases are described and assessed in the light of the uncertainties in future emissions and atmospheric concentrations of these gases, and of the limitations of the models

Predictions of the globally averaged temperature rise, produced by the doubling of atmospheric carbon dioxide over 70 years, range from 1·3 to 2·6°C, on average about 0·3°C decade^?1. The scattering of solar radiation by atmospheric aerosols is calculated to reduce this global warming to about 1·0°C or 0·2°C decade^?1. Warming is predicted to occur everywhere but to be most marked in high latitudes of the Northern Hemisphere.

Globally averaged precipitation is predicted to rise by a few per cent but with large geographical variations and areas of both increase and decrease. The largest increases are expected to occur in intertropical convergence zone, and in middle and high latitudes, especially in winter. Decreases are predicted in the subtropics. The best current estimate of the rise in sea level resulting from an annual increase of 1% p.a. of carbon dioxide is 4 cm decade^?1.     

Global Warming by Geothermal Heat from Fracking: Energy Industry’s Enthalpy Footprints

Hypothetical dry adiabatic lapse rate (DALR) air expansion processes in atmosphere climate models that predict global warming cannot be the causal explanation of the experimentally observed mean lapse rate (approx.−6.5 K/km) in the troposphere. The DALR hypothesis violates the 2nd law of thermodynamics. A corollary of the heat balance revision of climate model predictions is that increasing the atmospheric concentration of a weak molecular transducer, CO₂, could only have a net cooling effect, if any, on the biosphere interface temperatures between the lithosphere and atmosphere. The greenhouse-gas hypothesis, moreover, does not withstand scientific scrutiny against the experimental data. The global map of temperature difference contours is heterogeneous with various hotspots localized within specific land areas. There are regional patches of significant increases in time-average temperature differences, (∆<T>) = 3 K+, in a ring around the arctic circle, with similar hotspots in Brazil, South Africa and Madagascar, a 2–3 K band across central Australia, SE Europe centred in Poland, southern China and the Philippines. These global-warming map hotspots coincide with the locations of the most intensive fracking operational regions of the shale gas industry. Regional global warming is caused by an increase in geothermal conductivity following hydraulic fracture operations. The mean lapse rate (d<T>/dz)_z at the surface of the lithosphere will decrease slightly in the regions where these operations have enhanced heat transfer. Geothermal heat from induced seismic activity has caused an irreversible increase in enthalpy (H) input into the overall energy balance at these locations. Investigating global warming further, we report the energy industry’s enthalpy outputs from the heat generated by all fuel consumption. We also calculate a global electricity usage enthalpy output. The global warming index, <∆T-biosphere> since 1950, presently +0.875 K, first became non-zero in the early 1970’s around the same time as natural gas usage began and has increased linearly by 0.0175 K/year ever since. Le Chatelier’s principle, applied to the dissipation processes of the biosphere’s ΔH-contours and [CO₂] concentrations, helps to explain the global warming statistics.     

Innovative light-collecting module using prismatic array structures

Presently, energy conservation and carbon dioxide emission reduction have become increasingly important because of global warming. Using solar energy, which is considered as one of the most important renewable energy sources, does not only decrease the consumption of fossil fuels, but also slows down the pace of global warming. For indoor illumination, our team has developed a technique called ＂Natural Light Illumination.＂ Instead of using solar cells, our system directly guides sunlight into the interior of a structure. However, the efficiency of the light-collecting module is still low. To address this problem, we propose a new light- collecting module based on a prism array structure with high efficiency. We use optical sinmlation tools to design and simulate the efficiency of the module, which is found to be 57%. This value is higher than that of the original concentrator （i.e., 11%）.     

Variability of the terrestrial window and its physical implications

Summary We show that the frequencies of atmospheric molecular thermal vibrations significantly influence the spectral positioning of the terrestrial window. The bandpass filtering process of this window is confined to the region starting from theE-region and extending to an altitude not exceeding about 600 km. This indicates that a significant part of the infrared radiation emanating from lower altitudes is absorbed directly into the ionosphere. Implicitly, the infrared radiation field as viewed downward from the top of the ozonosphere is continuously ?mapped? into the ionosphere in terms of temperature and hence ionization variations. This mapping may be a vital cause of ionospheric irregularities. Factors that influence the transmission coefficient of the terrestrial window are mentioned and discussed. In particular, it is shown that if the terrestrial thermal radiation shifts in response to a temperature change in accordance with Wien's displacement law, the terrestrial window cannot correspondingly shift and continue aligning itself approximately with the peak of the spectrum unless different atmospheric molecules dominate the vibrational process. However, whether different molecules dominate the vibrational process or not, a change in atmospheric temperature makes the transmission coefficient of the window change in the same sense. Consequently, the much reported role played by the window in moderating the temperature of the Earth-Atmosphere system is apparently carried out even when the latter temperature changes provided that the accompanying adjustments do not put the spectral location of the window completely off the terrestrial radiation spectrum. Finally it is shown that if certain substances are introduced in sufficient quantities into the troposphere (in gaseous or aerosol forms), the bandpass filtering process of the terrestrial window may consequently operate in the latter and hence cause regional or global warming.     

High-sensitivity methane monitoring based on quasi-fundamental mode matched continuous-wave cavity ring-down spectroscopy

Continuous-wave cavity ring-down spectroscopy (CW-CRDS) is an important technical means to monitor greenhouse gases in atmospheric environment. In this paper, a CW-CRDS system is built to meet the needs of atmospheric methane monitoring. The problem of mode matching is explained from the perspective of transverse mode and longitudinal mode, and the influence of laser injection efficiency on measurement precision is further analyzed. The results of cavity ring-down time measurement show that the measurement precision is higher when the laser is coupled with the fundamental mode. In the experiment, DFB laser is used to calibrate the system with standard methane concentration, and the measurement residual is less than ±4×10^-4 μs^-1. The methane concentration in the air is monitored in real time for two days. The results show the consistency of the concentration changes over the two days, which further demonstrates the reliability of the system for the measurement of trace methane. By analyzing the influence of mode matching, it not only assists the adjustment of the optical path, but also further improves the sensitivity of the system measurement.